Effects of oxytetracycline and zinc ion on nutrient removal and biomass production via microalgal culturing in anaerobic digester effluent

Removal of nutrients from swine wastewater digester effluent (SWDE) by microalgae Coelastrella sp. and production of Coelastrella sp. were investigated at the presence of oxytetracycline (OTC) and Zn(II). Mechanisms of stress of OTC and Zn(II) on microalgae were discussed via analyzing the removal performance of SWDE and biochemical characteristics of microalgae. Results showed that removal efficiency of ammonia nitrogen and biomass yield of microalgae at the presence of 5000 mu g/L of OTC decreased by 13.1% - 50.1% and 28.2% -71.5%, respectively, when Zn concentration was increased from 0.50 mg/L to 5.0 mg/L. The presence of 5.0 mg/L Zn(II) promoted the accumulation of lipids in microalgae, and the presence of 50 mu g/L OTC increased unsaturation of fatty acid methyl ester. Content of glutathione and activity of both glutamine synthetase and superoxide dismutase decreased with the increase of OTC concentration, while content of adenosine triphosphatase increased when Zn(II) concentration was also increased.

Automated summary

This study investigated the removal of nutrients from swine wastewater digester effluent (SWDE) by microalgae Coelastrella sp. and the production of Coelastrella sp. in the presence of oxytetracycline (OTC) and zinc (II). The mechanisms of OTC and zinc (II) stress on microalgae were discussed by analyzing the removal performance of SWDE and biochemical characteristics of microalgae. The results showed that the presence of zinc (II) decreased the removal efficiency of ammonia nitrogen and biomass yield of microalgae in the presence of OTC. The presence of zinc (II) also promoted the accumulation of lipids in microalgae, while the presence of OTC increased the unsaturation of fatty acid methyl ester.