Characteristics of Tetracycline Degradation Coupled Simultaneous Nitrification-Denitrification and Phosphorus Removal in Aquaculture Wastewater

Although residual tetracycline, NH4+-N, and P in aquaculture wastewater have been frequently detected, their simultaneous removal has received little attention. The simultaneous and efficient removal of tetracycline, NH4+-N, COD, and P in aquaculture wastewater was achieved with a laboratory-scale moving bed biofilm reactor (MBBR) under different influent C/N ratios. The results suggested that tetracycline could be degraded efficiently without using an additional organic carbon source. Most of the tetracycline (>80%), NH4+-N (>73%), TN (>68%), TP (>59%), and COD (>78%) were synchronously removed under the higher C/N ratios. The electron transport system activity (ETSA), dissolved organic matter (DOM), and extracellular polymeric substances (EPS) were evaluated for biofilm performance during aquaculture wastewater remediation. The results indicated that the protein (PN) and polysaccharide (PS) concentrations, and fluorescence intensities were significantly different because the influent C/N ratios changed the biofilm activity. The ETSA values were lowest when tetracycline was the sole carbon source, which suggested that tetracycline affected the nitrification activity of biofilms. Sphingobacteriia, Betaproteobacteria, and Alphaproteobacteria were identified as the dominant bacterial classes. This study provides a new strategy for the removal of tetracycline and nutrients from aquaculture wastewater.