| The urban sewer system is an important part of the urban municipal system,which plays an important role in collecting,transporting domestic sewage and industrial sewage.As a kind of trace organic pollutants ubiquitous in water,PPCPs has the characteristics of persistence,bioaccumulation and refractory,which is likely to cause potential harm to the ecological environment and human health.Therefore,PPCPs are attracting more and more attention as an emerging pollutant.At present,most researches on urban sewer systems at home and abroad focus on the degradation analysis of conventional pollutants,but there are few studies on the migration characteristics and biochemical degradation of PPCPs in sewer systems.Therefore,this paper establishes two sets of 1200 m long urban sewer system pilot test equipment.The transfer and transformation of six typical PPCPs micro-pollutants in urban sewer system.At the same time,the microbial diversity and community structure changes along the pipe wall along the sewer system were further studied.The mechanism of biochemical degradation of PPCPs by sewer system microbial colonies was studied.In this study,SPE-HPLC was used to establish and optimize a method for quantitative detection of six PPCPs pollutants.The detection and recovery rate of the six PPCPs can reach more than 90%,and the relative standard deviation is less than 5%.The method has high precision and good repeatability.Based on the establishment of the detection method,the transfer and transformation of six PPCPs in urban sewer system were explored.The results show that the concentration of PPCPs decreases with the increase of the distance along the sewer system,and this phenomenon is especially obvious in the range of 200~600m,among which antibiotics TCY,SMX,analeptic CAF and personal care category TCS The degradation rate was significant.The average reduction rates were 32.1%,33.1%,31.5% and 29.8%,respectively.The AAP and DEET reduction rates were relatively low at 19.7% and 16.7%.Microorganisms can use PPCPs as nutrients to assist in their own growth and reproduction.The changes of PPCPs in the pipe network are mainly due to the existence of many different microbial flora along the sewer system.These groups have certain degradation to different PPCPs.Therefore,this experiment further uses 16 SrDNA high-throughput sequencing and molecular bioinformatics methods,the microbial diversity and community structure changes along the pipe wall were analyzed.Combined with the variation of target PPCPs in the sewer system,The relationship between the microbial communities along the pipeline and the degradation of target PPCPs was discussed.The results showed that the degree of biodiversity was higher in the range of 30~400m,1000~1200m,and was lower in the range of 400~1000m.Proteobacteria,Bacteroidetes and Firmicutes are the main dominant bacteria in the sewer system.As the length of the sewer system increases,the thick-walled bacteria gradually replaces the deformed bacteria to become the most dominant bacteria.Pseudomonas,Stenotrophomonas and Zoogloea are the functional microbial colonie most closely related to the reduction of target PPCPs in the sewer system.Among them,the degradation of Pseudomonas,Stenotrophomonas and Zoogloea and the adsorption of Zoogloea are the main factors.The above-mentioned flora mainly occurs in the range of 30~600m at the front end of the sewer system,which is consistent with the law that the concentration of PPCPs pollutants is significantly reduced within this range.Comprehensive analysis of the distribution of functional microbial communities in the sewer system and the variation of six PPCPs revealed the biodegradation mechanism of PPCPs by sewer system functional microorganisms. |
