Cultivation of microalgae in dairy effluent for oil production and removal of organic pollution load

Dairy effluent (DE) was evaluated for cultivation of the oleaginous micro alga Chlorococcum sp. RAP13 under mixotrophic and heterotrophic modes. The alga grew better and accumulated more lipids under heterotrophic cultivation. Supplementation of biodiesel industry waste glycerol (BDWG) to DE enhanced the biomass production as well as lipid accumulation. While the biomass yield was 0.8 g/L for mixotrophic cultivation, it was 1.48 g/L and 1.94 g/L respectively when cultivated with 4% or 6% BDWG. The cells accumulated 31% lipid when grown in mixotrophic mode, and heterotrophic cultivation with 4% or 6% BDWG resulted in a lipid accumulation of 39% and 42% respectively. Saturated fatty acids production was elevated in the DE, and the major fatty acid components of the algal oil were palmitic (16:0), oleic (18:1), stearic (18:0), linoleic (18:2) and linolenic (18:3) acids. DE quality improved with reduction in COD and BOD after algal cultivation.