A process and a system for extraction of oil from algal biomass

Abstract

The present disclosure relates to a process (100) and a system (200) for extracting oil from algal biomass. The process (100) involves obtaining a predetermined amount of algal biomass powder with a set moisture content and treating it with a wetting agent to form a swollen biomass mixture. This mixture is then extruded under specific conditions to disrupt the algae's cell walls. An inert anti-caking agent is added to produce a lump-free mixture, which is loaded into perforated vessels within a supercritical fluid extractor. Oil extraction occurs at 300 to 600 bar and temperatures between 34°C and 75°C. The extract, containing oil and other dissolved substances, is passed through a sequence of decreasing pressures in separator vessels to isolate the oil and other substances. This efficient method facilitates the selective recovery of oil and valuable compounds from algal biomass under controlled conditions, using supercritical fluid extraction.

Description

[0001] A PROCESS AND A SYSTEM FOR EXTRACTION OF OIL FROM ALGAL BIO¬

[0002] MASS

[0003] FIELD

[0004] The present disclosure relates to the field of biochemistry. More particularly, focused on the extraction of oil from algal biomass.

[0005] BACKGROUND

[0006] The background information herein below relates to the present disclosure but is not necessarily prior art.

[0007] Most of the omega-3 fatty acids, particularly docosahexaenoic acid (DHA) is recovered in oil (triglyceride) form by using solid liquid extraction, liquid-liquid extraction and / or supercritical fluid extraction from algae or fish. The oil is contained within the cell of the algae and the cell wall of the algae needs to be broken or leaked before extraction.

[0008] Conventionally, extraction of the oil from algal biomass requires some pretreatment prior to the extraction step. The pretreatment of algae such as grinding, sonication, ultrasonication and microwave and the like is used for breaking the cell wall. However, these methods are not efficient in breaking the cell wall, due to which these methods fail to improve the extraction yield. Further, the commercial methods for extraction of oil from algal biomass involve a wet process, wherein the algae are in an aqueous slurry form and the cell wall is broken in the slurry itself to carry out the extraction. The major component of the slurry is water, which also needs to be processed during extraction which consequently increases the input quantity, processing time and costs. Further, these methods also usually involve usage of toxic chemical solvents.

[0009] Therefore, there is felt a need for developing a process and a system for extraction of oil from algal biomass that mitigates the drawbacks mentioned herein above or at least a useful alternative.

[0010] OBJECTS

[0011] Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows. An object of the present disclosure is to ameliorate one or more problems of the background or to at least provide a useful alternative.

[0012] Another object of the present disclosure is to provide a process for the extraction of oil from algal biomass.

[0013] Still another object of the present disclosure is to provide a process for extraction of oil containing omega 3 fatty acids from algal biomass.

[0014] Yet another object of the present disclosure is to provide a process that is simple, cost- effective, and efficient for the extraction of oil from algal biomass.

[0015] Still another object of the present disclosure is to provide a process that maximizes the yield of oil and valuable compounds efficiently using supercritical fluid extraction techniques.

[0016] Yet another object of the present disclosure is to provide a process that enhances the handling of algal biomass by incorporating a wetting and anti-caking treatment, facilitating smoother processing and preventing clumping during the extraction process.

[0017] Still another object of the present disclosure is to provide a process that establishes controlled processing conditions that optimize the breakdown of algal cell walls and the subsequent extraction of oil, including specific pressures and temperatures tailored to maximize extraction efficiency and product quality.

[0018] Yet another object of the present disclosure is to provide a process that achieves a selective and staged separation of oil and other valuable dissolved substances from the algal biomass, utilizing a series of separator vessels under varying pressures and temperatures to ensure high purity and recovery of extracted components.

[0019] Still another object of the present disclosure is to provide a process that provides a scalable process that can be adapted for different scales of operation and types of algal biomass, thus broadening the applicability of the method across various industrial contexts.

[0020] Yet another object of the present disclosure is to provide a process that offers an extraction method that utilizes supercritical fluids, a greener alternative to traditional organic solvents, reducing environmental impact and enhancing the sustainability of the oil extraction process from algal biomass. Still another object of the present disclosure is to provide a system for the extraction of oil from algal biomass.

[0021] Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.

[0022] SUMMARY

[0023] The present disclosure provides a process for extracting oil from algal biomass, the process comprising: a. obtaining a predetermined amount of a powder of an algal biomass having a predetermined moisture content; b. adding a predetermined amount of a wetting agent to the powder of the algal biomass followed by mixing for a first predetermined time period to obtain a mixture of swollen algal biomass; c. extruding the mixture of the swollen algal biomass under predetermined conditions to break the cell walls of the algae to obtain an extruded biomass; d. mixing the extruded biomass with a predetermined amount of an inert anticaking agent to obtain a lump-free mixture; e. loading the lump-free mixture in at least one loading vessel having perforated meshes at an operative bottom and an operative top; f. placing the at least one loading vessel containing the lump-free mixture in at least one extraction vessel of a supercritical fluid extractor; g. extracting oil and dissolved substance from the lump-free mixture in the loading vessel by using the supercritical fluid at a 300 bar to 600 bar pressure and at a first predetermined temperature ranging from 34°C to 75°C for a second predetermined time period to obtain an extract dissolved in the pressurized supercritical fluid; h. separating the extracted oil and dissolved substances from the supercritical fluid at reduced pressure in the range of 30 bar to 200 bar at a temperature ranging from 25°C to 75°C on at least one separator vessel; and i. collecting the separated oil and dissolved substances.

[0024] In an embodiment, the step of separation (h) comprises the following: passing the supercritical fluid in which the extracted oil and dissolved substances are passed to a first separation vessel and separating a first fraction comprising essentially of oil separated by reducing the pressure of the supercritical fluid to between 30 bar to 200 bar pressure.

[0025] In an embodiment, the step of separation (h) comprises the following: passing the supercritical fluid from the first separation vessel to a second separation vessel and separating a second fraction comprising the remaining dissolved substances from the supercritical fluid by further reducing the pressure of the supercritical fluid to between 30 bar to 70 bar pressure.

[0026] In an embodiment, the process includes the step of recycling the supercritical fluid after the separation of oil and other dissolved substances.

[0027] In an embodiment, the wetting agent is a mixture of water and oil, and the predetermined amount of the wetting agent is in the range of 2 mass% to 15 mass% with respect to the total mass of the powder of the algal biomass.

[0028] In an embodiment, the inert anticaking agent comprises silicon dioxide, and the predetermined amount of the anticaking agent is in the range of 0 mass% to 7 mass% with respect to the total mass of the extruded biomass.

[0029] In an embodiment, the process is performed under reduced oxygen and light conditions to preserve the quality of the omega 3 fatty acids sensitive to atmospheric oxygen and light.

[0030] In an embodiment, the omega 3 fatty acids, including docosahexaenoic acid (DHA), are extracted from species of algae selected from the group consisting of Aurantiochytrium, Isochrysis spp., Schizochytrium, Thraustochytrium, Thalassiosira spp., and Crypthecodinium cohnii.

[0031] In accordance with another aspect, this disclosure provides a system for the extraction of oil from algal biomass comprising: a loading vessel, an extraction vessel, a super cooler, a booster pump, a CO2 pump, a super heater, a separation vessel, a condenser, and an evaporator.

[0032] The loading vessel having perforated meshes at an operative bottom and an operative top.

[0033] The extraction vessel is configured to receive the loading vessel and to contain a supercritical fluid.

[0034] The super cooler, at least one booster pump, at least one CO2 pump, and at least one super heater is configured for preparing and maintaining the supercritical fluid under predetermined conditions. The separation vessel is configured to receive the extract dissolved in the supercritical fluid and separate the oil and removing dissolved substances by reducing the pressure and the temperature of the supercritical fluid.

[0035] The condenser and at least one evaporator is configured to treat the separated supercritical fluid for recycling.

[0036] In an embodiment, the system includes the loading vessel is a stainless steel basket configured to prevent lumping of the mixture and to allow efficient extraction of the oil.

[0037] In an embodiment, the system includes the supercritical fluid comprises a carbon dioxide, and the system is configured to operate the supercritical fluid at pressures ranging from 300 bar to 600 bar and temperatures ranging from 34°C to 75°C .

[0038] In an embodiment, the system includes the separation vessel configured to operate at a reduced pressure ranging from 30 bar to 200 bar and a temperature ranging from 25 °C to 75°C to facilitate the separation of oil from the extract.

[0039] BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING

[0040] The process for extraction of oil from algal biomass in accordance with the present disclosure will now be described with the help of the accompanying drawing, in which:

[0041] Figure 1 illustrates a flow chart for a process of extraction of oil containing omega 3 fatty acids from an algal biomass in accordance with an embodiment of the present disclosure; and

[0042] Figure 2 illustrates a system for extraction of oil from an algal biomass in accordance with the present disclosure.

[0043] REFERENCE NUMERALS

[0044] 100 Process for extracting oil from algal biomass

[0045] 102 Loading Vessel

[0046] 104a, 104b Extraction vessel

[0047] 106 Super Cooler

[0048] 108 Booster pump

[0049] 110 CO2 pump 112 Super Heater

[0050] 114a First Separation Vessel

[0051] 114b Second Separation Vessel

[0052] 116 Condenser

[0053] 118 Evaporator

[0054] 124 CO2 tank

[0055] 200 System

[0056] DETAILED DESCRIPTION

[0057] The present disclosure envisages a process and a system for the extraction of oil from algal biomass using supercritical fluid.

[0058] Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.

[0059] Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.

[0060] The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open-ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and / or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.

[0061] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed elements.

[0062] The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.

[0063] Most omega-3 fatty acids, especially docosahexaenoic acid (DHA), are extracted from algae or fish oil in triglyceride form using methods like solid-liquid extraction, liquid-liquid extraction, or supercritical fluid extraction. The oil is locked within the cells of the algae, requiring the cell walls to be disrupted before the oil is extracted. Traditional pre-treatment methods for breaking these cell walls include grinding, sonication, ultrasonication, and microwaving. However, these methods often fail to efficiently disrupt the cell walls, leading to low extraction yields. Additionally, conventional oil extraction from algal biomass typically uses a wet process that involves breaking the cell walls within a water-based slurry. This process not only requires significant water processing, which increases the quantity of inputs, time, and costs, but it also commonly employs harmful chemical solvents.

[0064] The present disclosure envisages a process and a system for the extraction of oil from algal biomass.

[0065] In an aspect, the present disclosure provides a process for the extraction of oil from algal biomass.

[0066] The process for extraction of oil from algal biomass comprises the following steps: i. obtaining a predetermined amount of a powder of an algal biomass having a predetermined moisture content; ii. adding a predetermined amount of a wetting agent to the powder of the algal biomass followed by mixing for a first predetermined time period to obtain a mixture of swollen algal biomass; iii. extruding the mixture of the swollen algal biomass under predetermined conditions to break the cell walls of the algae to obtain an extruded biomass; iv. mixing the extruded biomass with a predetermined amount of an inert anticaking agent to obtain a lump-free mixture; v. loading the lump-free mixture in at least one loading vessel having perforated meshes at an operative bottom and an operative top; vi. placing the at least one loading vessel (102) containing the lump- free mixture in at least one extraction vessel (104a, 104b) of a supercritical fluid extractor; vii. extracting oil and dissolved substance from the lump-free mixture in the loading vessel (102) by using the supercritical fluid at a 300 bar to 600 bar pressure and at a first predetermined temperature ranging from 34 °C to 75 °C for a second predetermined time period to obtain an extract dissolved in the pressurized supercritical fluid; viii. separating the extracted oil and dissolved substances from the supercritical fluid at reduced pressure in the range of 30 bar to 200 bar at a temperature ranging from 25°C to 75°C on at least one separator vessel (114a, 114b); and ix. collecting the separated oil and dissolved substances.

[0067] In an embodiment, the step of separation (h) comprises the following: passing the supercritical fluid in which the extracted oil and dissolved substances are passed to a first separation vessel (114a) and separating a first fraction comprising essentially of oil separated by reducing the pressure of the supercritical fluid to between 30 bar to 200 bar pressure.

[0068] In an embodiment, the step of separation (h) comprises the following: passing the supercritical fluid from the first separation vessel (114a) to a second separation vessel (114b) and separating a second fraction comprising the remaining dissolved substances from the supercritical fluid by further reducing the pressure of the supercritical fluid to between 30 bar to 70 bar pressure.

[0069] In an embodiment, the process includes the step of recycling the supercritical fluid after the separation of oil and other dissolved substances.

[0070] In accordance with an embodiment of the present disclosure, the separated supercritical fluid so obtained after collecting the second fraction is condensed and recycled in step (vii) followed by repeating steps (viii) to (ix) to complete the extraction. A predetermined amount of a powder of an algal biomass having a predetermined moisture content anywhere between 0-5% is obtained.

[0071] In accordance with an embodiment of the present disclosure, the oil can include, but is not limited to, fatty acids. Other suitable oils can also be extracted.

[0072] In accordance with an embodiment, the fatty acid can include, but is not limited to, omega 3fatty acid, palmitic acid and waxes. Other suitable fatty acids can also be used.

[0073] In accordance with an embodiment of the present disclosure, the omega 3 fatty acid can include, but is not limited to, alphalinolenic acid (ALA), eicosapentaenoic acid (EP A), and docosahexaenoic acid (DHA). Other suitable omega 3fatty acids can also be used. In an embodiment, the omega 3 fatty acid is docosahexaenoic acid (DHA).

[0074] In an embodiment, the process of the present disclosure is illustrated as a flow chart in figure 1 and described in details as given below:

[0075] In accordance with an embodiment of the present disclosure, the powder of the algal biomass having a predetermined moisture content is obtained.

[0076] In accordance with an embodiment of the present disclosure, the algal biomass is obtained as a dehydrated powder from China. Other suitable algal biomass can also be used.

[0077] In accordance with an embodiment of the present disclosure, the predetermined moisture content is less than 5%.

[0078] Many species of algae that include oil containing omega 3 fatty acids and are amenable to the extraction process of the present disclosure. Particularly useful species that can include, but is not limited to, Aurantiochytrium, Isochrysis spp., Schizochytrium, Thraustochytrium and Thalassiosira spp. and the species Crypthecodinium cohnii, Odontella aurita, Pavlova lu- theri, Phaeodactylum tricornutum and Porphyridium cruentum. Useful microalgae is from classes including Bacillariophyceae, Eustigmatophyceae, and Chrysophyceae and / or from genera that can include Nannochloropsis, Chlorella, Dunaliella, Scenedesmus, Selenastrum, Oscillatoria, Phormidium, Spirulina, Amphora, and Ochromonas. Other nonlimiting examples of algae species that can include, but is not limited to Achnanthes orientalis, Agmen- ellum spp., Amphiprora hyaline, Amphora coffeiformis, Amphora coffeiformis var. linea, Amphora coffeiformis var. punctata, Amphora coffeiformis var. taylori, Amphora coffeiformis var. tenuis, Amphora delicatissima, Amphora delicatissima var. capitata, Amphora sp., Ana- baena, Ankistrodesmus, Ankistrodesmus falcatus, Boekelovia hooglandii, Borodinella sp., Botryococcus braunii, Botryococcus sudeticus, Bracteococcus minor, Bracteococcus medio- nucleatus, Carteria, Chaetoceros gracilis, Chaetoceros muelleri, Chaetoceros muelleri var. subsalsum, Chaetoceros sp., Chlamydomas perigranulata, Chlorella anitrata, Chlorella ant- arctica, Chlorella aureoviridis, Chlorella Candida, Chlorella capsulate, Chlorella desiccate, Chlorella ellipsoidea, Chlorella emersonii, Chlorella fusca, Chlorella fusca var. vacuolata, Chlorella glucotropha, Chlorella infusionum, Chlorella infusionum var. actophila, Chlorella infusionum var. auxenophila, Chlorella kessleri, Chlorella lobophora, Chlorella luteoviridis, Chlorella luteoviridis var. aureoviridis, Chlorella luteoviridis var. lutescens, Chlorella minia- ta, Chlorella minutissima, Chlorella mutabilis, Chlorella nocturna, Chlorella ovalis, Chlorella parva, Chlorella photophila, Chlorella pringsheimii, Chlorella protothecoides, Chlorella protothecoides var. acidicola, Chlorella regularis, Chlorella regularis var. minima, Chlorella regularis var. umbricata, Chlorella reisiglii, Chlorella saccharophila, Chlorella sac- charophila var. ellipsoidea, Chlorella salina, Chlorella simplex, Chlorella sorokiniana, Chlorella sp., Chlorella sphaerica, Chlorella stigmatophora, Chlorella vanniellii, Chlorella vulgaris, Chlorella vulgaris family order tertia, Chlorella vulgaris var. autotrophica, Chlorella vulgaris var. viridis, Chlorella vulgaris var. vulgaris, Chlorella vulgaris var. vulgaris family order tertia, Chlorella vulgaris var. vulgaris family order viridis, Chlorella xanthella, Chlorella zofingiensis, Chlorella trebouxioides, Chlorella vulgaris, Chlorococcurn infusionum, Chlorococcum sp., Chlorogonium,Chroomonas sp., Chrysosphaera sp., Cricosphae- ra sp., Crypthecodinium cohnii, Cryptomonas sp., Cyclotella cryptica, Cyclotella meneghini- ana, Cyclotella sp., Dunaliella sp., Dunaliella bardawil, Dunaliella bioculata, Dunaliella granulate, Dunaliella maritime, Dunaliella minuta, Dunaliella parva, Dunaliella peircei, Dunaliella primolecta, Dunaliella salina, Dunaliella terricola, Dunaliella tertiolecta, Dunaliella viridis, Dunaliella tertiolecta, Eremosphaera viridis, Eremosphaera sp., Ejfipsoidon sp., Euglena spp., Franceia sp., Fragilaria crotonensis, Fragilaria sp., Gleocapsa sp., Gloeo- thamnion sp., Haematococcus pluvialis, Hymenomonas sp., Isochrysis ajf. galbana, Isochry- sis galbana, Lepocinclis, Micractinium, Micractinium, Monoraphidium minutum, Mono- raphidium sp., Nannochloris sp., Nannochloropsis salina, Nannochloropsis sp., Navicula ac- ceptata, Navicula biskanterae, Navicula pseudotenelloides, Navicula pelliculosa, Navicula saprophila, Navicula sp., Nephrochloris sp., Nephroselmis sp., Nitschia communis, Nitzschia alexandrine, Nitzschia closterium, Nitzschia communis, Nitzschia dissipate, Nitzschia frustu- lum, Nitzschia hantzschiana, Nitzschia inconspicua, Nitzschia intermedia, Nitzschia micro- cephala, Nitzschia pusilia, Nitzschia pusilia elliptica, Nitzschia pusilia monoensis, Nitzschia quadrangular, Nitzschia sp., Ochromonas sp., Oocystis parva, Oocystis pusilia, Oocystis sp., Oscillatoria limnetica, Oscillatoria sp., Oscillatoria subbrevis, Parachiorella kessleri, Pascheria acidophila, Pavlova sp., Phaeodactylum tricomutum, Phagus, Phormidium, Platymonas sp., Pleurochrysis carterae, Pleurochrysis dentate, Pleurochrysis sp., Prototheca wickerhamii, Prototheca stagnora, Prototheca portoricensis, Prototheca moriformis, Prototheca zopfii, Pseudochlor ella aquatica, Pyramimonas sp., Pyrobotrys, Rhodococcus opacus, Sarcinoid chrysophyte, Scenedesmus armatus, Schizochytrium, Spirogyra, Spirulina platensis, Stichococcus sp., Synechococcus sp., Synechocystisf, Tagetes erecta, Tagetes patula, Tet- raedron, Tetraselmis sp., Tetraselmis suecica, Thalassiosira weissflogii, and Viridiella fridericiana. Preferably, the algae are autotrophic microalgae. In an embodiment, the algae species is Schizochytrium.

[0079] A predetermined amount of a wetting agent is added to the powder of the algal biomass followed by mixing for a first predetermined time period to obtain a mixture of swollen algal biomass.

[0080] In accordance with an embodiment of the present disclosure, the wetting agent can include, but is not limited to water, or a mixture of water and oil. Other suitable wetting agents can also be used.

[0081] In accordance with an embodiment of the present disclosure, the predetermined amount of the wetting agent is in the range of 2 mass% to 15 mass% with respect to the total mass of the powder of algal biomass.

[0082] The wetting agent is mixed with the powder of the algal biomass manually or by using a machine. The machine can include, but is not limited to, rapid mixer granulator. Other suitable machines can also be used.

[0083] In accordance with an embodiment of the present disclosure, the wetting agent is added to the powder of the algal biomass to achieve high efficiency in cell wall breaking. The cells of the algae can absorb the wetting agent through osmosis and swell to exert internal pressure on the cell wall.

[0084] The mixture of swollen algal biomass is extruded at predetermined conditions to break the cell wall of the algae by using an extrusion machine to obtain an extruded biomass. The powder of the algal biomass having a predetermined moisture content can have very fine particle size. The absorbed water increases the mass of the algae. The lesser is the particle size, the lesser would be surface area and porosity. Subsequently, the fine particle size of the powder of the algal biomass can reduce the efficiency of the process during the supercritical fluid extraction. So the surface area and porosity of the algal biomass is increased by extrusion. Extrusion is a mechanical process that can induces stress.

[0085] Further, the mechanical shearing force and the stresses that is induced during the extrusion can break the cell wall.

[0086] In accordance with an embodiment of the present disclosure, the steps (ii) and (iii) is repeated if the cell walls of the algae are not broken satisfactorily.

[0087] If the cell walls of the algae are broken, the extruded mass is come oily and sticky. A lab test can also be performed to determine the amount of oil released from the cells. The extruded biomass is added to ethyl acetate and stirred. The solvent layer is separated and the solvent in the separated solvent layer is evaporated. The amount of oil left after the evaporation of solvent and compared with the algae biomass certificate of analysis (COA) mentioning oil content.

[0088] The extruded biomass is mixed with a predetermined amount of an inert anticaking agent to obtain a lump-free mixture.

[0089] In accordance with the present disclosure, the inert anticaking agent is the food grade anticaking agent that can include, but is not limited to, silicon dioxide. Other suitable anticaking agents can also be used.

[0090] In accordance with an embodiment of the present disclosure, the food grade and inert anticaking agents is used to prevent lumping of the powder to obtain lump free mixture.

[0091] In accordance with an embodiment of the present disclosure, the predetermined amount of anticaking agent is the range of 0 mass% to 7 mass% with respect to the total mass of the extruded biomass.

[0092] In accordance with an embodiment of the present disclosure, the extruded biomass is mixed with the inert anticaking agent manually or by a machine. The machine can include, but is not limited to, rapid mixer granulator. Other suitable machines can also be used. The lumping of the mixture of the algal biomass can prevent the penetration of the supercritical fluid in the biomass and limit the extraction efficiency. So the mixture of the algal biomass should be lump free to carry out the process for the present disclosure.

[0093] The lump-free mixture is loaded in at least one loading vessel having perforated meshes at an operative bottom and at an operative top and placing the at least one loading vessel containing the lump free mixture in at least one extraction vessel (104a, 104b) of the supercritical fluid extractor.

[0094] In accordance with an embodiment of the present disclosure, the step of loading the lump free mixture in the loading vessel (102), having perforated meshes at the operative bottom and at the operative top, followed by placing in the extraction vessel can prevent lumping of the mixture and allows efficient extraction of the ingredients of the biomass. The loading vessel (102) can ensure the complete penetration of the supercritical fluid and total exposure of the biomass to the supercritical fluid.

[0095] The lump-free mixture in the loading vessel (102) is extracted by using a supercritical fluid at a 300 bar to 600 bar pressure and at a first predetermined temperature for a second predetermined time period to obtain an extract dissolved in the supercritical fluid.

[0096] In accordance with an embodiment of the present disclosure, the supercritical fluid can include but is not limited to, carbon dioxide. Other suitable supercritical fluids can also be used.

[0097] In accordance with an embodiment of the present disclosure, the pressure of the supercritical fluid in the extraction vessel (104a, 104b) is in the range of 300 bar to 600 bar. In accordance with an embodiment of the present disclosure, the temperature of the supercritical extraction vessel (104a, 104b) is in the range of 34°C to 75°C.

[0098] In accordance with an embodiment of the present disclosure, the time period of extraction and the flow rate of supercritical fluid depends on the amount of the lump free mixture of algal biomass loaded in the loading vessel (102).

[0099] In accordance with an embodiment of the present disclosure, a portion of supercritical fluid is vented off from the extraction vessel (104a, 104b) to remove excess of supercritical fluid from the extraction vessel (104a, 104b). This is done at the end of the extraction batch

[0100] The extract dissolved in the supercritical fluid is passed to a first separation vessel (114a) and a first fraction comprising essentially of the oil is separated by reducing the pressure and the temperature of the supercritical fluid to a second predetermined pressure and to a second predetermined temperature.

[0101] In accordance with an embodiment of the present disclosure, the second predetermined pressure is in the range of 30 bar to 200 bar. Other suitable predetermined pressures can also be used.

[0102] In accordance with an embodiment of the present disclosure, the second predetermined temperature is in the range of 25 °C to 75 °C. Other suitable predetermined temperature can also be used.

[0103] The supercritical fluid having remaining dissolved substances from a first separation vessel (114a) is carried to a second separation vessel (114b) and a second fraction comprising the remaining dissolved substances are separated from the supercritical fluid by further reducing the pressure of the supercritical fluid to a predetermined pressure.

[0104] In accordance with an embodiment of the present disclosure, the third predetermined pressure is in the range of 30 bar to 70 bar. Other suitable third predetermined pressure can also be used.

[0105] In accordance with an embodiment of the present disclosure, the remaining dissolved substances can include, but is not limited to, water, remaining oil, low grade oil mixture and other components which are no longer soluble in the supercritical fluid. Other suitable dissolved substances can also be used. In an embodiment, the remaining oil can include residual omega 3 fatty acid.

[0106] In accordance with an embodiment of the present disclosure, the remaining dissolved substances including water and remaining low grade oil is used as a wetting agent in step (ii).

[0107] The separated first fraction comprises essentially of oil and the separating a second fraction comprising the dissolved substances is collected from the supercritical extractor.

[0108] In an embodiment, the yield of the omega 3 fatty acids recovered from the second fraction by using the process of the present disclosure is in the range of 70% to 80%.

[0109] In accordance with an embodiment of the present disclosure, the process of the present disclosure is performed in a reduced oxygen and in a reduced light condition as the omega 3 fatty acid is sensitive to atmospheric oxygen and light. The process of the present disclosure limits the exposure of the omega 3 fatty acid from the light and atmospheric oxygen, thereby improving the quality of the omega 3 fatty acid.

[0110] The process of the present disclosure is developed, wherein the dry dehydrated algae biomass powder could be directly processed without the use of chemical solvents, which can greatly reduce the input quantity to be processed and thereby the process efficiently reduces the costs and improves the quality of the products.

[0111] The powder left behind in the extraction vessel after extraction is rich in protein and also contains some DHA and other fatty acids that is used as an ingredient in human or animal nutri- tion / supplements.

[0112] In another aspect, the present disclosure envisages a system for extraction of oil from algal biomass. The system (100) comprises at least one super cooler (SC) (106), at least one booster pump (BP) (108), at least one CO2 pump (110), at least one super heater (112), at least one extraction vessel (El, E2) (104a, 104b), at least one separation vessel (SI, S2) (114a, 114b), at least one condenser (116), at least one evaporator (118) and at least one CO2 tank (124).

[0113] In accordance with the present disclosure, the system for extraction of oil from algal biomass is illustrated in Figure 2.

[0114] In accordance with an embodiment of the present disclosure, the super cooler (SC) (106) is connected to a chiller which can reduce the temperature of a fluid medium to ensure that the fluid medium is in liquid state before entering the booster pump (108). If the fluid medium is in gas state, then the pump would not work. The booster pump (BP) (108) ensures a minimum basic pressure of the fluid medium before entry into main pump and reduces load and wear of seals in the main CO2 pump (110). The higher pressure ensures that the fluid medium remains in liquid form before entering the main CO2 pump (110).

[0115] In accordance with an embodiment of the present disclosure, the super heater (112) is connected to a hot water generator located next to the main pump used for heating the liquid fluid medium. This liquid fluid medium is passed through the super heater (112) after being pressurized to the set process pressure to achieve supercritical conditions.

[0116] In an embodiment, the fluid medium can include but is not limited to, carbon dioxide. The other suitable fluid media can also be used. In an embodiment, the system (200) is equipped with an advanced control unit that utilizes artificial intelligence to optimize the parameters of the supercritical fluid extraction based on real-time data analysis of the biomass characteristics and extraction efficiency.

[0117] In an embodiment, the loading vessel is configured with adjustable mesh sizes at both the top and bottom to accommodate different types of algal biomass, allowing for a customized approach to maximize extraction efficiency depending on the specific physical properties of the biomass used.

[0118] In an embodiment, the system incorporates a dual-phase separation mechanism in the separation vessels, allowing for simultaneous separation of different grades of oils and other valuable substances, which can then be directed to different collection chambers.

[0119] In an embodiment, the supercritical fluid extractor is integrated with a heat recovery system that captures and recycles heat generated during the extraction process to preheat the incoming supercritical fluid, thus reducing energy consumption and improving overall system efficiency.

[0120] In an embodiment, the process includes a post-extraction purification step where the extracted oil undergoes molecular distillation to remove any remaining impurities and concentrate the omega-3 fatty acids, enhancing the purity and quality of the final product.

[0121] In an embodiment, the booster pump (108) and CO2 pump (110) are configured to operate with variable speed settings, allowing for precise control over the flow rate of the supercritical fluid, which is adjusted in real-time based on the extraction stage and specific requirements of the biomass.

[0122] In an embodiment, the system includes an online diagnostic and monitoring platform that provides operators with real-time alerts and performance data, facilitating immediate adjustments to the operation parameters and preventive maintenance to avoid downtime.

[0123] The foregoing description of the embodiments has been provided for purposes of illustration and is not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure. The present disclosure is further illustrated herein below with the help of the following nonlimiting examples. The examples disclosed under these examples herein are intended merely to facilitate an understanding of how the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the experiments should not be construed as limiting the scope of embodiments herein. These laboratory-scale experiments can be scaled up to an industrial / commercial scale and the results obtained can be extrapolated to industrial / commercial scale.

[0124] EXPERIMENTAL SECTION

[0125] In this batch process, 100 kilograms of Schizochytrium biomass, known for its high DHA content, was utilized. The raw material (RM) used in this batch had a DHA content greater than 20%, another 2% w / w moisture added which helps in preparing the biomass for efficient cell wall disruption during extrusion. Additionally, an anti-caking agent, specifically 2% w / w silicon dioxide, was incorporated to prevent clumping of the biomass, ensuring a more uniform and effective extraction process.

[0126] The extraction process was carried out under controlled conditions, with the extraction pressure maintained at 350 bar and the temperature set at 60°C. These conditions were chosen to optimize the extraction of oil from the biomass while preserving the integrity of the DHA.

[0127] After the extraction, the oil-rich mixture was passed through two separation stages. The first separator (114a) operated at a pressure of 80 bar, while the second separator (114b) functioned at a reduced pressure of 48 bar. This stepwise pressure reduction facilitated the efficient separation of the crude oil from the supercritical fluid.

[0128] As a result of this process, the batch yielded 28% crude oil, with a remarkably high DHA content of 61%. This outcome highlights the effectiveness of the selected parameters and the use of anti-caking and wetting agents in maximizing both the yield and quality of the extracted oil.

[0129] Scenario 1: Without an Anticaking Agent or Special Vessel

[0130] In this scenario, the extraction process was conducted without the use of an anticaking agent or a specialized vessel. The algal biomass used was 100 kg of Schizochytrium, known for its high DHA content, with the biomass containing approximately 20% DHA. Before the extraction, a wetting agent was added to the biomass at a concentration of 2% w / w to facilitate the process. The extraction was carried out under the following conditions: an extraction pressure of 350 bar and an extraction temperature of 60°C. Following the extraction, the separation of the oil was conducted in two stages, with the first separator set at 80 bar and the second at 48 bar. Under these conditions, the yield of crude oil was observed to be 5%. The absence of an anticaking agent led to the formation of lumps in the biomass, which impeded the efficiency of the extraction process and resulted in a lower yield.

[0131] Scenario 2: With Anticaking Agent but Without Special Vessel

[0132] In a subsequent experiment, an anticaking agent (2% w / w silicon dioxide) was introduced to the same 100 kg batch of Schizochytrium biomass before the extrusion process. The purpose of the anticaking agent was to prevent the biomass from clumping, thereby improving the penetration of the supercritical fluid and enhancing the extraction efficiency. The extraction and separation parameters remained the same as in the previous scenario, with the extraction pressure at 350 bar, the temperature at 60°C, and the separation pressures at 80 bar and 48 bar, respectively. The inclusion of the anticaking agent resulted in a notable improvement in the yield, which increased to 7%. This increase in yield demonstrates the importance of preventing biomass clumping during the extraction process, even when a specialized vessel is not used. The better dispersion of the biomass allowed for more efficient extraction of the oil, highlighting the role of the anticaking agent

[0133] TECHNICAL ADVANCEMENTS

[0134] The present disclosure described herein above has several technical advantages including, but not limited to, the realization of: a process for extraction of oil from algal biomass that

[0135] • is simple and efficient;

[0136] • is a dry process where the algae is in powder form which reduces the total quantity of the input as compared to the conventional wet process;

[0137] • does not require toxic or other chemical solvents such as hexane, alcohol, vegetable oil and the like; and

[0138] • prevents lump formation; and a system for extraction of oil from algal biomass that • is simple and efficient. The embodiments herein and the various features and advantageous details thereof are explained with reference to the nonlimiting embodiments in the following description. Descriptions of well known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

[0139] The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and / or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

[0140] The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.

[0141] Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

[0142] The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher / lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.

[0143] While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

Claims

CLAIMS:

1. A process (100) for extracting oil from algal biomass, the process (100) comprising: a. obtaining a predetermined amount of a powder of an algal biomass having a predetermined moisture content; b. adding a predetermined amount of a wetting agent to the powder of said algal biomass followed by mixing for a first predetermined time period to obtain a mixture of swollen algal biomass; c. extruding the mixture of said swollen algal biomass under predetermined conditions to break the cell walls of the algae to obtain an extruded biomass; d. mixing the extruded biomass with a predetermined amount of an inert anticaking agent to obtain a lump-free mixture; e. loading said lump-free mixture in at least one loading vessel (102) having perforated meshes at an operative bottom and an operative top; f. placing the at least one loading vessel (102) containing the lump- free mixture in at least one extraction vessel (104a, 104b) of a supercritical fluid extractor; g. extracting oil and dissolved substance from the lump-free mixture in said loading vessel (102) by using said supercritical fluid at a 300 bar to 600 bar pressure and at a first predetermined temperature ranging from 34 °C to 75 °C for a second predetermined time period to obtain an extract dissolved in said pressurized supercritical fluid; h. separating the extracted oil and dissolved substances from said supercritical fluid at reduced pressure in the range of 30 bar to 200 bar at a temperature ranging from 25°C to 75°C on at least one separator vessel (114a, 114b); and i. collecting the separated oil and dissolved substances.

2. The process (100) as claimed in claim 1, wherein the step of separation (h) comprises the following: a. passing said supercritical fluid in which the extracted oil and dissolved substances are passed to a first separation vessel (114a) and separating a first fraction comprising essentially of oil separated by reducing the pressure of said supercritical fluid to between 30 bar to 200 bar pressure; and b. passing said supercritical fluid from the first separation vessel (114a) to a second separation vessel (114b) and separating a second fraction comprising the remaining dissolved substances from said supercritical fluid by further reduc-ing the pressure of said supercritical fluid to between 30 bar to 70 bar pressure.

3. The process (100) as claimed in claim 1, which includes the step of recycling the supercritical fluid after separation of oil and other dissolved substances.

4. The process (100) as claimed in claim 1, wherein said wetting agent is water, and the predetermined amount of said wetting agent is in the range of 2 mass% to 15 mass% with respect to the total mass of the powder of said algal biomass.

5. The process (100) as claimed in claim 1, wherein said inert anti-caking agent comprises silicon dioxide, and the predetermined amount of said anti-caking agent is in the range of 0 mass% to 7 mass% with respect to the total mass of the extruded biomass.

6. The process (100) as claimed in claim 1, wherein said process (100) is performed under reduced oxygen and light conditions to preserve the quality of the omega 3 -fatty acids sensitive to atmospheric oxygen and light.

7. The process (100) as claimed in claim 1, wherein the omega 3-fatty acids, including docosahexaenoic acid (DHA), are extracted from species of algae selected from the group consisting of Aurantiochytrium, Isochrysis spp., Schizochytrium, Thrausto- chytrium, Thalassiosira spp., and Crypthecodinium cohnii.

8. A system (200) for extraction of oil from algal biomass comprising: a. at least one loading vessel (102) having perforated meshes at an operative bottom and an operative top ; b. at least one extraction vessel (104a, 104b) configured to receive said loading vessel (102) and to contain a supercritical fluid; c. at least one super-cooler (106), at least one booster pump (108), at least one CO2 pump (110), and at least one super heater (112) configured for preparing and maintaining said supercritical fluid under predetermined conditions; d. at least one separation vessel (114a, 114b) configured to receive the extract dissolved in said supercritical fluid and separate the oil and removing dissolved substances by reducing the pressure and the temperature of said supercritical fluid; and e. at least one condenser (116) and at least one evaporator (118) configured to treat the separated supercritical fluid for recycling.

9. The system (200) as claimed in claim 7, wherein said loading vessel (102) is a stain- less-steel basket configured to prevent lumping of the mixture and to allow efficient extraction of the oil.

10. The system (200) as claimed in claim 7, wherein said supercritical fluid comprises carbon dioxide and said system (200) is configured to operate said supercritical fluid at pressures ranging from 300 bar to 600 bar and temperatures ranging from 34°C to 75°C .

11. The system (200) as claimed in claim 7, wherein said separation vessel (114a, 114b) is configured to operate at a reduced pressure ranging from 30 bar to 200 bar and a temperature ranging from 25°C to 75°C to facilitate the separation of oil from the extract.

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