Insight into the effect of oxytetracycline on the pollutant removal performance, nitrogen removal rate, microbial community and enzymatic activity of sequencing batch reactor

Abstract

The performance, nitrogen removal rate, microbial community and enzymatic activity of a sequencing batch reactor (SBR) have been evaluated under long-term exposure of oxytetracycline (OTC). The chemical oxygen demand (COD) and NH4+-N removals displayed no distinct variation under 5 mg/L OTC and then reduced with the increase of OTC concentration from 5 to 30 mg/L. The microbial oxygen uptake rate and dehydrogenase activity of activated sludge had no evident change under 10 mg/L OTC and then decreased with the increase of OTC concentration from 20 to 30 mg/L. The nitrification rate, denitrification rate, nitrifying enzymatic activity and denitrifying enzymatic activity of activated sludge gradually decreased with the increase of OTC concentration from 0 to 30 mg/L. Compared with 0 mg/L OTC, the OTC concentration at 30 mg/L could promote the microorganisms in the activated sludge to produce more reactive oxygen species production and lactate dehydrogenase release. The microbial diversity and abundance of SBR displayed some obvious changes under different OTC concentrations.