Nutrient removal from swine wastewater with growing microalgae at various zinc concentrations

Coelastrella sp. grows well in swine wastewater, and could remove nutrients from swine wastewater. Some typical pollutants such as Zn(II) in swine wastewater might affect the growth of microalgae and the nutrient removal performance. In this study, Coelastrella sp. was cultivated in swine wastewater at various Zn(II) concentrations, and the nutrient removal capacity and physiological and biochemical properties of the microalgae were examined to better apply this technology for the removal and recovery of nutrients from swine wastewater. Results revealed that excessive Zn(II) in swine wastewater inhibited microalgae growth and reduced the increase of pH value, thus decreased ammonia nitrogen volatilization and assimilation. Remarkably in swine wastewater, Zn(II) decreased the removal efficiency of phosphorus at low Zn(II) concentration, and promoted phosphorus precipitation and stimulated assimilation of phosphorus by Coelastrella sp. at high Zn(II) concentration. Hence in this study, we elucidated the mechanisms of nutrient removal from swine wastewater by the microalgae Coelastrella sp. in the stress of Zn(II). This study could be referred in future improvement and applications of microalgae culturing in swine wastewater treatment.