Cultivation of Chlorella zofingiensis in bench-scale outdoor ponds by regulation of pH using dairy wastewater in winter, South China

Cultivation of Chlorella zofingiensis and nutrients removal in dairy wastewater were investigated in bench-scale outdoor ponds in winter, South China. The impacts of the two types of pH regulations, 5∼6% CO2 and acetic acid (HAc) on this process were studied. After 6 days cultivation, the removal rates of total nitrogen (TN) and orthophosphate ( PO 4 3 - ) using CO2 regulation were better than those using HAc. The removal rates of PO 4 3 - and TN were 97.5% and 51.7%, respectively using CO2 regulation; 79.6% (TN) and 42.0% ( PO 4 3 - ) were obtained using HAc regulation. Higher biomass, protein, sugar content, and stable pH control were found using CO2 regulation. However, significantly higher lipid content (31.8%) was observed using HAc regulation. The dominant differences of fatty acids were the content of C18:1 and C18:3. The growth characteristics and environmental conditions especially during the typical logarithmic phase were also analyzed.