Phycoremediation and microalgae production using poultry effluent from anaerobic digestion as a culture medium

Abstract

Biological treatment of effluents with microalgae can be a sustainable and effective technology. It is mainly useful for the meat industry which produces large volumes of effluents from the animal slaughter, meat processing and the cleaning of their facilities. The objective of this paper was to determine the optimal operating conditions of the Scenedesmus obliquus culture for the removal of contaminants from poultry effluent and recovering valuable nutrients for biomass production. Experiments were performed at laboratory scale using poultry effluent from anaerobic digestion without dilution and the microalga Scenedesmus obliquus. The evaluation was based on four dilution rates from 0.20 to 0.35 1/day on semi-continuous growth bioreactor. Results demonstrated that the highest biomass productivity of 0.57 gbiomass/L day was achieved at 0.30 1/day. However, the highest nutrients removal efficiency was obtained at 0.20 1/day. In these conditions, the removal efficiency exceeded 80% for nitrogen and phosphorus and 99% for E. coli, at all dilution rates tested and was above 90% for COD. Also, using a dilution rate of 0.20 1/day, a quantum yield of up to 0.24 g/E and nutrient coefficient yields of up to 41 mgN/gbiomass and 32.32 mgP/gbiomass were achieved. In conclusion, cultivation of Scenedesmus obliquus in poultry effluents can be adjusted based on the objective. That is to say, a dilution rate of 0.30 1/day is recommended for biomass production and 0.20 1/day is suggested for tertiary treatment. The production of microalgae coupled with biological treatment allows recovery of nutrients, generating biomass and treating the industry effluents before their final disposal.