Cultivation of Chlorella vulgaris in a pilot-scale photobioreactor using real centrate wastewater with waste glycerol for improving microalgae biomass production and wastewater nutrients removal

To improve nutrients removal from real centrate wastewater and enhance the microalgae biomass production, cultivation of Chlorella vulgaris in lab and a pilot-scale photobioreactor with waste glycerol was studied. The results showed the optimal concentration of the crude glycerol was 1.0 g L⁻¹ with the maximum biomass productivity of 460 mg L⁻¹ d⁻¹ TVS, the maximum lipid content of 27%, the nutrient removal efficiency of all above 86%, due to more balanced C/N ratio. The synergistic relationship between the wastewater-borne bacteria and the microalgae had significant good influence on nutrient removal. In pilot-scale wastewater-based algae cultivation, with 1 g L⁻¹ waste glycerol addition, the average biomass production of 16.7 g m⁻² d⁻¹, lipid content of 23.6%, and the removal of 2.4 g m⁻² d⁻¹ NH₄⁺-N, 2.7 g m⁻² d⁻¹ total nitrogen, 3.0 g m⁻² d⁻¹ total phosphorous, and 103.0 g m⁻² d⁻¹ of COD were attained for 34 days semi-continuous mode.