Enrichment of Nitrifiers and the Influence of Antimicrobials on Nitrification during Batch Experiment

Abstract

The enrichment of nitrifying bacteria was realized and sludge yield was calculated for the batch experiment period. The influence of four kinds of antimicrobials on ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) was investigated using batch experiments. The specific ammonia-oxidizing activity (SAA) was 0.44 gN/gVSS/d and the specific nitrite-oxidizing activity (SNA) was 0.64 gN/gVSS/d. Below 400 mg/L antimicrobials, Cefalexin (CLX) almost has no adverse effect on nitrification and the highest inhibition caused by Sulfamethoxazole (SMX) was 15.4% and 23.9% to SAA and SNA respectively. Azithromycin (AZI) exhibited the most intense inhibitory effect. The relative activity of AOB and NOB were 39.0% and 29.8% respectively when AZI was 400 mg/L. Due to the complexation of Tetracycline (TC) with Ca 2+ and Mg 2+ , biomass showed obvious reduction with the foam on water surface. With the addition of 400 mg/L TC, only 76.9%, 13.7% and 8.1% of sludge remained when the substrate contained calcium or magnesium ions or both of them respectively.