Wastewater treatment method

Abstract

The present invention relates in part to methods of using filamentous green macroalgae under conditions of continuous flow of water for wastewater treatment.

Description

[0001] Wastewater Treatment Method

[0002] FIELD

[0003] The present invention relates in part to methods of using filamentous green macroalgae under conditions of continuous flow of water for wastewater treatment.

[0004] BACKGROUND

[0005] A major objective of wastewater treatment is to markedly remove contaminants that are present in wastewater such as debris, organic matter (often determined as Biological Oxygen Demand (BOD), nitrogen (N), and phosphorus (P) compounds prior to being discharged into receiving systems. Furthermore, contaminants can include other elements and hazardous components such as pathogens.

[0006] Most solid and particulate contaminants such as debris, sand, and organic matter are typically removed through primary screening (e.g. using filter screens, clarifiers) and secondary treatment (e.g. using biological filters, activated sludge systems, clarifiers).

[0007] As part of secondary treatment, biological wastewater treatment systems typically use activated sludge where aerated sewage is mixed with microorganisms, mainly bacteria. Organic matter and nutrients contained in wastewater are required for the life of these microorganisms which work together to break down the organic matter, that is subsequently separated from the treated wastewater. In general, activation systems are more effective than simple biological filters. Such wastewater treatment plants are divided into systems with a discontinuous and continuous flow of wastewater into the activation treatment tank, where both biomass systems are maintained in the water column.

[0008] Similarly to live bacteria and other microorganisms used in secondary treatment, microalgae - unicellular, microscopic algae - have been used to further improve wastewater quality downstream of the treatment process in a tertiary treatment step.

[0009] Many studies reveal that microalgae can substantially remove dissolved nitrogen, phosphorus, and hazardous components from various types of wastewater, including from municipal, industrial, agroindustrial, and livestock wastewaters, resulting in biomass production. Because certain microalgae species have evolved to survive in wastewater, this strategy can reduce manufacturing costs by combining wastewater treatment with the cultivation of microalgae. Thus, including microalgal bioremediation into a wastewater treatment infrastructure may be more affordable, cost-effective, and eco-friendly.

[0010] Traditional tertiary treatment solutions, including membrane bioreactors or reverse osmosis incur a significant added cost to the treatment process. Thus, these tertiary treatment systems are typically used in wastewater treatment plants located in urban areas where a higher and denser population can contribute financially to sewage treatment. Microalgal bioremediation represents an alternative nature-based solution to remove harmful nutrients from secondary treated effluent prior to discharge.

[0011] Although nature-based tertiary treatment solutions have evolved significantly in recent years, there remains a need for wastewater treatment systems and methods that allow for effective and or efficient wastewater treatment that avoid technical issues associated with the development of microalgal bioremediation technologies at scale.

[0012] SUMMARY

[0013] In one aspect the present invention provides a continuous flow wastewater treatment system comprising: a. a continuous flow macroalgal pond comprising wastewater to be treated b. a mass of filamentous green macroalgae in the continuous flow macroalgal pond c. a means for removing mass of filamentous green macroalgae from the continuous flow macroalgal pond, and d. a means for removing wastewater from the continuous flow macroalgal pond.

[0014] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the filamentous green macroalgae is uniseriate.

[0015] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the filamentous green macroalgae has a length of at least 1 mm.

[0016] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the filamentous green macroalgae has a length of at least 10 mm.

[0017] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the filamentous green macroalgae has a length of at least 20 mm.

[0018] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the filamentous green macroalgae has a diameter of at least 5 pm. In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the filamentous green macroalgae has a diameter of at least 60 pm.

[0019] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the mass of green macroalgae comprises one or more species of green macroalgae.

[0020] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the mass of green macroalgae comprises one or more macroalgal species of the division Chlorophyta.

[0021] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the mass of green macroalgae comprises one or more macroalgal species of the class Chlorophyceae.

[0022] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the mass of green macroalgae comprises one or more species of the genus Oedogonium.

[0023] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the mass of green macroalgae is planktonic.

[0024] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the means for removing mass of filamentous green macroalgae from the continuous flow macroalgal pond allows continuous flow of water to be treated through the means.

[0025] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the means for removing mass of filamentous green macroalgae from the continuous flow macroalgal pond is a screen.

[0026] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the screen is a mesh screen or a wedge wire screen.

[0027] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the means for removing wastewater from the continuous flow macroalgal pond prevents filamentous green macroalgae from passing through the means.

[0028] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the means for removing wastewater from the continuous flow macroalgal pond is a screen. In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the screen is a mesh screen or a wedge wire screen.

[0029] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the screen prevents filamentous green macroalgae with a filament length of at least 1mm from passing through the screen.

[0030] In one embodiment, the present invention provides a continuous flow wastewater treatment system according to any one of claims 1 to 19, wherein the system further comprises an agitator.

[0031] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the system further comprises an agitator for increasing separation of green macroalgae filaments, reducing interweaving of green macroalgae filaments, reducing formation of green macroalgae mats, and / or mixing wastewater.

[0032] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the system further comprises a wastewater inlet.

[0033] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the system further comprises an outlet for treated wastewater.

[0034] In one embodiment, the present invention provides a method of treating wastewater comprising passing wastewater through a wastewater treatment system as described herein.

[0035] In one aspect, the present invention provides a method of treating wastewater comprising; contacting a mass of filamentous green macroalgae with wastewater under conditions of continuous flow; and removing water contacted with the mass of filamentous green macroalgae under conditions of continuous flow.

[0036] In one embodiment, the present invention provides a method as described herein, wherein the method further comprises a step of removing a desired mass of filamentous green macroalgae under conditions of continuous flow.

[0037] In one embodiment, the present invention provides a method as described herein, wherein the filamentous green macroalgae is uniseriate.

[0038] In one embodiment, the present invention provides a method as described herein, wherein the filamentous green macroalgae has a length of at least 1 mm.

[0039] In one embodiment, the present invention provides a method as described herein, wherein the filamentous green macroalgae has a length of at least 10 mm. In one embodiment, the present invention provides a method as described herein, wherein the filamentous green macroalgae has a length of at least 20 mm.

[0040] In one embodiment, the present invention provides a method as described herein, wherein the filamentous green macroalgae has a diameter of at least 5 pm.

[0041] In one embodiment, the present invention provides a method as described herein, wherein the filamentous green macroalgae has a diameter of at least 60 pm.

[0042] In one embodiment, the present invention provides a method as described herein, wherein the mass of green macroalgae comprises one or more species of green macroalgae.

[0043] In one embodiment, the present invention provides a method as described herein, wherein the mass of green macroalgae comprises one or more macroalgal species of the division Chlorophyta.

[0044] In one embodiment, the present invention provides a method as described herein, wherein the mass of green macroalgae comprises one or more macroalgal species of the class Chlorophyceae.

[0045] In one embodiment, the present invention provides a method as described herein, wherein the mass of green macroalgae comprises one or more species of the genus Oedogonium.

[0046] In one embodiment, the present invention provides a method as described herein, wherein the mass of green macroalgae is planktonic.

[0047] In one embodiment, the present invention provides a method as described herein, wherein the step of removing a desired mass of filamentous green macroalgae from the continuous flow macroalgal pond is performed using a means that allows continuous flow of water through the means.

[0048] In one embodiment, the present invention provides a method as described herein, wherein the step of removing a desired mass of filamentous green macroalgae from the continuous flow macroalgal pond is performed using a screen. In one embodiment, the present invention provides a method as described herein, wherein the step of removing a desired mass of filamentous green macroalgae from the continuous flow macroalgal pond is performed using a mesh screen or a wedge wire screen.

[0049] In one embodiment, the present invention provides a method as described herein, wherein the step of removing wastewater from the continuous flow macroalgal pond is performed using a means that prevents filamentous green macroalgae from passing through the means. In one embodiment, the present invention provides a method as described herein, wherein the step of removing wastewater from the continuous flow macroalgal pond is performed using a mesh screen or a wedge wire screen. In one embodiment, the present invention provides a method as described herein, wherein the screen prevents filamentous green macroalgae with a filament length of at least 1 mm from passing through the screen.

[0050] BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 shows a diagrammatic cross-sectional view of one embodiment of a wastewater treatment system according to the invention.

[0052] Figure 2 shows a Process Diagram of one embodiment of a wastewater treatment system according to the invention.

[0053] Figure 3 shows the correlation between the load (flux) of incoming nutrients and the load removal rate of these nutrients as a result of the macroalgal treatment, at the system of Example 1, in relation to Total Nitrogen (over 300 data points). Figure 3 demonstrates that the method and system for treating wastewater described herein is able to remove nitrogen (e.g. Total Nitrogen) from incoming wastewater to be treated at levels commensurate with the nitrogen (Total Nitrogen) load in the incoming (influent) water.

[0054] Figure 4 shows the correlation between the load (flux) of incoming nutrients and the load removal rate of these nutrients as a result of the macroalgal treatment, at the system of Example 1, in relation to Total Phosphorous (over 300 data points). Figure 4 demonstrates that the method and system for treating wastewater described herein is able to remove phosphorus (e.g. Total Phosphorous) from incoming wastewater to be treated at levels commensurate with the phosphorus (Total Phosphorus) load in the incoming (influent) water.

[0055] Figure 5 shows the correlation between the load (flux) of incoming nutrients and the load removal rate of these nutrients as a result of the macroalgal treatment, at the system of Example 1, in relation to Oxidised Nitrogen (over 300 data points). Figure 5 demonstrates that the method and system for treating wastewater described herein is able to remove nitrogen (e.g. Oxidised Nitrogen) from incoming wastewater to be treated at levels commensurate with the nitrogen (Oxidised Nitrogen) load in the incoming (influent) water.

[0056] Figure 6 shows the correlation between the load (flux) of incoming nutrients and the load removal rate of these nutrients as a result of the macroalgal treatment, at the system of Example 1, in relation to Ammonia Nitrogen (over 300 data points). Figure 6 demonstrates that the method and system for treating wastewater described herein is able to remove nitrogen (e.g. Ammonia Nitrogen) from incoming wastewater to be treated at levels commensurate with the nitrogen (Ammonia Nitrogen) load in the incoming (influent) water.

[0057] Figure 7 shows the correlation between the load (flux) of incoming nutrients and the load removal rate of these nutrients as a result of the macroalgal treatment, in the system of Example 1, in relation to Ortho-Phosphate (over 300 data points). Figure 7 demonstrates that the method and system for treating wastewater described herein is able to remove phosphorus (e.g. Ortho-Phosphate) from incoming wastewater to be treated at levels commensurate with the phosphorus (Ortho-Phosphate) load in the incoming (influent) water.

[0058] Figure 8A shows the correlation between the load (flux) of incoming faecal coliform and the load removal rate of faecal coliform as a result of the macroalgal treatment, in the system of Example 1 (over 200 data points). Figure 8B shows the correlation between the load (flux) of incoming E. coli and the load removal rate of E.coli as a result of the macroalgal treatment, in the system of Example 1 (over 100 data points). Figure 8 demonstrates that the method and system for treating wastewater described herein is able to remove faecal coliform and E.coli from incoming wastewater to be treated at levels commensurate with the faecal coliform and E. coli load in the incoming (influent) water.

[0059] Figure 9 shows a typical growth curve of filamentous green macroalgae in a continuous flow macroalgal pond treating municipal wastewater. Figure 9 shows the three growth phases, with the exponential growth phase showing an exponential increase in density (and productivity) between 0.5 g / L and 3.5 g / L.

[0060] Figure 10 shows a top view schematic of one embodiment of a continuous flow macroalgal pond according to the invention.

[0061] Figure 11 shows a side view schematic of one embodiment of a continuous flow macroalgal pond according to the invention.

[0062] Figure 12 shows wedge wire features suitable for use in wedge wire screens described herein.

[0063] DETAILED DESCRIPTION

[0064] The present invention relates in part to the use of filamentous green macroalgae under conditions of continuous flow for wastewater treatment, including removing mass of filamentous green macroalgae from a wastewater treatment system under conditions of continuous flow. Importantly, the present inventors have demonstrated that filamentous green macroalgae can be used. Without wishing to be bound by theory, the use of filamentous green macroalgae allows for the removal of nutrients and exchange of dissolved gasses from wastewater under conditions of continuous flow, and also the management of biomass of filamentous algae under conditions of continuous flow, including the separation of biomass from water in a cost-effective manner.

[0065] Accordingly, in a first aspect the present invention provides a continuous flow wastewater treatment system comprising: a continuous flow macroalgal pond, a) a mass of filamentous green macroalgae in the continuous flow macroalgal pond, b) a means for removing mass of filamentous green macroalgae from the continuous flow macroalgal pond, and c) a means for removing wastewater from the continuous flow macroalgal pond.

[0066] Figure 1 shows a schematic of the continuous flow wastewater treatment system comprising a continuous flow macroalgal pond (high rate algal pond; HRAP), which contains a mass of filamentous green macroalgae in the continuous flow macroalgal pond, a means for removing mass of filamentous green macroalgae from the continuous flow macroalgal pond ('macroalgae harvest line'), so that the mass of filamentous green macroalgae in the continuous flow macroalgal pond is maintained at a desired mass (e.g. density), an inlet ('wastewater inlet') for addition of wastewater to be treated in the continuous flow treatment system and a means for separating treated wastewater from macroalgae ('mesh screen'), and a means for removing wastewater treated by the continuous flow treatment system ('treated water outlet'). Also shown is an agitator ('paddlewheel') for providing continuous flow, increasing separation of green macroalgae filaments, reducing interweaving of green macroalgae filaments, reducing formation of green macroalgae mats, and / or mixing wastewater. Figures 10 and 11 show schematics of one embodiment of a continuous flow macroalgal pond.

[0067] Figure 2 shows a Process Diagram of one embodiment of a wastewater treatment system according to the invention. Wastewater from a wastewater source (e.g. raw sewage) undergoes primary, secondary, and possibly tertiary treatment. Secondary or tertiary treated effluent is provided to a continuous flow macroalgal pond ('high-rate macroalgal pond'). Wastewater is treated by contacting with filamentous green macroalgae, to promote the breakdown of organic contaminants, nutrient uptake, gas exchange, and macroalgal growth. Treated water is discharged from the continuous flow macroalgal pond using a means (e.g. a 'mesh screen' as per Figure 1) that allows treated water to pass through the means, and prevents filamentous macroalgal biomass to pass through the means to be retained in the continuous flow macroalgal pond. The treatment system also comprises a separate harvest line for removing mass of filamentous green macroalgae from the continuous flow macroalgal pond, and a harvest unit comprising a means (e.g. a 'harvest screen' as per Figure 10) that allows passage of water through the unit, and allows retention of filamentous macroalgal biomass on the screen. In one aspect the present invention provides systems and methods which avoid the use of microalgae, which cannot be maintained in the treatment system under conditions of continuous flow without using cost-prohibitive separation solutions. in one aspect the present invention provides systems and methods which also avoid the problem of microalgae not being able to be separated from the treated water during harvest without using cost- prohibitive settlement (e.g. gravity) ponds or engineered solutions based on filtration and / or centrifugation principles.

[0068] As used herein, the term continuous flow refers to the wastewater treatment systems described herein operating in continuous flow of water, including wherein the continuous flow macroalgal pond comprising a mass of filamentous green macroalgae is in contact with wastewater to be treated is in continuous flow.

[0069] In one embodiment, there is a continuous flow of influent wastewater to be treated into the system and moving through the system in contact with a mass of filamentous green macroalgae. Microalgal wastewater systems operate in batch mode whereby a reactor (e.g. photobioreactor) in the wastewater treatment system performs treatment steps or periods on a batch quantity of influent wastewater contained in the reactor before discharge. Batch flow systems have been used previously using microalgae, to provide a controlled reactor environment for treatment. However, batch flow systems are unable to deal with continuous inflow of wastewater into the reactor. Traditional continuous flow wastewater systems utilise a number of approaches to treat and clarify water, including primary screening, clarifiers, activated sludge beds, trickling biofilters, membrane bioreactors and / or reverse osmosis.

[0070] In contrast, the wastewater treatment system of the present invention comprising filamentous green macroalgae operates in continuous flow, including wherein a continuous flow of influent enters the system to contact a mass of filamentous green macroalgae, and / or does not require the approaches of traditional tertiary systems, including, membrane bioreactors and / or reverse osmosis systems, that require a significantly higher energy input for a similar treatment output.

[0071] In one embodiment, the present invention provides a continuous flow wastewater treatment system comprising: a. a continuous flow macroalgal pond comprising wastewater to be treated b. a mass of filamentous green macroalgae in the continuous flow macroalgal pond c. a means for removing mass of filamentous green macroalgae from the continuous flow macroalgal pond, and d. a means for removing treated water from the continuous flow macroalgal pond.

[0072] As disclosed herein, the continuous flow systems may be associated with a Hydraulic Loading Rate (i.e. HLR, or 'exchange rate') of between 0% and about 400% of the volume of the continuous flow macroalgal pond per day. Note that a Hydraulic Loading Rate of 100% per day is equivalent to a Hydraulic Retention Time (HRT) of one day.

[0073] In one embodiment, the hydraulic loading rate is more than 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300 350 or 400% of the volume of the continuous flow macroalgal pond per day.

[0074] As used herein, the term wastewater includes municipal wastewater, agricultural wastewater and industrial wastewater. There are four categories of municipal wastewater, including raw wastewater, which is municipal wastewater prior to primary settling, primary effluent wastewater, which is wastewater after primary settling, secondary effluent wastewater, which is wastewater after secondary treatment - where the remaining organic matter is consumed by microorganisms - and tertiary effluent wastewater, which is the wastewater after tertiary treatment and removal of dissolved contaminants. The present inventors have demonstrated the systems and methods described herein are able to treat wastewater with high nutrient loads, as is demonstrated in Figures 3 to 8. For example, in one embodiment, primary and secondary wastewater can be treated to form secondary and tertiary treated wastewater, respectively.

[0075] Accordingly, in one embodiment the wastewater to be treated is selected from the group consisting of municipal wastewater, agricultural wastewater and industrial wastewater.

[0076] In another embodiment, municipal wastewater, to be treated is secondary or tertiary effluent wastewater.

[0077] In Example 1, the secondary effluent wastewater to be treated had a continuous Flow rate of up to 4.3 kL / d (86 L / m2 / day), a Total Nitrogen concentration (TN) of up to 9.44 mg / L, a Total Phosphorus concentration (TP) of up to 2.81 mg / L, an Ammonia Nitrogen concentration (N-NH3) of up to 4.95 mg / L, an Oxidised Nitrogen concentration (N-NOX, i.e. as the sum of nitrite and nitrate) of up to 8.53 mg / L, a Phosphate concentration (P-PO4) of up to 2.06 mg / L, a Pathogen concentration (e.g. faecal coliform) of up to 85,000 CFU / lOOmL, a Pathogen concentration (e.g. Escherichia coli or E. coli) of up to 67,000 CFU / lOOmL, a Dissolved Inorganic Nitrogen (DIN) in TN of up to 97 %, a Dissolved Inorganic Phosphorus (DIP) in TP of up to 92 %, a TN:TP ratio of up to 37, a D IN :D IP ratio of up to 69, a TN flux of up to 0.71 g / m2 / d, a TP flux of up to 0.14 g / m2 / d, a N-NH3 flux of up to 0.31 g / m2 / d, a N-NOXflux of up to 0.65 g / m2 / d, a P-PO4 flux of up to 0.11 g / m2 / d, a Pathogen flux (e.g. faecal coliform) of up to 575 x 10A3 CFU / m2 / d, a Pathogen flux (e.g. E coli) of up to 423 x 10A3 CFU / m2 / d, a pH of up to 8.2, a Water Temperature of up to 35 °C, a Turbidity of up to 24 NTU, a BOD5of up to 30 mg / L, and a Total Suspend Solids of up to 100 mg / L.

[0078] In Example 2 the wastewater to be treated had a Flow rate of up to 0.8 kL / d (16 L / m2 / d), a Total Nitrogen concentration (TN) of up to 37.5 mg / L, a Total Phosphorus concentration (TP) of up to 15.8 mg / L, an Ammonia Nitrogen concentration (N-NH3) of up to 6.5 mg / L, a Nitrite concentration (N-NO2) of up to 0.9 mg / L, a Nitrate concentration (N-NO3) of up to 31.9 mg / L, a Phosphate concentration (P- PO4) of up to 8.9 mg / L, a Pathogen concentration (e.g. faecal coliform) of up to 115,000 CFU / lOOmL, a Pathogen concentration (e.g. E. coli) of up to 46,000 CFU / lOOmL, a Dissolved Inorganic Nitrogen (DIN) in TN of up to 100 %, a Dissolved Inorganic Phosphorus (DIP) in TP of up to 100 %, a TN:TP ratio of up to 6, a D IN :DI P ratio of up to 5.4, a TN flux of up to 3.0 g / m2 / d, a TP flux of up to 1.3 g / m2 / d, a N-NH3 flux of up to 0.4 g / m2 / d, a N-NO2 flux of up to 0.5 g / m2 / d, a N-NO3 flux of up to 2.6 g / m2 / d, a P-PO4 flux of up to 0.7 g / m2 / d, a Pathogen flux (e.g. faecal coliform) of up to 755 x 10A3 CFU / m2 / d, a Pathogen flux (e.g. E coli) of up to 468 x 10A3 CFU / m2 / d, a pH of up to 7.8, a Water Temperature of up to 40 °C, a Turbidity of up to 146 NTU, a BOD5of up to 28 mg / L, a COD of up to 503 mg / L, and a Total Suspend Solids of up to 50 mg / L.

[0079] Accordingly, in one embodiment, the wastewater to be treated has a Flow rate of at least 1 L / d. Without wishing to be bound by theory, the flow rate can be from 0 L / d for up to 2 weeks to 50 ML / d and over, depending on the size of the facility and the number of HRAPs (i.e. facility footprint).

[0080] In one embodiment, the wastewater to be treated has a Total Nitrogen concentration (TN) of between 0 and 50 mg / L. As used herein, total nitrogen refers to all organic and inorganic compounds containing nitrogen.

[0081] In one embodiment, the wastewater to be treated has a Total Phosphorus concentration (TP) of between 0 and 30 mg / L. As used herein, total phosphorus refers to all organic and inorganic compounds containing phosphorus.

[0082] In one embodiment, the wastewater to be treated has an Ammonia Nitrogen concentration (N-NH3) of between 0 and 50 mg / L. As used herein ammonia (e.g. N-NH3) refers to nitrogen in ammonia.

[0083] In one embodiment, the wastewater to be treated has an Oxidised Nitrogen concentration (N-NOX) of between 0 and 50 mg / L. As used herein, Oxidised Nitrogen (or N-NOX) refers to the sum of nitrogen in Nitrite (NO2) and Nitrate (NO3). N-NO2 refers to nitrogen in Nitrite (NO2) and N-NO3 refers to nitrogen in Nitrate (NO3). In one embodiment, the wastewater to be treated has a Phosphate concentration (P-PO4) of between 0 and 30 mg / L. As used herein, phosphate refers to ortho-phosphate (or Soluble Reactive Phosphorus - e.g. SRP). As used herein P-PO4 refers to phosphorus in ortho-phosphate.

[0084] In one embodiment, the wastewater to be treated has a Pathogen concentration of between 0 and 500,000 CFU (Colony Forming Units) / 100mL. As used herein pathogen concentration includes, but is not limited to, faecal coliform and Escherichia coli (E. coli).

[0085] In one embodiment, the wastewater to be treated has a DIN in TN of between 50 and 100 %. As used herein Dissolved Inorganic Nitrogen (DIN) refers to the sum of nitrogen in ammonia, nitrite, and nitrate.

[0086] In one embodiment, the wastewater to be treated has a DIP in TP of between 3 and 100 %. As used herein Dissolved Inorganic Phosphorus (DIP) refers to phosphorus in dissolved ortho-phosphate.

[0087] In one embodiment, the wastewater to be treated has a TN flux of between 0 and 3.0 g / m2 / d.

[0088] As used herein, flux relates to the amount of nutrient or component that is transferred from wastewater being treated, per unit of space and per unit of time. For example, mass flux is a function of flow and concentration (i.e. also referred to as nutrient load or loading rate), and is the rate of mass flow per unit of area, and can be expressed in g / m2 / d or kg / ha / year. For example, in the context of wastewater treatment, TN flux (in g / m2 / d) refers to the mass of TN in wastewater (in grams of Total Nitrogen) transferred to a square metre of continuous flow macroalgae pond (in m2) in a defined period (in days). For example, TN flux refers to the rate of TN mass transfer into the filamentous green macroalgae, TP flux refers to the rate of TP mass transfer into the filamentous green macroalgae, etc.

[0089] In one embodiment, the wastewater to be treated has a TP flux of between 0 and 1.3 g / m2 / d.

[0090] In one embodiment, the wastewater to be treated has a N-NH3 flux of between 0 and 0.5 g / m2 / d.

[0091] In one embodiment, the wastewater to be treated has a N-NO2 flux of between 0 and 0.5 g / m2 / d.

[0092] In one embodiment, the wastewater to be treated has a N-NO3 flux of between 0 and 2.6 g / m2 / d.

[0093] In one embodiment, the wastewater to be treated has a P-PO4 flux of between 0 and 0.7 g / m2 / d.

[0094] In one embodiment, the wastewater to be treated has a Pathogens flux (e.g. faecal coliform) of between 0 and 1,000 x 10A3 CFU / m2 / d.

[0095] In one embodiment, the wastewater to be treated has an E. coli flux of between 0 and 500 x 10A6 CFU / m2 / d. As used herein, pathogen flux relates to the amount of pathogen transferred from the wastewater to the system containing a biomass of filamentous green macroalgae.

[0096] In one embodiment, the wastewater to be treated has a pH of between 5 and 9.

[0097] In one embodiment, the wastewater to be treated has a Water Temperature of between 5 and 40 °C.

[0098] In one embodiment, the wastewater to be treated has a BOD5 of between 0 and 50 mg / L.

[0099] In one embodiment, the wastewater to be treated has a Total Suspend Solids of between 0 and 100 mg / L.

[0100] Importantly, the present inventors have demonstrated that the methods and systems for treating wastewater described herein reduces nutrient concentrations significantly or completely, as is set out in the Examples.

[0101] Accordingly, in one embodiment, the present invention provides a method and system for treating wastewater which can reduce the Total Nitrogen concentration (TN) to less than 9.44, 8, 7, 6, 5, 4, 3, 2, 1, or 0.1 mg / L.

[0102] In another embodiment, the present invention provides a method and system for treating wastewater which can reduce the Total Phosphorus concentration (TP) to 0.01 mg / L.

[0103] In a further embodiment, the present invention provides a method and system for treating wastewater which can reduce the nitrogen in ammonia concentration (N-NH3) to O.Olmg / L.

[0104] In a further embodiment, the present invention provides a method and system for treating wastewater which can reduce the nitrogen in Nitrite concentration (N-NO2) to O.Olmg / L.

[0105] In a further embodiment, the present invention provides a method and system for treating wastewater which can reduce the nitrogen in Nitrate concentration (N-NO3) to O.Olmg / L.

[0106] In a further embodiment, the present invention provides a method and system for treating wastewater which can reduce the phosphate in orthophosphate concentration (P-PO4) to 0.001 mg / L.

[0107] In a further embodiment, the present invention provides a method and system for treating wastewater which can reduce the Pathogen concentration (e.g. faecal coliform) to 1 CFU / lOOmL.

[0108] In a further embodiment, the present invention provides a method and system for treating wastewater which can reduce the Pathogen concentration (e.g. E. coli) to 1 CFU / lOOmL.

[0109] In a further embodiment, the present invention provides a method and system for treating wastewater which can reduce the TN flux to 0.01 g / m2 / d. In a further embodiment, the present invention provides a method and system for treating wastewater which can reduce the TP flux to 0.001 g / m2 / d.

[0110] In a further embodiment, the present invention provides a method and system for treating wastewater which can reduce the N-NH3 flux to 0.001 g / m2 / d.

[0111] In a further embodiment, the present invention provides a method and system for treating wastewater which can reduce the N-NO2 flux to 0.001 g / m2 / d.

[0112] In a further embodiment, the present invention provides a method and system for treating wastewater which can reduce the N-NO3 flux to 0.001 g / m2 / d.

[0113] In a further embodiment, the present invention provides a method and system for treating wastewater which can reduce the P-PO4 flux to 0.001 g / m2 / d.

[0114] In a further embodiment, the present invention provides a method and system for treating wastewater which can reduce the faecal coliform to 0.001 10A3 CFU / m2 / d.

[0115] In a further embodiment, the present invention provides a method and system for treating wastewater which can reduce the E. coli to 1 CFU / m2 / d.

[0116] As used herein, the term continuous flow macroalgal pond refers to a shallow raceway pond or ponds capable of holding water to be treated under conditions of continuous flow. Continuous flow of wastewater can be achieved using gravity systems, or a pumping device, to pump wastewater to the raceway pond and an overflow system to discharge the treated water.

[0117] In one embodiment, the continuous flow macroalgal pond comprises a means for agitation. Agitation of wastewater and filamentous green macroalgae can be achieved using an agitation system, such as a paddlewheel, a pump, a rotating arm, or other suitable means to produce continuous flow in the continuous flow macroalgal pond. The means for agitation reduces interweaving of the filaments of the filamentous green macroalgae, thereby reducing the formation of floating macroalgal mats. The means for agitation also mixes the wastewater and mass of filamentous green macroalgae, nutrients and gases on a continuous basis.

[0118] Accordingly, in one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the continuous flow macroalgal pond further comprises an agitator for increasing separation of green macroalgae filaments, reducing interweaving of green macroalgae filaments, reducing formation of green macroalgae mats, and / or mixing wastewater.

[0119] In one embodiment, the agitator is a paddlewheel. Pond depth is suitable for growth of a mass of filamentous green macroalgae. For example, in one embodiment, the pond depth is between 150 mm and 600 mm. In another embodiment, the pond depth is around 750 mm. Hydraulic loading rates of the continuous flow macroalgal pond are determined by influent flow rate, influent nutrients concentration, productivity rate of the filamentous green macroalgae and other factors.

[0120] In one embodiment, agitation is achieved using a low-power paddlewheel, which circulates the wastewater through the channels. Without wishing to be bound by theory, continuously mixing the wastewater avoids thermal stratification and maintains a homogenous distribution of filamentous green macroalgae in a continuous flow environment throughout the channels for optimal growth and wastewater treatment. This environment helps to maximise the breakdown of organic matter and removal of nutrients via filamentous green macroalgal uptake. Dissolved carbon uptake by the filamentous green macroalgae through photosynthesis, and shallow depth combined with mixing helps to maximise pathogen inactivation via high diurnal water pH and sunlight (i.e. ultraviolet radiation), respectively.

[0121] For example, as is shown in Figure 9, the biomass of filamentous green macroalgae can be managed at different densities and at different growth rates (different productivities) in the continuous flow macroalgal pond. For example, biomass of filamentous green macroalgae can be maintained at a density in the exponential growth phase of the filamentous green macroalgae, or in the light saturation phase of filamentous green macroalgae growth.

[0122] Examples 1 and 3 show the management of biomass of filamentous green macroalgae at different densities.

[0123] The design of high-rate algal ponds (HRAPs) is known in the art. As used herein the term continuous flow macroalgal pond refers to a high-rate algal pond that is configured to provide for continuous flow of wastewater to be treated comprising a biomass of filamentous green macroalgae, including being configured to manage the biomass of filamentous green macroalgae under continuous flow. In one embodiment, the continuous flow macroalgal pond is a HRAP configured to provide continuous mixing, and a homogenous distribution of filamentous green macroalgae within the HRAP (i.e. prevent the formation of floating mats, and static zones).

[0124] An advantage of the continuous flow macroalgal pond as used herein is that their design is simple once the principle of biomass management of filamentous green macroalgae is known, and cost effective. In brief, hydraulic loading rate (i.e. exchange rate, or Hydraulic Retention Time) for the continuous flow macroalgal pond can be calculated using factors such as system peak factors, any pre-treatment system (e.g. inclusive of but not limited to anaerobic lagoons, Imhoff tanks, large septic tanks, anaerobic digestors), and other systems such as buffer storage or pumping to allow for continuous flow, preferably at a continuous flow rate, and to minimise batch flow. The continuous flow system can all be configured in either a single or series loop arrangement as required, and likely to be governed by land shape and area available and the grade across the site. The design of the continuous flow macroalgal pond system is not limited to achieving the hydraulic retention time in a single HRAP. Multiple HRAPs may be used in parallel or in series in order to achieve the required hydraulic retention time.

[0125] In one embodiment, overall channel length to total channel width, is typically not less than 6:1 for single channel designs.

[0126] In another embodiment, the continuous flow macroalgal pond orientation is typically selected to minimise wall shading and / or wind exposure (i.e. the formation of waves).

[0127] In another embodiment, the continuous flow macroalgal pond wastewater depth is operated between around 150 mm to around 750 mm deep. The continuous flow macroalgal pond can be operated at a fixed depth or at variable depth for example, as one means of accommodating variable inflow rates.

[0128] In another embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the one or more species of filamentous green macroalgae is selected for a desired productivity in the continuous flow wastewater treatment system. For example, the present inventors have demonstrated herein the growth of filamentous green macroalgae following different inoculation densities. Without wishing to be bound by theory, the biomass of filamentous green macroalgae can be managed at different densities of biomass corresponding to different productivities in the growth curve of biomass of filamentous green macroalgae, and which allows for the removal (i.e. harvest) of biomass under conditions of flow to maintain the desired density and / or productivity.

[0129] In another embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the one or more species of green macroalgae is selected for being endemic to the geographic location of the treatment system.

[0130] In another embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the one or more species of green macroalgae is selected for a productivity of between 0 g and 20 g dry weight per square metre per day in the continuous flow wastewater treatment system.

[0131] For example, Example 1 demonstrates the one or more species of green macroalgae is selected for a productivity of between 1 g and 12 g dry weight per m2per day in the continuous flow wastewater treatment system. For example, Example 3 demonstrates the one or more species of green macroalgae is selected for a productivity of between 1 g and 15 g dry weight per m2per day in the continuous flow wastewater treatment system. For example, dry weight refers to biomass which typically has 10 to 15% moisture content by weight. Fresh weight refers to biomass which typically has 80 to 85% moisture content by weight.

[0132] In another embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the mass of green macroalgae in the continuous flow macroalgal pond is maintained at a density between 0.1 g fresh weight per L water and 5 g fresh weight per L water. For example, Figure 9 demonstrates the mass of green macroalgae in the continuous flow macroalgal pond can be maintained at a density between 0.15 g fresh weight per L water and 4.5 g fresh weight per L water. Figure 9 also demonstrates the mass of green macroalgae in the continuous flow macroalgal pond can be maintained at a density corresponding to the exponential growth phase of the filamentous green macroalgae, at between 0.5 g fresh weight per L water and 3.5 g fresh weight per L water.

[0133] In another embodiment, the continuous flow macroalgal pond volume and hydraulic retention time (HRT) are used to determine the design of the continuous flow macroalgal pond.

[0134] In another embodiment, the continuous flow macroalgal pond comprises a liner suitable for wastewater treatment in the configuration and channel cross section, and / or the ability of the lining material to be installed in the continuous flow macroalgal pond.

[0135] In another embodiment, wherein the continuous flow macroalgal pond comprises a paddlewheel, paddlewheel design is well known in the field, including the selection and number of blades, motor, reduction gearbox, direct drive coupling including shear pin, a slipping clutch, concrete base or similar rigid material laid under the paddlewheel to provide physical protection to the pond liner, critical dimensions (e.g. paddlewheel clearances) are maintained in service, mounting, jointing requirements etc. For example, in one embodiment, the area of the channel where the paddlewheel is installed shall have vertical side walls to minimise paddlewheel by-pass. In one embodiment, the structure shall incorporate the channel transition from the general channel cross section to the vertical wall. In another embodiment, the channel shall be designed to minimise wheel movement and prevent it coming into contact with the channel walls or floor and / or to protect the liner.

[0136] In one embodiment, the agitation means is used to achieve a mean surface flow velocity of between 0.2 m / s and 0.6 m / s.

[0137] In one embodiment, the continuous flow macroalgal pond comprises a wastewater inlet for providing wastewater to be treated (influent) to the continuous flow macroalgal pond.

[0138] In one embodiment, the continuous flow macroalgal pond comprises an outlet for wastewater treated by a system as described herein.

[0139] In one embodiment, the outlet pipe for wastewater treated by the system as described herein is located downstream of the exchange screen, and used to discharge treated wastewater by gravity overflow.

[0140] In one embodiment, the means for removing mass of filamentous green macroalgae from the continuous flow macroalgal pond is comprised in a harvest unit. As used herein, the harvest unit is configured to allow retention of filamentous green macroalgae, and passage of water through the unit, under conditions of continuous flow of water.

[0141] For example, in one embodiment, the harvest unit comprises a filter. Suitable filter materials include but are not limited to electroformed screens, stacked disc filters, fabrics and membranes, woven metals, etched metal screens, and wedge wire screens.

[0142] A wedge wire screen as described herein is configured to allow the passage of water and small particles through the screen but prevent filamentous green macroalgae from passing through the screen. The screen aperture size will depend on the species of filamentous green macroalgae being used, and flow rate.

[0143] In a preferred embodiment, the screen allows passage of filamentous green macroalgae with a filament length of less than 1 mm through the screen. In this embodiment, the screen prevents passage of filamentous green macroalgae with a filament length of 1 mm or more through the screen.

[0144] In one embodiment, the screen prevents passage of filamentous green macroalgae with a diameter of at least 5 pm through the screen. In a preferred embodiment, the screen prevents passage of filamentous green macroalgae with a diameter of at least 10 pm through the screen. In another preferred embodiment, the screen prevents passage of filamentous green macroalgae with a diameter of at least 15 pm through the screen. In a further preferred embodiment, the screen prevents passage of filamentous green macroalgae with a diameter of at least 20, 25, 30, 35, 40, 45, 50 or 60 pm through the screen.

[0145] In one embodiment, the screen is a flat or a curved wedge wire screen.

[0146] Wedge wire screen can be manufactured in a variety of widths, arc lengths, apertures or wedge wires to suit the flow rate of water and the species of filamentous green macroalgae being used. Figure 12 shows technical information relating to wedge wires that are suitable for use in the wedge wire screens described herein.

[0147] The screen material is chosen to be able to not fail under load of filamentous green macroalgae under conditions of continuous flow.

[0148] In one preferred embodiment, the screen has the following parameters:

[0149] Type: Flat or Curved screen

[0150] Wire Type: M47 wire (1.19 mm Width / Wedge Relief Angle 13°)

[0151] Material: Stainless Steel 316 Grade

[0152] Aperture: 0.5mm

[0153] Open Area: 29.5%

[0154] Flow Rate: 6,000 litres / hour / m2

[0155] Flow Rate (MAX): 24,000 litres / hour / m2

[0156] In a preferred embodiment, the screen is designed to not block under load of filamentous green macroalgae. For example, if the screen is in the continuous flow macroalgal pond floor, a means to prevent blockages is aeration, e.g. a continuous air supply diffused through the screen (e.g. at a rate of 9,000 litres per hour) is used to prevent blockages.

[0157] If the screen is vertical, a means to prevent blockages may not be needed.

[0158] In one embodiment wherein the screen is a curved wedge wire screen, the screen has the following parameters:

[0159] Type: Curved Sieve Screen

[0160] Radius: R2036

[0161] Face Arc Length: 1600 mm Wire Type: M47 wire (1.19 mm head width / Wedge Relief Angle 13°)

[0162] Material: Stainless Steel 316 Grade

[0163] Aperture: 0.2 mm

[0164] Open Area: 14.3%

[0165] Flow Rate (MAX): 50,000 litres / hour / m2

[0166] In a preferred embodiment, the screen aperture allows passage of filamentous green macroalgae with a filament length of less than 1 mm through the screen. In this embodiment, the screen aperture prevents passage of filamentous green macroalgae with a filament length of 1 mm or more through the screen. For example, in another preferred embodiment, the screen prevents passage of filamentous green macroalgae with a filament length of at least 10 mm through the screen. In another preferred embodiment, the screen prevents passage of filamentous green macroalgae with a filament length of at least 15, 20, 25, 50, 75, 100, 200, 300, 400, 500, 600, 700 or 750 mm through the screen.

[0167] In one embodiment, the screen aperture prevents passage of filamentous green macroalgae with a diameter of at least 5 pm through the screen. In a preferred embodiment, the aperture prevents passage of filamentous green macroalgae with a diameter of at least 10 pm through the screen. In another preferred embodiment, the aperture prevents passage of filamentous green macroalgae with a diameter of at least 15 pm through the screen. In a further preferred embodiment, the aperture prevents passage of filamentous green macroalgae with a diameter of at least 20, 25, 30, 35, 40, 45, 50 or 60 pm through the screen.

[0168] In one embodiment, the continuous flow macroalgal pond comprises a harvest line for transferring treated water and filamentous green macroalgae to a harvest unit. For example, in one embodiment the harvest line comprises a system capable of collecting and pumping treated water and macroalgae to the harvest unit.

[0169] In one embodiment, the continuous flow macroalgal pond is connected to the harvest unit by a harvest line for transfer of filamentous green macroalgae and water being treated to the harvest unit.

[0170] In another embodiment, the harvest unit comprises a filter or 'screen' for separating green macroalgae from the water being treated.

[0171] Accordingly, in one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the system further comprises a harvest unit for separating green macroalgae from the water being treated, wherein the harvest unit is downstream from the continuous flow macroalgal pond. In one embodiment, the treated water and macroalgae are pumped to a box at the back of the harvest unit overflowing onto a curved wedge wire screen allowing passage of the treated water and retention of filamentous macroalgae on the screen.

[0172] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the outlet for treated wastewater is downstream of the exchange screen for separating green macroalgae from the water being treated.

[0173] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the continuous flow macroalgal pond further comprises a nursery unit comprising a stock culture of biomass of filamentous green macroalgae. In one embodiment, the nursery unit comprises a tank with a central overflow standpipe, using aeration to maintain macroalgae suspended in the water column. The nursery unit can be operated in batch, with nutrient- free freshwater (e.g. bore water), and using synthetic nutrients at optimal level to control filamentous green macroalgae productivity. The nursery unit can be used to provide biomass of filamentous green macroalgae to the continuous flow macroalgal pond.

[0174] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the nursery unit is connected upstream of the continuous flow macroalgal pond.

[0175] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, comprising an inlet for delivering wastewater to be treated by the system into the continuous flow macroalgal pond, such as delivering primary or secondary treated wastewater into the continuous flow macroalgal pond.

[0176] As used herein, the term mass of filamentous green macroalgae refers to a mass of one or more macroalgal species of the division Chlorophyta, including filamentous Chlorophyta. The term includes macroalgal species of the class Chlorophyceae.

[0177] Without wishing to be bound by theory, the use of filamentous green macroalgae allows for the management of biomass under conditions of continuous flow, including cost-effective separation of biomass from water, water from biomass, and managing productivity of biomass and hydraulic retention times for treatment of water.

[0178] The ability to manage biomass of filamentous green macroalgae under conditions of continuous flow allows for simple design, resulting in energy and cost effective separation of biomass from water, water from biomass, and managing productivity of biomass and hydraulic retention times for treatment of water, relative to microalgal approaches. As demonstrated in the Examples, the use of filamentous macroalgal biomass under conditions of continuous flow allows for the management of the biomass under conditions to treat wastewater, and is able to reduce the load of nutrients from incoming wastewater to be treated at levels commensurate with the load in the incoming (influent) wastewater.

[0179] Without wishing to be bound by theory, filamentous green macroalgae have a high surface area of contact with water to optimise exchange of dissolved gasses (CO2, O2), and nutrients (N, P, and other elements), and when grown unattached (planktonic) in the water column in the systems described herein, allow for efficient use of sunlight. This allows for the ability to reduce the footprint of the system, but also for cost effective management of the biomass of filamentous green macroalgae using the filters described herein, such as a wedge wire screen, for separation of biomass from treated water under conditions of continuous flow. Furthermore, the use of unbranched (uniseriate) filamentous green macroalgae prevent interweaving and prevent the formation of floating mats. This allows for filamentous green macroalgae to be maintained in a homogenous 3-dimensional, free-floating state under flow. Further advantages of the use of filamentous green macroalgae under continuous flow conditions is that filamentous green macroalgae tend to have a simple structure (i.e. without complex organs) where nearly every cell is a highly effective photosynthetic unit, allowing for productivity of the biomass to be calculated and managed.

[0180] Filamentous green macroalgae can be selected to have a high growth rate, and / or a high tolerance to environmental fluctuations (e.g. light, temperature) for year-round, effective wastewater treatment. Because filamentous freshwater green macroalgae are naturally found on land in creeks, discharge channels, ditches, etc., and typically have a high affinity for nutrients, and are capable of surviving in extreme conditions (e.g. nutrient-rich wastewater), lines can be identified and selected that are suited to the conditions of the geographic location of the continuous flow macroalgal pond.

[0181] Accordingly, in one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the filamentous green macroalgae is uniseriate. As used herein, "uniseriate" and "multiseriate" refer to the width of a filament (in terms of the number of cell laters). Uniseriate filaments (such as Oedogonium and Rhizoclonium species) are one cell wide. Multiseriate filaments (such as some Ulva and Cladophora species) are more than one cell wide. Some taxa, such as Stigonema, may have uniseriate and multiseriate parts.

[0182] Green freshwater macroalgae are generally found in stagnant freshwater bodies, with the free- floating species forming poly-algal patches or mat-like structures that give them a static habitat, and can also be known as a macroalgal bloom. Without wishing to be bound by theory, the present inventors have demonstrated herein that freshwater filamentous macroalgae such as Oedogonium can be used for wastewater treatment by growth in conditions of continuous flow, avoiding the formation of mat structures or poly-algal patches, and which allows for the management of biomass and its productivity, including allowing the removal of biomass from the system under conditions of continuous flow. Importantly, the maintenance of the filamentous green macroalgae in a filamentous and planktonic state, allows for the removal of treated water from the system without loss of biomass of macroalgae.

[0183] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the filamentous green macroalgae comprised unbranched filaments.

[0184] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the filaments of the filamentous green macroalgae have a length of at least 1 mm. In another embodiment, filaments of the filamentous green macroalgae have a length of at least 5 mm. In another embodiment, filaments of the filamentous green macroalgae have a length of at least 10 mm.

[0185] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the filaments of the filamentous green macroalgae have a mean length of at least 1 mm. In another embodiment, filaments of the filamentous green macroalgae have a mean length of at least 5 mm. In another embodiment, filaments of the filamentous green macroalgae have a mean length of at least 10 mm.

[0186] In one embodiment, the filamentous green macroalgae has a filament length at least 20 mm, at least 30 mm, at least 40 mm, at least 50 mm, at least 60 mm, at least 70 mm, at least 80 mm, at least 90 mm, at least 100 mm, at least 150 mm, at least 200 mm, at least 250 mm, at least 300 mm, at least 350 mm, at least 400 mm, at least 450 mm, at least 500 mm, at least 550 mm, at least 600 mm, at least 650 mm, at least 700 mm or at least 750 mm.

[0187] In one embodiment, the filamentous green macroalgae has a mean filament length at least 20 mm, at least 30 mm, at least 40 mm, at least 50 mm, at least 60 mm, at least 70 mm, at least 80 mm, at least 90 mm, at least 100 mm, at least 150 mm, at least 200 mm, at least 250 mm, at least 300 mm, at least 350 mm, at least 400 mm, at least 450 mm, at least 500 mm, at least 550 mm, at least 600 mm, at least 650 mm, at least 700 mm or at least 750 mm.

[0188] Without wishing to be bound by theory, the present inventors have shown that avoiding aeration as a means of providing continuous flow results in reduced breakage of filaments, and the use of a paddlewheel results in reduced breakage of filaments. In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the filamentous green macroalgae has a diameter of at least 5 pm. In a preferred embodiment, the filamentous green macroalgae has a diameter of at least 10 pm. In a preferred embodiment, the filamentous green macroalgae has a diameter of at least 15 pm. In another preferred embodiment, the filamentous green macroalgae has a diameter of at least 20, 25, 30, 35, 40, 45 or 50 pm.

[0189] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the filamentous green macroalgae has a diameter of no more than 60 pm.

[0190] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the mass of green macroalgae comprises one or more species of green macroalgae.

[0191] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the mass of green macroalgae comprises one or more macroalgal species of the division Chlorophyta.

[0192] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the mass of green macroalgae comprises one or more macroalgal species of the class Chlorophyceae.

[0193] In one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the mass of green macroalgae comprises a species of Oedogonium.

[0194] In one embodiment the filamentous green macroalgae is a species of Zygogonium, Mougeotia, Spirogyra, Zygnema, Ulothrix or Oedogonium species. In one embodiment, the filamentous green macroalgae is an Oedogonium species.

[0195] In one embodiment, the at least one macroalgae is a strain of filamentous green macroalgae local (e.g. endemic) to the geographic site of the continuous flow macroalgal pond.

[0196] Importantly, the present inventors have demonstrated that green macroalgae, when in a filamentous state, can be cultivated in conditions of continuous water flow to treat wastewater. Without wishing to be bound by theory, using filamentous green macroalgae under conditions that reduce the formation of algal mats allows for wastewater treatment and management of filamentous green macroalgae, including allowing for removal of treated water from the system under continuous flow, as well as removal of biomass under conditions of continuous flow. Furthermore, using filamentous green macroalgae under conditions that reduce the presence of stressed forms, for example, short filaments, for wastewater treatment and management of biomass of filamentous green macroalgae, including allowing for removal of treated water free from biomass from the system under continuous flow, as well as removal of biomass under conditions of continuous flow.

[0197] For example, the use of planktonic filamentous green macroalgae under conditions of continuous flow allows for the homogenous distribution of macroalgae throughout the continuous flow macroalgal pond, horizontally and vertically, to optimise the use of 3-dimensional space, homogenous mixing with water, nutrients, dissolved gasses, and / or homogenous exposure to sunlight.

[0198] Accordingly, in one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the mass of green macroalgae is planktonic.

[0199] Accordingly, in one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein the mass of filamentous green macroalgae is predominantly planktonic. As used herein, the term predominantly planktonic refers to 80% or more of the mass of filamentous green macroalgae is planktonic. Preferably, 85, 90, 95% or more of the mass of filamentous green macroalgae is planktonic. As used herein, the term planktonic as it relates to macroalgae, includes green macroalgae that is not benthic, and is free floating in the continuous flow macroalgal pond.

[0200] The present inventors have demonstrated in Example 2 that filamentous green macroalgae can be inoculated into a continuous flow macroalgal pond at different inoculation densities (g / L). The ability to maintain planktonic filamentous green macroalgae allows for the management of mass by removal of planktonic filamentous green macroalgae under conditions of water flow, for example by pumping treated water and a mass of planktonic filamentous green macroalgae to the harvest unit, and by removal using a mesh screen of defined size and aperture. Therefore, the mass of filamentous green macroalgae in the system can be managed under conditions of flow by removing mass based on the productivity of the system, and also the removal of treated wastewater from the system using a mesh screen of defined size and aperture.

[0201] As demonstrated herein, the use of filamentous green macroalgae and a mesh screen (e.g. wedge wire screen) allows for the retention of macroalgae within the treatment system under conditions of continuous flow, with a water discharge point located downstream of the mesh screen and / or the ability to harvest macroalgae from the treated water downstream of the treatment system.

[0202] Accordingly, in one embodiment, the present invention provides a continuous flow wastewater treatment system as described herein, wherein means for removing mass of filamentous green macroalgae from the continuous flow macroalgal pond allows continuous flow of water to be treated through the means.

[0203] In one embodiment, the means for removing mass of filamentous green macroalgae from the continuous flow macroalgal pond is a screen. In a preferred embodiment, the screen is a wedge wire screen. Importantly, the means for removing wastewater from the continuous flow macroalgal pond prevents filamentous green macroalgae from passing through the means.

[0204] For example, wherein the means for removing wastewater from the continuous flow macroalgal pond is a screen, the screen prevents unbranched filaments from passing through the screen (e.g. through a wedge wire screen).

[0205] In a preferred embodiment, the screen allows passage of filamentous green macroalgae with a filament length of less than 1 mm through the screen. In this embodiment, the screen prevents passage of filamentous green macroalgae with a filament length of 1 mm or more through the screen.

[0206] In one embodiment, the screen prevents passage of filamentous green macroalgae with a diameter of at least 5 pm through the screen. In a preferred embodiment, the screen prevents passage of filamentous green macroalgae with a diameter of at least 10 pm through the screen. In another preferred embodiment, the screen prevents passage of filamentous green macroalgae with a diameter of at least 15 pm through the screen. In a further preferred embodiment, the screen prevents passage of filamentous green macroalgae with a diameter of at least 20, 25, 30, 35, 40, 45, 50, 55 or 60 pm through the screen.

[0207] In a preferred embodiment, the screen allows passage of filamentous green macroalgae with a filament length of less than 1 mm through the screen. In this embodiment, the screen prevents passage of filamentous green macroalgae with a filament length of 1 mm or more through the screen.

[0208] In a further aspect, the present invention provides a method of treating wastewater comprising passing wastewater through a wastewater treatment system as described herein.

[0209] In another aspect, the present invention provides a method of treating wastewater comprising: contacting a mass of filamentous green macroalgae with wastewater under conditions of continuous flow, and removing water contacted with the mass of filamentous green macroalgae under conditions of continuous flow.

[0210] As used herein, the term contacting refers to the mixing of wastewater to be treated with a biomass of filamentous green macroalgae, or with water comprising filamentous green macroalgae, to allow for the biomass of filamentous green macroalgae to grow in the presence of the water to be treated. Without wishing to be bound by theory, contacting nutrient rich wastewater with filamentous green macroalgae that have a high surface area allows for exchange of dissolved gasses (CO2, O2), and nutrients (N, P, and other elements). Contacting wastewater with unattached (planktonic) filamentous green macroalgae in the water column in the systems described herein, under conditions of continuous flow, allow for efficient use of sunlight for biomass productivity. Furthermore, productivity of the biomass of filamentous green macroalgae contacted with the wastewater can be managed using the filters described herein, such as a wedge wire screen, for removal of treated water under conditions of continuous flow.

[0211] Furthermore, the use of unbranched (uniseriate) filamentous green macroalgae under conditions of flow reduces interweaving and reduces the formation of floating mats. This allows for maintenance of the biomass in a homogenous 3-dimensional, free-floating state under flow. Further advantages of the use of filamentous green microalgae under flow conditions is that filamentous green macroalgae tend to have a simple structure (i.e. without complex organs) where every cell is a highly effective photosynthetic unit, allowing for productivity of the biomass to be calculated and managed.

[0212] In one embodiment of the method, the method further comprises a step of removing a desired mass of filamentous green macroalgae under conditions of continuous flow.

[0213] In one embodiment of the method, the filamentous green macroalgae is uniseriate.

[0214] In one embodiment of the methods, the filaments of the filamentous green macroalgae have a mean length of at least 1 mm. In another embodiment, filaments of the filamentous green macroalgae have a mean length of at least 5 mm. In another embodiment, filaments of the filamentous green macroalgae have a mean length of at least 10 mm.

[0215] In one embodiment, the filamentous green macroalgae has a filament length at least 20 mm, at least 30 mm, at least 40 mm, at least 50 mm, at least 60 mm, at least 70 mm, at least 80 mm, at least 90 mm, at least 100 mm, at least 150 mm, at least 200 mm, at least 250 mm, at least 300 mm, at least 350 mm, at least 400 mm, at least 450 mm, at least 500 mm, at least 550 mm, at least 600 mm, at least 650 mm, at least 700 mm or at least 750 mm.

[0216] In one embodiment, the filamentous green macroalgae has a mean filament length at least 20 mm, at least 30 mm, at least 40 mm, at least 50 mm, at least 60 mm, at least 70 mm, at least 80 mm, at least 90 mm, at least 100 mm, at least 150 mm, at least 200 mm, at least 250 mm, at least 300 mm, at least 350 mm, at least 400 mm, at least 450 mm, at least 500 mm, at least 550 mm, at least 600 mm, at least 650 mm, at least 700 mm or at least 750 mm. In a preferred embodiment, the filamentous green macroalgae has a filament length of at least 20 mm, at least 25 mm, at least 30 mm, at least 35 mm, at least 40 mm, at least 45 mm, or at least 50 mm. As discussed above, without wishing to be bound by theory, the present inventors have shown that avoiding aeration as a means of providing continuous flow results in reduced breakage of filaments, and the use of a paddlewheel results in reduced breakage of filaments.

[0217] In one embodiment of the method, the filamentous green macroalgae has a diameter of at least 5 pm, at least 10 pm, at least 15 pm, at least 20 pm, at least 25 pm, at least 30 pm, at least 35 pm, at least 40 pm, at least 45 pm, at least 50 pm, at least 55 pm or at least 60 pm.

[0218] In one embodiment of the method, the mass of green macroalgae comprises one or more species of green macroalgae.

[0219] In one embodiment of the method, wherein the mass of green macroalgae comprises one or more macroalgal species of the division Chlorophyta.

[0220] In one embodiment of the method, the mass of green macroalgae comprises one or more macroalgal species of the class Chlorophyceae.

[0221] In one embodiment of the method, the mass of green macroalgae comprises a species of Oedogonium.

[0222] In one embodiment of the method, the mass of green macroalgae is planktonic.

[0223] In one embodiment of the method, the step of removing a desired mass of filamentous green macroalgae from the continuous flow macroalgal pond is performed using a means that allows continuous flow of water through the means.

[0224] In one embodiment of the method, the step of removing a desired mass of filamentous green macroalgae from the continuous flow macroalgal pond is performed using a mesh screen as described herein.

[0225] In one embodiment of the method, the step of removing a desired mass of filamentous green macroalgae from the continuous flow macroalgal pond is performed using a wedge wire screen as described herein.

[0226] In one embodiment of the method, the step of removing wastewater from the continuous flow macroalgal pond is performed using a means that prevents filamentous green macroalgae from passing through the means as described herein. In one embodiment of the method, the step of removing wastewater from the continuous flow macroalgal pond is performed using a mesh screen.

[0227] In one embodiment of the method, the step of removing wastewater from the continuous flow macroalgal pond is performed using a wedge wire screen as described herein.

[0228] EXAMPLE 1: Treating wastewater using filamentous green macroalgae under conditions of continuous flow, in the temperate region.

[0229] To examine the treatment of wastewater using filamentous green macroalgae under conditions of continuous flow, a continuous flow wastewater treatment system was constructed in the temperate region of the Earth, between 23.5° and 66.5° latitude.

[0230] In brief, a system comprising several continuous flow macroalgal ponds was inoculated with a mass of filamentous green macroalgae (Oedogonium sp.) at a density of between 0.15 and 2.0 g / L, fw (grams fresh weight of filamentous green macroalgae per L water). During treatment of wastewater, the mass of filamentous green macroalgae was maintained at a density of between 0.15 and 4.0 g / L, fw, with mass of filamentous green macroalgae regularly being removed (harvested) from the continuous flow macroalgal pond when the mass of filamentous green macroalgae is between a density of between 1.0 and 4.0 g / L, fw. The mass of filamentous green macroalgae is maintained in the continuous flow macroalgal pond maintained in a water depth of between 0.25 and 0.35 m, with a water velocity of between 0.2 and 0.3 m / s. The exchange rate was between 0 and 69 vol, % / d (% (volume. % per day). Under these conditions, the productivity (continuous growth rate) of the mass of filamentous green macroalgae was between 1 to 12 g / m2 / d dry weight (grams dry weight filamentous green macroalgae per square meter per day. Continuous growth of the filamentous green macroalgae under conditions of continuous flow allows for continuous treatment of wastewater and continuous harvest of mass of filamentous green macroalgae under conditions of flow, including to maintain optimal algal density in the continuous flow macroalgal pond.

[0231] The continuous flow macroalgal pond used in this example had a length of 25 m, width of 2 m, a surface area of 50 m2, a height of 0.5 m and a length to width ratio of 13.

[0232] A mass of filamentous green macroalgae used in this system was a monoculture of Oedogonium sp. with a filament length comprised between 1 mm and 100 mm, and a cell diameter comprised between 20 pm and 50 pm. Additionally, filaments of macroalgae were uniseriate, planktonic, and reproducing mainly vegetatively by fragmentation. The characteristics of the wastewater treated by this system are shown below in Table 1.

[0233] Table 1

[0234] As shown in Table 1, the method and system for treating wastewater described herein is surprisingly able to drastically reduce Total Nitrogen concentration (TN), Total Phosphorus concentration (TP), Ammonia Nitrogen concentration (N-NH3), Oxidised Nitrogen concentration (N-NOX), and Phosphate concentration (P-PO4) to low and / or below detection levels.

[0235] Unexpectedly, the method and system for treating wastewater described herein is also able to drastically reduce pathogen concentration, such as faecal coliform including E. coli, to extremely low and / or below detection levels.

[0236] Table 1 also demonstrates that the method and system for treating wastewater described herein is surprisingly able to drastically reduce TN flux, TP flux, N-NH3 flux, N-NOxflux, P-PO4 flux, and Pathogen flux (e.g. faecal coliform and E. coli) to low or below detection levels.

[0237] Importantly, Figure 3 demonstrates that the method and system for treating wastewater described herein is able to remove nitrogen (e.g. Total Nitrogen) from incoming wastewater to be treated at levels commensurate with the nitrogen (Total Nitrogen) load in the incoming (influent) water. For example, Figure 3 shows the that the method and system for treating wastewater described herein is surprising effective at reducing total nitrogen to low levels.

[0238] Figure 4 demonstrates that the method and system for treating wastewater described herein is able to remove phosphorus (e.g. Total Phosphorous) from incoming wastewater to be treated at levels commensurate with the phosphorus (Total Phosphorus) load in the incoming (influent) water. For example, Figure 4 shows the that the method and system for treating wastewater described herein is surprising effective at reducing total phosphorus to low or below detection levels.

[0239] Figure 5 demonstrates that the method and system for treating wastewater described herein is able to remove nitrogen (e.g. Oxidised Nitrogen) from incoming wastewater to be treated at levels commensurate with the nitrogen (Oxidised Nitrogen) load in the incoming (influent) water. For example, Figure 5 shows the that the method and system for treating wastewater described herein is surprising effective at reducing oxidised nitrogen to low levels. Figure 6 demonstrates that the method and system for treating wastewater described herein is able to remove nitrogen (e.g. Ammonia Nitrogen) from incoming wastewater to be treated at levels commensurate with the nitrogen (Ammonia Nitrogen) load in the incoming (influent) water. For example, Figure 6 shows the that the method and system for treating wastewater described herein is surprising effective at reducing total ammonia nitrogen to low or below detection levels.

[0240] Figure 7 demonstrates that the method and system for treating wastewater described herein is able to remove phosphorus (e.g. Ortho-Phosphate) from incoming wastewater to be treated at levels commensurate with the phosphorus (Ortho-Phosphate) load in the incoming (influent) water. For example, Figure 7 shows the that the method and system for treating wastewater described herein is surprising effective at reducing total ortho-phosphate to low or below detection levels.

[0241] Figure 8A demonstrates that the method and system for treating wastewater described herein is able to remove faecal coliforms from incoming wastewater to be treated at levels commensurate with the faecal coliform load in the incoming (influent) water.

[0242] Figure 8B demonstrates that the method and system for treating wastewater described herein is able to remove E. coli from incoming wastewater to be treated at levels commensurate with the E. coli load in the incoming (influent) water.

[0243] For example, as is also shown in Table 1, the method and system for treating wastewater described herein can reduce the Total Nitrogen concentration (TN) to 0.1 mg / L. Table 1 also shows the method and system for treating wastewater can reduce the Total Phosphorus concentration (TP) to 0.01 mg / L. Table 1 also shows the method and system for treating wastewater can reduce the Ammonia Nitrogen concentration (N-NH3) to 0.01 mg / L. Table 1 also shows the method and system for treating wastewater can reduce the Oxidised Nitrogen concentration (N-NOX) to 0.01 mg / L. Table 1 also shows the method and system for treating wastewater can reduce the Phosphate concentration (P-PO4) to 0.001 mg / L. Table 1 also shows the method and system for treating wastewater can reduce the Pathogen concentration (e.g. faecal coliform and E. coli) to 1 CFU / lOOmL. Table 1 also shows the method and system for treating wastewater can reduce the TN flux to 0.01 g / m2 / d. Table 1 also shows the method and system for treating wastewater can reduce the TP flux to 0.001 g / m2 / d. Table 1 also shows the method and system for treating wastewater can reduce the N-NH3 flux to 0.001 g / m2 / d. Table 1 also shows the method and system for treating wastewater can reduce the N-NOXflux to 0.001 g / m2 / d. Table 1 also shows the method and system for treating wastewater can reduce the P-PO4 flux to 0.001 g / m2 / d. Table 1 also shows the method and system for treating wastewater can reduce the Pathogen flux (e.g. faecal coliform and E. coli) to 0.001 10A3 CFU / m2 / d. As is also shown in Table 1, the method and system for treating wastewater described herein can accept (e.g. treat wastewater having) a Total Nitrogen concentration (TN) up to 9.44 mg / L. Table 1 also shows the method and system for treating wastewater can accept a Total Phosphorus concentration (TP) up to 2.81 mg / L. Table 1 also shows the method and system for treating wastewater can accept an Ammonia Nitrogen concentration (N-NH3) up to 4.95 mg / L. Table 1 also shows the method and system for treating wastewater can accept an Oxidised Nitrogen concentration (N-NOx) up to 8.53 mg / L. Table 1 also shows the method and system for treating wastewater can accept a Phosphate concentration (P-PO4) up to 2.06 mg / L.Table 1 also shows the method and system for treating wastewater can accept a Pathogen concentration (e.g. faecal coliform) up to 85,000 CFU / lOOmL. Table 1 also shows the method and system for treating wastewater can accept a Pathogen concentration (e.g. E. coli) up to 67,000 CFU / lOOmL. Table 1 also shows the method and system for treating wastewater can accept a DIN in TN up to 97%. Table 1 also shows the method and system for treating wastewater can accept a DIP in TP up to 92%. Table 1 also shows the method and system for treating wastewater can accept a TN:TP ratio up to 37. Table 1 also shows the method and system for treating wastewater can accept a DI N: DIP ratio up to 69. Table 1 also shows the method and system for treating wastewater can accept a TN flux up to 0.71 g / m2 / d. Table 1 also shows the method and system for treating wastewater can accept a TP flux up to 0.14 g / m2 / d. Table 1 also shows the method and system for treating wastewater can accept a N-NH3 flux up to 0.31 g / m2 / d. Table 1 also shows the method and system for treating wastewater can accept a N-NOXflux up to 0.65 g / m2 / d. Table 1 also shows the method and system for treating wastewater can accept a P-PO4 flux up to 0.11 g / m2 / d. Table 1 also shows the method and system for treating wastewater can accept a Pathogen flux (e.g. faecal coliform) up to 575 10A3 CFU / m2 / d. Table 1 also shows the method and system for treating wastewater can accept a Pathogen flux (e.g. E. coli) up to 423 10A3 CFU / m2 / d. Table 1 also shows the method and system for treating wastewater can accept a pH up to 8.2. Table 1 also shows the method and system for treating wastewater can accept a Water Temperature up to 35 °C. Table 1 also shows the method and system for treating wastewater can accept a Turbidity up to 24 NTU. Table 1 also shows the method and system for treating wastewater can accept a BOD5up to 30 mg / L. Table 1 also shows the method and system for treating wastewater can accept a Total Suspend Solids up to 100 mg / L.

[0244] EXAMPLE 2: Filamentous green macroalgae productivity under conditions of continuous flow.

[0245] To examine the productivity of filamentous green macroalgaeunder conditions of continuous flow, Oedogonium was inoculated into a continuous flow wastewater treatment system as described herein comprising continuous flow macroalgal ponds. Density over 21 days was monitored to determine the growth rate of the filamentous green macroalgae.

[0246] Figure 9 shows a typical growth curve of macroalgae in a continuous flow macroalgal pond macroalgal pond treating municipal wastewater. This figure shows the three growth phases, with the exponential growth phase showing an exponential increase in density (and productivity) between 0.5 g / L and 3.5 g / L.

[0247] EXAMPLE 3: Treating wastewater using filamentous green macroalgae under conditions of continuous flow in the tropical region.

[0248] In Example 1, the treatment of wastewater using filamentous green macroalgae under conditions of continuous flow was examined in the temperate region of the Earth, using a productivity (continuous growth rate) of the mass of filamentous green macroalgae between 1 to 12 g / m2 / d dry weight (grams dry weight filamentous green macroalgae per square metre per day).

[0249] A second continuous flow wastewater treatment system was constructed to examine the treatment of wastewater using a tropical species of filamentous green macroalgae under tropical conditions, below 23.5° latitude. The filamentous green macroalgae (Oedogonium sp.) had a productivity (continuous growth rate) of between 1 to 15 g / m2 / d dry weight (grams dry weight filamentous green macroalgae per square metre per day).

[0250] Without wishing to be bound by theory, the tropical species of filamentous green macroalgae, under tropical conditions, below 23.5° latitude had a higher productivity than the productivity of the filamentous green macroalgae (Oedogonium sp.) in Example 1, with environmental / geographic conditions influencing growth rate (productivity). As is demonstrated in Example 1, Example 2 and this example, the biomass of filamentous green macroalgae can be managed and maintained at different densities and productivities. For example, a desired density of filamentous green macroalgae can be maintained under conditions of continuous flow by removing biomass of filamentous green macroalgae under conditions of continuous flow, and / or by removing treated water under conditions of continuous flow.

[0251] In brief, a continuous flow macroalgal pond was inoculated with a mass of filamentous green macroalgae (Oedogonium) at a density of between 0.15 and 2.0 g / L, fw (grams fresh weight of filamentous green macroalgae per litre water). During treatment of wastewater, the mass of filamentous green macroalgae was maintained at a density of between 0.15 and 4.5 g / L, fw, with mass of filamentous green macroalgae being removed (harvested) from the continuous flow macroalgal pond when the mass of filamentous green macroalgae is at a density of between 1.0 and 4.5 g / L, fw. The mass of filamentous green macroalgae was maintained in the continuous flow macroalgal pond maintained in a water depth of between 0.2 and 0.5 m, with a water velocity of between 0.1 and 0.5 m / s. The exchange rate was between 0 and 40 vol, % / d (volume. % per day). Under these conditions, the productivity (continuous growth rate) of the mass of filamentous green macroalgae was between 1 to 15 g / m2 / d dry weight (grams dry weight filamentous green macroalgae per square metre per day). Continuous growth of the filamentous green macroalgae under conditions of continuous flow allows for continuous treatment of wastewater and continuous harvest of mass of filamentous green macroalgae under conditions of flow, including to maintain optimal algal density in the continuous flow macroalgal pond.

[0252] The continuous flow macroalgal pond used in this example had a length of 10 m, width of 1 m, a surface area of 10 m2, a height of 0.6 m and a length to width ratio of 10.

[0253] A mass of filamentous green macroalgae used in this system was a monoculture of Oedogonium sp. with a filament length comprised between 1 mm and 750 mm, and a cell diameter comprised between 10 pm and 60 pm. Additionally, filaments of macroalgae were uniseriate, planktonic, and reproducing mainly vegetatively by fragmentation.

[0254] The characteristics of the wastewater treated by this system are shown below in Table 2.

[0255] Table 2

[0256] As is shown in Table 2, the method and system for treating wastewater with a range of productivity of between 1 and 15 g / m2 / d dry weight described herein is surprisingly able to reduce Total Nitrogen concentration (TN), Total Phosphorus concentration (TP), Ammonia Nitrogen concentration (N-NH3), Nitrite concentration (N-NO2), Nitrate concentration (N-NO3), Phosphate concentration (P-PO4), Pathogen concentration (e.g. faecal coliform and E. coli), TN flux, TP flux, N-NH3 flux, N-NO2 flux, N- NO3 flux, P-PO4 flux, Pathogens flux (e.g. faecal coliform and E. coli) to low and / or below detection levels.

[0257] Table 2 also demonstrates that a method and system for treating wastewater described herein is surprisingly able to drastically reduce Total Nitrogen concentration (TN), Total Phosphorus concentration (TP), Ammonia Nitrogen concentration (N-NH3), Nitrite concentration (N-NO2), Nitrate concentration (N-NO3), Phosphate concentration (P-PO4), Pathogen concentration (e.g. faecal coliform and E. coli).

[0258] For example, as is also shown in Table 2, the method and system for treating wastewater described herein can reduce the Total Nitrogen concentration (TN) to 0.1 mg / L. Table 2 also shows the method and system for treating wastewater can reduce the Total Phosphorus concentration (TP) to 0.01 mg / L. Table 2 also shows the method and system for treating wastewater can reduce the Ammonia Nitrogen concentration (N-NH3) to 0.01 mg / L. Table 2 also shows the method and system for treating wastewater can reduce the Nitrite concentration (N-NO2) to 0.01 mg / L. Table 2 also shows the method and system for treating wastewater can reduce the Nitrate concentration (N-NO3) to 0.01 mg / L. Table 2 also shows the method and system for treating wastewater can reduce the Phosphate concentration (P-PO4) to 0.001 mg / L. Table 2 also shows the method and system for treating wastewater can reduce the Pathogen concentration (e.g. faecal coliform and E. coli) to 1 CFU / lOOmL. Table 2 also shows the method and system for treating wastewater can reduce the TN flux to 0.01 g / m2 / d. Table 2 also shows the method and system for treating wastewater can reduce the TP flux to 0.001 g / m2 / d. Table 2 also shows the method and system for treating wastewater can reduce the N-NH3 flux to 0.001 g / m2 / d. Table 2 also shows the method and system for treating wastewater can reduce the N-NO2 flux to 0.001 g / m2 / d. Table 2 also shows the method and system for treating wastewater can reduce the N-NO3 flux to 0.001 g / m2 / d. Table 2 also shows the method and system for treating wastewater can reduce the P-PO4 flux to 0.001 g / m2 / d. Table 2 also shows the method and system for treating wastewater can reduce the Pathogen flux (e.g. faecal coliform and E. coli) to 0.001 10A3 CFU / m2 / d.

[0259] As is also shown in Table 2, the method and system for treating wastewater described herein can accept (treat water having) a Total Nitrogen concentration (TN) up to 37.5 mg / L. Table 2 also shows the method and system for treating wastewater can accept a Total Phosphorus concentration (TP) up to 15.8 mg / L. Table 2 also shows the method and system for treating wastewater can accept an Ammonia Nitrogen concentration (N-NH3) up to 6.5 mg / L. Table 2 also shows the method and system for treating wastewater can accept a Nitrite concentration (N-NO2) up to 0.9 mg / L. Table 2 also shows the method and system for treating wastewater can accept a Nitrate concentration (N-NO3) up to 31.9 mg / L. Table 2 also shows the method and system for treating wastewater can accept a Phosphate concentration (P-PO4) up to 8.9 mg / L. Table 2 also shows the method and system for treating wastewater can accept a Pathogen concentration (e.g. faecal coliform) up to 115,000 CFU / lOOmL. Table 2 also shows the method and system for treating wastewater can accept a Pathogen concentration (e.g. E. coli) up to 46,000 CFU / lOOmL. Table 2 also shows the method and system for treating wastewater can accept a DIN in TN up to 100%. Table 2 also shows the method and system for treating wastewater can accept a DIP in TP up to 100%. Table 2 also shows the method and system for treating wastewater can accept a TN:TP ratio up to 6. Table 2 also shows the method and system for treating wastewater can accept a DIN:DIP ratio up to 5.4. Table 2 also shows the method and system for treating wastewater can accept a TN flux up to 3.0 g / m2 / d. Table 2 also shows the method and system for treating wastewater can accept a TP flux up to 1.3 g / m2 / d. Table 2 also shows the method and system for treating wastewater can accept a N-NH3 flux up to 0.4 g / m2 / d. Table 2 also shows the method and system for treating wastewater can accept a N-NCh flux up to 0.5 g / m2 / d. Table 2 also shows the method and system for treating wastewater can accept a N-NO3 flux up to 2.6 g / m2 / d. Table 2 also shows the method and system for treating wastewater can accept a P-PO4 flux up to 0.7 g / m2 / d. Table 2 also shows the method and system for treating wastewater can accept a Pathogen flux (e.g. faecal coliform) up to 755 10A3 CFU / m2 / d. Table 2 also shows the method and system for treating wastewater can accept a Pathogen flux (e.g. E. coli) up to 468 10A3 CFU / m2 / d. Table 2 also shows the method and system for treating wastewater can accept a pH up to 7.8. Table 2 also shows the method and system for treating wastewater can accept a Water Temperature up to 40 °C. Table 2 also shows the method and system for treating wastewater can accept a Turbidity up to 146 NTU. Table 2 also shows the method and system for treating wastewater can accept a BOD5up to 28 mg / L. Table 2 also shows the method and system for treating wastewater can accept a COD up to 503 mg / L. Table 2 also shows the method and system for treating wastewater can accept a Total Suspend Solids up to 50 mg / L.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A continuous flow wastewater treatment system comprising: a. a continuous flow macroalgal pond comprising wastewater to be treated b. a mass of filamentous green macroalgae in the continuous flow macroalgal pond c. a means for removing mass of filamentous green macroalgae from the continuous flow macroalgal pond, and d. a means for removing wastewater from the continuous flow macroalgal pond.

2. A continuous flow wastewater treatment system according to claim 1, wherein the filamentous green macroalgae is uniseriate.

3. A continuous flow wastewater treatment system according to claim 1 or claim 2 wherein the filamentous green macroalgae has a length of at least 1 mm.

4. A continuous flow wastewater treatment system according to claim 1 or claim 2, wherein the filamentous green macroalgae has a length of at least 10 mm.

5. A continuous flow wastewater treatment system according to claim 1 or claim 2, wherein the filamentous green macroalgae has a length of at least 20 mm.

6. A continuous flow wastewater treatment system according to claim 1 or claim 2, wherein the filamentous green macroalgae has a diameter of at least 5 pm.

7. A continuous flow wastewater treatment system according to claim 1 or claim 2, wherein the filamentous green macroalgae has a diameter of at least 60 pm.

8. A continuous flow wastewater treatment system according to any one of claims 1 to 7 , wherein the mass of green macroalgae comprises one or more species of green macroalgae.

9. A continuous flow wastewater treatment system according to any one of claims 1 to 8, wherein the mass of green macroalgae comprises one or more macroalgal species of the division Chlorophyta.

10. A continuous flow wastewater treatment system according to any one of claims 1 to 9, wherein the mass of green macroalgae comprises one or more macroalgal species of the class Chlorophyceae.

11. A continuous flow wastewater treatment system according to any one of claims 1 to 10, wherein the mass of green macroalgae comprises one or more species of the genus Oedogonium.

12. A continuous flow wastewater treatment system according to any one of claims 1 to 11, wherein the mass of green macroalgae is planktonic.

13. A continuous flow wastewater treatment system according to any one of claims 1 to 12, wherein the means for removing mass of filamentous green macroalgae from the continuous flow macroalgal pond allows continuous flow of water to be treated through the means.

14. A continuous flow wastewater treatment system according to any one of claims 1 to 13, wherein the means for removing mass of filamentous green macroalgae from the continuous flow macroalgal pond is a screen.

15. A continuous flow wastewater treatment system according to claim 14, wherein the screen is a mesh screen or a wedge wire screen.

16. A continuous flow wastewater treatment system according to any one of claims 1 to 15, wherein the means for removing wastewater from the continuous flow macroalgal pond prevents filamentous green macroalgae from passing through the means.

17. A continuous flow wastewater treatment system according to any one of claims 1 to 16, wherein the means for removing wastewater from the continuous flow macroalgal pond is a screen.

18. A continuous flow wastewater treatment system according to claim 16, wherein the screen is a mesh screen or a wedge wire screen.

19. A continuous flow wastewater treatment system according to any one of claims 14 to 16, wherein the screen prevents filamentous green macroalgae with a filament length of at least 1mm from passing through the screen.

20. A continuous flow wastewater treatment system according to any one of claims 1 to 19, wherein the system further comprises an agitator.

21. A continuous flow wastewater treatment system according to any one of claims 1 to 20, wherein the system further comprises an agitator for increasing separation of green macroalgae filaments, reducing interweaving of green macroalgae filaments, reducing formation of green macroalgae mats, and / or mixing wastewater.

22. A continuous flow wastewater treatment system according to any one of claims 1 to 21, wherein the system further comprises a wastewater inlet.

23. A continuous flow wastewater treatment system according to any one of claims 1 to 22, wherein the system further comprises an outlet for treated wastewater.

24. A method of treating wastewater comprising passing wastewater through a wastewater treatment system according to any one of claims 1 to 23.

25. A method of treating wastewater comprising contacting a mass of filamentous green macroalgae with wastewater under conditions of continuous flow; and removing water contacted with the mass of filamentous green macroalgae under conditions of continuous flow.

26. A method of claim 25, wherein the method further comprises a step of removing a desired mass of filamentous green macroalgae under conditions of continuous flow.

27. A method according to claim 25 or claim 26, wherein the filamentous green macroalgae is uniseriate.

28. A method according to any one of claims 25 to 27, wherein the filamentous green macroalgae has a length of at least 1 mm.

29. A method according to any one of claims 25 to 27, wherein the filamentous green macroalgae has a length of at least 10 mm.

30. A method according to any one of claims 25 to 27 , wherein the filamentous green macroalgae has a length of at least 20 mm.

31. A method according to any one of claims 25 to 27, wherein the filamentous green macroalgae has a diameter of at least 5 pm.

32. A method according to any one of claims 25 to 27, wherein the filamentous green macroalgae has a diameter of at least 60 pm.

33. A method according to any one of claims 25 to 32 wherein the mass of green macroalgae comprises one or more species of green macroalgae.

34. A method according to any one of claims 25 to 33, wherein the mass of green macroalgae comprises one or more macroalgal species of the division Chlorophyta.

35. A method according to any one of claims 25 to 34, wherein the mass of green macroalgae comprises one or more macroalgal species of the class Chlorophyceae.

36. A method according to any one of claims 25 to 35, wherein the mass of green macroalgae comprises one or more species of the genus Oedogonium.

37. A method according to any one of claims 25 to 36, wherein the mass of green macroalgae is planktonic.

38. A method according to any one of claims 25 to 37, wherein the step of removing a desired mass of filamentous green macroalgae from the continuous flow macroalgal pond is performed using a means that allows continuous flow of water through the means.

39. A method according to any one of claims 25 to 37, wherein the step of removing a desired mass of filamentous green macroalgae from the continuous flow macroalgal pond is performed using a screen.

40. A method according to any one of claims 25 to 37, wherein the step of removing a desired mass of filamentous green macroalgae from the continuous flow macroalgal pond is performed using a mesh screen or a wedge wire screen.

41. A method according to any one of claims 24 to 38, wherein the step of removing wastewater from the continuous flow macroalgal pond is performed using a means that prevents filamentous green macroalgae from passing through the means.

42. A method according to any one of claims 24 to 38, wherein the step of removing wastewater from the continuous flow macroalgal pond is performed using a mesh screen or a wedge wire screen.

43. A method according to any one of claims 39 to 42, wherein the screen prevents filamentous green macroalgae with a filament length of at least 1 mm from passing through the screen.

Images