| The pollution of rivers in China is becoming more and more serious.At present,various technologies and methods have been adopted to control the pollution of rivers.As a new type of environmental pollutants,drug pollutants have attracted wide attention.Due to the large daily use of drugs and the low efficiency of sewage treatment plants,drugs enter the water body through various channels.Drugs in rivers are frequently detected and may adversely affect river pollution.The paper selected polyurethane foam rotating biological contactor,using three different inoculants to study the start-up and operation of the polyurethane foam rotating biological contactor.The effects of norfloxacin,ibuprofen and the mixture of norfloxacin and ibuprofen on the performance of biological rotating contactors in treating polluted river water were discussed,and the related mechanism was explored.This paper will provide some theoretical support and scientific basis for the treatment of polluted river water.The main conclusions are as follows:(1)Three inoculums(polluted river water,sediment,activated sludge)were used for start-up of the polyurethane foam rotating biological contactors.The results showed that the start-up time of contactors inoculated with sediment and activated sludge was similar,but the river water was slower than that of the other two to achieve stability.In the steady running stage,the removal rates of NH4+-N,TN and CODMn in three groups of polyurethane foam rotating biological contactors were all above 88%,71%and 77%,respectively.For the removal rates of TP,contactors inoculated with river water and sediment were above 80%.While contactors inoculated with the activated sludge was only about 60%.The microbials activity of biofilm on the polyurethane foam rotating biological contactors were manifested as follows:river water<sediment<activated sludge.(2)After the stabilization of the polyurethane foam rotating biological contactors,the effects of the concentration of norfloxacin at 0.05 ?g·L-1?0.5 ?g·L-1?5?g·L-1 and 500 ?g·L-1 on the performance of the polyurethane foam rotating biological contactors in treating polluted river water were investigated.The results showed that the removal rates of NH4+-N and TN in three groups of contactors decreased after adding norfloxacin,and the degree of influence was river water>sediment>activated sludge.When the concentration of norfloxacin reached 0.5(ig-L-1,the removal rates decreased significantly.The removal rate of TP was more significantly affected by norfloxacin than by NH4+-N and TN,and the degree of influence was activated sludge>river water>sediment.However,the removal rate of CODMn was obviously different.When the concentration of norfloxacin reached 5 ug·L-1,the removal rate of CODMn in the three groups of contactors decreased slightly.Only when the concentration of norfloxacin reached 500 ?g·L-1,the removal rate of CODMn in the three groups of contactors decreased significantly,and the degree of influence was river water>sediment>activated sludge.In addition,the rotating biological contactor had a certain removal effect on norfloxacin.Biofilm analysis showed that the higher the concentration of norfloxacin,the stronger the inhibitory effect on the microbial activity of biofilm.Three-dimensional fluorescence spectra showed that when the concentration of norfloxacin was lower than 5 ?g L-1,microorganisms could secrete aromatic proteins.When the concentration increased from 5?g·L-1 to 500?g·L-1,soluble microbial metabolites and humus-like substances increased,and ultimately humus-like substances became the main peak.High-throughput sequencing of biofilms showed that microbial species diversity and abundance decreased with the increase of norfloxacin dosage.The relative abundances of Proteobacteria,Bacteroidetes and Nitrospirae reduced.(3)After the stabilization of the polyurethane foam rotating biological contactors,the effects of the concentration of at ibuprofen 0.05 ?g·L-1?0.5?g·L-1?5?g·L-1 and 500 ?g·L-1 on the performance of the polyurethane foam rotating biological contactors in treating polluted river water were investigated.The results showed that the removal rates of NH4+-N and TN in three groups of contactors decreased after adding ibuprofen.When the concentration of ibuprofen reached 5 ?g·L-1,the removal rates of NH4+-N and TN in three groups of contactors decreased significantly,and the degree of influence was river water>sediment>activated sludge.The effect of ibuprofen on the removal rate of TP was more obvious than that of NH4+-N and TN,and the degree of influence was activated sludge>river water>sediment.However,the removal rate of CODMn was also significantly different.When the concentration of ibuprofen was less than 500 ?g·L-1,the removal rate of CODMn in three groups of contactors has almost no change.Only when the concentration of ibuprofen reached 500 ?g·L-1,the removal rate of CODMn was affected to a certain extent,and the degree of influence was river water>sediment>activated sludge.In addition,the rotating biological contactor had a certain removal effect on ibuprofen.The results showed that the microbial activity of biofilm was inhibited by ibuprofen.Three-dimensional fluorescence spectra showed that the main peaks of EPS were soluble microbial products and aromatic proteins I and II when the concentration of ibuprofen was less than ?g·L-1.When the concentration of ibuprofen reached 5 ?g·L-1,humus-like substances appeared in EPS,but the fluorescence intensity was very weak.When the concentration of ibuprofen increased to 500 ?g·L-1,the fluorescence peak related to humus-like substances in EPS became the main peak,and the fluorescence intensity was strong.Biofilm microbial diversity analysis showed that the number of microbial species and the number of functional bacteria decreased.(4)After the stabilization of the polyurethane foam rotating biological contactors,the effects of the mixture concentration of norfloxacin and ibuprofen at 0.05?g·L-1?0.5?g·L-1?5?g·L-1 and 500 ?g·L-1 on the performance of the polyurethane foam rotating biological contactors in treating polluted river water were investigated.The results showed that the removal rates of NH4+-N,TN and TP had been significantly affected when the concentration of drug mixture was 0.05?g·L-1.The removal rates of NH4+-N,TN and TP were more significantly affected when the concentration of drug mixture continued to increase.In addition,the degree ofinfluence of the removal rate ofNH4+-N and TN of three groups of contactors was river water>sediment>activated sludge,and the degree of influence of the removal rate of TP was activated sludge>river water>sediment.However,the removal rate of CODMn was obviously different.When the concentration of drug mixture was less than 5 ?g·L-1,the removal rate of CODMn in the contactor inoculated with river water decreased slightly.When the concentration reached 5 ?g·L-1,the removal rate of CODMn in the three groups of contactors began to decrease significantly.At the same time,and the degree of influence was river water>sediment>activated sludge.The rotating biological contactor had a certain removal effect on drug mixtrue.The results showed that the drug mixture had a significant inhibitory effect on the microbial activity of biofilm.Three-dimensional fluorescence spectra showed that when the concentration of drug mixture was 0.05 ?g L-1,weak fluorescence peaks related to humus-like substances appeared in biofilm EPS.When the concentration of drug mixture was more than 0.05 ?g·L-1,the fluorescence intensity of soluble microbial products and humus-like substances in EPS gradually increased and became the main peak.When the concentration of drug mixture reached 5 ?g L-1,the fluorescence intensity of humus-like substances in EPS increased gradually.Humus-like fluorescence peaks became the only major peaks.High-throughput sequencing of biofilms showed that drug mixtures reduced microbial species diversity and abundance.At the same time,with the increase of the concentration of the drug mixture,the relative abundances of Proteobacteria,Chloroflexi,Bacteriodetes and Nitrospirae gradually decreased. |
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