Excess nutrients, particularly nitrogen and phosphorus remained in the anaerobically digested (AD) manure effluent, have major impacts on the environment if disposed inappropriately. Algal cultivation, with the advantages of faster uptake of nutrients in waste streams, year-round production, and higher photosynthetic efficiency, represents one of the best processes for the removal of excessive nutrients. Meanwhile, algae have also been proved as one of the most promising non-food-crop-based feedstock for biofuels production. This study focuses on a practically and economically feasible algal cultivation system that satisfies the needs of nutrient removal, carbon sequestration, and biofuels production. Non-filamentous green algae, especially Chlorella sp., were able to tolerate high nutrient loadings in a five-month cultivation; a chemically pretreated AD effluent which initially contained 200 mg/L of total nitrogen and 2.4 mg/L of total dissolved phosphorus (TDP) provided an optimal nutrient concentration for the cultivation of selected algae strain. Additionally, the cultivation of selected algal strain with optimal pretreated AD effluent in a pilot-scale semi-continuously fed raceway pond revealed a stable productivity of 6.83 g volatile solids (VS)/ m2/day.
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