A process and system for separating algal hydrophobic products from an algal biomass stream

Abstract

Systems and processes for separating algal hydrophobic products from an algal biomass stream are disclosed. The process includes introducing the algal biomass stream into a counter-current separation device, the algal biomass stream containing an aqueous solution, an extraction solvent, algal hydrophobic products and an algal biomass; introducing an aqueous stream into the counter-current separation device, wherein the aqueous stream contacts the algal biomass stream, and allowing separation of an organic phase and an aqueous phase in the counter-current separation device, the organic phase containing at least a portion of the extraction solvent and at least a portion of the algal hydrophobic products, and the aqueous phase containing at least a portion of the algal biomass, wherein an interface is formed between the organic phase and the aqueous phase.

Description

A PROCESS AND SYSTEM FOR SEPARATING ALGAL HYDROPHOBIC PRODUCTS FROM AN ALGAL BIOMASS STREAMTECHNICAL FIELD

[0001] The present disclosure relates to processes and systems for separating algal hydrophobic products from an algal biomass stream.BACKGROUND

[0002] Algae offers an opportunity as a crop to supply algal oil for renewable fuels derived from seawater, atmospheric CO2, sunlight, and nutrients. Algae can be grown on non-arable land for terrestrial crops, which is an additional benefit. Once the algal biomass has been harvested, the algal oils and the aqueous growth medium must be separated from the algal protein before either can be used for commercial purposes.

[0003] There is an increasing interest in using algal biomass as a key intermediate for a plethora of sustainable products, such as a source of renewable energy, as a mode to safely and efficiently capture carbon dioxide from the atmosphere for carbon sequestration, as a source of natural carotenoids and as a renewable source of chemical intermediates. For example, an algal concentrate that is produced by a harvester is often passed through an extraction process to separate the algal oil from the algal biomass.

[0004] U.S. Patent No. 7,662,616 discloses a method for growing algal cells, separating the algal cells, lysing the algal cells to release the oil, and then separating the oil from the algal biomass. The cells are specifically lysed to release the oil, and a solvent is not used in this method.

[0005] U.S. Patent No. 10,472,316 discloses a process for obtaining microbial oil by: 1 ) lysing the cells, 2) demulsifying the lysed cell composition, and 3) separating the oil from the lysed cells, wherein step 2) is accomplished by adding an ionic compound. The cells are specifically lysed to release the oil, and a solvent is not used in this method.

[0006] U.S. Patent No. 11 ,124,736 discloses a process for obtaining microbial oil by; 1 ) lysing the cells, 2) demulsifying the lysed cell composition, and 3) separating the oil from the lysed cells, wherein step 2) is accomplished byagitation. The cells are specifically lysed to release the oil, and a solvent is not used in this method.

[0007] U .S. Patent No. 4,341 ,038 discloses a method to obtain oil products from algae by growing microalgae, harvesting the algae, extracting the oil from the algae, and recovering the oil and algal residue. An extraction step takes place at a temperature between 280 and 350 °C. Extraction at this temperature degrades valuable carotenoids found in the algal oil. This patent does not disclose separation of the solvent from the algal biomass and an effect that temperature can have on that separation.

[0008] U .S. Patent No. 4,680,314 discloses a process to produce a carotene dissolved in edible oil by concentrating algae, adding oil to the algae, forming an emulsion at a temperature sufficient to extract carotene from the algae, and separating the oil phase containing carotene from the water phase containing algae. In this process, centrifugation is disclosed to separate the phases created in the extraction process. However, centrifugation equipment is expensive, involves a high level of maintenance and is energy intensive.

[0009] U.S. Patent No. 4,680,314 also discloses processes that involve flocculating an algal biomass prior to harvesting. Unfortunately, the flocculant can contaminate the algal biomass in subsequent processing.

[0010] U.S. Patent No. 5,951 ,875 discloses a process for dewatering and extracting carotenoids from an aqueous suspension of microalgae by rupturing the cells, concentrating the cells in an adsorptive bubble separation process, contacting algal concentrate with a solvent, phase separating the extract, algal residue, and raffinate, and concentrating the carotenoids.

[0011] This patent discloses that the resulting liquid-liquid-solid dispersion produced by the extraction can be separated by settling in a gravity or centrifugal field. While gravity settling can cost less than centrifugation, it involves a large amount of time to achieve adequate separation of the phases at ambient temperature. Additionally, high amounts of energy and freshwater usage are required for these separation processes.

[0012] U.S. Patent No. 4,554,390 discloses a process for extracting materials from an algae source that involves using a solvent that performs a dual function,i.e., a solvent capable of damaging cell membranes and extracting cellular materials from the damaged cells.

[0013] U.S. Patent No. 4,851 ,339 discloses a process to harvest and dewater algae that involves (i) lysing the algae in buffered distilled water, and then taking the algal residue and extracting the wet material with vegetable oil to separate the oil from the algal biomass or (ii) directly separating the oil and meal physically, and then absorbing the solvent onto starch or silica gel to recover the solvent. The patent discloses using filtration and centrifugation to separate the extract, raffinate, and algal biomass.

[0014] U.S. Patent No. 5,310,554 discloses a wet extraction method wherein an extraction solvent is used to extract the algal oil and algal carotenoids, the method further involving the removing of the extraction solvent, and passing the desolventized extract through a chromatographic column to recover betacarotene. The patent also discloses the use of expensive centrifuges to separate the extract from the raffinate.

[0015] U.S. Patent No. 5,378,369 discloses a wet extraction method wherein a vegetable oil is the solvent, and the extract is passed through a semi-permeable membrane to effect microfiltration or ultrafiltration of the extract, wherein the extract passes through the membrane and the aqueous phase is retained.

[0016] In wet extraction processes where algal oil is extracted from an algal biomass rich stream by a non-polar solvent with low solubility in water, thereby creating an extract phase, some of the extract containing algal oil and other valuable components like beta-carotene is lost when recovering the biomass due to entrainment of the extract phase with the algal biomass. A possible cause of the entrainment of the extract phase in the algal biomass is the formation of a stable emulsion once the algal biomass mixes with the non-polar solvent.

[0017] After extraction, a biomass rich stream also needs to be desalted, desolventized and / or dried for stabilization. Any entrained extract that is present in the biomass rich stream from the extraction represents product losses of algal oil and carotenoids. There is also a need to remove salt from the algal oil for successful use in various applications, including the use of algal oil as feedstock for various renewable products or processes.

[0018] Thus, to address the foregoing issues, a more economical and efficient process for separating algal hydrophobic products from an algal biomass stream is desirable.SUMMARY

[0019] Disclosed herein is a process for separating algal hydrophobic products from an algal biomass stream, the process including (i.e., comprising) at least one or more of: introducing the algal biomass stream into a counter-current separation device, the algal biomass stream containing an aqueous solution, an extraction solvent, algal hydrophobic products and an algal biomass; introducing an aqueous stream into the counter-current separation device, wherein the aqueous stream contacts the algal biomass stream; and allowing separation of an organic phase and an aqueous phase in the counter-current separation device, the organic phase containing at least a portion of the extraction solvent and at least a portion of the algal hydrophobic products, and the aqueous phase containing at least a portion of the algal biomass, wherein an interface is formed between the organic phase and the aqueous phase.

[0020] Also disclosed herein is a system for separating and optionally desalting algal hydrophobic products from an algal biomass stream, the system including at least one or more of: a counter-current separation device possessing an algal biomass stream input and at least one aqueous stream input, wherein the algal biomass stream input is either located at a position below or above the aqueous stream input; an algal biomass stream feed line configured to communicate with the algal biomass stream input and an extraction zone; and at least one aqueous stream feed line configured to communicate with the at least one aqueous stream input and an aqueous stream reservoir.

[0021] Disclosed herein is a system for separating and desalting algal hydrophobic products from an algal biomass stream, the system including at least one or more of: a means for (i) performing a counter-current extraction between an algal biomass stream and an aqueous stream and (ii) producing an interface between an organic phase and an aqueous phase, the organic phase being essentially free of algal biomass; an extraction zone configured totransport an algal biomass stream to the means; and an aqueous stream reservoir configured to transport at least one aqueous stream to the means.BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Other features and advantages of the methods and systems disclosed herein will be apparent to those skilled in the art reading the following detailed description in conjugation with the exemplary embodiments illustrated in the drawings, wherein:

[0023] FIG. 1 depicts an exemplary embodiment of a separating process for the isolation of algal hydrophobic products from an algal biomass stream, the process involving counter-current mixing of an algal biomass steam and an aqueous stream in a counter-current separation device, separating the resulting mixture into an organic phase and an aqueous phase and recovering the overflow and underflow of the counter-current separation device.

[0024] FIG. 2 depicts an exemplary embodiment of a separating process for the isolation of algal hydrophobic products from an algal biomass stream, the process involving counter-current mixing of an algal biomass steam and three aqueous streams in a counter-current separation device, separating the resulting mixture into an organic phase and an aqueous phase and recovering the overflow and underflow of the counter-current separation device.

[0025] FIG. 3 depicts an exemplary embodiment of a separating process for the isolation of algal hydrophobic products from an algal biomass stream, the process involving counter-current mixing of an algal biomass steam and an aqueous stream in a counter-current separation device possessing two coalescers, separating the resulting mixture into an organic phase and an aqueous phase and recovering the overflow and underflow of the countercurrent separation device.

[0026] FIG. 4 depicts an exemplary embodiment of a separating process for the isolation of algal hydrophobic products from an algal biomass stream, the process involving counter-current mixing of an algal biomass steam and an aqueous stream in a counter-current separation device equipped with a mixer and containing three coalescers, separating the resulting mixture into anorganic phase and an aqueous phase and recovering the overflow and underflow of the counter-current separation device.

[0027] FIG. 5 depicts an exemplary embodiment of a separating process for the isolation of algal hydrophobic products from an algal biomass stream, the process involving counter-current mixing of an algal biomass steam and an aqueous stream in a counter-current separation device equipped with a mixer and containing three coalescers, separating the resulting mixture into an organic phase and an aqueous phase and transferring the overflow and underflow of the counter-current separation device into a coalescer system. DETAILED DESCRIPTION

[0028] It has been surprisingly discovered that an improved separation of algal hydrophobic products from an algal biomass stream can occur in a countercurrent separation device when the algal biomass stream, derived from an extraction process, is contacted with at least one counter-flowing aqueous stream.

[0029] Extraction processes involving contacting of an algal concentrate with an extraction solvent to extract algal oils and other valuable components from the algal concentrate tend to easily form a stable emulsion, thus making the separation of the extract from the algal biomass and the raffinate formed from the extraction process slow and difficult. Indeed, in extraction processes where algae oil is extracted with an extraction solvent from an algal concentrate containing an algal biomass, the algal biomass tends to reside near the interface between the extract phase and the raffinate phase.

[0030] Surprisingly, the separation processes disclosed herein have been discovered to allow algal hydrophobic products to be extracted from an algal concentrate with an extraction solvent and separated from the algal biomass and the raffinate more efficiently. In the separation processes disclosed herein, an algal biomass stream containing an emulsion of algal biomass, extraction solvent, algal hydrophobic products and raffinate is counter-currently contacted with an aqueous stream in a counter-current separation device. The aqueous stream draws out the extraction solvent and entrained algal hydrophobic products from the emulsion, thus allowing the formation of an organic and aqueous phase in the counter-current separation device.

[0031] As the extraction solvent and the algal hydrophobic products contained within the emulsion rise through the wash water of the aqueous stream near the top of the counter-current separation device to form the organic phase, the algal biomass and raffinate optionally contained in the emulsion are collected near the bottom of the counter-current separation device with the wash water, thereby forming the aqueous phase. Because essentially all of the algal biomass is located in the aqueous phase and little to no biomass is present at the interphase formed between the organic and aqueous phase, the separation processes disclosed herein provide an improved selectivity of algal hydrophobic products (e.g., oil) to biomass.

[0032] The separation processes disclosed herein also provide exemplary advantages over other known processes for recovering algal hydrophobic products from an algal biomass stream. For example, exemplary embodiments disclosed herein are capable of recovering algal hydrophobic products without the need of a solvent capable of both disrupting algae cells and extracting products from the damaged cells. Other exemplary processes disclosed herein can isolate hydrophobic products from an algal biomass at a high separation and extraction efficiency while avoiding the cost of using expensive centrifugation and filtration equipment. Exemplary embodiments disclosed herein can also attain a high extraction efficiency while avoiding the use of high amounts of energy and fresh water.

[0033] Accordingly, one aspect of the present disclosure is a process for separating algal hydrophobic products from an algal biomass stream, the process including at least one or more of: introducing the algal biomass stream into a counter-current separation device, the algal biomass stream containing an aqueous solution, an extraction solvent, algal hydrophobic products and an algal biomass; introducing an aqueous stream into the counter-current separation device, wherein the aqueous stream contacts the algal biomass stream; and allowing separation of an organic phase and an aqueous phase in the counter-current separation device, the organic phase containing at least a portion of the extraction solvent and at least a portion of the algal hydrophobic products, and the aqueous phase containing at least a portion of the algalbiomass, wherein an interface is formed between the organic phase and the aqueous phase.

[0034] FIG. 1 shows an exemplary embodiment of the separating process. In this embodiment, an algal biomass stream (102) is transferred into a countercurrent separation device (100).

[0035] The expression “algal biomass stream” refers to a stream originating from an extraction process where an algal concentrate containing an algal biomass solution or suspension that includes natural products (e.g., algal oils, proteins, lipids, carotenoids, hydrophobic products), an aqueous solution such as algal growth medium, and a biomass is contacted with an extraction solvent.

[0036] The expression “algal concentrate” refers to a stream containing an algal biomass solution or suspension that includes natural products (e.g., algal oils, proteins, lipids, carotenoids, hydrophobic products), an aqueous solution such as algal growth medium, and a biomass that is optionally derived from an algal feedstock source or optionally from a unit operation that concentrates the algal biomass in the algal concentrate.

[0037] In exemplary embodiments, the algal concentrate originates from at least one or a combination of plant, algae, micro-organism, bacteria, or microalgae feedstock sources. Suitable algae or microalgae feedstock sources can be derived from the culturing of algae in an algal aquaculture pond. These algal aquaculture ponds can be operated in batch, continuous, semi-continuous or other modes known in the art to produce the desired algae in the algal concentrate.

[0038] The algal aquaculture pond can be any type of algal aquaculture pond used to grow algae, including, but not limited to open pond, closed pond, raceway pond, enclosed or partly enclosed photobioreactor, tubular reactor, flat panel (i.e., flat-plate) reactor, column reactor, enclosed raceway, covered pond, open raceway pond, earthen pond, pond in a greenhouse, fermenter, naturally occurring body of water, solar salt pond, or any combinations thereof.

[0039] Open algal aquaculture ponds can be configured either with or without agitation or liners. When present, suitable liner materials include plastic, cement or clay. Plastic algal aquaculture pond liners are typically formed from polyethylene, polypropylene, or polyvinyl chloride. Different types of these basicpolymers can be used, for example linear low-density polyethylene liners are occasionally used for algae cultivation at large scale. These liners can also include additives, such as carbon black to provide resistance to ultraviolet radiation. These liners can also include Nylon or other fibers to provide additional structural integrity. Raven Industries (South Dakota) provides a full line of suitable liners that include one or more layers of materials. Suitable clay liners include bentonite clay. However, when algal aquaculture ponds are flooded, components in the water, especially saline, can often form a barrier that seals the algal aquaculture pond. It can also be desirable to include liners in just a portion of the algal aquaculture pond where they are specifically needed. For example, liners can be utilized to protect earthen borders where the hydraulic flow is elevated.

[0040] In exemplary embodiments, additional aqueous medium is periodically or continuously provided to the feedstock source to replace water that evaporates from the feedstock source and / or increase the liquid depth of the feedstock source, i.e., the depth of the algal growth medium. The additional aqueous medium can be combined with recycled algal growth medium to form an aqueous medium that enters a feedstock source optionally via an algal pretreatment unit to form an algal aquaculture medium. If the algal growth medium in the feedstock source contains mineral salt, the salinity of the additional aqueous medium fed to the feedstock source can be less than the highest salinity experienced by the algae in the feedstock source.

[0041] The amount of the additional aqueous medium possibly added each day can depend upon several factors: salinity targets in the feedstock source, the wind speed and the relative humidity. Daily evaporation rates can be a major factor in the determination of daily water needs for the feedstock source. If evaporation rates are high, then the salinity of the feedstock source will increase, and water will be required to make up for the losses and to maintain the salinity target for each feedstock source. Wind tends to accelerate evaporation rates, and thus the higher the wind speed, the higher the evaporation rates for a given salinity. The amount of moisture in the atmosphere is termed the relative humidity, and the lower this value the higher the evaporation rates when all other factors are constant. Consequently, the rateand amount of evaporation directly influences the daily demand for additional aqueous medium.

[0042] In exemplary embodiments, the algal biomass stream and / or the algal concentrate can contain a biomass concentration greater than about 10 ppm, 100 ppm, 0.1wt%, 1wt%, 10wt%, 20wt%, 30wt%, 40wt% or 50wt%.

[0043] As used herein, the term “about” refers to a value that is ± 5% of the stated value. In addition, it is understood that reference to a range of a first value to a second value includes the range of the stated values, e.g., a range of about 1 to about 5 also includes the more precise range of 1 to 5. It is also understood that the ranges disclosed herein include any selected subrange within the stated range, e.g., a subrange of about 50 to about 60 is contemplated in a disclosed range of about 1 to about 100.

[0044] In exemplary embodiments, the algal biomass stream and / or the algal concentrate has a suitable viscosity so that it can be pumped. A suitable viscosity for pumping can be less than 10,000 cp, less than about 1 ,000 cp and / or less than 500 cp.

[0045] The algal concentrate, the algal biomass and / or the algal aquaculture medium containing algal biomass can undergo various harvesting processes before advancing to the extraction processes upstream of the separation processes disclosed herein. These harvesting processes can include, but are not limited to, fracking, adsorptive bubble separation, filtration, deep bed filtration, belt pressing, screw pressing, centrifugation, adsorption, sedimentation, mechanical floatation, froth flotation, flocculation and combinations thereof. Examples of these harvesting processes and equipment which can be used to perform these processes can be found in U.S. Pat. No. 5,541 ,056; U. S. Pat. No. 4,554,390; U.S. Pat. No. 4,115,949; U.S. Pat. No. 5,951 ,875; U.S. Pat. No. 4,680,314; U.S. Pat. No. 6,524,486; U.S. Pat. No.6,405,948; U.S. Pat. No. 5,776,349; U.S. Pat. No. 6,000,551 ; U.S. Pat. No.8,512,998; U.S. Pat. No. 4,397,741 ; U.S. Pat. No. 4,938,865; U.S. Pat. No.5,188,726; U.S. Pat. No. 5,332,100; WO 2008 / 156,795; WO 2008 / 156,835; U.S.Pat. No. 4,981 ,582; U.S. Pat. No. 5,167,798; all the contents of which are incorporated herein by reference in their entireties.

[0046] In exemplary embodiments, prior to an adsorptive bubble separation process, the biomass e.g. in the algal concentrate can be flotation conditioned by a number of processes. Suitable flotation conditioning processes that can be used prior to the adsorptive bubble separation unit include, but are not limited to, adding a flotation aid, adding a frother, adding a collector, adding an activator, adding a depressor, and combinations thereof.

[0047] Collectors selectively render one or more of the species of particles in the algal concentrate hydrophobic, thereby assisting in the process of collection by gas bubbles. Activators aid the adsorption of the collector to certain particles increasing the number of those particles which become hydrophobic.Depressors inhibit the adsorption of the collector to certain undesired particles decreasing the number of those particles which become hydrophobic. Also, frothing agents and frothers can be added to the algal concentrate to assist in the formation of a stable froth on the surface of a liquid.

[0048] Sedimentation process can include the addition of alum to and / or lack agitation of the algal concentrate. The addition of ferric chloride can also be included in sedimentation processes to cause flocculation. Any polymer or ions that cause flocculation can also be used during sedimentation processes. Cyclones can also be used to accelerate the rate of sedimentation. Any sedimentation equipment known in the art can be used to separate the flocculated natural products from an aqueous salt solution prior to an adsorptive bubble separation process.

[0049] Adsorption can be used as a conditioning process to reduce the volumetric flow of the algal concentrate to an adsorptive bubble separation unit. Some feedstocks, for example Dunaliella salina, can be concentrated by adsorbing the algae onto a hydrophobic surface, and then desorbing the algae with another fluid. Thus, adsorption can be used to preconcentrate the algal concentrate.

[0050] Deep bed filtration can be used to further concentrate the algal concentrate in addition to an adsorptive bubble separation process. Deep bed filtration relies upon a bed of granular media, usually sand, through which the algal concentrate containing natural products flows downward under gravity. The natural products are deposited in the pores of the granular media and in theinterstitial spaces between the grains of media. Deep bed filtration should not be confused with straining filtration. Straining takes place on the surface of a mesh or fabric, and is only suitable to further concentrate the algal concentrate with natural products that will not blind the filtration equipment.

[0051] Adsorptive bubble processes can include a step of rendering material or natural products within the algal concentrate hydrophobic by treating particle surfaces with chemicals, or other techniques that selectively modify the material or natural products to be separated. In some cases, the particles or natural products are not initially hydrophobic, and need to be rendered hydrophobic to be separated or harvested from the algal concentrate.

[0052] A flocculating agent can be utilized during adsorptive bubble separation processes to cause accumulations of algal biomass or natural products to float out during adsorptive bubble processes.

[0053] The algal concentrate or the biomass included in the algal concentrate can also be subjected to a cell rupturing process before proceeding to the extraction process. The algal concentrate can include cellular material which contains natural products. In these instances, rupturing the cell wall and / or cell membrane of the cellular material can release natural products that can be purified in later processes. Cell rupturing can be achieved by a number of methods which include, but are not limited to, chemical, physical or mechanical methods. Chemical methods can include enzymatic digestion, detergent solubilization, lipid dissolution with a solvent, and alkali treatment (lipid saponification). Physical methods can include osmotic shock, decompression, sonication, heat treatment, and freeze-thawing. Mechanical methods can include grinding, high shear homogenization, passing the algal concentrate across a pressure drop, and pressure extrusion.

[0054] Other cell disruption processes which can be used include pumping the algal concentrate at high pressures through a restricted orifice valve. An equipment which can perform this disruption method is, as an example, the MICROFLUIDIZER™ cell disruption equipment of Microfluidics, Newton, MA, US, which utilizes pressures of about 5,000 to 40,000 psig (345 - 2760 bar).

[0055] A mill, such as a vibratory mill, can also be used to rupture cellular material in the algal concentrate.

[0056] In exemplary embodiments wherein the algal concentrate contains algae or microalgae, fracking processes can be performed on the algal concentrate before the extraction process. The partial rupturing of algae is referred to as fracking. Fracked algae can be advantageous over completely ruptured algae due to the difference in size of the resulting particles. Particles resulting from fracking algae are larger than the particles resulting from the complete rupturing of algae and thus adsorptive bubble separation processes can be more effective when larger particles are present. Fracking the algae or microalgae can produce fracked cells possessing hydrophobic components while still retaining a significant portion of the intracellular material within the cellular membrane. This can result in increased recovery of the intracellular material. Fracking can take place in any device known in the art in which algae or microalgae can be partially ruptured including, but not limited to, a vibratory mill, a French press, a pump, an agitated vessel, or combinations thereof.

[0057] As used herein, the term “algae” refers to unicellular and multicellular eukaryotic algae, microalgae, diatoms, dinoflagellates, coccolithophores, cyanobacteria and combinations thereof.

[0058] The algae or microalgae which can be present in the algal biomass stream and / or algal concentrate can include, but is not limited to, algae from the divisions of Bacillariophyta, Chlorophycophyta, Chrysophycophyta, Cyanophycophyta, Cryptophycophyta, Phaeophycophyta, Pyrrhophycophyta, Rhodophycophyta and combinations thereof. The algae or microalgae present in the algal biomass stream and / or algal concentrate can include, but is not limited to, species from the following genera: Acutodesmus, Achnahtes, Amphipora, Amphora, Anabaena, Ankistrodesmus, Arthrospira (also known as Spirulina), Asteromonas, Asterionella, Boekelovia, Borodinella, Botryococcus, Bracteacoccus, Carteria, Chaetoceros, Chlamydomonas, Chlorella, Chlorococcum, Chlorogonium, Chloromonas, Chroomonas, Chrysophaera, Ceratium, Closterium, Coccolithus, Coelastrella, Coscinodiscus, Cosmarium, Cricosphaera, Crocosphaera, Crypthecodinium, Cryptomonas, Cyanocystis, Cyanospira, Cyclotella, Desmodesmus, Ditylum, Dunaliella, Ellipsoidon, Emiliania, Eremosphaera, Euglena, Fragilaria, Franceia, Galdieria, Gracilaria, Graesiella, Guinardia, Haematococcus, Halocafeteria, Halospirulina,Hantzschia, Hymenomonas, Isochrysis, Lepocinclis, Limnothrix, Micractinium, Microactinium, Microcystis, Monochrysis, Monodus, Monoraphidium, Muriellopsis, Nannochloris, Nannochloropsis, Navicula, Neochloris, Neospongiococcum, Nephrochloris, Nephroselmis, Nitzschia, Nodularia, Nostoc, Ochromonas, Oedogonium, Oocystis, Oscillatoria, Ostreococcus, Parachlorella, Pavlova, Peridinium, Phaeodactylum, Picochlorum, Platymonas, Pleurochrysis, Pleurococcus, Porphyra, Porphyridium, Prochlorococcus, Prototheca, Prymnesium, Pseudanabaena, Pseudochlorella, Pseudochoricystis, Pseudoneochloris, Pyramimonas, Pyrobotrys, Rhodomonas, Scenedesmus, Schizochytrium, Scytonema, Skeletonema, Spirogyra, Stichococcus, Synechococcus, Tetrachlorella, Tetradesmus, Tetraselmis, Thalassiosira, Tisochrysis, Tolypothrix, Tribonema, Trichodesmium, Ulothrix, Vaucheria, Viridiella, Volvox, and genetically-engineered varieties or combinations (mixtures, mixed cultures, co-cultures or synthetic co-cultures) thereof. In exemplary embodiments, the algae or microalgae is selected from the group including Dunaliella sp., Dunaliella bardawil, Dunaliella salina, Dunaliella kone, Dunaliella tertiolecta, Dunaliella parva and Dunaliella viridis, and any combination thereof. In exemplary embodiments, the algae or microalgae is Dunaliella salina, Dunaliella bardawil, Dunaliella kone or any combination thereof.

[0059] The algae or microalgae which can be present in the algal biomass stream and / or algal concentrate can also include any microalgal species (including diatoms, coccolithophorids and dinoflagellates) selected from, but not limited to, Amphora sp., Ankistrodesmus sp., Arthrospira (Spirulina) plantesis, Botryococcus braunii, Chlamydomonas sp., Chlamydomonas reinhardtii, Chlorella protothecoides, Chlorella sp., Closterium sp., Cosmarium sp., Crypthecoddinium cohnii, Cyclotella sp., Dunaliella salina, Dunaliella tertiolecta, Haematococcus pluvialis, Hantzschia sp., Nannochloris sp., Nannochloropsis sp., Navicula sp., Neochloris oleoabundans, Nitzschia sp., Phaeodactylum tricornutum, Scenedesmus sp., Schiochytrium limacinum, Stichococcus sp., Tetraselmis suecica, and Thalassiosira pseudonana, and genetically- engineered varieties or combinations (mixtures, or mixed cultures) of these microalgal species.

[0060] The algae or microalgae which can be present in the algal biomass stream and / or the algal concentrate can also include algae with flagella, cilia and / or eyespots. Flagella are a tail-like projection that protrudes from the cell body of certain algae and functions in locomotion. Cilia are an adaptation that allows independent cellular creatures, like algae, to move around in search of food. Photosensitive eyespots are found in some free-swimming unicellular algae. Photosensitive eyespots are sensitive to light. They enable the algae to move in relation to a light source. Such algae have the capability of independent motion, phototaxis, and can move towards the surface during daylight. Phototaxis is the movement of microalgae in response to light. Certain algae (e.g., Dunaliella) can perceive light by means of a sensitive eyespot and move to regions of higher light concentration to enhance photosynthesis.

[0061] The algae or microalgae which can be present in the algal biomass stream and / or algal concentrate also include marine algae that thrive at salt concentrations above that found in seawater. Suitable marine algae can be selected from, but are not limited to, Amphora sp. (diatom), Arthrospira sp., Arthrospira (Spirulina) obliquus, Arthrospira (Spirulina) platensis, Chlorella sp., Chlorella fusca, Chlorella protothecoides, Chlorella pyrenoidosa, Chlorella stigmataphora, Chlorella vulgaris, Chlorella zofingiensis, Dunaliella sp., Dunaliella bardawil, Dunaliella salina, Dunaliella tertiolecta, Dunaliella viridis, Isochrysis galbana, Microcystis sp., Nannochloropsis sp., Nannochloropsis salina, Navicula sp. (diatom), Navicula saprophila (diatom), Nitzschia laevis (diatom), Nitzschia alba (diatom), Nitzschia communis (diatom), Nitzschia paleacea (diatom), Nitzschia closterium (diatom), Nitzschia palea, (diatom), and genetically-engineered varieties or combinations (mixtures, or mixed cultures) of these algal species.

[0062] In exemplary embodiments, the algae is microalgae. In other exemplary embodiments, the algae or microalgae have not been genetically modified or do not originate from genetically engineered algae or microalgae.

[0063] In exemplary embodiments, the algae or microalgae which can be present in the algal biomass stream and / or algal concentrate include a group of algae or microalgae that has not been genetically modified or does not originate from genetically engineered algae or microalgae. This group of algae ormicroalgae can include, but is not limited to, Dunaliella sp., Dunaliella bardawil, Dunaliella kone, Dunaliella salina, Dunaliella bioculata, Dunaliella granulata, Dunaliella maritima, Dunaliella minuta, Dunaliella parva, Dunaliella peircei, Dunaliella polymorpha, Dunaliella primolecta, Dunaliella pseudosalina, Dunaliella quartolecta, Dunaliella terricola, Dunaliella tertiolecta, and Dunaliella viridis.

[0064] All of the possible algae and microalgae which can be included in the algal biomass stream and / or algal concentrate can also be included within any biomass present in the algal biomass stream and / or algal concentrate.

[0065] The expression “natural products” refers to products which are naturally produced or found within an environment or a living organism. Natural products can include those which are hydrophobic, hydrophilic or amphipathic.

[0066] In exemplary embodiments, the natural products are those which are naturally produced by a plant, a microbe, an algae or microalgae species which can be included within the algal biomass stream, the algal concentrate or the biomass in the algal biomass stream and / or the algal concentrate. These natural products can include one or more of lipids, algal lipids, carotenoids, fatty acids, algal fatty acids, triacylglycerols, diacylglycerols, monoacylglycerols, oils, algal oils, chlorophyll, glycerol, phospholipids, carbohydrates, fibers, and proteins.

[0067] In exemplary embodiments, the algal biomass stream and / or algal concentrate contains an aqueous salt solution.

[0068] The expression “aqueous salt solution” refers to a solution containing water and at least one salt. The salt can be any one or combination of salts found in sea water, terminal lakes, or aquifers. In exemplary embodiments the aqueous salt solution is or includes culture medium of the algal biomass stream and / or algal concentrate.

[0069] The aqueous salt solution can contain concentrations of salts which range from trace amounts to saturating amounts. Suitable terms to describe the salinity or salt concentration of the aqueous salt solution range from fresh water, brackish water, salt water, brine, and saturated brine, respectively, as the salt concentration in the aqueous salt solution increase. The desired concentration of salt in the aqueous salt solution will depend on the type of feedstock (e.g.,algae species) present in the algal biomass stream and / or the algal concentrate.

[0070] The expression “salinity” refers to the total amount of dissolved salts in the aqueous solution. Salts which can be dissolved and found in the aqueous solution include, but are not limited to, those found in natural waters such as sodium chloride, magnesium chloride, calcium and magnesium sulfates, bicarbonates, and carbonates. It is a standard practice to express salinity as parts per thousand (%o), which is not a true percent but an approximation of the milligrams of salt per gram of water. In more general terms, salinity is indicated by the water source, such as a freshwater, a brackish water, a saline water, and a brine. Ranges of salinity are associated with these general terms and these ranges are defined as < 0.05 wt% for freshwater, 0.05 - 3 wt% for brackish water, 3 - 5 wt% for saline water, and > 5 wt% for a brine.

[0071] Various combinations of ions found in seawater can be included in the aqueous salt solution. Suitable ion combinations can be derived from one or more of the following sources including: water derived from streams, lakes, rivers, or other sources associated with fresh water; water derived from underground aquifers that can include various ion concentrations; water derived from industrial, agricultural, or municipal sources that can or cannot have received treatment; or water derived from brackish sources where fresh water is combined with sea water or ocean water in various proportions; sea water or ocean water that can be derived from the various seas and oceans located around the globe; water derived from terminal lakes; or combinations thereof. The combination of ions for the aqueous salt solution can be derived directly from these sources, or can be derived by evaporating the desired amount of water from any of these sources to leave the desired ion-rich solution for use as the aqueous salt solution. An example of an ion combination source is disclosed in U.S. Pat. No. 6,986,323, the contents of which are included herein by reference. Other examples include the evaporation of ancient sea waters that form terminal lakes, such as the Great Salt Lake in Utah, and that form various aquifers. The combination of ions can result up to and include crystallizers wherein sodium chloride ions are precipitated.

[0072] Any one or more of the aqueous salt solution, the algal biomass stream and / or the algal concentrate can have a salinity that is about 5 wt% or greater than 5 wt%, about 6 wt% or greater than 6 wt%, about 7 wt% or greater than 7 wt%, for example at least about 8 wt%, at least about 9 wt%, at least about 10 wt%, at least about 11 wt%, at least about 12 wt%, at least about 13 wt%, at least about 14 wt%, at least about 15 wt%, at least about 16 wt%, at least about 17 wt%, at least about 18 wt%, at least about 19 wt%, at least about 20 wt%, at least about 21 wt%, at least about 22 wt%, at least about 23 wt%, at least about 24 wt%, or at least about 25 wt%. In exemplary embodiments, any one or more of the aqueous salt solution, the algal biomass stream and / or the algal concentrate is saturated with salt. In other exemplary embodiments, any one or more of the aqueous salt solution, the algal biomass stream and / or the algal concentrate can have a salinity that is about 5 wt% to about saturation, from about 10 wt% to saturation, from about 20 wt% to saturation, from about 5 wt% to about 20 wt%, from about 10 wt% to about 20 wt%, from about 5 wt% to about 15 wt%, from about 10 wt% to about 15 wt%, or from about 5 wt% to about 10 wt%. In exemplary embodiments, any one or more of the aqueous salt solution, the algal biomass stream and / or the algal concentrate has a salinity greater than 5 wt%, greater than 10 wt%, greater than 15 wt% or greater than 20 wt%.

[0073] As used herein, wt% refers to a dry mass of a component in a solution in grams divided by 100 grams of the solution.

[0074] At least one salt can either be present in the aqueous salt solution or added to the algal biomass stream and / or algal concentrate to increase its salinity. The presence of salt, and specifically elevated salt compositions provides several advantages. First, the presence of salt in the algal biomass stream and / or algal concentrate can reduce solvent solubility in a raffinate layer, and thus reduce either potential solvent loss or solvent recovery costs. Second, the presence of salt in the algal biomass stream and / or algal concentrate can increase the density of a raffinate layer, thus enhancing phase separation rates that lead to reduced decanter sizes. Third, the presence of salt in any one or more of the aqueous salt solution, the algal concentrate and / or the algal biomass stream can retard spoilage of the biomass in the processing step. All ofthese advantages, alone or in combination adds significant value to the processes disclosed herein.

[0075] The at least one salt can be selected from, but not limited to, a sea salt, an underground salt, a salt of aquifer water, a salt of a terminal lake, sodium chloride, and / or any combination thereof.

[0076] The biomass in any one or more of the aqueous salt solution, the algal concentrate and / or the algal biomass stream can include or be a plant biomass, a microbial biomass, an algal biomass or any combination thereof.

[0077] All of the possible plants and / or microbes which can be included in the algal biomass stream and / or algal concentrate can also be included within the biomass in the aqueous salt solution.

[0078] All of the possible plant or microbial biomass which can be included in the algal biomass stream and / or algal concentrate include any plant or microbial biomass.

[0079] The biomass can also include or contain some or all of the natural products within the algal biomass stream and / or algal concentrate.

[0080] The biomass content in the algal biomass stream and / or algal concentrate can be as low as about 0.05 wt%, greater than about 0.5 wt% and even greater than 1 wt%. The maximum biomass content in the algal biomass stream and / or algal concentrate is limited as the maximum amount of biomass that allows the algal biomass stream and / or algal concentrate to flow, and this is less than about 20 wt%, or less than about 10 wt%.

[0081] The algal biomass stream and / or the algal concentrate can contain a water content before the separation processes disclosed herein. The water content can be about 0.1 wt% to about 5 wt%, about 5 wt% to about 10 wt%, about 10 wt% to about 15 wt%, about 15 wt% to about 20 wt%, about 20 wt% to about 30 wt%, about 30 wt% to about 40 wt%, about 40 wt% to about 50 wt%, or about any range within 0.1 wt% to 50 wt% of the total weight of the algal biomass stream and / or the algal concentrate. In exemplary embodiments, the algal biomass stream and / or the algal concentrate contains a water content before the extraction process that is greater than 50 wt% or about any range within 50 wt% to 99 wt%.

[0082] The biomass can include or be a conditioned biomass. As used herein “a conditioned biomass” refers to a biomass that has been treated with one or more conditioning processes before the separation processes disclosed herein. Suitable conditioning processes can include, but are not limited to, fracking, adsorptive bubble separation, filtration, deep bed filtration, belt pressing, screw pressing, centrifugation, adsorption, sedimentation, mechanical floatation, froth flotation, flocculation and combinations thereof.

[0083] In exemplary embodiments, the separation process includes obtaining the algal biomass stream from an upstream extraction process, the upstream extraction process optionally including (i) forming a dispersion by contacting an algal concentrate with an extraction solvent in an extraction zone, (ii) passing the dispersion to a separation zone, and (iii) separating the dispersion into two or more (such as three) layers, wherein the algal biomass stream is obtained from at least one of the layers. In exemplary embodiments, the extraction zone of the upstream extraction process is an upstream extraction zone, and the separation zone of the upstream extraction process is an upstream separation zone.

[0084] In exemplary embodiments, the separation process includes obtaining the algal biomass stream from an upstream extraction process, the upstream extraction process being a liquid-liquid-solid extraction process including at least one or more of the following: forming a dispersion by contacting (e.g., by intimately contacting) the algal concentrate with an extraction solvent in an extraction zone; passing the dispersion to a separation zone; separating the dispersion into multiple layers, the layers including: a solvent extract layer containing at least one hydrophobic natural product and an extraction solvent, a raffinate layer containing an aqueous salt solution, and a rag layer containing a lipid-depleted biomass; and isolating at least part of the solvent extract layer, at least part of the raffinate layer and / or at least part of the rag layer. In exemplary embodiments, the extraction zone of the upstream extraction process is an upstream extraction zone, and the separation zone of the upstream extraction process is an upstream separation zone.

[0085] The expression “liquid-liquid-solid extraction” refers to a process wherein an algal concentrate containing an algal biomass that includes one or morenatural products is (e.g., intimately) contacted with an extraction solvent capable of extracting one or more of the hydrophobic natural products from the algal biomass.

[0086] The term “dispersion” relates to a heterogeneous mixture containing an aqueous salt solution, algal biomass, and extraction solvent. The dispersion can exist as an emulsion.

[0087] The algal biomass stream can contain portions of the rag layer, the solvent extract layer and the raffinate layer formed from the liquid-liquid-solid extraction process. In exemplary embodiments, the algal biomass stream contains at least a portion of the rag layer and at least a portion of the solvent extract layer.

[0088] The extraction solvent must form a second liquid phase or layer with the algal concentrate in the extraction zone. Suitable extraction solvents include, but are not limited to a non-polar solvent, a non-polar organic solvent, a dense gas solvent, an aqueous two-phase solvent, a deep eutectic solvent (DES) and / or a natural deep eutectic solvent (NADES) (such as choline chloride, glucose, lactic acid, malic acid, and / or any combination thereof), an ionic liquid, or any combination thereof or any combination of solvents such as miscible solvents.

[0089] In an exemplary embodiment, the extraction solvent is or includes at least one or more of a non-polar solvent, a non-polar organic solvent, a dense gas solvent, an aqueous two-phase solvent, a deep eutectic solvent (DES), a natural deep eutectic solvent (NADES), an ionic liquid, or any combination thereof.

[0090] In another exemplary embodiment, the extraction solvent is or includes at least one or more of a non-polar solvent, a non-polar organic solvent, a dense gas solvent, an aqueous two-phase solvent, a deep eutectic solvent (DES), a natural deep eutectic solvent (NADES), or any combination thereof.

[0091] In another exemplary embodiment, the extraction solvent is or includes at least one or more of a non-polar solvent, a non-polar organic solvent, a dense gas solvent, an aqueous two-phase solvent, or any combination thereof.

[0092] In another exemplary embodiment, the extraction solvent is or includes at least one or more of a non-polar solvent, a non-polar organic solvent, a dense gas solvent, or any combination thereof.

[0093] The extraction solvent can be chosen such that its polarity is appropriate to extract the desired natural products. Thus, the optimal extraction solvent for the liquid-liquid-solid extraction process can depend on which natural products are desired to be extracted.

[0094] Any solvent system that forms a second immiscible liquid phase or layer with the algal concentrate can be used as the extraction solvent. These solvent systems should not adversely impact the quality or quantity of the natural products. These solvent systems can include, but are not limited to, synthetic and / or natural flavorants, edible oils, petrochemicals, dense gases, and combinations of these so long as the mixture of the solvent system and the algal concentrate forms two immiscible liquid phases at a desired extraction zone temperature. Some of these solvents are more desirable than others for various reasons as discussed below and the results obtained are not necessarily equivalent.

[0095] The solvent system can include petrochemical solvents due to their low viscosity and favorable solute molecular diffusivity. Natural oils are soluble in petrochemical solvents and concentrated extracts are possible. Suitable petrochemical solvents can include those that are disclosed in "Organic Solvents: Physical Properties and Methods of Purification", edited by J. A. Riddick et al, Volume 2, Fourth Edition, ISBN Number 0-471- 08467-0, such as 2-methyl oxolane. In exemplary embodiments, the petrochemical solvents can include, but are not limited to, aliphatic hydrocarbons (such as pentane, hexane, heptane, octane, nonane, decane, dodecane, cyclohexane, petroleum ether, their isomers, and mixtures thereof), aromatic hydrocarbons (including but not limited to benzene, toluene, xylene), alcohols (including, but not limited to butanol, pentanol, hexanol, octanol, dodecanol, cyclohexanol, benzyl alcohol, their isomers, and combinations thereof), ketones (including, but not limited to methyl isobutyl ketone, hexanone, heptanone, octanone, their isomers, and combinations thereof), esters (including, but not limited to methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pentyl acetate, hexyl acetate, ethylpropionate, ethyl butyrate, ethyl valerate, their isomers, and combinations thereof) and / or ethers (including but not limited to 2-methyltetrahydrofuran, diisopropyl ether, methyl tert-butyl ether, cyclopentyl methyl ether, and combinations thereof). Combinations of petrochemical solvents can also be used if desired.

[0096] The petrochemical solvents can also contain one or more co-solvents to improve extractability of solutes. Examples of these co-solvents include methanol, ethanol, 1 -propanol, 2-propanol, 1 -hexanol, 2-methoxy ethanol, acetone, tetrahydrofuran, 1 ,4-dioxane, acetonitrile, dichloromethane, chloroform, dimethyl sulfoxide, formic acid, carbon disulfide, methylene chloride, amines, chelating agents, phase transfer catalysts and combinations thereof. The co-solvents can also be added to the algal biomass stream to enhance recovery of a solute or hydrophobic natural product in the extraction solvent.

[0097] The edible oils which can be included within the solvent system can be chosen from those obtained from plant or animal sources, such as fish oils. Edible vegetable oil solvents include, but are not limited to, those derived from corn, olive, algae, soybean, flax, safflower, sunflower, palm, jatropha, coconut, other oils known in the art, and combinations thereof. Compared to petrochemical solvents, edible oils can be more viscous, and the solute molecular diffusivity is lower.

[0098] The solvent system can also include synthetic and natural flavorants. These flavorants can be more desirable than petrochemical solvents and edible oils if the natural products are to be used for human or animal consumption. Naturally derived flavorants have appeal in nutritional supplements. Flavorants classified by the Flavor and Extract Manufacturers Association, or FEMA, as Generally Recognized As Safe, or GRAS, do not have the drawbacks of petrochemical solvents in association with nutritional supplements. The presence of residual flavorant solvents in nutritional supplements is generally acceptable in comparison with petrochemical solvents, which reduces downstream purification and recovery costs. The flavorants can be chosen from those which have boiling points, viscosities, and molecular diffusivity properties comparable to petrochemical solvents. Examples of such flavorants include, but are not limited to, methyl-, ethyl-, propyl-, butyl-, isobutyl-, benzyl-, and octyl-esters with the carboxylic acid component of the ester including acetate, ethanoate, propionate, butyrate, hexanoate, caproate, heptanoate, octanoate, decanoate, cinnamate, and isovalerate. Other examples of flavorants which can be used include, but are not limited to, benzaldehyde, other aldehydes, limonene, and other terpenes. Combinations of flavorants can also be used.

[0099] Suitable dense gases which can be used as the extraction solvent include, but are not limited to, carbon dioxide, ethane, propane, butane, chlorofluorocarbons, and mixtures thereof. The dense gas extraction can be operated in any manner known in the art including leaching, batch extraction, and continuous countercurrent extraction as described in U.S. Pat. No.6,106,720 and U.S. Pat. No. 5,932,101 , the contents of which are incorporated herein by reference in their entirety. Additional suitable dense gases can be methane, isobutane, dimethyl ether, sulfur hexafluoride, ammonia, fluorocarbons, and mixtures thereof. Any combination of the above dense gases can also be used.

[0100] The dense gases can also contain one or more co-solvents to improve extractability of solutes. Examples of these co-solvents include methanol, ethanol, 1 -propanol, 2-propanol, 1 -hexanol, 2-methoxy ethanol, acetone, tetra hydrofuran, 1 ,4-dioxane, acetonitrile, dichloromethane, chloroform, dimethyl sulfoxide, formic acid, carbon disulfide, methylene chloride, amines, chelating agents, phase transfer catalysts and combinations thereof. Other examples of dense gases and co-solvents are listed in U.S. Pat. Nos. 4,345,976 and 5,490,884, the contents of which are incorporated herein by reference in their entirety. The co-solvents can also be added to the algal biomass stream to enhance recovery of a solute or hydrophobic natural product in the extraction solvent.

[0101] The solvent system can also include an ionic liquid. Suitable ionic liquids include, but are not limited to, solvent systems that are in the liquid phase at the extraction temperature, those that include a cation and an anion, and those that are immiscible with a water-rich algal concentrate phase.

[0102] In exemplary embodiments, the extraction solvent is selected such that the selectivity of the extraction solvent for specific non-polar compounds versus specific salts is greater than unity (i.e., greater than 1 ). The selectivity iscalculated by dividing the distribution coefficient for a specific non-polar compound of interest to the distribution coefficient for a specific salt of interest. The distribution coefficients are defined as the concentration of the nonpolar compound in the extract phase divided by the concentration of the nonpolar compound in the raffinate phase.

[0103] In exemplary embodiments, forming the dispersion by contacting the algal concentrate with the extraction solvent involves using an algal concentrate or algal biomass to extraction solvent ratio (e.g., a volumetric ratio) of from about 8 to about 0.1 , from about 5 to about 0.2, or 1 (e.g., a 1 to 1 volumetric ratio).

[0104] The algal concentrate can contact the extraction solvent for about 1 minute to 5 hours, or for about 2 minutes to 5 hours, and the contact time can differ based on the type of contactor used in the extraction zone. When a centrifugal extractor is used for the extraction zone, the contact time can range from about 0.5 to 10 minutes, or less than 2 minutes. When an agitated vessel is used for the extraction zone, the contact time can range from about 1 minute to 5 hours, or between 2 and 120 minutes. Preferably, the contact time will be 5 to 60 minutes. The algal concentrate can contact the extraction solvent for about 2 to 180 minutes, about 5 to 180 minutes or about 10 to 60 minutes in a counter-current extraction column. In exemplary embodiments the dispersion is retained in the countercurrent extraction column for a residence time of about 2 minutes to about 2 hours.

[0105] The extraction zone can include a mixer, a static mixer, a settler, a cocurrent extraction column, a countercurrent extraction column, a centrifugal extractor, an emulsion phase contactor, or any combination thereof known in the art. The extraction zone may be upstream to the system as disclosed in the present disclosure and configured to operatively communicate with the algal biomass stream feed line, or the counter-current separation device of the system may comprise the extraction zone configured to operatively communicate with the algal biomass stream feed line.

[0106] Suitable mixers for the extraction zone include agitated vessels where a mechanical agitator is used to intimately contact the algal concentrate and the extraction solvent. The mechanical agitator can include one or more impellerson a rotating shaft. Suitable impellers include, but are not limited to Rushton Turbines, flat-blade turbines, pitch-blade turbines, marine propellers, hydrofoils, impellers that are sold by Chemineer (Dayton Ohio), or SPX / Lightnin (Rochester, New York). Regardless of the type of impeller used, the degree of agitation required is important for efficient mass transfer of the solute. The degree of agitation required can be calculated by the minimum impeller speed to completely disperse one immiscible liquid in another, as defined by Skelland and Ramsay [1987 l&EC Res. 26, 1 , 77-81], Skelland and Moeti [1989, l&EC Res. 28, 1 , 122-127] and Skelland and Kanel [1993, l&EC Res. 29, 7, 1300- 1306]. Static mixers of any design can also be used as the extraction zone. Suitable static mixers include, but are not limited to, those produced by Chemineer in their Kenics line.

[0107] The extraction zone can be followed by a separation zone, and mass transfer can continue to occur while the dispersion is separating in the separation zone. In an exemplary embodiment, there is a balance between the amount of shear energy added in the extraction zone to generate an acceptable drop size distribution in the liquid-liquid dispersion in order to achieve acceptable mass transfer kinetics in the extraction zone, and reasonable decantation kinetics in the separation zone. Since the separation zone can be larger in volume than the extraction zone, it is advantageous not to add too much shear that generates a small drop size distribution that would increase the size of the decanter.

[0108] Suitable extraction columns which can be used as the extraction zone include, but are not limited to, those that are mechanically agitated and those that have stationary internals. The latter is preferred when the extraction solvent is a dense gas and / or the operating pressure of the extractor is elevated so that more expensive mechanical seals are needed. Suitable extraction columns with stationary internals can include, but are not limited to, packed, perforated plate, baffle tray, and combinations thereof. Suitable packings include structured or random packings that are known to those skilled in the art. Suitable mechanically agitated extraction columns can include, but are not limited to, the Karr reciprocating plate column, the York Scheibel column, and the rotating disc column, all made by Koch Modular Process Technology Corporation, which islocated in Paramus, N.J., the Kuhni column, which is sold by Sulzer in Switzerland, the asymmetric rotating disc column, pulsed columns, and combinations thereof.

[0109] The separation zone can include or be a decanter which is configured to perform at least one or more of gravity settling, centrifugal settling, and / or combinations thereof to separate the dispersion into the multiple layers. In exemplary embodiments, the separation zone can include one or more fixed or moving separation aids like mesh pad coalescers, wire pad coalescers, structured packing, inclined plates, perforated plates, baffles, ultrasonic waves, acoustic waves, and / or combinations thereof.

[0110] In an exemplary embodiment, the extraction zone includes a mixer and / or a countercurrent extraction column, and / or the separation zone includes a decanter.

[0111] In exemplary embodiments, the extraction zone and separation zone are combined in a countercurrent extraction column. The counter-current separation device may comprise the countercurrent extraction column. In exemplary embodiments, the system further comprises an upstream countercurrent extraction column comprising a combined upstream extraction zone and upstream separation zone, wherein the algal biomass stream feed line being configured to communicate with the algal biomass stream input and the upstream separation zone of the upstream countercurrent extraction column. In exemplary embodiments, the extraction zone and separation zone are combined in a countercurrent extraction column, and the system further comprises an upstream countercurrent extraction column comprising a combined upstream extraction zone and upstream separation zone, wherein the algal biomass stream feed line being configured to communicate with the algal biomass stream input and the upstream separation zone of the upstream countercurrent extraction column. In these exemplary embodiments, the raffinate layer can exit the column at one end while the solvent extract layer can exit the column at the opposite end. The rag layer can be removed from the countercurrent extraction column with either the raffinate layer or the solvent extract layer, or alternatively removed from the extraction column as a sidedraw. Any of the types of extraction columns described above can be usedfor countercurrent extraction. The algal concentrate can contact the extraction solvent for about 5 to 180 minutes, about 5 to 180 minutes or about 10 to 60 minutes in a counter-current extraction column.

[0112] Suitable centrifugal extractors that can be used to provide both the extraction zone and the separation zone include, but are not limited to those produced by CINC, Alfa Lavel, Podbielniak, Robatel, Westfalia, and combinations of these centrifugal extractors.

[0113] Suitable emulsion phase contactors that can be used to provide both the extraction zone and the separation zone include, but are not limited to, those produced by Schlumberger termed the NATCO dual frequency electrostatic treater.

[0114] The separation of the dispersion into multiple layers can be carried out or performed under a gravitational field or by decanting.

[0115] Separating the dispersion into multiple layers can occur in as little as 10 minutes to about 24 hours, at least 20 minutes to 12 hours, at least 30 minutes to 6 hours, or 40 minutes to 3 hours.

[0116] Separating the dispersion into multiple layers can occur or can be performed at a pressure ranging from atmospheric to supercritical conditions for the extraction solvent.

[0117] Separating the dispersion into multiple layers can occur or can be performed e.g. at a temperature of less than 100°C such as about 20°C to about 90°C, about 30°C to about 90°C, about 40°C to about 90°C, about 50°C to about 90°C, about 60°C to about 90°C, about 35°C to about 80°C, about 35°C to about 70°C or about 40°C to about 70°C.

[0118] The solvent extract layer can include at least one hydrophobic natural product present within the dispersion. These hydrophobic natural products can include one or more selected from the group including lipids, algal lipids, carotenoids, fatty acids, algal fatty acids, triacylglycerols, diacylglycerols, monoacylglycerols, oils, algal oils and combinations thereof.

[0119] The carotenoids can include beta-carotene, alpha-carotene, lutein, zeaxanthin, beta-cryptoxanthin, astaxanthin, phytoene, phytofluene, lycopene, and / or combinations thereof.

[0120] The solvent extract layer can include extraction solvent, algal oil, carotenoids, trace amounts of water and salt. The solvent extract layer can contain extraction solvent in amounts of more than 50 wt%, such as above 60 wt% or above 70 wt% of its total weight; algal oil in amounts than less 30 wt%, such as less than 20 wt% or less than 10 wt% of its total weight; carotenoids in amounts less than 5 wt%, such as less than 3 wt% or less than 1 wt% of its total weight; water in amounts less than 10 wt%, such as less than 5 wt% or less than 2 wt% of its total weight; and / or salt in amounts less than 3 wt%, such as less than 2 wt% or less than 1 wt% of its total weight.

[0121] The solvent extract layer can include limited amounts of lipid-depleted biomass and an aqueous salt solution.

[0122] The raffinate layer can include an aqueous salt solution depleted of hydrophobic natural products. The raffinate layer can possess a salt concentration of above 5 wt%, above 7 wt%, above 10 wt% above 15 wt%, above 18 wt% up to saturation. In an exemplary embodiment, the raffinate layer has a salinity of about 5 wt% or greater, about 10 wt% or greater, about 15 wt% or greater, or about 20 wt% or greater. In exemplary embodiments a salinity of the raffinate layer is about 5 wt% or greater than 5 wt%, about 6 wt% or greater than 6 wt%, about 7 wt% or greater than 7 wt%, for example at least about 8 wt%, at least about 9 wt%, at least about 10 wt%, at least about 11 wt%, at least about 12 wt%, at least about 13 wt%, at least about 14 wt%, at least about 15 wt%, at least about 16 wt%, at least about 17 wt%, at least about 18 wt%, at least about 19 wt%, at least about 20 wt%, at least about 21 wt%, at least about 22 wt%, at least about 23 wt%, at least about 24 wt%, or at least about 25 wt%. In other exemplary embodiments the raffinate layer is saturated with salt. In more exemplary embodiments, the raffinate layer can have a salinity that is about 5 wt% to about saturation, from about 10 wt% to saturation, from about 20 wt% to saturation, from about 5 wt% to about 20 wt%, from about 10 wt% to about 20 wt%, from about 5 wt% to about 15 wt%, from about 10 wt% to about 15 wt%, or from about 5 wt% to about 10 wt%.

[0123] The raffinate layer can contain algal growth medium that is depleted in algal biomass and / or algal oils.

[0124] The raffinate layer can include water, salts, trace amounts of extraction solvent, trace amounts of algal biomass (such as less than 5 wt% or less than 1 wt% of its total weight) and / or trace amounts of algal oil (such as less than 5 wt% or less than 1 wt% of its total weight). The raffinate layer can contain water above 50 wt% (such as from 60 wt% to 90 wt%, 70 wt% to 85 wt% or 80 wt% to 90 wt%) or at about 50 wt% of its total weight, and / or the raffinate layer can contain salt from about 0.1 wt% to about 50 wt%, about 5 wt% to about 40 wt%, about 10 wt% to 30 wt%, and / or about 15 wt% to 26 wt% of its total weight. The raffinate layer can also contain trace amounts of the extraction solvent in both soluble and / or insoluble forms. The solubility of the extraction solvent in the raffinate layer influences the amount, or concentration, of the extraction solvent in the raffinate layer. The soluble amount of extraction solvent can be experimentally determined by measuring the solubility of the extraction solvent in the raffinate layer as a function of temperature, pressure, pH, salinity, and / or other factors known to those skilled in the art. The insoluble amount of the extraction solvent in the raffinate layer can be determined by the amount of entrainment of both extraction solvent droplets and the amount of extraction solvent that is associated with entrained algal biomass in the raffinate layer. Trace amounts of algal oil in the raffinate layer can be present in the solvent of the raffinate layer and / or in the algal biomass as unextracted oil.

[0125] The rag layer can form at any location between, above or below the solvent extract and raffinate layers. The rag layer can include a lipid-depleted biomass. The lipid-depleted biomass can include at least one or more of, chlorophyll, glycerol, phospholipids, proteins, carbohydrates, fibers, and limited amounts of lipids, carotenoids and / or raffinate relative to the dispersion or any combination thereof. In exemplary embodiments, the rag layer contains at most about 45 wt% solvent extract layer, about 45 wt% raffinate layer and about 10 wt% lipid-depleted biomass. In an exemplary embodiment, the rag layer contains at most about 60 wt% solvent extract layer (such as from 30 wt% to 60 wt%, e.g., 40 wt% to 50 wt% or about 45 wt%), at most about 60 wt% raffinate layer (such as from 30 wt% to 60 wt%, e.g., 40 wt% to 50 wt% or about 45 wt%) and / or about from 2 wt% to 20 wt% lipid-depleted biomass (e.g., from 5 wt% to 10 wt%).

[0126] The rag layer can contain a majority of the algal biomass. Reducing the volume of the rag layer can be desirable to minimize the cost of further processing the rag layer to recover any entrained algal biomass.

[0127] The rag layer can include water, salt, extraction solvent, algae oil, and / or algal biomass. In exemplary embodiments, the rag layer is a mixture of three layers: 1) a layer containing algal biomass that has been depleted of non-polar compounds, 2) at least a portion of the solvent extract layer, and 3) at least a portion of the raffinate layer. The ratio of these three layers can vary depending on the conditions used to separate the dispersion into multiple layers. The layer containing the algal biomass that has been depleted of non-polar compounds can vary from about 0.01 wt% of the total weight of the rag layer to about 20 wt%. The solvent extract layer and the raffinate layer can vary from about 1 wt% to about 99 wt% of the total weight of the rag layer. In exemplary embodiments, the layer containing algal biomass that has been depleted of non-polar compounds is between about 1 and 10 wt% of the total weight of the rag layer, and the solvent extract layer and the raffinate layer range from about 10 wt% to 90 wt% of the total weight of the rag layer.

[0128] In exemplary embodiments, the rag layer includes an algal biomass having a particle distribution size from about 0.1 microns to about 1000 microns, about 0.2 microns to about 100 microns, from about 0.4 microns to about 25 microns, from about 0.4 microns to about 20 microns or at least 20 microns.

[0129] The rag layer can have an intermediate density between the solvent extract layer and the raffinate layer, so in decantation and / or centrifugation processes, it is located between the solvent extract layer and the raffinate layer.

[0130] In exemplary embodiments, the rag layer does not exist as a true thermodynamic phase and exists as a mixture of solid algal biomass, raffinate layer and solvent extract layer. The raffinate layer and the solvent extract layer can exist as true thermodynamic phases.

[0131] In exemplary embodiments, the liquid-liquid-solid extraction process includes performing a heat exchange before the algal concentrate enters the extraction zone, before the extraction solvent enters the extraction zone, and / or before the dispersion enters the separation zone.

[0132] In exemplary embodiments, the liquid-liquid-solid extraction process includes isolating at least part of the solvent extract layer, at least part of the raffinate layer and / or at least part of the rag layer. The solvent extract layer can be e.g., overflowed or pumped out of the separation zone, the rag layer can be pumped out of the separation zone and / or the raffinate layer can be removed e.g., from the bottom of the separation zone.

[0133] In exemplary embodiments, the liquid-liquid-solid extraction process includes contacting the isolated solvent extract layer with an aqueous phase to remove any residual salt concentrations that can be present within the solvent extract layer.

[0134] In exemplary embodiments, the liquid-liquid-solid extraction process includes using a coalescer after formation of the dispersion.

[0135] In exemplary embodiments, the liquid-liquid-solid extraction process includes filtering the solvent extract layer after isolation to remove any entrained biomass and / or filtering the raffinate layer after isolation to remove any entrained biomass.

[0136] In exemplary embodiments, the liquid-liquid-solid extraction process includes evaporating the extraction solvent from the solvent extract layer after isolation of the solvent extract layer.

[0137] In exemplary embodiments, the liquid-liquid-solid extraction process is performed at a temperature of about 100°C (e.g., 100 ± 1-10°C) or less, about 95°C (e.g., 95 ± 1-10°C) or less, about 90°C (e.g., 90 ± 1-10°C) or less, about 85°C or less, about 80°C or less, about 75°C or less, about 70°C or less, about 65°C or less, about 60°C or less, or e.g., within a temperature range from 5 to 90°C, from 25 to 90°C, from 30 to 90°C, from 40 to 90°C, from 50 to 90°C, from 55 to 90°C, from 60 to 90°C, from 40 to 80°C, from 50 to 80°C, or from 60 to 80°C. It is advantageous to operate the extraction at a temperature below 100°C to preserve the algal oils and carotenoids.

[0138] In exemplary embodiments, forming the dispersion by contacting the algal concentrate with the extraction solvent in the extraction zone and separating the dispersion into multiple layers in the separation zone can be performed at the same or different temperatures.

[0139] In exemplary embodiments, the separating of the dispersion into multiple layers occurs or is performed at a temperature of about 100°C or less, about 95°C or less, about 90°C or less, about 85°C or less, about 80°C or less, about 75°C or less, about 70°C or less, about 65°C or less, about 60°C or less, or within a temperature range from 35 to 90°C, from 40 to 90°C, from 45 to 90°C, from 50 to 90°C, from 55 to 90°C, from 60 to 90°C, from 30 to 80°C, from 35 to 80°C, from 40 to 80°C, from 45 to 80°C, from 50 to 80°C, from 55 to 80°C, or from 60 to 80°C, from 30 to 70°C, from 35 to 70°C, from 40 to 70°C, from 45 to 70°C, from 50 to 70°C, from 55 to 70°C, or from 60 to 70°C.

[0140] In exemplary embodiments, the separating of the dispersion into multiple layers occurs or is performed at a temperature of about 40°C to 90°C, 50°C to 90°C, 60°C to 90°C, 35°C to 80°C, 35°C to 70°C or 40°C to 70°C.

[0141] In exemplary embodiments, the liquid-liquid-solid extraction process can be performed without addition of salt during the forming of the dispersion and during the separating of the dispersion into the multiple layers. For some exemplary embodiments, the extraction process includes performing the forming, passing, separating and isolating steps without an addition of salt. In other exemplary embodiments, the biomass or algal concentrate containing the biomass in an aqueous salt solution does not include added salt.

[0142] In exemplary embodiments, the liquid-liquid-solid extraction process is a continuous process. The liquid-liquid-solid extraction process can be configured as a continuous process wherein the forming, passing, separating and isolating steps are performed sequentially. Continuous operation can allow for the production of biofuels and / or other hydrophobic natural products with reduced capital and operating costs. In exemplary embodiments, the algal concentrate and the extraction solvent are contacted so that the solvent receives the hydrophobic natural products. In other exemplary embodiments, the hydrophobic natural products are either pressed from the biomass or extracted with additional algal (or vegetable) oil. The resulting raffinate phase and the extract phases are separated so that the hydrophobic natural products can be further processed into desirable products.

[0143] A variety of extraction equipment components can be used for continuous extraction including, but not limited to, mixers and settlers,countercurrent extraction columns, centrifugal extractors, and other classes of extractors known in the art as described by Pratt et al., Selection, Design, PilotTesting, and Scale-Up of Extraction Equipment, Chapter 8, in Science and Practice of LiquidLiquid Extraction, Volume 1 , Clarendon Press, Oxford, 1992, the contents of which are incorporated herein by reference. The algal concentrate and the extraction solvent can be contacted in a countercurrent or co-current flow.

[0144] Suitable centrifugal extractors can include, but are not limited to, those manufactured by GEA Westfalia Separator GmbH, which is headquartered in Oelde, Germany; Alfa Laval, with a location in Richmond, Virginia; Robatel, which is located in Pittsfield, Massachusetts; and Podbelniak, which is manufactured by Baker Perkins of Saginaw, Michigan.

[0145] Suitable other extraction equipment includes, but is not limited to, hollow fiber membrane extractors and other novel extractor designs known in the art. In some cases, hollow fiber membrane extractors are used since they obviate the need to separate the solvent from the algal biomass.

[0146] Gravity settling is useful in a continuous extraction process. Separation of the multiple layers can be achieved in a centrifugal or gravitational force field, but gravity settling is usually of lower cost. A coalescer can be added to assist in the decantation. The raffinate layer can be coalesced to recover any additional extraction solvent that is entrained before being recycled to a bioreactor or returned to a pond, depending on the type of aquaculture practiced. A coalescer, liquid / liquid / solid centrifuge, flotation cell, and / or liquid / liquid cyclone can be used to recover solvent from the aqueous salt solution, or the aqueous salt solution can be recycled to a flotation device for cleanup.

[0147] Suitable materials for the construction of the mixer, decanter, and / or extraction equipment include, but are not limited to, steel, concrete, non-ferrous material, plastics, fiberglass, fiberglass reinforced plastic such as fiberglass reinforced HDPE, and combinations thereof. Non-ferrous materials are advantageous due to the salt content of the algal concentrate and the raffinate layer in the extraction process. The salinity of these components could cause stress corrosion cracking in ferrous materials, greatly increasing themaintenance required on the mixer, decanter, and extraction equipment. Plastic and fiberglass equipment is resistant to the effects of the elevated salinity and can be less expensive than equipment constructed of ferrous material.

[0148] The solvent extract layer, the lipid-depleted biomass, the rag layer, the raffinate layer and / or a combination thereof can be stabilized against degradation by any means known in the art including, but not limited to, one or more of the following methods: the addition of antioxidants, storage of the material in the absence of light exposure, storage under an inert environment such as nitrogen, argon, or carbon dioxide, chilling, and subjecting the material to a thermal cycle to destroy bacteria. Suitable antioxidants include, but are not limited to carotenoids, tertiary butyl hydroquinone (TBHQ), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), vitamin E, vitamin C, rosemary extracts, and combinations thereof.

[0149] Exemplary advantages of performing a liquid-liquid-solid extraction process disclosed herein include, but are not limited to, not drying the biomass prior to the hydrophobic natural products being extracted, traditional liquid-liquid extraction equipment can be used instead of expensive leaching equipment, salt does not need to be removed prior to the extraction process, and / or washing of the solvent extract layer can be accomplished in traditional liquidliquid extraction equipment.

[0150] In exemplary embodiments, the separation process includes obtaining the algal biomass stream from an upstream extraction process, the upstream extraction process being a liquid-liquid-solid extraction process including at least one or more of the following: contacting the algal concentrate with a first solvent in a first contacting unit to form a first dispersion; allowing the first dispersion to phase separate into a first separated liquid phase and a first remaining dispersion; removing at least a portion of the first separated liquid phase from the first remaining dispersion; contacting the first remaining dispersion with a second solvent in a second contacting unit to form a second dispersion; allowing the second dispersion to phase separate into a biomassrich phase, a heavy separated liquid phase and a light separated liquid phase; and separating at least one or more of the biomass-rich phase, the heavyseparated liquid phase, and / or the light separated liquid phase for output as recovered products and / or the algal biomass stream.

[0151] The liquid-liquid-solid extraction process described above can also include at least one or more of the following: measuring decantation curves that form upon and / or during contact in the first contacting unit; selecting a phase with the shortest time to reach 90% of a dimensionless height asymptote and removing a desired amount of said phase from the first contacting unit before passing the first remaining dispersion to the second contacting unit; determining decantation curves formed upon and / or during contact in the second contacting unit; and selecting operating parameters for the second contacting unit to optimize the overall extraction costs of the process.

[0152] The first contacting unit can be, but is not limited to, a mixer-settler, a counter-current extraction column, a centrifugal extractor, a membrane extractor, an emulsion phase contactor and any extractor that employs nonstandard contact methods (e.g., extractors that use electrical fields, ultrasonic waves, and / or microwave waves to aid in the extraction of materials) and combinations thereof. Suitable mixer-settlers include a mixing section (or contacting unit) and a settling section (or separating unit). Suitable mixers, or contacting units include, but are not limited to static mixers, in-line mixers, agitated vessels, eductors, extraction columns operated in co-current mode, and other means known in the art, and combinations thereof. Suitable settlers or separating units include, but are not limited to gravity decanters, coalescers, electrically enhanced coalescers, cyclones, centrifuges, and other means known in the art, and combinations thereof. Many different designs of mixersettlers have been developed for mining and minerals applications, and these are described by T.C. Lo et al., (1991 ) [Handbook of Solvent Extraction, ISBN 0-89464-546-3],

[0153] Suitable counter-current extraction columns include, but are not limited to, those that are mechanically agitated and those that have stationary internals. The latter is preferred when the first and / or second solvent is a dense gas and / or the operating pressure of the extractor is elevated so that more expensive mechanical seals are needed. Suitable extraction columns with stationary internals can include, but are not limited to, those that contain eitherstructured or random packing, perforated plates, baffle trays, sieve trays, spray columns, and combinations thereof. Suitable packings include structured or random packings that are known to those skilled in the art. Suitable mechanically agitated extraction columns can include, but are not limited to, the Karr reciprocating plate column, the York Scheibel column, and the rotating disc column, all made by Koch Modular Process Technology Corporation, which is located in Parasippany, N.Y., the Kuhni column, which is sold by Sulzer in Switzerland, the asymmetric rotating disc column, pulsed columns, and combinations thereof.

[0154] Suitable centrifugal extractors that can be used as the first contacting unit include, but are not limited to those produced by CINC, Alfa Lavel, Podbielniak, Robatel, Westfalia, and combinations of these centrifugal extractors. Other suitable centrifugal extractors include but are not limited to those manufactured by GEA Westfalia Separator GmbH, which is headquartered in Oelde, Germany; Alfa Laval, with a location in Richmond, Virginia; Robatel, which is located in Pittsfield, Massachusetts; and Podbielniak, which is manufactured by Baker Perkins of Saginaw, Michigan.

[0155] Suitable emulsion phase contactors that can be used as the first contacting unit include, but are not limited to, those produced by Schlumberger termed the NATCO dual frequency electrostatic treater.

[0156] The first solvent can be any solvent that, upon contacting and / or during contacting with the algal concentrate, is capable of separating the first dispersion into at least a two-layer extraction system, wherein at least one layer rapidly settles.

[0157] A layer that “rapidly settles” is one that reaches 90% of a dimensionless height asymptote within about 30 minutes or less on a decantation curve and has a dimensionless height 90 (DH90) ratio of the fast separating layer to the slow separating layer of less than 0.8. A DH90 ratio is the ratio of the settling time for the rapidly settling layer at DH90 to the settling time for the slowest settling layer at DH90.

[0158] The first solvent can be an extraction solvent including, but not limited to, a non-polar solvent, a non-polar organic solvent, a dense gas solvent, an aqueous two-phase solvent, an ionic liquid, a light solvent or a combinationthereof. The first solvent can also be a mixture of miscible solvents. The first solvent is chosen such that it can form an immiscible liquid phase with the algal concentrate and has a density that differs from the algal concentrate. Thus, an optimal extraction solvent can depend on which natural products are desired to be extracted from the algal concentrate.

[0159] The expression “light solvent” refers to a solvent that forms a liquid phase that floats on top of the other liquid phases during the phase separations and is in contact with the vapor phase. The expression “heavy solvent” refers to a solvent that forms a heavy liquid phase that collects at the bottom of a settler and is typically in contact with the bottom of the tank or vessel, and / or is just above an even heavier solid phase.

[0160] In exemplary embodiments, the first solvent is a solvent system that forms a two-layer extraction system with the algal concentrate. These solvent systems should not adversely impact the quality or quantity of the natural products. These solvent systems can include any one or more of the synthetic and / or natural flavorants, edible oils, petrochemicals, bio-based chemicals, dense gases, ionic liquids and combinations of these disclosed herein so long as the mixture of the solvent system and the algal concentrate form two immiscible phases. The solvent system can also include any one or more of the petrochemical solvents disclosed herein due to their low viscosity and favorable solute molecular diffusivity. Natural oils are soluble in petrochemical solvents and concentrated extracts are possible.

[0161] The first solvent can be a hydrocarbon, ester, ketone, acetate, dense gas, and other solvents identified by J. A. Riddick et al., (1986) [Organic Solvents: Physical Properties and Methods of Purification, 4th Edition, ISBN 0- 471-08467-0],

[0162] In exemplary embodiments, the contacting of the algal concentrate and the first solvent in the first contacting unit occurs under a solvent to feed stream ratio (e.g., a volumetric ratio) from about 9 to about 0.1 , from about 5 to about 0.2, or of 1 (e.g., a 1 to 1 volumetric ratio).

[0163] In exemplary embodiments, the contacting of the algal concentrate and the first solvent in the first contacting unit occurs for about 1 minute to 30 minutes, for about 5 minutes to 10 minutes, or any amount of time under 15minutes. The contacting time can differ based on the type of first contacting unit used and the extraction kinetics to extract the desired solute from the solid matrix. For example, when the first contacting unit is a centrifugal extractor, the contact time may range from about 0.5 to 10 minutes, or less than 2 minutes. When an agitated vessel is used for the first contacting unit, the contact time may range from about 1 minute to 10 minutes. The algal concentrate can contact the first solvent for about 2 to 15 minutes, about 5 to 10 minutes or about 10 to 15 minutes in a counter-current extraction column. Also for example, when the extraction kinetics of the solute from the solid matrix is rapid relative to the interfacial mass transfer kinetics, then the contact time may range in the various contacting equipment as just described. However, if the extraction kinetics are slow relative to the interfacial mass transfer kinetics, then the required contact time may be longer.

[0164] The term “first dispersion” relates to a heterogeneous mixture containing at least a portion of the algal concentrate and at least a portion of the first solvent along with the biomass.

[0165] In exemplary embodiments, the separation of the first dispersion into the first separated liquid phase and the first remaining dispersion does not occur in the first contacting unit and instead occurs within a first separating unit.

[0166] The first separating unit can include, but is not limited to, a decanter, a coalescer, a centrifuge, an electrically enhanced decanter, a hydroclone or combinations thereof.

[0167] The first contacting unit and the first separating unit can be combined in, for example, a batch-operating mixer-settler, counter-current extraction column, a centrifugal extractor, and other methods known in the art, and combinations thereof.

[0168] In exemplary embodiments, the first separating unit includes or is a decanter which is configured to perform at least one or more of gravity settling, centrifugal settling, and / or combinations thereof to separate the first dispersion into the first separated liquid phase and the first remaining dispersion. In exemplary embodiments, the first separating unit includes one or more fixed or moving separation aids, for example, mesh pad coalescers, wire padcoalescers, structured packing, inclined plates, perforated plates, baffles, ultrasonic waves, acoustic waves, and / or combinations thereof.

[0169] The allowing of the first dispersion to phase separate into the first separated liquid phase and the first remaining dispersion can occur for about 1 minute to 30 minutes, 5 minutes to 15 minutes, 1 minute to 5 minutes, 5 minutes to 10 minutes, or any amount of time under 15 minutes.

[0170] In exemplary embodiments, the first separated liquid phase and the first remaining dispersion do not phase separate in less than 30 minutes under gravitational acceleration.

[0171] The allowing of the first dispersion to phase separate into the first separated liquid phase and the first remaining dispersion can be performed at ambient conditions so that the temperature can range from 5 to 90°C and the pressure can be atmospheric. In exemplary embodiments, the allowing of the first dispersion to phase separate into the first separated liquid phase and the first remaining dispersion is performed at room temperature. In other exemplary embodiments, the allowing of the first dispersion to phase separate into the first separated liquid phase and the first remaining dispersion is performed at 70°C.

[0172] In exemplary embodiments, the allowing of the first dispersion to phase separate into the first separated liquid phase and the first remaining dispersion includes retaining the feed stream in the first separating unit for a set period of time until the first separated liquid phase and the first remaining dispersion form. The set period of time can be any time from 1 minute to 30 minutes, 2 minutes to 15 minutes, 5 minutes to 15 minutes, 1 minute to 5 minutes, 5 minutes to 10 minutes, or any amount of time under 15 minutes.

[0173] In exemplary embodiments, at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt% or any amount from 50 wt% to 99 wt% of the first separated liquid phase is removed from the first remaining dispersion.

[0174] In exemplary embodiments, the first separated liquid phase contains a higher concentration of the aqueous solution originating from the algal concentrate than the first remaining dispersion. The first separated liquid phase can contain up to 50 wt%, up to 60 wt%, up to 70 wt%, up to 80 wt%, up to 90wt% or any amount from 50 wt% to 99 wt% of the aqueous solution relative to the total wt% of the first separated liquid phase.

[0175] In exemplary embodiments, the first separated liquid phase reaches 90% of a dimensionless height asymptote within about 30 minutes ((settle) < 30 min) during the forming of the first separated liquid phase and the first remaining dispersion from the first dispersion.

[0176] In exemplary embodiments, the first separated liquid phase and the first remaining dispersion have a settling time ratio at DH90 of about 0.8 or less.

[0177] In exemplary embodiments, the allowing of the first dispersion to phase separate into the first separated liquid phase and the first remaining dispersion includes maintaining a first solvent to algal concentrate ratio of about 0.1 to 10 and / or a flux of about 10 m3 / h / m2to 80 m3 / h / m2.

[0178] In an exemplary embodiment, the allowing of the first dispersion to phase separate into the first separated liquid phase and the first remaining dispersion include maintaining a first solvent to feed stream ratio of about 0.1 to 10.

[0179] In exemplary embodiments, the removing of the first separated liquid phase from the first remaining dispersion can include transferring the first separated liquid phase from the first separating unit and / or the first contacting unit to a first separated liquid phase processing unit. The first separated liquid phase processing unit can include, but is not limited to, crystallization ponds, polishing ponds and / or combinations thereof. In these embodiments, at least a portion of the first remaining dispersion remains in the first separating unit and / or the first contacting unit.

[0180] In exemplary embodiments, the first remaining dispersion is transferred to at least one auxiliary contacting unit and / or separating unit before the first remaining dispersion is transferred to the second contacting unit. For example, the first remaining dispersion can be transferred to at least one, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, at least nine, or at least ten or more auxiliary contacting units and / or separating units before being transferred to the second contacting unit.

[0181] In exemplary embodiments, the first remaining dispersion is contacted with the first solvent in one or more auxiliary contacting units.

[0182] The second contacting unit can include, but is not limited to, any of the mixer-settlers, counter-current extraction columns, centrifugal extractors, membrane extractors, extractors that employs non-standard contact methods (e.g., extractors that use electrical fields, ultrasonic waves, and / or microwave waves to aid in the extraction of materials) and combinations thereof that the first contacting unit can include. In exemplary embodiments, the second contacting unit contains at least one different extraction equipment from the first contacting unit.

[0183] The second solvent can be any solvent that can form the second dispersion upon and / or during contact with the first remaining dispersion. In exemplary embodiments, the second solvent is the same as the first solvent to reduce the complexity of the solvent recovery system. In other exemplary embodiments, the second solvent differs from the first solvent in order to facilitate better phase separation of the remaining layers. In other exemplary embodiments, the second solvent differs from the first solvent in order to facilitate recovery of a different solute from the system. The second solvent can be any solvent or solvent system of the first solvent.

[0184] In exemplary embodiments, the second solvent is a solvent that has a density that is at least about 0.05 g / cm3less than the density of the first separated liquid phase.

[0185] In exemplary embodiments, the second solvent is a solvent that has an apparent viscosity that is at least about 1 mPa / s less than the viscosity of the first separated liquid phase, when the apparent viscosity is optionally measured according to ISO 2884-1 :1999.

[0186] In exemplary embodiments, the second solvent is added to the first remaining dispersion in a ratio of about 0.1 to 10.

[0187] The term “second dispersion” relates to the heterogeneous mixture containing at least a portion of the first remaining dispersion and at least a portion of the second solvent. The second dispersion can have a higher concentration of biomass than the first dispersion. Therefore, different methods of handling the second dispersion than those deployed to handle the first dispersion can be necessary.

[0188] In exemplary embodiments, the contacting between the first remaining dispersion and the second solvent in the second contacting unit can occur from 1 minute to about 60 minutes, but additional time may be required if the leaching kinetics are slow relative to the interfacial mass transfer kinetics.

[0189] In exemplary embodiments, the separation of the second dispersion into the biomass-rich phase, the heavy separated liquid phase and the light separated liquid phase does not occur in the second contacting unit and instead occurs within a second separating unit.

[0190] The operating conditions of the second contacting and second separating unit can differ significantly from the operating conditions of the first contacting and first separating unit. In exemplary embodiments, the temperature of the first and second contacting and separating units differ. In other exemplary embodiments, the pH and or the salinity of the first and second contacting and separating units differ. In other exemplary embodiments, the pressure of the first and second contacting and separating units differ. In other exemplary embodiments, the equipment types used for the first and second contacting and separating units differ. Other exemplary embodiments have the gravitational acceleration used in the first and second contacting and separating units differ. These differences between the first and second contacting and separating units can result from the removal of the first separated liquid phase.

[0191] In exemplary embodiments, the second dispersion is transferred to at least one other auxiliary contacting unit and / or separating units before the second dispersion is transferred to the second separating unit. For example, the second dispersion can be transferred to at least one, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, at least nine, or at least ten or more auxiliary contacting units and / or separating units before being transferred to the second separating unit.

[0192] In exemplary embodiments, the second dispersion is contacted with the second solvent in one or more auxiliary contacting units.

[0193] In exemplary embodiments, the method includes adding the first solvent, the second solvent and / or any other solvent to any of the auxiliary contacting and / or separating units.

[0194] In exemplary embodiments, the phase separation of the second dispersion into the biomass-rich phase, the heavy separated liquid phase and the light separated liquid phase occurs in the second contacting unit. In these embodiments, the second separating unit can be optional.

[0195] In the second contacting unit or the second separating unit, the second dispersion can be contacted with the second solvent. The hydrophobic algal products or algal oils in the second dispersion are transferred from the second dispersion into the extraction solvent (i.e., the second solvent). The second dispersion then separates into multiple phases. One phase can be depleted of hydrophobic algal components and contain the aqueous solution originating from the algal concentrate (i.e., the heavy separated liquid phase). Algal biomass can collect at a fluid-fluid interface, and this material is a component of the biomass-rich layer. The biomass-rich layer can also include salt-laden lipid-depleted algal biomass as well as limited amounts of the heavy separated liquid phase. Thus, two immiscible fluid phases, the heavy separated liquid phase and the light separated liquid phase, and a biomass-rich layer can be formed. Either of the two immiscible fluid phases can be made the continuous phase. The biomass-rich layer of algal biomass is formed between the light separated liquid phase, which includes lipids, carotenoids, and the extraction solvent, and the heavy separated liquid phase, which is rich in water and salts and usually contains trace amounts of lipids and carotenoids. The algal biomass of the biomass-rich layer can be rich in chlorophyll, glycerol, phospholipids, and proteins and can be used to form the algal biomass stream.

[0196] The phase separation of the second dispersion can be performed at ambient conditions so that the temperature and pressure can range from 5 to 90°C and the pressure is atmospheric. The phase separation can be performed at much higher temperatures. Bloch et al. in U.S. Pat. No. 4,341 ,038 teach that phase separation processes can be operated at temperatures to 300°C, to obtain certain results. The phase separation can operate at a temperature below 100°C to preserve the algal oils and carotenoids. Likewise, the pressure can be increased for the use of supercritical fluids. U.S. Pat. No. 6,106,720 teaches the advantages of high-pressure phase separations.

[0197] The second separating unit can include, but is not limited to, a decanter, a coalescer, a centrifuge, an electrically enhanced decanter, a hydrocyclone or combinations thereof.

[0198] The second contacting unit and the second separating unit can be combined in, for example, a batch-operating mixer-settler, counter-current extraction column, a centrifugal extractor, and other methods known in the art, and combinations thereof.

[0199] In exemplary embodiments, the second separating unit includes or is a decanter which is configured to perform at least one or more of gravity settling, centrifugal settling, and / or combinations thereof to separate the second dispersion into the biomass-rich phase, the heavy separated liquid phase and the light separated liquid phase. In exemplary embodiments, the second separating unit includes one or more fixed or moving separation aids, for example, mesh pad coalescers, wire pad coalescers, structured packing, inclined plates, perforated plates, baffles, ultrasonic waves, acoustic waves, and / or combinations thereof.

[0200] In exemplary embodiments, the method includes reducing the total extraction volume of the first, second and / or auxiliary contacting units and separating units. In exemplary embodiments, the total extraction volume is reduced by more than 20%, or by more than 40%, when compared to the total extraction volume of a single contacting and separating unit.

[0201] In exemplary embodiments, the second dispersion is allowed a specified period of time to phase separate into the biomass-rich phase, the heavy separated liquid phase and the light separated liquid phase. The specified period of time can be from at least 10 minutes to about 24 hours, at least 20 minutes to 12 hours, at least 30 minutes to 6 hours, or 40 minutes to 3 hours.

[0202] The term “biomass-rich phase” relates to a fluid layer or phase that includes a majority of the biomass originating from the algal concentrate and may also include at least a portion of the heavy separated liquid phase and at least a portion of the light separated liquid phase.

[0203] The biomass-rich phase can form at any location between, above or below the heavy separated liquid phase and the light separated liquid phase. Inexemplary embodiments, the biomass-rich phase forms between the heavy separated liquid phase and the light separated liquid phase.

[0204] In exemplary embodiments, the biomass-rich phase forms below the light separated liquid phase.

[0205] The biomass-rich phase can include a lipid-depleted biomass. The lipid-depleted biomass can include at least one or more of, chlorophyll, glycerol, phospholipids, proteins, carbohydrates, fibers, and limited amounts of lipids, carotenoids and / or salts relative to the second dispersion or any combination thereof.

[0206] In exemplary embodiments, the biomass-rich phase composition contains about 10 wt% biomass, about 45 wt% of light separated liquid phase and about 45wt% of the heavy separated liquid phase.

[0207] In exemplary embodiments, the biomass-rich phase contains at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt% or any amount from 50 wt% to 99 wt% of biomass. The biomass present in the biomass-rich phase can include lipid-depleted biomass. The amount of lipid- depleted biomass in the biomass-rich phase can be at most 10 wt%, at most 20 wt%, at most 30 wt%, at most 40 wt%, at most 50 wt%, at most 60 wt%, at most 70 wt%, at most 80 wt%, at most 90 wt% or any amount from 50 wt% to 99 wt% of the total weight of the biomass-rich phase.

[0208] The term “heavy separated liquid phase” relates to a phase or layer that is composed mostly of water or saltwater and may contain at least a portion of the biomass-rich layer and at least a portion of the second solvent used to create the second dispersion. In exemplary embodiments, less than 10%, 20%, 30% of the biomass-rich layer is entrained in the heavy separated liquid phase.

[0209] The heavy separated liquid phase can include an aqueous salt solution depleted of hydrophobic natural products.

[0210] The heavy separated liquid phase and / or the first separated liquid phase can possess a salt concentration of above 5 wt%, above 7 wt%, above 10 wt% above 15 wt%, above 18 wt% up to saturation. In exemplary embodiments a salinity of the heavy separated liquid phase layer and / or the first separated liquid phase is about 5 wt% or greater than 5 wt%, about 6 wt% or greater than 6 wt%, about 7 wt% or greater than 7 wt%, for example at leastabout 8 wt%, at least about 9 wt%, at least about 10 wt%, at least about 11 wt%, at least about 12 wt%, at least about 13 wt%, at least about 14 wt%, at least about 15 wt%, at least about 16 wt%, at least about 17 wt%, at least about18 wt%, at least about 19 wt%, at least about 20 wt%, at least about 21 wt%, at least about 22 wt%, at least about 23 wt%, at least about 24 wt%, or at least about 25 wt%. In other exemplary embodiments, the heavy separated liquid phase and / or the first separated liquid phase is saturated with salt, e.g., contains a salt concentration of at least 26.5 wt%. In exemplary embodiments, the heavy separated liquid phase and / or the first separated liquid phase can have a salinity that is about 5 wt% to about saturation, from about 10 wt% to saturation, from about 20 wt% to saturation, from about 5 wt% to about 20 wt%, from about 10 wt% to about 20 wt%, from about 5 wt% to about 15 wt%, from about 10 wt% to about 15 wt%, or from about 5 wt% to about 10 wt%.

[0211] In exemplary embodiments, the heavy separated liquid phase includes a polar organic solvent, for example, methanol, dimethyl sulfoxide, or dimethylformamide.

[0212] The term “light separated liquid phase” relates to a phase or layer that is composed mostly of a solvent and contains at least one hydrophobic natural product originating from the biomass of the feed stream.

[0213] The first solvent can include or is the same solvent that is used as the second solvent. The second solvent can also include a portion of the first solvent.

[0214] The light separated liquid phase may also contain at least a portion of the biomass-rich layer.

[0215] The light separated liquid phase can include at least one hydrophobic natural product. These hydrophobic natural products can include, but are not limited to, one or more of lipids, algal lipids, carotenoids, fatty acids, algal fatty acids, triacylglycerols, diacylglycerols, monoacylglycerols, oils, algal oils and combinations thereof.

[0216] The carotenoids can include beta-carotene, alpha-carotene, lutein, zeaxanthin, beta-cryptoxanthin, astaxanthin, phytoene, phytofluene, lycopene, and / or combinations thereof.

[0217] The light separated liquid phase can also include limited amounts of lipid-depleted biomass and the aqueous salt solution.

[0218] In exemplary embodiments, the separating of at least one or more of the biomass-rich phase, the heavy separated liquid phase, and / or the light separated liquid phase for output as recovered products includes removing at least a portion of one or more of the biomass-rich phase, the heavy separated liquid phase, and / or the light separated liquid phase from the second contacting unit and / or the second separating unit.

[0219] The separation of the biomass-rich phase, the heavy separated liquid phase and the light separated liquid phase can be carried out or performed under a gravitational field.

[0220] The separation of the biomass-rich phase, the heavy separated liquid phase and the light separated liquid phase can occur or can be performed at a pressure ranging from atmospheric to supercritical conditions for the light solvent.

[0221] In exemplary embodiments, the liquid-liquid-solid extraction process can include performing a temperature and / or pressure adjustment before the algal concentrate contacts the first solvent in the first contacting unit, before the first solvent enters the first contacting unit, during the contacting of the algal concentrate with the first solvent in the first contacting unit and / or any combination thereof.

[0222] In exemplary embodiments, the liquid-liquid-solid extraction process is a multi-stage process. A “multistage” liquid-liquid-solid extraction process is one wherein at least the first contacting unit, the first separating unit, the second contacting unit, the second separating unit and / or any combination thereof is at least duplicated to achieve the liquid-liquid-solid extraction process.

[0223] In exemplary embodiments, the liquid-liquid-solid extraction process includes outputting at least a portion of the biomass-rich phase and, optionally, at least a portion the heavy separated liquid phase and / or at least a portion of the light separated liquid phase as the algal biomass stream.

[0224] In exemplary embodiments, at least a portion of the light separated liquid phase is overflowed or pumped out of the second contacting unit or second separating unit, the biomass-rich phase is pumped out of the secondcontacting unit or second separating unit and / or the heavy separated liquid phase is removed from the bottom of the second contacting unit or second separating unit.

[0225] In exemplary embodiments, the liquid-liquid-solid extraction process is configured as a continuous process wherein the receiving of the algal concentrate from the feed source, the contacting of the algal concentrate with the first solvent in the first contacting unit to form the first dispersion, the allowing of the first dispersion to phase separate into the first separated liquid phase and the first remaining dispersion, the removing of at least a portion of the first separated liquid phase from the first remaining dispersion, the contacting of the first remaining dispersion with the second solvent in the second contacting unit to form the second dispersion, the allowing of the second dispersion to phase separate into the biomass-rich phase, the heavy separated liquid phase and the light separated liquid phase, and the separating of the at least one or more biomass-rich phase, heavy separated liquid phase, and / or light separated liquid phase are performed sequentially. Continuous operation can allow for the production of biofuels and / or other hydrophobic natural products with reduced capital and operating costs.

[0226] A variety of extraction equipment components can be used for continuous extraction including: the mixers and settlers, the countercurrent extraction columns, the centrifugal extractors, and the other classes of extractors disclosed herein.

[0227] The light separated liquid phase, the heavy separated liquid phase, the biomass-rich phase or a combination thereof can be stabilized against degradation by any of the following means including, but not limited to, with the addition of antioxidants, storage of the material in the absence of light exposure, storage under an inert environment such as nitrogen, argon, or carbon dioxide, and subjecting the material to a thermal cycle to destroy bacteria. Suitable antioxidants include, but are not limited to carotenoids, tertiary butyl hydroquinone (TBHQ), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), vitamin E, vitamin C, rosemary extracts, and combinations thereof.

[0228] In exemplary embodiments, the first contacting unit and the second contacting unit are countercurrent extraction columns, wherein the contacting of the algal concentrate with the first solvent to form the first dispersion and the allowing of the first dispersion to phase separate into the first separated liquid phase and the first remaining dispersion occur in the first contacting unit, and wherein the contacting of the first remaining dispersion with the second solvent to form the second dispersion and the allowing of the second dispersion to phase separate into the biomass-rich phase, the heavy separated liquid phase and the separated light separated liquid phase occur in the second contacting unit.

[0229] In exemplary embodiments, the liquid-liquid-solid extraction process includes repeating the contacting of the algal concentrate with the first solvent, or another solvent, in the first contacting unit to form the first dispersion and / or repeating the allowing of the first dispersion to phase separate into the first separated liquid phase and the first remaining dispersion in the first separating unit before the first remaining dispersion is transferred to the second contacting unit and / or any auxiliary contacting or separating unit.

[0230] In exemplary embodiments, the introducing of the algal biomass stream is performed at a first position within an active section of the countercurrent separation device, wherein the first position is located within 10% of a total length dimension of the active section of the counter-current separation device starting from a bottom of the active section. This may enable improved mixing of the aqueous stream and the algal biomass stream.

[0231] As used herein, the phrase “active section of the counter-current separation device” refers to the section or area of the counter-current separation device where the algal biomass stream and the aqueous stream contact one another or mix with each other.

[0232] In exemplary embodiments, the separation process includes introducing the algal biomass stream continuously into the counter-current separation device.

[0233] In exemplary embodiments, the separation process includes introducing the algal biomass stream periodically into the counter-current separation device. The term “periodically” in this context can include adding thealgal biomass stream to the counter-current separation device with a rate of 1 pulse every 30 seconds to 2 pulses every second, 1 pulse every 10 seconds, or 1 pulse per second.

[0234] In exemplary embodiments, at least part of the algal biomass stream is in the form of an emulsion.

[0235] In exemplary embodiments, the algal biomass stream being introduced into the counter-current separation device is a liquid-liquid-solid dispersion. The solid in this dispersion system can predominately include algal biomass and, optionally, also minor amounts of solid dirt and salts. The fraction of solids in this dispersion system can range from about 0.5-20 wt%, 1-15 wt%, 2-10 wt%. One of the liquids in this dispersion system is an aqueous phase that can include predominately water and, optionally, also minor amounts of salts, residual solvents, and other components used to adjust the pH or stabilize the algal biomass. Salts that can be present in this dispersion system include, but are not limited to, salts from ions that typically occur in seawater, such as NaCI. Residual solvents that can be present in this dispersion system include any potential extraction solvent disclosed herein. Components used to adjust the pH of the algal biomass include both strong and weak acids. Components used to stabilize the oils can include water-soluble antioxidants such as ascorbic acid, citric acid, formic acid, propionic acid, and other water-soluble antioxidants. The fraction of the aqueous phase in this dispersion system can range from about 10 to 80 wt%, 15-70 wt%, or 20-50 wt%.

[0236] In exemplary embodiments, the algal biomass stream includes from about 0.5 wt% to about 20 wt% solids.

[0237] In exemplary embodiments, the algal biomass stream includes about 10 wt% to about 80 wt% of an aqueous solution, wherein the aqueous solution contains at least one additive selected from a group including salts, solvents, pH adjusters and stabilizers.

[0238] In exemplary embodiments, the algal biomass stream includes about 10 wt% to about 80 wt% of the extraction solvent. The extraction solvent must form a second fluid phase (e.g., an organic phase) with the aqueous phase in the algal biomass stream when the two phases are allowed to separate. The extraction solvent can be selected from any of the petrochemical solvents,edible oil-based solvents, dense gas solvents, aqueous two-phase solvents, ionic liquid solvents, and combinations of miscible solvents disclosed herein. The extraction solvent can be chosen such that its polarity is appropriate to extract at least one algal hydrophobic product (e.g., algal oil, algal carotenoids, and other valuable non-polar compounds). The extraction solvent can also be any solvent system disclosed herein that forms a second immiscible liquid phase or layer with the algal biomass stream and does not adversely impact the quality or quantity of the natural products. These solvent systems can include synthetic and / or natural flavorants, edible oils, petrochemical solvents, dense gases, and combinations thereof so long as the solvent systems and the biomass forms two immiscible liquid phases at a desired phase separation zone temperature.

[0239] In exemplary embodiments, the algal biomass stream does not contain flocculants to lower the risk of contamination of the algal biomass.

[0240] The counter-current separation device can be an extraction column operated in counter-current mode. In these embodiments, the algal biomass stream and the aqueous stream(s) enter at different positions on the extraction column and that the extract or organic phase flows in the opposite direction of the raffinate or aqueous phase through the extraction column.

[0241] Suitable extraction columns which can be used include, but are not limited to, those that are mechanically agitated and those that have stationary internals. The latter can be used when the extraction solvent in the algal biomass stream is a dense gas and / or the operating pressure of the extraction column is elevated so that more expensive mechanical seals are needed. Suitable extraction columns with stationary internals can include, but are not limited to, spray, packed, perforated plate, baffle tray, sieve tray, and combinations thereof. Suitable packings include structured or random packings that are known to those skilled in the art. Suitable mechanically agitated extraction columns can include, but are not limited to: the KARR® reciprocating plate column, the Scheibel® Column, the rotating disc column (RDC), all made by Koch Modular Process Systems (KMPS), which is located in Paramus, USA, the Kuhni column, which is sold by Sulzer in Switzerland, the asymmetric rotating disc column, pulse columns, and combination thereof.

[0242] In exemplary embodiments, the counter-current separation device has a length-to-diameter ratio from about 2 to about 150, from about 2 to 100, from about 2 to 50, from about 2 to about 30, from about 2 to about 20, from about 2 to about 15, or greater than 2.

[0243] In exemplary embodiments, the separation process includes operating the counter-current separation device at about 50% to about 95% of a measured flooding flux of the counter-current separation device. Flux is defined as the volumetric flow rate of the combined liquid phase inputs (algal biomass stream plus all the aqueous streams) divided by the cross-sectional area of the counter-current separation device. The cross-sectional area of the countercurrent separation device is taken in the active section, where droplets are flowing in a countercurrent manner. For a given counter-current separation device, the flux can vary considerably depending on the physical properties, including but not limited to the densities and viscosities of each phase along with the interfacial tension, the presence of surfactants, and the direction of mass transfer. Typically, the flux can be increased to the point where the counter-current separation device floods. In exemplary embodiments, the counter-current separation device operates close to its flooding point. Thus, a desired flux in the counter-current separation device can be found by experimenting with specific systems and operating conditions and measuring the flux at which the counter-current separation device floods (flooding flux). The counter-current separation device can be operated so that the chosen operating flux minimizes the overall cost of the counter-current separation device based on its diameter and height.

[0244] In addition to the algal biomass stream (102), the exemplary process depicted in FIG. 1 also includes transferring an aqueous stream (104) into the counter-current separation device (100). The aqueous stream (104) flows in a direction opposite or counter-currently to the direction of the algal biomass stream (102).

[0245] The aqueous stream entering the counter-current separation device can be obtained from one or more sources including, but not limited to, a municipality, a potable water supply, distillation, reverse osmosis, a purification system, an ocean, a sea, a lake, a river or stream, an underground aquifer, acanal, an irrigation canal, or any combination thereof. The aqueous medium contained within the aqueous stream can include water, mineral salts, heavy metals, solvents, and / or other compounds found in water. In an exemplary embodiment, the aqueous stream is obtained from a potable water supply.

[0246] The aqueous stream entering the counter-current separation device can have a salinity greater than 5 wt% up to saturation, 10 wt % to saturation or 15 wt% to 25 wt%. In an exemplary embodiment, the aqueous stream entering the counter-current separation device has a salinity less than 5 wt%, less than 4 wt%, less than 3 wt%, less than 2 wt%, less than 1 wt%, less than 0.5 wt%, less than 0.1 wt% or less than 0.05 wt%.

[0247] The aqueous stream can contain any combination of ions found in seawater disclosed herein.

[0248] In exemplary embodiments, the introducing of the aqueous stream is performed at a second position within the active section of the counter-current separation device, wherein the second position is located within 10% of a total length dimension of the active section starting from a top of the active section. This may enable improved mixing of the aqueous stream and the algal biomass stream.

[0249] In exemplary embodiments, the separation process includes introducing the aqueous stream continuously into the counter-current separation device.

[0250] In exemplary embodiments, the separation process includes introducing the aqueous stream periodically into the counter-current separation device. The term “periodically” in this context can include adding the aqueous stream to the counter-current separation device with a rate of 1 pulse every 30 seconds to 2 pulses every second, 1 pulse every 10 seconds, or 1 pulse per second.

[0251] In exemplary embodiments, the aqueous stream has a lower salinity than the algal biomass stream. An advantage of using an aqueous stream with a lower salinity than the algal biomass stream is that the aqueous stream can remove salt more effectively from the extraction solvent and / or extract phase entrained within the algal biomass stream.

[0252] In exemplary embodiments, the separation process includes introducing the algal biomass stream and the aqueous stream into the counter-current separation device at an algal biomass stream-to-aqueous stream ratio fromabout 0.1 to 10 or from about 0.2 to 8. The volumetric flow for the algal biomass stream and the aqueous stream(s) can be measured in cubic meters per hour. The aqueous stream volumetric flow is the sum of the volumetric flow of all of the aqueous streams introduced into the counter-current separation device.

[0253] The exemplary process in FIG. 1 also depicts the counter-current mixing of the algal biomass stream (102) and the aqueous stream (104) in a mixing zone (106) of the counter-current separation device (100). After the mixing, the resulting dispersion is allowed to separate in a separation zone (108) of the counter-current separation device (100) until an organic phase (110), and aqueous phase (112) and an interface (114) form. The organic phase contains algal hydrophobic products (116) and leaves the counter-current separation device (100) as an overflow stream (118). The aqueous phase (112) contains algal biomass (120) and leaves the counter-current separation device (100) as an underflow stream (122). It should be understood that the terms “mixing zone” may be interchangeable with the terms “extraction zone” as used herein and hereafter. Therefore, the exemplary process in FIG. 1 also depicts the counter-current mixing of the algal biomass stream (102) and the aqueous stream (104) in an extraction zone (106) of the counter-current separation device (100).

[0254] In exemplary embodiments, the aqueous phase contains essentially all of the algal biomass contained in the algal biomass stream. In this context, “essentially all” means that at least 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95wt% or 99 wt% of the algal biomass contained in the algal biomass stream is contained in the aqueous phase.

[0255] The aqueous phase can predominately contain the raffinate and algal biomass containing a slight amount of entrained extract phase. The salinity of the aqueous phase can be less than the algal biomass stream due to dilution with the aqueous stream(s).

[0256] In exemplary embodiments, the organic phase contains essentially all of the extraction solvent and, optionally, essentially all of the algal hydrophobic products entrained in the algal biomass stream. In this context, “essentially all” means that at least 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95wt% or 99wt% of the extraction solvent and algal hydrophobic products entrained in the algal biomass stream is contained in the organic phase.

[0257] The organic phase can contain dissolved algal hydrophobic products from the algal biomass stream and, optionally, contain a slight amount of entrained biomass and entrained raffinate droplets. The salt concentration of the organic phase can be less than the extract entrained in the algal biomass stream.

[0258] The interface located between the organic and aqueous phases can be a flat liquid-liquid interface that covers the cross sectional area of the countercurrent separation device. In exemplary embodiments, on one side of the interface, the organic phase is the continuous phase, and on the other side of the interface, the aqueous phase is the continuous phase. In exemplary embodiments, solids do not accumulate or accumulate to a much lower extent in the interface compared to e.g. conventional processes practiced in the art and comparative examples provided in the present disclosure. In exemplary embodiments, the interface contains a volumetric region of an emulsion optionally extending less than about 10 centimeters or less than about 5 centimeters on each side of the liquid-liquid interface and does not accumulate substantial amounts of solids. In the comparative examples provided in the present disclosure, the interface contains an emulsion that contains the solids in the volumetric region of the interface on both sides of the liquid-liquid interface.

[0259] A possible way to determine the efficiency of the separation process is to calculate that selectivity of the process. The selectivity of the process can be calculated by dividing the extraction factor of the algal hydrophobic products by the extraction factor of the algal biomass. The higher the selectivity - the better the separation process is at separating the algal hydrophobic products from the algal biomass. A formula for calculating selectivity is provided below:S = Dm (oil) + Dm (biomass)

[0260] S is the selectivity of the separation process, Dm (oil) is the extraction factor of at least one hydrophobic product, and Dm (biomass) is the extraction factor of the algal biomass.

[0261] As used herein, the term “extraction factor” is defined as the mass flow of either an algal hydrophobic product or an algal biomass in the counter-currentseparation device’s overflow divided by the mass flow of the algal hydrophobic product or the algal biomass in the counter-current separation device’s underflow. A formula for calculating an extraction factor is provided below: Dm (component) = m(component)OVerfiow + m(component)Underfiow

[0262] The component can be either an algal hydrophobic product or an algal biomass, m(component)OVerfiow is the mass flow of the component into the overflow of the counter-current separation device, and m(component)Underfiow is the mass flow of the component into the underflow of the counter-current separation device.

[0263] The extraction factor can show the efficiency of the counter-current separation device’s ability to extract or move an algal hydrophobic product into one outlet stream versus another. If the extraction factor of the algal hydrophobic product is unity, then the algal hydrophobic product flows evenly into the overflow and underflow streams of the counter-current separation device, thus resulting in poor separation of the algal hydrophobic product in the process. If the extraction factor of the algal hydrophobic product is very high, the algal hydrophobic product will predominately exit the counter-current separation device in the overflow stream. If the extraction factor of the algal hydrophobic product is very low, then the algal hydrophobic product will predominately exit the counter-current separation device in the underflow stream. The extraction factor for every hydrophobic algal product can be different depending on the extraction process used to extract the hydrophobic algal product from the algal concentrate.

[0264] In exemplary embodiments, the separation process includes (i) counter- currently mixing the algal biomass stream and the aqueous stream in a first separation device, (ii) transferring the resulting dispersion from the countercurrent mixing to a second counter-current separation device, an extraction zone or a separation zone, and (iii) allowing the resulting dispersion to separate into the organic phase, interphase and aqueous phase in the second countercurrent separation device, extraction zone or separation zone.

[0265] In exemplary embodiments, the algal hydrophobic products entrained in the algal biomass stream have an extraction factor greater than unity (i.e., greater than 1 ).

[0266] In exemplary embodiments, the algal biomass entrained in the algal biomass stream has an extraction factor less than unity.

[0267] In exemplary embodiments, the separation process has a selectivity of at least 2, at least 3, at least 4, or at least 5. In exemplary embodiments, the separation process has a selectivity of at least 10 or at least 20.

[0268] In exemplary embodiments, the separation process includes operating the counter-current separation device at atmospheric pressure. The operating of the counter-current separation device at atmospheric pressure can occur throughout the entire separation process or can occur at specific steps of the separation process.

[0269] The counter-current separation device can operate at nearly atmospheric pressure. In exemplary embodiments, the counter-current separation device operates under a slight vacuum that is about up to about 30% below atmospheric pressure. In other exemplary embodiments, the counter-current separation device operates under a slight amount of pressure wherein the solvent vaporizes below a certain operating pressure (e.g., about 2-10 bar). In other exemplary embodiments, the operating pressure of the counter-current separation device is greater than the vapor pressure of lowest boiling solvent in the system so that gas bubbles of solvent are not generated in the countercurrent separation device.

[0270] In exemplary embodiments, the separation process includes operating the counter-current separation device at a temperature ranging from 0°C to 150°C. The operating of the counter-current separation device at a temperature ranging from 0°C to 150°C can occur throughout the entire separation process or can occur at specific steps of the separation process.

[0271] The operating temperature in the counter-current separation device can range from about 0-150°C, 0-100°C, 10-100°C, 20-80°C, or 30-70°C. The minimum temperature that the counter-current separation device can operate at is based on the viscosity and freezing point of the components in the algal biomass stream and aqueous stream. The maximum temperature that the counter-current separation device can operate at is based on the degradation temperature of the components in the system.

[0272] The counter-current separation device can operate at a pH between 2- 12, 3-11 or 4-10. The minimum pH is set to allow preservation of the components in the system when acids are added to stabilize the components. The maximum pH is set to that which occurs naturally in aquaculture systems during daylight respiration.

[0273] In exemplary embodiments, the separation process includes recovering the organic phase and / or the aqueous phase from the counter-current separation device. Additionally, or alternatively, the process further comprises, after allowing separation of an organic phase and an aqueous phase, recovering, at least partially, preferably essentially all, the algal hydrophobic products and / or recovering, at least partially, preferably essentially all, the algal biomass.

[0274] In exemplary embodiments, the separation process includes operating the process in a continuous flow.

[0275] In exemplary embodiments, the separation process includes introducing one or more additional aqueous streams into the counter-current separation device. In an exemplary embodiment, an aqueous stream containing a low salinity (e.g., < 0.05 wt%) and an aqueous stream containing a higher salinity (e.g., 3 - 5 wt% or > 5 wt%) are introduced into the counter-current separation device, the aqueous stream containing the low salinity being introduced at a position above the aqueous stream containing the higher salinity. Performing the separation process in this manner can allow the organic phase or extract phase exiting the top of the counter-current separation device to have a low salinity, and reduce the amount of water with low salinity used during the process. In these exemplary embodiments, the aqueous stream containing a low salinity can be a freshwater stream and the aqueous stream containing the higher salinity can be a sea water stream.

[0276] An exemplary process wherein the separation process includes introducing one or more additional aqueous streams is shown in FIG. 2. In this embodiment, an algal biomass stream (202) is transferred into a counter-current separation device (200). In addition to the algal biomass stream (202), the exemplary process depicted in FIG. 2 also includes transferring a first aqueous stream (204a), a second aqueous stream (204b) and a third aqueous stream(204c) into the counter-current separation device (200). The aqueous streams (204a, 204b, 204c) flow in a direction opposite or counter-currently to the direction of the algal biomass stream (202).

[0277] The exemplary process in FIG. 2 also depicts the counter-current mixing of the algal biomass stream (202) and the aqueous streams (204a, 204b, 204c) in a mixing zone (206) (extraction zone (206)) of the countercurrent separation device (200). After the mixing, the resulting dispersion is allowed to separate in a separation zone (208) of the counter-current separation device (200) until an organic phase (210), and aqueous phase (212) and an interface (214) form. The organic phase (210) contains algal hydrophobic products (216) leaves the counter-current separation device (200) as an overflow stream (218). The aqueous phase (212) contains algal biomass (220) and leaves the counter-current separation device (200) as an underflow stream (222).

[0278] In exemplary embodiments, the separation process includes introducing one or more additional aqueous streams into the counter-current separation device, wherein the one or more additional aqueous streams are ordered from low salinity to high salinity, the stream with the lowest salinity being the closest to the top of the counter-current separation device.

[0279] In exemplary embodiments, the separation process includes (i) introducing a freshwater stream at a position within the active section of the counter-current separation device, wherein the position is located within 10% of a total length dimension of the active section starting from a top of the active section, (ii) introducing a first additional aqueous stream having a salinity of about 3.5 wt% or more below the position of the freshwater stream, and (iii) introducing a second aqueous stream having a salinity of about 6 wt% or more below the first additional aqueous stream. This may enable improved mixing of the aqueous stream and the algal biomass stream.

[0280] In exemplary embodiments, the separation process includes introducing one or more additional aqueous streams into the counter-current separation device at a position different from the position that the algal biomass stream is introduced into the counter-current separation device.

[0281] In exemplary embodiments, the separation process includes introducing one or more additional aqueous streams into the counter-current separation device continuously.

[0282] In exemplary embodiments, the separation process includes introducing one or more additional aqueous streams into the counter-current separation device periodically. The term “periodically” in this context can include introducing the one or more additional aqueous streams into the counter-current separation device with a rate of 1 pulse every 30 seconds to 2 pulses every second, 1 pulse every 10 seconds, or 1 pulse per second.

[0283] In exemplary embodiments, the counter-current separation device includes at least one coalescer that is optionally located in the counter-current separation device and / or connected to the counter-current separation device.

[0284] An exemplary process wherein the counter-current separation device includes at least one coalescer located in the counter-current separation device is shown in FIG. 3. In this embodiment, an algal biomass stream (302) is transferred into a counter-current separation device (300). In addition to the algal biomass stream (302), the exemplary process depicted in FIG. 3 also includes transferring an aqueous stream (304) into the counter-current separation device (300). The aqueous stream (304) flows in a direction opposite or counter-currently to the direction of the algal biomass stream (302).

[0285] The exemplary process in FIG. 3 also depicts the counter-current mixing of the algal biomass stream (302) and the aqueous stream (304) in a mixing zone (306) (extraction zone (306) of the counter-current separation device (300). After the mixing, the resulting dispersion is transferred through a coalescer (308) to help enhance recovery of various small droplets of extraction solvent and / or algal hydrophobic products and is allowed to separate in a separation zone (310) of the counter-current separation device (300) until an organic phase (312), an aqueous phase (314) and an interface (316) form. The organic phase (312) contains algal hydrophobic products (318) and leaves the counter-current separation device (300) as an overflow stream (320). The aqueous phase (314) is transferred through a coalescer (324) to help enhance recovery of algal biomass (322) and leaves the counter-current separation device (300) as an underflow stream (326).

[0286] The at least one coalescer can be selected from mesh pad coalescers, wire pad coalescers, plastic pad coalescers, glass pad coalescers, structured packing, inclined plates, perforated plates, baffles, ultrasonic waves, acoustic waves, electric fields, gravitational fields, and combinations thereof.

[0287] In exemplary embodiments, the counter-current separation device includes multiple coalescers located between agitators in the counter-current separation device. There may be between about 2 and 200 separate mixeragitator pairs located along the length of the extraction zone.

[0288] An exemplary process wherein the counter-current separation device includes multiple coalescers located in the counter-current separation device is shown in FIG. 4. In this embodiment, an algal biomass stream (402) is transferred into a counter-current separation device (400). In addition to the algal biomass stream (402), the exemplary process depicted in FIG. 4 also includes transferring an aqueous stream (404) into the counter-current separation device (400). The aqueous stream (404) flows in a direction opposite or counter-currently to the direction of the algal biomass stream (402).

[0289] The exemplary process in FIG. 4 also depicts the counter-current mixing of the algal biomass stream (402) and the aqueous stream (404) in a mixing zone (406) (extraction zone (406) of the counter-current separation device (400), the mixing zone (406) (extraction zone (406) containing three coalescers (408a, 408b and 408c) to help enhance the recovery of biomass materials. The counter-current separation device (400) is also equipped with a mixer (410) to aid in the counter-current mixing of the algal biomass stream (402) and the aqueous stream (404). After the mixing, the resulting dispersion is allowed to separate in a separation zone (412) of the counter-current separation device (400) until an organic phase (414), an aqueous phase (416) and an interface (418) form. The organic phase contains algal hydrophobic products (420) and leaves the counter-current separation device (400) as an overflow stream (422). The aqueous phase (416) contains algal biomass (424) and leaves the countercurrent separation device (400) as an underflow stream (426).

[0290] An exemplary process wherein the counter-current separation device includes at least one coalescer system connected to the counter-current separation device is shown in FIG. 5. In this embodiment, an algal biomassstream (502) is transferred into a counter-current separation device (500). In addition to the algal biomass stream (502), the exemplary process depicted in FIG. 5 also includes transferring an aqueous stream (504) into the countercurrent separation device (500). The aqueous stream (504) flows in a direction opposite or counter-currently to the direction of the algal biomass stream (502).

[0291] The exemplary process in FIG. 5 also depicts the counter-current mixing of the algal biomass stream (502) and the aqueous stream (504) in a mixing zone (506) (extraction zone (506) of the counter-current separation device (500), the mixing zone (506) (extraction zone (506) containing three coalescers (508a, 508b and 508c) to help enhance the recovery of biomass materials. The counter-current separation device (500) is also equipped with a mixer (510) to aid in the counter-current mixing of the algal biomass stream (502) and the aqueous stream (504). After the mixing, the resulting dispersion is allowed to separate in a separation zone (512) of the counter-current separation device (500) until an organic phase (514), an aqueous phase (516) and an interface (518) form. The organic phase contains algal hydrophobic products (520) and leaves the counter-current separation device (500) as an overflow stream (522).

[0292] The aqueous phase (516) contains algal biomass (524) and leaves the counter-current separation device (500) as an underflow stream (526). The underflow stream (526) is transferred to a coalescer system (528) containing at least one coalescer (530) that enhances recovery of various small droplets of raffinate and / or algal biomass. Once the underflow stream (526) passes through the at least one coalescer (530), the algal biomass (524) is separated from at least a portion of the raffinate and subjected to further downstream processing. The overflow stream (522) is also transferred to a coalescer system (532) containing at least one coalescer (534) that enhances recovery of various small droplets of an organic solvent. Once the overflow stream (522) passes through the at least one coalescer (534), the algal hydrophobic products (520) are separated from at least a portion of the organic phase and subjected to further downstream processing.

[0293] Another aspect of the present disclosure is a system for separating and optionally desalting algal hydrophobic products from an algal biomass stream, the system including at least one or more of: a counter-current separationdevice possessing an algal biomass stream input and at least one aqueous stream input, wherein the algal biomass stream input is either located at a position below or above the aqueous stream input; an algal biomass stream feed line configured to communicate with the algal biomass stream input and an extraction zone; and at least one aqueous stream feed line configured to communicate with the at least one aqueous stream input and an aqueous stream reservoir. In exemplary embodiments, the system comprises a countercurrent separation device possessing an algal biomass stream input and at least one aqueous stream input, wherein the algal biomass stream input is either located at a position below or above the aqueous stream input, and wherein the counter-current separation device comprises an extraction zone; an algal biomass stream feed line configured to communicate with the algal biomass stream input and the extraction zone; and at least one aqueous stream feed line configured to communicate with the at least one aqueous stream input and an aqueous stream reservoir. In exemplary embodiments, the system comprises a counter-current separation device possessing an algal biomass stream input and at least one aqueous stream input, wherein the algal biomass stream input is either located at a position below or above the aqueous stream input; an upstream extraction zone; an algal biomass stream feed line configured to communicate with the algal biomass stream input and the upstream extraction zone; and at least one aqueous stream feed line configured to communicate with the at least one aqueous stream input and an aqueous stream reservoir. In embodiments, the system comprises a counter-current separation device possessing an algal biomass stream input and at least one aqueous stream input, wherein the algal biomass stream input is either located at a position below or above the aqueous stream input; an extraction zone, preferably the extraction zone is an upstream extraction zone; an aqueous stream reservoir configured to transport at least one aqueous stream to the at least one aqueous stream input; an algal biomass stream feed line configured to communicate with the algal biomass stream input and the extraction zone preferably the upstream extraction zone; and at least one aqueous stream feed line configured to communicate with the at least one aqueous stream input and the aqueous stream reservoir. It should be understood that the terms “extractionzone” may be interchangeable with the terms “mixing zone” as used herein and hereafter.

[0294] As used herein, the phrase “configured to communicate” includes any structural component that is capable of connecting one component of the system to another (e.g., a tube, a pipe, or a canal).

[0295] In exemplary embodiments, the counter-current separation device of the system includes an underflow output and an overflow output. In exemplary embodiments the underflow output is configured to remove at least part of the algal biomass and at least part of the aqueous solution from the counter-current separation device, and / or the overflow output is configured to remove at least part of the extraction solvent and at least part of the algal hydrophobic products from the counter-current separation device.

[0296] In exemplary embodiments, the system includes at least one coalescer located either within the counter-current separation device or in at least one coalescing system in communication with the counter-current separation device.

[0297] In exemplary embodiments, the at least one coalescer is located in the at least one coalescing system and the at least one coalescing system is in communication with either the underflow output or the overflow output of the counter-current separation device.

[0298] In exemplary embodiments, the at least one coalescer is a mesh pad coalescer, a wire pad coalescer, a plastic pad coalescer, a glass pad coalescer, a structured packing, an inclined plate, a perforated plate, a baffle, an ultrasonic wave, an acoustic wave, an electric field or a gravitational field.

[0299] In exemplary embodiments, the counter-current separation device of the system includes one or more additional aqueous stream inputs located at a position either above or below the position of the at least one aqueous stream input and above the position of the algal biomass stream input. These embodiments may allow one to add an aqueous stream with lower salinity close to the top of the countercurrent separation device and, therefore, one may use seawater as a feed lower in the separation device. There may be a salinity gradient in the extraction zone, so these embodiments may allow for less fresh water usage. Therefore, these embodiments may allow for a more sustainable process and device to be used in this process.

[0300] In exemplary embodiments, the one or more additional aqueous stream inputs are configured to communicate with one or more additional aqueous stream feed lines.

[0301] In exemplary embodiments, the one or more additional aqueous stream feed lines are configured to communicate with one or more additional aqueous stream reservoirs.

[0302] The aqueous stream reservoirs can be an open lake, a pond, and / or a vessel holding an aqueous media that can be derived from a distillation process, a membrane process, an adsorption process, or another desalination process, or combinations thereof.

[0303] In exemplary embodiments, the extraction zone of the system includes at least one or more of a separation device, a static mixing device, a co-current extraction column, a countercurrent extraction column, a centrifugal extractor, an agitated vessel, an emulsion phase separation device, and / or any combination thereof.

[0304] In exemplary embodiments, the system includes at least one separation zone configured to separate an algal dispersion into multiple layers. In exemplary embodiments, the separation zone is located within the extraction zone. In exemplary embodiments, the separation zone includes a decanter configured to perform at least one of gravity settling, centrifugal settling or combinations thereof. In exemplary embodiments, the separation zone includes one or more fixed or moving separation aids like mesh pad coalescers, wire pad coalescers, structured packing, inclined plates, perforated plates, baffles, ultrasonic waves, acoustic waves, and / or combinations thereof. The separation zone can also include centrifugal extractors and / or emulsion phase contactors disclosed herein. The at least one separation zone can be included within the at least one extraction zone, outside the at least one extraction zone or at any location in the system. In embodiments, the at least one separation zone configured to separate an algal dispersion into multiple layers is at least two separation zones configured to separate an algal dispersion into multiple layers, wherein one of the at least two separation zones is a separation zone (108, 208, 310, 412, 512) of the counter-current separation device (100, 200, 300, 400, 500) and one of the at least two separation zones is an upstreamseparation zone located within the upstream extraction zone and configured to operatively communicate with the algal biomass stream feed line (i.e., therefore, also with the counter-current separation device (100, 200, 300, 400, 500).

[0305] In exemplary embodiments, the system includes at least one controller configured to maintain a given flow ratio of an algal biomass stream to an aqueous stream that is fed to the counter-current separation device. The at least one controller can include, but is not limited to, process control systems provided by ABB, Siemens, Emerson, and others known to those skilled in the art. These control systems can manipulate process control valves that regulate flow of the streams as desired.

[0306] The controller can be configured to regulate the ratio of the flow rates of the algal biomass stream and the aqueous stream(s). The controller can also be configured to regulate the counter-current separation device’s flux (cubic meters / hour / m2) by regulating the flow of the algal biomass stream and the aqueous stream(s).

[0307] In exemplary embodiments, the system includes at least one algal aquaculture zone configured to operatively communicate with the extraction zone, preferably the upstream extraction zone. The at least one algal aquaculture zone can include tubular reactors, photobioreactors, enclosed raceways, covered ponds, open raceways, open ponds, earthen ponds, ponds in greenhouses, clear plastic bags hung either indoors or outdoors, fermenters, naturally occurring bodies of water, solar salt ponds, and combinations thereof.

[0308] In exemplary embodiments, the system includes at least one harvesting zone configured to operatively communicate with the extraction zone, preferably the upstream extraction zone, and the at least one algal aquaculture zone, the at least one harvesting zone optionally being configured to perform an adsorptive bubble separation process on an algal biomass stream.

[0309] The harvesting zone can include a harvester. In exemplary embodiments, the harvester contains or is an adsorptive bubble separation unit. The adsorptive bubble separation unit can utilize a flotation aid, a frother, a collector, and / or an activator, or any combination thereof. In other exemplary embodiments, the harvester includes or is a filter, a deep bed filter, a belt press, a screw press, a centrifuge, an adsorber, a sedimentation unit, a mechanicalflotation unit, a dissolved gas flotation unit, a froth flotation unit, a flocculation unit, or any combination thereof.

[0310] Another aspect of the present disclosure is a system for separating and desalting algal hydrophobic products from an algal biomass stream, the system including at least one or more of: a means for (i) performing a counter-current extraction between an algal biomass stream and an aqueous stream and (ii) producing an interface between an organic phase and an aqueous phase, the organic phase being essentially free of algal biomass; an extraction zone, preferably an upstream extraction zone, configured to transport an algal biomass stream to the means; and an aqueous stream reservoir configured to transport at least one aqueous stream to the means. Additionally, or alternatively, the extraction zone is an upstream extraction zone configured to transport an algal biomass stream to the means, and the system comprises at least one algal aquaculture zone configured to operatively communicate with the upstream extraction zone.

[0311] In exemplary embodiments, the means includes, but is not limited to, any counter-current separation device disclosed herein, and other structural components known in the art capable of performing counter-current extractions. In exemplary embodiments, the extraction zone is an upstream extraction zone configured to operatively communicate with the algal biomass stream feed line or configured to transport an algal biomass stream to the means.

[0312] Exemplary uses of the systems, processes, products, components and compositions disclosed herein are also encompassed by the present disclosure. For example, any of the systems disclosed herein can also be used to separate and / or desalt algal hydrophobic products from an algal biomass stream. Any of the processes disclosed herein can be used (e.g., in combination with the systems disclosed herein) to separate and / or desalt algal hydrophobic products from the algal biomass stream.

[0313] The algal hydrophobic products separated from an algal biomass stream and / or desalted with the systems and processes disclosed herein can include at least one or more of lipids, algal lipids, carotenoids, fatty acids, algal fatty acids, triacylglycerols, diacylglycerols, monoacylglycerols, oils, algal oils or any combination thereof.

[0314] Any of the components that can be included within the systems disclosed herein can be located at any position in the system.

[0315] The algal hydrophobic products and / or the algal biomass recovered from the systems and separation processes disclosed herein can be used to produce various products including, but not limited to, biofuels, animal feed, animal feed ingredients, human food, human food ingredients, soil builders, chemical intermediates, renewable plastics, renewable polymers, renewable chemicals, nutraceuticals, cosmaceuticals, soaps or components of a soap or detergent compositions, spa products, and cosmetic ingredients (e.g., carotenoids, omega fatty acids, and other lipids).

[0316] Biofuels that can be produced from high temperature processing of the recovered algal hydrophobic products and / or algal biomass include, but are not limited to, biodiesel, green diesel, renewable diesel, sustainable aviation fuel, jet fuel, marine fuel, methane, alcohols, and dried algal biomass. Algal biodiesel is produced via any transesterification process known in the art, including those which utilize two immiscible liquid phases, and those that utilize a solid acid catalyst. For example, sustainable aviation fuel, renewable diesel or green diesel can be produced by hydrogenation, cracking, or a combination thereof of the algal oil or any derivative thereof in order to produce hydrocarbons that can be used directly in the existing diesel distribution system. Methane and / or hydrogen can be produced from the recovered algal hydrophobic products and / or algal biomass by any anaerobic process known in the art. Fermentation of the recovered algal hydrophobic products and / or algal biomass can occur through any process known in the art to produce methanol, ethanol, butanol, n- butanol, i-butanol, other alcohols, and combinations thereof. The recovered algal hydrophobic products and / or algal biomass can be torrified for the production of a soil builder or for use in combination with coal for power or steam generation. The biomass material can be processed e.g. via hydrothermal liquefaction or hydrothermal carbonization to produce bio-based oil (also referred to as biocrude or biocrude oil), chemicals and / or char. The recovered algal hydrophobic products and / or algal biomass can be gasified, pyrolyzed or combusted either by itself or in combination with coal or biomass.

[0317] Suitable animal feeds include, but are not limited to, feeds for shrimp, fish, shellfish, brine shrimp, chickens, poultry, cows, ducks, dogs, pigs, sheep, goats, and combinations thereof.

[0318] Suitable dietary supplements include, but are not limited to alphacarotene, beta-carotene, lutein, zeaxanthin, cryptoxanthin, phytoene, phytofluene, and the various cis- and trans-isomers and the various alpha, beta, gamma, delta isomers of the various carotenoids, and combinations thereof. Suitable dietary supplements also include various unsaturated fatty acids as well as protein meal, protein concentrates, protein isolates, biomass powder and / or algae biomass powder.

[0319] Suitable methods of carbon storage include, but are not limited to, burying the recovered algal hydrophobic products and / or algal biomass, sinking them, torifying them and using them as a soil builder, or combinations thereof.

[0320] Suitable methods for water and wastewater treatment include, but are not limited to, removal of BOD (biological oxygen demand), and or TOC (total organic carbon) from a water stream. This can be useful for municipal wastewater treatment processes, and it can be important for the treatment of brines being used for the production of sodium chloride salt and other salts via evaporation.

[0321] Suitable methods to process the recovered algal hydrophobic products and / or algal biomass into useful compounds include, but are not limited to, torification, gasification, pyrolysis, liquefaction, hydrothermal liquefaction, fermentation, anaerobic digestion, drying, combustion, burial, and combinations thereof. Suitable applications of the torified algal hydrophobic products and / or algal biomass include, but are not limited to, a soil builder and a material to be combined with coal, wood, or other combustible material for power generation. Suitable applications of gasified algal hydrophobic products and / or algal biomass include, but are not limited to, the production of the entire suite of products that can be produced via syngas chemistry, as described by the Gasification Technologies Council. Suitable products from syngas include, but are not limited to, chemicals, fertilizers, power generation, substitute natural gas, hydrogen, and transportation fuels. Suitable chemicals include, but are not limited to, hydrogen, carbon monoxide, methanol, dimethyl ether, acetic acid,propionic acid, butyric acid, acetic anhydride, methyl acetate, ethylene, propylene, olefins, and combinations thereof. Suitable fertilizers that can be produced from the syngas include, but are not limited to ammonia, ammonium nitrate, urea, and others known in the art. Suitable substitute natural gas can be generated from the syngas produced by gasifying the recovered algal hydrophobic products and / or algal biomass, and this includes methane. Suitable liquid fuels include gasoline, diesel fuel, jet fuels, and combinations thereof. All of the chemicals that are produced by Eastman Chemicals and by Sasol via their gasification processes can also be produced by the gasification of the recovered algal hydrophobic products and / or algal biomass. Products produced by the utilization of syngas can also be produced by gasification of the recovered algal hydrophobic products and / or algal biomass. Illustrative processes are described in U. S. Pat. No. 6,310,260, the contents of which are incorporated herein by reference in their entirety, include, for example, hydroformylation, hydroacylation (intramolecular and intermolecular), hydrocyanation, hydroamidation, hydroesterification, aminolysis, alcoholysis, hydrocarbonylation, reductive hydroformylation, hydrogenation, olefin oligomerization, hydroxycarbonylation, carbonylation, olefin isomerization, transfer hydrogenation and the like. Other processes involve the reaction of organic compounds with carbon monoxide, or with carbon monoxide and a third reactant, e.g., hydrogen, or with hydrogen cyanide, in the presence of a catalytic amount of a metal-organophosphorus ligand complex catalyst. More advantageous processes include hydroformylation, hydrocyanation, hydrocarbonylation, hydroxycarbonylation and carbonylation.Examples

[0322] The present disclosure will be described in more detail with reference to the following Examples, which shows exemplary embodiments in accordance with the present disclosure. The present disclosure is not limited to these exemplary embodiments.

[0323] Example 1

[0324] The objective of this example was to separate algal oil containing carotenoids from an algal biomass stream originating from an liquid-liquid-solid extraction.

[0325] A semi-continuous algal biomass liquid-liquid-solid extraction process was performed at 70 °C and produced an algal biomass stream containing an emulsion of water, salt, algal biomass and extract phase including heptane solvent, algal oil, and hydrophobic materials such as carotenoids. This stream was collected. The bottom layer containing water and salt settled rapidly within a few minutes, and was thereafter decanted off, allowing for a draw-off from the remaining middle layer emulsion (i.e., the “rag layer”) to be taken as an algal biomass stream. The formed extract layer was not touched.

[0326] The algal biomass stream containing the “rag layer” was fed to the bottom of an extraction column at a temperature of 50°C. Fresh DI water was added at the top of the extraction column, and this stream was heated to 50°C. The DI water to algal biomass stream ratio was 1 :1 on a mass basis, with a flux of 62% of flooding. The algal biomass stream was maintained as the dispersed phase and the interface was formed at the top of the column.

[0327] The underflow (raffinate) from the extraction column included a dispersion of water, salt, algal biomass and solvent phase. The overflow (extract) included the algal oil, carotenoids, and solvent.

[0328] The overflow was found to contain very few algal solids, less than 5% of the total biomass feed. The underflow was centrifuged, and three distinct phases were observed on a volume basis; a top solvent-rich phase of about 21 %, a central aqueous phase of about 76%, and a bottom solid-rich phase of about 3%. Thus, the biomass was wetted by water instead of solvent.

[0329] In the column overflow, the process recovered 65% of the extract entrapped in the rag layer. At the same time, the chloride concentration of the extract phase was reduced by about 38%, and sodium by about 60% (chlorides reduced from 13 ppm to <8 ppm, sodium reduced from 7 ppm to 2.7 ppm).

[0330] The concentration of oil was determined via the concentration of the marker compound beta-carotene. The extraction factor for oil, Dm(oil), was defined as the ratio of the total mass of oil in the overflow to that of the underflow, giving a Dm(oil) of 1 .11 .

[0331] The extraction factor for the biomass, Dm(biomass), was defined as the ratio of the total mass of solid in the overflow to that of the underflow, giving a resulting Dm(biomass) of 0.05.

[0332] Process performance of the separation of oil and biomass was evaluated based on the selectivity of oil to biomass. The selectivity (S) of oil to biomass was defined as the ratio of the extraction factors Dm(oil) to Dm(biomass), resulting in a selectivity of oil to biomass of 20.7. This shows that the process of Example 1 is selective for oil instead of biomass.

[0333] Example 2: Comparative Example

[0334] The objective of this example was to separate algal oil (containing carotenoids) from algal biomass.

[0335] An algal biomass stream containing an emulsion of water, salt, algal biomass, carotenoids, and algal oil was preheated to a process temperature of 70°C and fed to the top of an extraction column (same column as in Example 1)-

[0336] A solvent stream containing heptane was fed to the bottom of the extractor at 70°C. The solvent stream to algal biomass stream ratio was maintained at 0.5 with a flux of 44% of flooding. The algal biomass stream was maintained as the dispersed phase and the interface was formed at the bottom of the column.

[0337] The underflow (raffinate) from the extraction column contained a dispersion of water, salt, algal biomass and solvent phase. The overflow (extract) contained the algal oil and carotenoids. The overflow was found to contain very few algal solids, less than 5% of the total biomass feed.

[0338] The extraction factor for oil, Dm(oil), in this example was measured via the marker compound beta carotene, and was found to be 0.11 . The extraction factor for biomass, Dm(biomass), in this example was found to be 0.05.

[0339] Process performance of the separation of oil and biomass was evaluated in this example based on the selectivity of oil to biomass. The selectivity (S) of oil to biomass was defined as the ratio of the extraction factors Dm(oil) to Dm(biomass), resulting in a selectivity of oil to biomass of 2.1 .

[0340] When compared to the process of Example 1 , the process of Example 1 had a selectivity of oil to biomass that was about 10 times greater than the process of Example 2, thereby indicating that the process of Example 1 had better process performance in separating oil from biomass.

[0341] Examples 3 and 4: Comparative Examples

[0342] Examples 3 and 4 were carried out in a similar manner as Example 2, but with varying flux, solvent-to-algal biomass stream ratios and agitation. Also, in these examples the overflow (extract) contained algal oil, carotenoids, and very few algal solids (i.e., less than 5% of the total biomass feed).

[0343] Table 1 below presents an overview of the process parameters and results for Examples 1-4. The agitation rate in all examples was about the same. A Karr column was used for all the examples with a 125 length-to- diameter ratio of the active section.Table 1 : Overview of results for Examples 1-4Table 1 Legend: A. Example Number, B. Temperature [°C], C. Solvent, D.Solvent to Feed Ratio (mass), E. Flux [% of flooding], F. Extract recovered in column overflow, G. Biomass recovered in column underflow, H. Extraction factor for oil,Dm(oil), I. Extraction factor for biomass, Dm(biomass), J. Selectivity of oil to biomass.

[0344] Examples 1-4 clearly show the order of magnitude in process improvement, in terms of selectivity of oil to biomass, that the processes disclosed herein provide.

[0345] Example 5: Comparative Example (mixer-settler)

[0346] Saline aqueous D. salina (1 wt% biomass in 20 wt-% saline solution, termed “the feed”) was added to a suitable, 3L batch reactor with the following parameters: a jacketed, cylindrical mixer-settler vessel with straight verticalwalls to allow the phases to settle by gravity. Additional four equally spaced vertically arranged baffles were used to aid in mixing. A condenser was used to retain the solvent while allowing the system to be swept with an inert gas. An overhead variable speed drive was connected to a radial turbine with 4 blades placed in the aqueous phase. This agitated vessel served as both the mixer and settler. Thus, the impeller was operated during the mixing step, and it was turned off to initiate the settling step.

[0347] The feed was heated to process temperature of 70 °C, and after reaching the target temperature, heptane (“solvent”) was added in a volumetric solvent:feed ratio of 0.25 so that two phases were clearly visible. Rotary mixing was initiated to allow for intimate contact to occur. Visually uniform mixing occurred. This mixing was continued for a predetermined time of 10 min. When the rotary mixer was turned-off, the phases (“layers”) were allowed to separate at process temperature of 70 °C. The biomass rag layer settled between the bottom layer (the “raffinate”) and the upper layer (the “extract”).

[0348] A second stage of extraction was performed on the first extract and the first biomass layer (termed “the second feed”) that remained in the agitated vessel after a substantial portion of the first raffinate was removed from the first extractor. In the second extractor, the impeller was lowered to an elevation of 0.225 times the vessel diameter after the first raffinate was removed. A second solvent (heptane) was added in a solvent:second feed ratio of 1 , and the contents of the vessel were heated to 70°C. Once the vessel contents reached the desired temperature, agitation commenced, and the impeller speed was increased to 200% of the minimum impeller speed for complete dispersion of the two phases. The liquid-liquid-solid dispersion was agitated for 10 minutes in a mixing mode to facilitate mass transfer. After mixing, the agitation was stopped and the phases were allowed to decant. The biomass containing layer settled in between the liquid-liquid interface.

[0349] An overview of the biomass behavior for Examples 1-5 are presented in Table 2 below.Table 2: Overview of biomass behavior for Examples 1-5

[0350] The continuous phase determines the position of the interface in the contactor. In Example 1 , it was surprisingly discovered that the algal biomass didn’t go to the interface at the top of the column, which would have been expected based on Examples 2-5.

[0351] It will be appreciated by those skilled in the art that the present disclosure can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the disclosure is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein.

Claims

CLAIMS1 . A process for separating algal hydrophobic products from an algal biomass stream, the process comprising: introducing the algal biomass stream into a counter-current separation device, the algal biomass stream containing an aqueous solution, an extraction solvent, algal hydrophobic products and an algal biomass; and introducing an aqueous stream into the counter-current separation device, wherein the aqueous stream contacts the algal biomass stream, and allowing separation of an organic phase and an aqueous phase in the counter-current separation device, the organic phase containing at least a portion of the extraction solvent and at least a portion of the algal hydrophobic products, and the aqueous phase containing at least a portion of the algal biomass, wherein an interface is formed between the organic phase and the aqueous phase, wherein at least part of the algal biomass stream is in the form of an emulsion.

2. The process of claim 1 , wherein the aqueous phase contains essentially all of the algal biomass.

3. The process of any one of the previous claims, wherein the organic phase contains essentially all of the extraction solvent and optionally essentially all of the algal hydrophobic products.

4. The process of any one of the previous claims, wherein the active section of the counter-current separation device has a length-to-diameter ratio from 2 to 150.

5. The process of any one of the previous claims, wherein the introducing of the algal biomass stream is performed at a first position within an active section of the counter-current separation device, wherein the first position is located within 10% of a total length dimension of the active section starting from a bottom of the active section.

6. The process of any one of the previous claims, wherein the introducing of the aqueous stream is performed at a second position within the active section of the counter-current separation device, wherein the second position is located within 10% of a total length dimension of the active section starting from a top of the active section.

7. The process of any one of the previous claims, wherein the algal biomass stream is a liquid-liquid-solid dispersion.

8. The process of any one of the previous claims, wherein the algal biomass stream comprises: from about 0.5 wt% to about 20 wt% solids.

9. The process of any one of the previous claims, wherein the algal biomass stream comprises: about 10 wt% to about 80 wt% the aqueous solution, wherein the aqueous solution contains at least one additive selected from a group consisting of salts, solvents, pH adjusters and stabilizers.

10. The process of any one of the previous claims, wherein the algal biomass stream comprises: about 10 wt% to about 80 wt% of the extraction solvent.11 . The process of any one of the previous claims, wherein the extraction solvent is selected from a group consisting of a petrochemical solvent, an edible oil-based solvent, a dense gas solvent, an aqueous two-phase solvent, an ionic liquid solvent, and a combination of miscible solvents.

12. The process of any one of the previous claims, wherein the introducing of the algal biomass stream and the introducing of the aqueous stream are performed at an algal biomass stream-to-aqueous stream ratio from about 0.

113. The process of any one of the previous claims, comprising: operating the counter-current separation device at atmospheric pressure.

14. The process of any one of the previous claims, comprising: operating the counter-current separation device at a temperature ranging from 0°C to 150°C.

15. The process of any one of the previous claims, wherein the process has a selectivity for the algal hydrophobic products to the algae biomass of at least one or more of at least 2, at least 3, at least 4, and / or at least 5.

16. The process of any one of the previous claims, comprising: introducing one or more additional aqueous streams into the countercurrent separation device.

17. The process of claim 16, wherein the introducing of the one or more additional aqueous streams is performed at a position different from the position that the algal biomass stream is introduced into the counter-current separation device.

18. The process of any one of the previous claims, wherein the countercurrent separation device comprises: at least one coalescer that is optionally located in the countercurrent separation device and / or connected to the counter-current separation device.

19. The process of claim 18, wherein the at least one coalescer is selected from a group consisting of mesh pad coalescers, wire pad coalescers, structured packing, inclined plates, perforated plates, baffles, ultrasonic waves, acoustic waves, electric fields and gravitational fields.

20. The process of any one of the previous claims, comprising: obtaining the algal biomass stream from an upstream extraction process, the upstream extraction process optionally including: forming a dispersion by contacting an algal concentrate with the extraction solvent in an extraction zone; passing the dispersion to a separation zone; and separating the dispersion into two or more layers, wherein the algal biomass stream is obtained from at least one of the layers.21 . The process of any one of the previous claims, comprising: recovering the organic phase and / or the aqueous phase from the counter-current separation device.

22. The process of any one of the previous claims, wherein the introducing of the aqueous stream into the counter-current separation device is performed continuously or periodically.

23. The process of any one of the previous claims, wherein the introducing of the aqueous stream into the counter-current separation device is performed continuously.

24. The process of any one of the previous claims, wherein the introducing of the algal biomass stream into the counter-current separation device is performed continuously or periodically.

25. The process of any one of claims 16 to 23, wherein the introducing of the one or more additional aqueous streams into the counter-current separation device is performed continuously or periodically.

26. The process of any one of the previous claims, comprising: operating the counter-current separation device at about 50% to about 95% of a measured flooding flux of the counter-current separation device.

27. The process of any one of the previous claims, comprising: operating the process in a continuous flow.

28. A system for separating and optionally desalting algal hydrophobic products from an algal biomass stream, the system comprising: a counter-current separation device possessing an algal biomass stream input and at least one aqueous stream input, wherein the algal biomass stream input is either located at a position below or above the aqueous stream input; and an algal biomass stream feed line configured to communicate with the algal biomass stream input and an extraction zone; and at least one aqueous stream feed line configured to communicate with the at least one aqueous stream input and an aqueous stream reservoir; and at least one algal aquaculture zone configured to operatively communicate with the extraction zone.

29. The system of claim 28, wherein the system further comprises the extraction zone, wherein the extraction zone being configured to operatively communicate with the algal biomass stream feed line; and optionally the system further comprises an aqueous stream reservoir configured to operatively communicate with the at least one aqueous stream feed line.

30. The system of claim 28 or 29, wherein the counter-current separation device comprises: an underflow output and an overflow output.31 . The system of any one of claims 28 to 30, comprising: at least one coalescer located either within the counter-current separation device or in at least one coalescing zone in communication with the counter-current separation device.

32. The system of claim 31 , wherein the at least one coalescer is located in the at least one coalescing zone and the at least one coalescing zone is in communication with either the underflow output or the overflow output.

33. The system of any one of claims 28 to 32, wherein the at least one coalescer is selected from a group consisting of mesh pad coalescers, wire pad coalescers, structured packing, inclined plates, perforated plates, baffles, ultrasonic waves, acoustic waves, electric fields and gravitational fields.

34. The system of any one of claims 28 to 33, wherein the counter-current separation device comprises: one or more additional aqueous stream inputs located at a position either above or below the position of the at least one aqueous stream input and above the position of the algal biomass stream input.

35. The system of claim 34, wherein the one or more additional aqueous stream inputs are configured to communicate with one or more additional aqueous stream feed lines.

36. The system of claim 35, wherein the one or more additional aqueous stream feed lines are configured to communicate with one or more additional aqueous stream reservoirs.

37. The system of any one of claims 28 to 36, wherein the extraction zone is or comprises: at least one or more of static mixing device, a co-current extraction column, a countercurrent extraction column, a centrifugal extractor, an agitated vessel, an emulsion phase separation device, and / or any combination thereof.

38. The system of any one of claims 28 to 37, wherein the system comprises:at least one separation zone configured to separate an algal dispersion into multiple layers, wherein the at least one separation zone includes a decanter configured to perform at least one of gravity settling, centrifugal settling or combinations thereof.

39. The system of any one of claims 28 to 38, wherein the system comprises at least two separation zones configured to separate an algal dispersion into two or multiple layers, wherein one of the at least two separation zones is a separation zone (108, 208, 310, 412, 512) of the counter-current separation device (100, 200, 300, 400, 500) and one of the at least two separation zones is an upstream separation zone located within the upstream extraction zone and configured to operatively communicate with the algal biomass stream feed line.

40. The system of any one of claims 28 to 39, comprising: at least one controller configured to transfer an algal biomass stream through the algal biomass stream input at a first flowrate and / or transfer an aqueous stream through the at least one aqueous stream input at a second flowrate.41 . The system of any one of claims 28 to 40, comprising: at least one algal aquaculture zone configured to operatively communicate with the extraction zone.

42. The system of any one of claims 28 to 41 , comprising: at least one harvesting zone configured to operatively communicate with the extraction zone and the at least one algal aquaculture zone, the at least one harvesting zone optionally being configured to perform an adsorptive bubble separation process on an algal biomass stream.

43. The system of any one of claims 28 to 42, the system comprising:a counter-current separation device possessing an algal biomass stream input and at least one aqueous stream input, wherein the algal biomass stream input is either located at a position below or above the aqueous stream input; an extraction zone; an aqueous stream reservoir configured to transport at least one aqueous stream to the at least one aqueous stream input; an algal biomass stream feed line configured to communicate with the algal biomass stream input and the extraction zone; and at least one aqueous stream feed line configured to communicate with the at least one aqueous stream input and the aqueous stream reservoir.

44. A system for separating and desalting algal hydrophobic products from an algal biomass stream, the system comprising: a means for (i) performing a counter-current extraction between an algal biomass stream and an aqueous stream and (ii) producing an interface between an organic phase and an aqueous phase, the organic phase being essentially free of algal biomass; an extraction zone configured to transport an algal biomass stream to the means; and an aqueous stream reservoir configured to transport at least one aqueous stream to the means.

45. The system as claimed in any of claims 28 to 44, wherein the extraction zone is an upstream extraction zone configured to operatively communicate with the algal biomass stream feed line or configured to transport an algal biomass stream to the means.

46. Use of the system of any one of claims 28 to 45 for separating and optionally desalting algal hydrophobic products from an algal biomass stream.

47. The use of claim 46, wherein the separating and optionally desalting algal hydrophobic products from the algal biomass stream is performed by the process of any one of claims 1 -27.

48. The use of claims 46 or 47, or the process of claims 1 -27, or the system of claims 28 - 45, wherein the algal hydrophobic products include at least one of lipids, algal lipids, carotenoids, fatty acids, algal fatty acids, triacylglycerols, diacylglycerols, monoacylglycerols, oils, algal oils or combinations thereof.

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