Cultivation of Chlorella pyrenoidosa and Scenedesmus obliquus in swine wastewater: Nitrogen and phosphorus removal and microalgal growth

Using microalgae to treat swine wastewater can effectively reduce the increasing pollution and save the cost of cultivating microalgae. In this study, the growth and denitrification and phosphorus removal effects of Scenedesmus obliquus and Chlorella pyrenoidosa at different dilutions in swine wastewater were investigated to solve the problem that microalgae could not be cultivated in the raw swine wastewater. After diluting the swine wastewater 8 and 12 times, the growth was optimized after 11 days of cultivation of Scenedesmus obliquus and 9 days of cultivation of Chlorella pyrenoidosa. Compared to Chlorella pyrenoidosa, the biomass and chlorophyll-a content were higher in Scenedesmus obliquus, at 1.48 g/L and 18.46 mg/L, respectively. The removal of nitrogen and phosphorus indicators was almost 100 %. Subsequently, Scenedesmus obliquus was cultured in an 8-fold dilution of swine and domestic wastewater, with dry weights of 0.83 g/L and 1.44 g/L, and lipid contents of 41.26 % and 25.11 %, respectively. Compared to Chlorella pyrenoidosa, Scenedesmus obliquus was more tolerant to nitrogen and phosphorus in swine wastewater, and at the same time, it had a higher growth rate, making it more suitable for treating swine wastewater and accumulating biomass.