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Moringa oleifera is characterized by high coagulation properties, low cost and low toxicity hence is very promising to be utilized as an alternative coagulant to recover microalgae biomass from its suspension system. Hence, this study was performed with the objective to investigate the potentiality of M . oleifera as coagulant agent in harvesting microalgae and to investigate the effect of zeta potential in its coagulation-flocculation activity. Bradford protein assay was applied for rapid and accurate determination of protein concentration in the M . oleifera seed powder and protein powder. The flocculation activities were determined at isoelectric pH by computing the flocculation efficiency in terms of microalgae biomass recovery and removal percentage at various coagulant dosages. It was observed that the protein concentration was 211.71 μg g −1 mL −1 in M . oleifera seed powder and 188.16 μg g −1 mL −1 in protein powder which yielded 97% and 78% of biomass recovery, respectively at the dosage of 10 mg L −1 . Result showed that M . oleifera seed derivatives supersede chemical coagulant, alum which yielded 34% of biomass recovery at the same dosage. M . oleifera seed powder and protein powder was proven to be highly promising bio-coagulant and suitable alternative to the chemical coagulant in environmentally-sustainable harvesting of microalgae biomass. [ABSTRACT FROM AUTHOR]

Moringa oleifera (MO) seed has been widely used for water treatment purposes due to their good flocculation, low cost and non-toxic characteristics. However, these advantages had not yet been utilized for the microalgae harvesting technology. Until today, the harvesting of microalgae biomass still depend on sophisticated and complex approaches such as hollow fiber filtration, chemical flocculants and Alfa Laval decanter technology. Thus, in this study the potential of natural plant-based coagulant was investigated. MO seed derivatives were determined for the harvesting of suspended freshwater microalgae, Chlorella sp.. Flocculation characteristics with various dosages were optimized. The output of this study proved that primary and tertiary MO derivatives yield excellent flocculation efficiency of more than 95% at 20 min sedimentation. In fact, MO derivatives even supersede chemical flocculants, Aluminum Sulfate in terms of flocculation efficiency and biomass recovery at a low dosage of 10 mg L −1 and normal pH (6.9–7.5). Seed powder had the highest removal efficiency whereas seed protein had the highest biomass recovery. Utilization of M. oleifera derivatives as bio-coagulant provides several advantages such as lower impact on the environment, lower cost for microalgae harvesting, allow rapid microalgae culture expansion and as chemical-free green technology. [ABSTRACT FROM AUTHOR]

Bioremediation of aquaculture wastewater utilizing naturally occurring bacteria and microalgae have been widely used since 1990s in open pond. However, the relationship between both bioremediators especially in term of nutrient reduction had not been studied thoroughly in enclosed treatment system. Bioremediation of either Effective Microorganisms (EM) or microalgae (MA) independently required additional supply of oxygen and carbon dioxide, respectively to sustain their growth and treatment efficiency. Conversely, symbiotic bioremediation could omit these requirement due to the associate relation between both in term of respiration. EM bioremediation would produce CO 2 and consume O 2 whereas microalgae is vice versa. On top of that, both EM and microalgae simultaneously function as degradation of organic matter. In this study, symbiotic MA–EM showed higher removal percentage and removal rate on phosphorus of 99.15% and 0.534 mg L −1 d −1 as compared to 49.73% and 0.130 mg L −1 d −1 for the conventional MA bioremediation. However, inoculation of EM in the symbiotic MA–EM bioremediation did not significantly improved the removal of ammonia. With proper optimization of inoculation volume and bioremediation mode, symbiotic relations of these two microorganisms would benefits in designing more robust, economical and least maintenance on the wastewater treatment system. [ABSTRACT FROM AUTHOR]

This study focuses on the evaluation of the performance of Chlorella sp. in removing nutrient in aquaculture wastewater and its correlation with the kinetic growth of Chlorella sp. The treatment was applied with various Chlorella sp. inoculation dosage ranging from 0% to 60% (v/v) of wastewater. The optimum inoculation dosage was recorded at 30% (v/v) with effluent concentration of ammonia and orthophosphate recording at 0.012 mg L −1 and 0.647 mg L −1 , respectively on Day 11. The optimum dosage for bio-flocculation process was obtained at 30 mg L −1 of Aspergillus niger with a harvesting efficiency of 97%. This type of development of phytoremediation with continuous bio-harvesting could promote the use of sustainable green technology for effective wastewater treatment. [ABSTRACT FROM AUTHOR]

Nannochloropsis sp. and Tetraselmis sp. are widely used in aquaculture as a source of protein, lipid and carbohydrate. The growth and proximate composition of microalgae could be affected by different culture conditions especially salinity, temperature and light. Thus, this study was aimed to compare the growth and proximate composition of Nannochloropsis sp. and Tetraselmis sp. cultured in different salinities and pH under different culture conditions. In this study Nannochloropsis sp. and Tetraselmis sp. were isolated from South China Sea and cultured at different salinities of 20, 30 and 40 ppt and different pH of 5.5, 7.5, 8.5 and 9.5 under natural and control condition until stationary phase. Results showed that Nannochloropsis sp. and Tetraselmis sp. had significantly higher ( p < 0.05) cell density, lipid and carbohydrate content under control condition at 30 ppt. However, protein content was significantly higher ( p < 0.05) in Nannochloropsis sp. when cultured under natural condition at 30 ppt. High cell density, protein, lipid and carbohydrate content was obtained when cultured at pH 7.5 and 8.5 for both species. The output of this study could be considered for Nannochloropsis sp. and Tetraselmis sp. cultivation to provide appropriate levels of protein, lipid and carbohydrate as feed supplement for aquaculture organisms. [ABSTRACT FROM AUTHOR]