Increased Microalgae Growth and Nutrient Removal Using Balanced N:P Ratio in Wastewater
2013
Lee, S.H., Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea | Ahn, C.Y., Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea | Jo, B.H., Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea | Lee, S.A., Chungnam National University, Daejeon. Republic of korea | Park, J.Y., Korea Institute of Energy Research, Daejeon, Republic of Korea | An, K.G., Chungnam National University, Daejeon. Republic of korea | Oh, H.M., Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
Microalgal cultivation using wastewater is now regarded as essential for biodiesel production, as two goals can be achieved simultaneously; that is, nutrient removal efficiency and biomass production. Therefore, this study examined the effects of carbon sources, the N:P ratio, and the hydraulic retention time (HRT) to identify the optimal conditions for nutrient removal efficiency and biomass production. The effluent from a 2nd lagoon was used to cultivate microalgae. Whereas the algal species diversity and lipid content increased with a longer HRT, the algal biomass productivity decreased. Different carbon sources also affected the algal species composition. Diatoms were dominant with an increased pH when bicarbonate was supplied. However, 2% CO2 gas led to a lower pH and the dominance of filamentous green algae with a much lower biomass productivity. Among the experiments, the highest chlorophyll-a concentration and lipid productivity were obtained with the addition of phosphate up to 0.5 mg/l P, since phosphorus was in short supply compared with nitrogen. The N and P removal efficiencies were also higher with a balanced N:P ratio, based on the addition of phosphate. Thus, optimizing the N:P ratio for the dominant algae could be critical in attaining higher algal growth, lipid productivity, and nutrient removal efficiency.
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