Effect Of Ciprofloxacin On Biological Nitrogen And Phosphorus Removal From Wastewater

In recent years,the abuse of antibiotics becomes increasingly serious.Ciprofloxacin(CIP),a typcal Fluoroquinolone antibiotics(FQs),has a extensive use of medical treatment because of its puissant sterilization.However,the extra antibiont accompanying with various environmental medium enter into human's living environment and cause a negative effect on human life.The long-term exist of FQs affects microorganism selective pressuring,induces antibiotics resistance genes(ARGs)and drug resistant genes.The precious studies have a extensive attention on the FQs exist in municipal sewage treatment system.It has great significance of analysis the migration rule of FQs and its grug resistant gene in sewage disposal process.In this stud,a laboratory sacle sequencing batch(SBRs)was established as a simulation of sewage treatment system in sewage treatment plant.This paper mainly studies the effect of CIP on the SBRs processing system,lay a good foundation for research the effect of antibiotics and the removal of CIP.In this work,both short-term and long-term experiments were therefore conducted to assess the effects of CIP(0.2 and 2 mg·L-1)on wastewater nutrient removal.The results showed that both levels of CIP had no acute and chronic adverse effects on the surface integrity and viability of activated sludge.Short-term exposure to all the CIP levels induced negligible influences on wastewater nutrient removal.However,the prolonged exposure to CIP decreased total phosphorus and nitrogen removal efficiencies from 96.8,95.8%(control)to 91.7,84.9%(0.2 mg·L-1)and 90.5%,80.2%(2 mg·L-1),respectively.The mechanism study showed that CIP exposure suppressed denitrification and phosphorus uptake processes.It was also found the transformations of intracellular polyhydroxyalkanoates consumption and glycogen synthesis in anaerobic stage were affected.Moreover the activities of nitrite reductase and polyphosphate kinase were inhibited by the presence of CIP.Further analysis with high-throughput sequencing revealed that compared with the control,the abundances of polyphosphate accumulating organisms,glycogen accumulating organisms and denitrifying bacteria in CIP exposure reactors reduced,which were consistent with the decreased nutrient removal performance measured in these reactors.