Mixed Wastewater Coupled with CO(2) for Microalgae Culturing and Nutrient Removal

Biomass, nutrient removal capacity, lipid productivity and morphological changes of Chlorella sorokiniana and Desmodesmus communis were investigated in mixed wastewaters with different CO(2) concentrations. Under optimal condition, which was 1:3 ratio of swine wastewater to second treated municipal wastewater with 5% CO(2), the maximum biomass concentrations were 1.22 g L(-1) and 0.84 g L(-1) for C. sorokiniana and D. communis, respectively. Almost all of the ammonia and phosphorus were removed, the removal rates of total nitrogen were 88.05% for C. sorokiniana and 83.18% for D. communis. Lipid content reached 17.04% for C. sorokiniana and 20.37% for D. communis after 10 days culture. CO(2) aeration increased intracellular particle numbers of both microalgae and made D. communis tend to be solitary. The research suggested the aeration of CO(2) improve the tolerance of microalgae to high concentration of NH(4)-N, and nutrient excess stress could induce lipid accumulation of microalgae.