Inhibitory Effects Of Erythrocin And Oxytetracycline On Enhanced Biological Phosphorus Removal System

Antibiotics are widely used pharmaceuticals and personal care products(PPCPs),which are increasingly being discharged into the aquatic environment via wastewater treatment plants(WWTPs)effluents.Antibiotics can detect at levels ranging from ng L-1 up to μg L-1 in domestic and hospital effluents,but effluents of pharmaceutical manufacturing facilities can reach to mg L-1.Moreover,due to its special physicochemical and biological characteristics,most currently used antibiotics are more difficult to be biodegraded by activated sludge than they were.Hence,it will be existed in WWTPs and it is meaningful to understand in-depth the performance of WWTPs after exposure to antibiotics.The performances of enhanced biological phosphorus removal(EBPR)systems in terms of the variations of phosphorus-removal(P-removal)efficiency,volatile fatty acid(VFA)concentration,polyhydroxyalkanoates(PHAs)content,extracellular polymeric substance(EPS)concentration and special oxygen utilization rate(SOUR)after exposure to erythromycin and oxytetracycline for 24 h were evaluated in this research.The P-removal efficiency decreased to 63.3 and 61.2%under the effect of erythromycin(lOmg/L)and oxytetracycline(lOmg/L)for 24 h,respectively.In the process of VFA consumption,no obvious inhibitory effects were detected.However,serious negative effects were detected in the process of PHAs production and consumption.Meanwhile,the PN in EPS declined by 26.7%at least after exposure to antibiotics with high concentration(10mg/L).According to the SOUR analysis,high concentrations(lOmg/L)of antibiotics seriously inhibit the oxygen utilization process(decline by 16.0%at least).Results of contrastive analysis show that oxytetracycline had more serious negative effects than erythromycin on the performance of EBPR system,and the processes in aerobic stage were inhibited more grievously than those in anaerobic stage in the EBPR system.After exposure to antibiotics for 7 days,although the macro performance,such as P-removal process,PHAs,EPS and SOUR,in each reactor was similar,the variation of microbial community was quite different among each reactor.The species richness in the EBPR system was reduced under the condition of high concentration(5 and 10 mg/L)ERY,OTC and its combined antibiotics.Results of similarity analysis show that high concentration(5 and 10 mg/L)ERY and OTC could induce serious microbial community shift,while combined antibiotics could induce more.Accumulibacter and Competibacter were two primary microorganisms on genus level in EBPR system.Accumulibacter decreased seriously due to exposure to antibiotics,while Competibacter increased in all experimental reactors especially in combined antibiotics reactor.Additionally,the ARB was different in each reactor.