| The pollution of nitrogen and phosphorus are still the main water environment problem in China at this stage,and the large-scale use and irrational discharge of antibiotics have brought new risks to the water environment.Antibiotics will not only cause resistance and induce resistance genes in humans and animals,it will also affect the conventional water treatment process,In the decentralized sewage treatment technology,the bioretention system has a well ability to degrade nitrogen and phosphorus.It is of great practical significance to improve the bioretention system's ability to treat antibiotic-containing wastewater by conducting research on enhanced nitrogen and phosphorus removal by the bioretention system under antibiotic stress.In order to clarify the effect of antibiotics on the wastewater denitrification and dephosphorization in bioretention tank,five groups of bioretention tank reactors(control group BRC,activated carbon enhanced group AB,activated carbon plus lead enhanced group EAB,lead enhanced group EB,activated carbon-catalyzed Iron-lead reinforcement group(EFB)to explore the system's adaptability to nitrogen and phosphorus without antibiotic intervention and the strengthening effect of different strengthening methods on the system.The results show that each enhanced group has improved the removal of conventional indicators.The addition of activated carbon and iron particles in the submerged area of the biological retention tank can effectively improve the removal effect of total nitrogen by 8%-23% and the removal rate of phosphorus by 9%-21%,And effectively fix phosphorus.Except for EB,the enhanced group can ensure stable water quality,and the effluent nitrogen and phosphorus levels are better than the Class A discharge standard of urban sewage plants.On the basis of enhanced nitrogen and phosphorus removal and stable operation,the stress effects of two common antibiotics sulfamethoxazole(SMX)and tetracycline(TC)on the reactor were investigated.The results showed that in the enhanced group EFB and AB,the low concentration of two antibiotics(0.8mg/L)did not significantly inhibit or promote the removal of total nitrogen,while the reduction process of nitrite in the control group BRC and the enhanced group EAB quickly returned to stability after being temporarily suppressed;high concentration(1.6 mg/L)The effects of two antibiotics on the reactor are divided into two stages.Among them,the addition of 1.6 mg/L SMX can promote the removal of total nitrogen,and the 1.6 mg/L TC causes the death of microorganisms with a large number.The rapid rise of effluent COD and TP will paralyze the reactor,and at the same time,it will greatly affect the denitrification process by inhibiting the activity of denitrifying bacteria;Through fluorescent quantitative PCR analysis of functional genes,it was found that the step of reducing nitrous oxide to nitrogen was significantly inhibited during the denitrification process,followed by the process of nitrite reduction to nitric oxide,encoding the functional gene nosZ of two reductase,NirS abundance showed regular changes.The phosphorus removal mainly result of some microorganisms release polyphosphate phosphorus after being killed by tetracycline in high concentration.But when tetracycline reduced to 1.2mg/L,these inhibitation processes can be recovered within a week.According to the outflow of the four enhanced groups,EFB has the highest removal rate of various nutrients during the entire stress process,and the expression of denitrification-related functional genes wre more stable.It can cope with the impact of antibiotics and maintain normal water treatment capacity.The research results for the application of bioretention system in the treatment of wastewater containing antibiotics,proposed a technical approach to enhance the response to shocks and maintain treatment capacity. |
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