Evaluation of the removal of nutrients coupling of the cultivation of Spirulina platensis with piggery wastewater

Abstract The discharge of livestock wastewater without treatment in depth severely harm to the environment and human health, cultivation microalgae as feedstock for biodiesel and animal feed additive using livestock wastewater coupling of the treatment of wastewater has become a research topic. In this study, the cultivation conditions of Spirulina platensis using piggery wastewater were optimized by response surface method, and the removal of nutrients from the piggery wastewater coupling of Spirulina platensis as the feedstock for animal feed additive was evaluation. The results of single factor experiments confirmed cupric ion seriously inhibited the growth of Spirulina platensis, while nitrogen, phosphorous and zinc all low promotes high inhabitation. Spirulina platensis grew well in the dilution piggery wastewater supplemented with moderate sodium bicarbonate, which indicated it is the limited nutrients. The OD560 of S. platensi reached 1.83 at the optimal conditions proposed by response surface method as follows: piggery wastewater was diluted to 4 times, 7 g/L sodium bicarbonate, pH 10.5, initial OD560 0.63, light intensity 3030 lux, light/dark 16/8 and cultured time 8 days. Spirulina platensis cultured in the diluted piggery wastewater contained 43.75% protein, 9.4% crude lipid, 8.826 mg/g chlorophyll, 4.18% total sugar, 27.7 mg/kg Cu and 246.2 mg/kg Zn. The analysis of the chemical compositions of Spirulina platensis indicated it can as the feedstock for animal feed additive. The removal efficiency of TN, TP, COD, Zn and Cu from the wastewater was 76%, 72%, 93.1%, 93.5% and 82.5%, respectively. These results demonstrated the removal of nutrients from piggery wastewater coupling culturing S. platensi as the feedstock for animal feed additive is feasible.