Carbohydrates Production and Bio-flocculation Characteristics in Cultures of Arthrospira (Spirulina) platensis: Improvements Through Phosphorus Limitation Process

Carbohydrates are a desirable biomass compound for the generation of several biofuels. Phosphorus nutrient limitation causes a significant increase in the carbohydrate content of the cyanobacterium Arthrospira (Spirulina) platensis. Carbohydrates accumulated up to a content of 63.09?±?3.43?% (±SD) in both batch and semi-continuous cultures. In order the production of carbohydrate-rich biomass through nutrient limitation to be maximized, it is suggested that the limited nutrients have to be supplied in amounts that they on one hand can support the biomass production while on the other hand they alter the composition of the biomass. In this study, phosphorus of 1.82?±?0.16?mg g^?1 of dry biomass was the optimized amount for the maximization of carbohydrates production by A. platensis. Regarding the need to decrease the application amounts of nutrients for biomass production, this study demonstrates that the phosphorus supply could be decreased an order of magnitude with no significant decrease in biomass production. In addition, it was observed that biomass rich in carbohydrates bio-flocculates, during settling without the addition of any flocculation agent or any other intervention. The bio-flocculation efficiency appears to be related with the carbohydrate content of the biomass. In maximum carbohydrate content (60?%), the biomass bio-flocculated at 68.49?±?7.73?% the first 15?min and reached 80.25?±?5.58?% 60?min after settling. The produced carbohydrates might be used as feedstock for biofuel generation, while the bio-flocculation and the overall settling characteristics of the carbohydrate-rich biomass could make its harvesting process much easier.     

Efficiency of copper removal by Sargassum sinicola in batch and continuous systems

The efficiency of batch and continuous systems of copper removal by Sargassum sinicola was studied. The effects of flow rate, initial metal concentration, and bed density on the capacity of the continuous system were also recorded. In batch systems, the maximum biosorption capacity was calculated as 49.63?±?0.88 mg g^?1; in the continuous system, under the following conditions: flow rate of 10 mL min^?1, initial solution of 200 mg Cu L^?1, bed density of 150 g L^?1, and higher copper removal of 62.39?±?1.91 mg g^?1 was achieved. The Thomas model can be used to predict the breakthrough curves, but it underestimated breakthrough time.     

A novel method to harvest <Emphasis Type="Italic">Chlorella</Emphasis> sp. by co-flocculation/air flotation

Objectives

To develop a more effective dissolved air flotation process for harvesting microalgae biomass, a co-flocculation/air flotation (CAF) system was developed that uses an ejector followed by a helix tube flocculation reactor (HTFR) as a co-flocculation device to harvest Chlorella sp. 64.01.

Results

The optimal size distribution of micro-bubbles and an air release efficiency of 96 % were obtained when the flow ratio of inlet fluid (raw water) to motive fluid (saturated water) of the ejector was 0.14. With a reaction time of 24 s in the HTFR, microalgae cells and micro-bubbles were well flocculated, and these aerated flocs caused a fast rising velocity (96 m/h) and high harvesting efficiency (94 %).

Conclusions

In a CAF process, micro-bubbles can be encapsulated into microalgae flocs, which makes aerated flocs more stable. CAF is an effective approach to harvesting microalgae.

     

Rapid harvesting of freshwater microalgae using chitosan

In this study, chitosan was used as a flocculant to harvest freshwater microalgae Chlorella vulgaris. The recovery efficiency of C. vulgaris was tested at various chitosan concentrations. 120 mg/L of chitosan showed the highest efficiency (92 ± 0.4%) within 3 min. The maximum concentration factor of 10 was also achieved at this dose of chitosan. The harvesting efficiency was pH dependent. pH 6.0 showed the highest harvesting efficiency (99 ± 0.5%). Measurement of zeta-potential confirmed that the flocculation was induced by charge neutralization. This study showed that a biopolymer, chitosan, can be a promising flocculant due to its high efficacy, low dose requirements, and short settling time.     

Effects of fungal-assisted algal harvesting through biopellet formation on pesticides in water

Recent research has demonstrated the potential of using filamentous fungi to form pellets with microalgae (biopellets), in order to facilitate harvesting of microalgae from water following algae-based treatment of wastewater. In parallel, there is a need to develop techniques for removing organic pollutants such as pesticides and pharmaceuticals from wastewater. In experiments using the microalga Chlorella vulgaris, the filamentous fungus Aspergillus niger and biopellets composed of these microorganisms, this study investigated whether fungal-assisted algal harvesting can also remove pesticides from contaminated water. A mixture of 38 pesticides was tested and the concentrations of 17 of these were found to be reduced significantly in the biopellet treatment, compared with the control. After harvesting, the concentration of total pesticides in the algal treatment did not differ significantly from that in the control. However, in the fungal treatment and biopellet treatment, the concentration was significantly lower (59.6?±?2.0 µg/L and 56.1?±?2.8 µg/L, respectively) than in the control (66.6?±?1.0 µg/L). Thus fungal-assisted algal harvesting through biopellet formation can also provide scope for removing organic pollutants from wastewater, with removal mainly being performed by the fungus.     

Evaluation of electro‐coagulation–flocculation for harvesting marine and freshwater microalgae

Although microalgae are considered as a promising feedstock for biofuels, the energy efficiency of the production process needs to be significantly improved. Due to their small size and low concentration in the culture medium, cost‐efficient harvesting of microalgae is a major challenge. In this study, the use of electro‐coagulation–flocculation (ECF) as a method for harvesting a freshwater (Chlorella vulgaris) and a marine (Phaeodactylum tricornutum) microalgal species is evaluated. ECF was shown to be more efficient using an aluminum anode than using an iron anode. Furthermore, it could be concluded that the efficiency of the ECF process can be substantially improved by reducing the initial pH and by increasing the turbulence in the microalgal suspension. Although higher current densities resulted in a more rapid flocculation of the microalgal suspension, power consumption, expressed per kg of microalgae harvested, and release of aluminum were lower when a lower current density was used. The aluminum content of the harvested microalgal biomass was less than 1% while the aluminum concentration in the process water was below 2 mg L⁻¹. Under optimal conditions, power consumption of the ECF process was around 2 kWh kg⁻¹ of microalgal biomass harvested for Chlorella vulgaris and ca. 0.3 kWh kg⁻¹ for Phaeodactylum tricornutum. Compared to centrifugation, ECF is thus more energy efficient. Because of the lower power consumption of ECF in seawater, ECF is a particularly attractive method for harvesting marine microalgae. Biotechnol. Bioeng. 2011;108: 2320–2329. © 2011 Wiley Periodicals, Inc.     

<Emphasis Type="Italic">Tetraselmis suecica</Emphasis> culture for CO<Subscript>2</Subscript> bioremediation of untreated flue gas from a coal-fired power station

The accumulation of atmospheric CO₂, primarily due to combustion of fossil fuels, has been implicated in potential global climate change. The high rate of CO₂ bioremediation by microalgae has emerged as a favourable method for reducing coal-fired power plant emissions. However, coal-fired power station flue gas contains other chemicals such as SO_x which can inhibit microalgal growth. In the current study, the effect of untreated flue gas as a source of inorganic carbon on the growth of Tetraselmis in a 1000 L industrial-scale split-cylinder internal-loop airlift photobioreactor was examined. The culture medium was recycled after each harvest. Tetraselmis suecica grew very well in this airlift photobioreactor during the 7-month experiment using recycled medium from an electroflocculation harvesting unit. Increased medium SO₄ ^2? concentration as high as 870 mg SO₄ ^2??L^?1 due to flue gas addition and media recycling had no negative effect on the overall growth and productivity of this alga. The potential organic biomass productivity and carbon sequestration using an industrial-scale airlift PBR at International Power Hazelwood, Gippsland, Victoria, Australia, are 178.9?±?30 mg L^?1 day^?1 and 89.15?±?20 mg?‘C’?L^?1 day^?1, respectively. This study clearly indicates the potential of growing Tetraselmis on untreated flue gas and using recycled medium for the purpose of biofuel and CO₂ bioremediation.     

Determination of Mass Transfer Coefficients for A Mixture of Compost,Sugarcane Bagasse,and Granulated Activated Carbon as Packing Medium in Biofilter

ABSTRACT

A laboratory-scale biofilter unit packed with a mixture of compost, sugarcane bagasse, and granulated activated carbon (GAC) in the ratio of 55:30:15 by weight was used for a biofiltration study of air stream containing benzene, toluene, ethylbenzene, and o-xylene (BTEX). The effect of superficial velocity on mass transfer coefficient for the packing was studied by maintaining gas flow rates of 3, 4, 5, 6, and 8 L min^?1 for inlet concentrations of 0.1, 0.4, and 0.8 g m^?3 for each of benzene, toluene, ethylbenzene, and o-xylene. The maximum elimination capacity was found to be 20.92, 22.72, 20.73, and 18.94 g m^?3 h^?1 for BTEX, respectively, for stated flow rates. Removal efficiency of BTEX decreased from 99% to 71% for increasing inlet concentration from 0.1 to 0.8 g m^?3. Gas film mass transfer coefficient predicted by modified Onda's equation was within ±10% of the experimental values.     

Magnetophoretic harvesting of freshwater microalgae using polypyrrole/Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanocomposite and its reusability

A magnetophoretic harvesting agent, a polypyrrole/Fe₃O₄ magnetic nanocomposite, is proposed as a cost and energy efficient alternative to recover biomass of the microalgae Botryococcus braunii, Chlorella protothecoides, and Chlorella vulgaris from their culture media. The maximal recovery efficiency reached almost 99 % for B. braunii, 92.4 % for C. protothecoides, and 90.8 % for C. vulgaris. The maximum adsorption capacity (Q ₀) of the magnetic nanocomposite for B. braunii (63.49 mg dry biomass mg^?1 PPy/Fe₃O₄) was higher than that for C. protothecoides (43.91 mg dry biomass mg^?1 PPy/Fe₃O₄) and C. vulgaris (39.98 mg dry biomass mg^?1 PPy/Fe₃O₄). The highest harvesting efficiency for all the studied microalgae were at pH 10.0, and measurement of zeta-potential confirmed that the flocculation was induced by charge neutralization. This study showed that polypyrrole/Fe₃O₄ can be a promising flocculant due to its high efficacy, low dose requirements, short settling time, its integrity with cells, and with great potential for saving energy because of its recyclability.     

Microalgae-mediated brewery wastewater treatment: effect of dilution rate on nutrient removal rates,biomass biochemical composition,and cell physiology

Microalgae have been used to remove nitrogen, phosphorus, and chemical oxygen demand (COD) from brewery wastewater (BWW). The microalga Scenedesmus obliquus was grown on BWW, using bubble column photobioreactors that operated under batch and continuous regimes. For the first time, the cell physiological status cell membrane integrity and enzymatic activity was monitored during the microalgae based BWW treatment, using flow cytometry. All the cultivations batch and continuous displayed a proportion of cells with intact membrane >?87%, although the continuous cultivations displayed a lower proportion of cells with enzymatic activity (20–40%) than the batch cultivations (97%). The dilution rate of 0.26 day^?1 was the most favorable condition, since the microalgae cultivation attained the maximum biomass productivity (0.2 g ash-free dry weight day^?1) and the total nitrogen and COD removal rates were the highest (97 and 74%, respectively), while the phosphorous removal rate was the third (23%).     

Ultrasound, a new separation technique to harvest microalgae

In this article it is proven that ultrasound can be used to harvest microalgae. The separation process is based on gentle acoustically induced aggregation followed by enhanced sedimentation. In this paper, the efficiency of harvesting and the concentration factor of the ingoing biomass concentration are optimized and the relevance of this process compared to other harvesting processes is determined. For the optimisation, five parameters were modeled simultaneously by the use of an experimental design. An experimental design was chosen, because of possible interaction effects between the different parameters. The efficiency of the process was modeled with a R-squared of 0.88. The ingoing flow rate and the biomass concentration had a lot of influence on the efficiency of the process. Efficiencies higher than 90% were reached at high biomass concentrations and flow rates of 4–6 L day^–1. At most, 92% of the organisms could be harvested and a concentration factor of 11 could be achieved at these settings. It was not possible to harvest this microalga with higher efficiencies due to its small size and its small density difference with water. The concentration factor of the process was modeled with a R-squared of 0.75. The ingoing flow rate, biomass concentration and ratio between harvest flow and ingoing flow rate had a significant effect on the concentration factor. Highest concentration factors, up to 20, could be reached at low biomass concentrations and low harvest flows. On industrial scale, centrifuges can better be used to harvest microalgae, because of lower power consumption, better efficiencies and higher concentration factors. On lab- or pilot-plant scale, an ultrasonic harvesting process has the advantages that it can be operated continuously, it evokes no shear stress and the occupation space is very small. Also, when the algae excrete a soluble high valued product this system can be used as a biofilter.     

Comparison of mutant and parent strains of Clostridium acetobutylicum: butyrate uptake at different temperatures

A high butanol producing mutant strain of Clostridium acetobutylicum ATCC 4259 was obtained by chemical mutagenesis. Both mutant and parent strains were evaluated for butyrate uptake using the culture effluents of solventogenic fermentor-2 of the two-fermentor continuous system. Batch incubation of fermentor-2 culture effluents at 37?°C indicated lower butyrate uptake rates for mutant and parent strain, at 0.05 and 0.03?g?l^?1?h^?1, respectively. Increased butyrate uptake rates of 0.33 and 0.26 g l^?1 h^?1 for mutant and parent strain, respectively, were observed when effluents were batch incubated at lower temperature of 30?°C. Butyrate conversion efficiency, at 5?±?0.1 g l^?1 of externally added butyrate, were 98.8% and 96.9% for mutant and parent strain, respectively. Butyrate up to the externally added concentration of 11.4 g l^?1 did not inhibit butyrate uptake. The maximum butyrate consumption at a slightly reduced uptake rate was seen at 10.2 g l^?1 butyrate concentration at 27?°C. Based on the results under different temperatures, the electron flow pattern has been computed and the mechanism for butyrate uptake has been hypothesized.     

Feasibility study of biogas upgrading coupled with nutrient removal from anaerobic effluents using microalgae-based processes

The present research was conducted to simultaneously optimize biogas upgrading and carbon and nutrient removal from centrates in a 180-L high-rate algal pond interconnected to an external CO₂ absorption unit. Different biogas and centrate supply strategies were assessed to increase biomass lipid content. Results showed 99 % CO₂ removal efficiencies from simulated biogas at liquid recirculation rates in the absorption column of 9.9 m³ m^?2 h^?1, concomitant with nitrogen and phosphorus removal efficiencies of 100 and 82 %, respectively, using a 1:70 diluted centrate at a hydraulic retention time of 7 days. The lipid content of the harvested algal–bacterial biomass remained low (2.9–11.2 %) regardless of the operational conditions, with no particular trend over time. The good settling characteristics of the algal–bacterial flocs resulted in harvesting efficiencies over 95 %, which represents a cost-effective alternative for algal biomass reutilization compared to conventional physical–chemical techniques. Finally, high microalgae biodiversity was found regardless of the operational conditions.     

Performance of bioelectrochemical systems inoculated with Desmodesmus sp. A8 under different light sources

Light source can affect the stomata opening, photosynthesis process, and pigment content in microalgae cells. In this study, growth rate, chlorophyll a (chl a) content, and electrogenic capability of Desmodesmus sp. A8 were investigated under incandescent and fluorescent lamps. Growth rate, productivity, and chl a content of strain A8 exposed to incandescent light were recorded as 0.092 ± 0.010 day^?1, 0.019 ± 0.008 g L^?1 day^?1, and 15.10 ± 1.40 mg L^?1, which decreased to 0.086 ± 0.006 day^?1, 0.012 ± 0.004 g L^?1 day^?1, and 10.06 ± 1.59 mg L^?1, respectively, under fluorescent light. The stable current density of bioelectrochemical systems inculcated with strain A8 under incandescent and fluorescent lamps were 249.76 and 158.41 mA m^?2 at ?0.4 V vs. Ag/AgCl, coupling with dissolved oxygen within biofilm decreasing from 15.91 to 10.80 mg L^?1. This work demonstrated that illuminating microalgae under an incandescent lamp can improve biomass production and electrogenic capabilities.     

pH effects on growth and lipid accumulation of the biofuel microalgae Nannochloropsis salina and invading organisms

Biofuels derived from non-crop sources, such as microalgae, offer their own advantages and limitations. Despite high growth rates and lipid accumulation, microalgae cultivation still requires more energy than it produces. Furthermore, invading organisms can lower efficiency of algae production. Simple environmental changes might be able to increase algae productivity while minimizing undesired organisms like competitive algae or predatory algae grazers. Microalgae are susceptible to pH changes. In many production systems, pH is kept below 8 by CO₂ addition. Here, we uncouple the effects of pH and CO₂ input, by using chemical pH buffers and investigate how pH influences Nannochloropsis salina growth and lipid accumulation as well as invading organisms. We used a wide range of pH levels (5, 6, 7, 8, 9, and 10). N. salina showed highest growth rates at pH 8 and 9 (0.19?±?0.008 and 0.19?±?0.011, respectively; mean ± SD). Maximum cell densities in these treatments were reached around 21 days into the experiment (95.6?×?10⁶?±?9?×?10⁶ cells mL^?1 for pH 8 and 92.8?×?10⁶?±?24?×?10⁶ cells mL^?1 for pH 9). Lipid accumulation of unbuffered controls were 21.8?±?5.8 % fatty acid methyl esters content by mass, and we were unable to trigger additional significant lipid accumulation by manipulating pH levels at the beginning of stationary phase. Ciliates (grazing predators) occurred in significant higher densities at pH 6 (56.9?±?39.6?×?10⁴ organisms mL^?1) than higher pH treatments (0.1–6.8?×?10⁴ organisms mL^?1). Furthermore, the addition of buffers themselves seemed to negatively impact diatoms (algal competitors). They were more abundant in an unbuffered control (12.7?±?5.1?×?10⁴ organisms mL^?1) than any of the pH treatments (3.6–4.7?×?10⁴ organisms mL^?1). In general, pH values of 8 to 9 might be most conducive to increasing algae production and minimizing invading organisms. CO₂ addition seems more valuable to algae as an inorganic carbon source and not as an essential mechanism to reduce pH.     

Bioinspired Ultrastrong Nanocomposite Membranes for Salinity Gradient Energy Harvesting from Organic Solutions

Efforts to extract energy from waste organic solutions can not only support clean environments but also help to alleviate the energy crisis. Here, a bioinspired ultrastrong nanocomposite membrane is developed via the layer‐by‐layer method based on aramid nanofiber‐graphene oxide (AGO) with good mechanical properties for salinity gradient energy harvesting from organic solutions. Benefiting from the 1D and 2D network interlocking arrangement, the AGO membrane shows an unprecedented mechanical stress of 688 MPa and maintains its integrity after soaking in organic solvents for 24 h. Impressively, when LiCl is diluted in methanol, the AGO membrane device with a working area of 113 mm² produces a current and a measured power generation of 28 ± 11 µA and 3140 ± 960 nW (C_feed = 2 mol L^?1), respectively. Thus, the working area of the AGO membrane for salinity gradient energy harvesting and temperature‐related energy harvesting enables its use in practical applications. In addition, 14 cells with the methanol‐LiCl solution (C_feed = 1 mol L^?1) can produce a voltage up to 1.82 V to light a liquid crystal display. Therefore, this AGO nanocomposite membrane presents a promising avenue to harvest salinity gradient energy from organic solutions.     

Evaluation of antioxidant capacities of green microalgae

Three strains of green microalgae, Chlorococcum sp.C53, Chlorella sp. E53, and Chlorella sp.ED53 were studied for their antioxidant activities. Crude extracts of these microalgae in hot water and in ethanol were examined for their total phenolic contents and for their antioxidant capacities. In order to determine their phenolic contents, the Folin–Ciocalteu method was used. As for the determination of their antioxidant capacities, four different assays were used: (1) total antioxidant capacity determination; (2) DPPH radical scavenging assay; (3) ferrous ion chelating ability assay; and (4) inhibition of lipid peroxidation (using thiobarbituric acid reactive substance). For all the strains we have studied, their ethanolic extract showed more antioxidant activities than their hot water extract. Categorically, the ethanolic extract of Chlorella sp.E53 exhibited both the highest total phenolic content of 35.5?±?0.14 mg gallic acid equivalent (GAE) g^?1 dry weight and the highest DPPH radical scavenging of 68.18?±?0.38 % at 1.4 mg mL^?1 (IC₅₀ 0.81 mg mL^?1), whereas Chlorella sp.ED53 showed both the highest ferrous ion chelation activity of 42.78?±?1.48 % at 1 mg mL^?1 (IC₅₀ 1.23 mg mL^?1) and the highest inhibition of lipid peroxidation of 87.96?±?0.59 % at 4 mg mL^?1. This high level of inhibition is comparable to 94.42?±?1.39 % of butylated hydroxytoluene, a commercial synthetic antioxidant, at the same concentration.     

Non-water miscible ionic liquid improves biocatalytic production of geranyl glucoside with <Emphasis Type="Italic">Escherichia coli</Emphasis> overexpressing a glucosyltransferase

Whole cells of Escherichia coli overexpressing a glucosyltransferase from Vitis vinifera were used for the glucosylation of geraniol to geranyl glucoside. A high cell density cultivation process for the production of whole-cell biocatalysts was developed, gaining a dry cell mass concentration of up to 67.6 ± 1.2 g L^?1 and a glucosyltransferase concentration of up to 2.7 ± 0.1 g protein L^?1 within a process time of 48 h. Whole-cell batch biotransformations in milliliter-scale stirred-tank bioreactors showed highest conversion of geraniol at pH 7.0 although the pH optimum of the purified glucosyltransferase was at pH 8.5. The biocatalytic batch process performance was improved significantly by the addition of a water-immiscible ionic liquid (N-hexylpyridinium bis(trifluoromethylsulfonyl)imid) for in situ substrate supply. The so far highest final geranyl glucoside concentration (291 ± 9 mg L^?1) and conversion (71 ± 2 %) reported for whole-cell biotransformations of geraniol were achieved with 5 % (v/v) of the ionic liquid.     

Treatment of old landfill leachate with high ammonium content using aerobic granular sludge

Background

Aerobic granular sludge has become an attractive alternative to the conventional activated sludge due to its high settling velocity, compact structure, and higher tolerance to toxic substances and adverse conditions. Aerobic granular sludge process has been studied intensively in the treatment of municipal and industrial wastewater. However, information on leachate treatment using aerobic granular sludge is very limited.

Methods

This study investigated the treatment performance of old landfill leachate with different levels of ammonium using two aerobic sequencing batch reactors (SBR): an activated sludge SBR (ASBR) and a granular sludge SBR (GSBR). Aerobic granules were successfully developed using old leachate with low ammonium concentration (136 mg L^?1 NH₄ ⁺-N).

Results

The GSBR obtained a stable chemical oxygen demand (COD) removal of 70% after 15 days of operation; while the ASBR required a start-up of at least 30 days and obtained unstable COD removal varying from 38 to 70%. Ammonium concentration was gradually increased in both reactors. Increasing influent ammonium concentration to 225 mg L^?1 N, the GSBR removed 73 ± 8% of COD; while COD removal of the ASBR was 59 ± 9%. The GSBR was also more efficient than the ASBR for nitrogen removal. The granular sludge could adapt to the increasing concentrations of ammonium, achieving 95 ± 7% removal efficiency at a maximum influent concentration of 465 mg L^?1 N. Ammonium removal of 96 ± 5% was obtained by the ASBR when it was fed with a maximum of 217 mg L^?1 NH₄ ⁺-N. However, the ASBR was partially inhibited by free-ammonia and nitrite accumulation rate increased up to 85%. Free-nitrous acid and the low biodegradability of organic carbon were likely the main factors affecting phosphorus removal.

Conclusion

The results from this research suggested that aerobic granular sludge have advantage over activated sludge in leachate treatment.

     

Effective biomass harvesting of marine diatom Chaetoceros muelleri by chitosan-induced flocculation,preservation of biomass,and recycling of culture medium for aquaculture feed application

Microalgae are a promising new source of biomass; however, large-scale economical harvesting of microalgal biomass is a major technological and economic challenge, limiting the commercial production of microalgal biomass for high-value compounds. In this study, the cationic polymer chitosan was used for the harvesting of the marine diatom Chaetoceros muelleri. Natural flocculation, and pH and chitosan-induced flocculation were studied in detail. The effects of flocculant dosage, culture pH, initial biomass concentration, and sedimentation time were investigated on biomass recovery. The results showed that flocculation efficiency can reach > 99% with an optimum dosage of chitosan (80 mg L^?1) at pH 9.6 and settling time of 40 minutes for biomass concentration from 0.2 to 1.2 g L^?1. The reusability of the recycled water, preservation of biomass after harvesting, and cost of the harvesting process were evaluated. The results showed that the chitosan-induced flocculation offers an efficient, cost-effective, rapid, and sustainable harvesting method for C. muelleri biomass for food and feed applications in aquaculture.