In this study, cultivation of Chlorella vulgaris with actual effluent from aquaculture system in which coho salmon (Oncorhynchus kisutch) grew was conducted, and applicability of cultivated Chlorella vulgaris as feed was investigated. Firstly, growth characteristics of Chlorella vulgaris and indigenous microalgae which inhibited Chlorella vulgaris growth were compared by batch cultivations. Secondary, semi-continuous cultivation of Chlorella vulgaris under 6-day of hydraulic retention time was conducted to evaluate characteristics of Chlorella vulgaris growth and nutrient removals. Finally, amino acids composition in cultivated Chlorella vulgaris was analysed. The batch experiments revealed that indigenous microalgae growth was negligible, compared to Chlorella vulgaris. A dominant existence of Chlorella vulgaris with 82 mg/L of suspended solids were achieved in the semi-continuous cultivation. The aquaculture effluent contained 14.1 mg-N/L of inorganic nitrogen and 1.13 mg-P/L of PO_4~(3-) , and the continuous cultivation removed 40.3% of inorganic nitrogen. Meanwhile, PO_4~(3-) which was the limiting factor of Chlorella vulgaris growth was exhausted. Major amino acids contained in cultivated Chlorella vulgaris were arginine and glutamine acid, and utilisation of Chlorella vulgaris as protein, specifically the two amino acids, source was suggested.
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