The acute effects of erythromycin and oxytetracycline on enhanced biological phosphorus removal system: shift in bacterial community structure.

Since extensive application, an increasing amount of antibiotics has been released into wastewater treatment plants. In this study, the enhanced biological phosphorus removal (EBPR) system was fed with synthetic wastewater containing erythromycin (ERY) and oxytetracycline (OTC) for 7 days to evaluate the variations of solution ortho-P (SOP), volatile fatty acid (VFA), poly-bhydroxyalkanoates (PHAs), specific oxygen uptake rater (SOUR), and microbial community in the EBPR system. The obtained results showed that the P-removal efficiency decreased to 0.0%, and at the end of the experiment, only less than 20% of the VFA could be consumed. Besides, the variable processes of P and PHAs were destroyed. Moreover, to better grasp the inhibitory mechanism of antibiotics, microbial community compositions of activated sludge sampled in all reactors were investigated by high-throughput sequencing techniques. Results of comparative and evolutionary analysis revealed that high concentrations (5 and 10 mg/L) of ERY and OTC could seriously shift microbial communities, while combined antibiotics could induce more. Additionally, Accumulibacter and Competibacter were two primary microorganisms at the genus level in the EBPR system. Accumulibacter decreased seriously for exposure to antibiotics, while Competibacter increased in all experimental reactors especially in combined antibiotics reactor.