Nutrient removal from piggery wastewater by Desmodesmus sp.CHX1 and its cultivation conditions optimization.

Combination of microalgae cultivation and piggery wastewater treatment has become a hot topic in recent years. Nutrient removal from aerated piggery wastewater (APW) by Desmodesmus sp. CHX1 and the optimization of cultivation conditions were investigated in this study. Results indicated that Desmodesmus sp. CHX1 showed an efficient growth in APW, with specific growth rate of 0.26-0.56 d-1. The biomass yield based on nutrient consumption was 9.65 g biomass/g NH4-N and 209.15 g biomass/g total phosphorus (TP) respectively. Desmodesmus sp. CHX1 performed well in nutrient removal from APW, with ammonium nitrogen (NH4-N) and TP removal efficiency (RE) of 78.46% and 91.66% respectively after 7 days of culture. Nutrient removal process fitted the pseudo-first-order kinetic equations well, with removal rate (RR) constant of 0.24 d-1 for NH4-N and 0.28 d-1 for TP. The optimum conditions for nutrient removal from APW by Desmodesmus sp. CHX1 were light intensity of 150 μmol photons m-2 s-1 in the photoperiod for 24 h when the temperature was set at 35°C with alga cell inoculation concentration of 30%. The removal efficiencies of NH4-N and TP were 88.26% and 95.06% respectively under the optimal conditions after 7 days of culture. Our results can be a good reference for enhancement of microalga production and the nutrient RE and further extend the application of the large-scale piggery wastewater treatment under a controlled environment.