Effect Of PAEs Pollution On Microbial Community And Its Biodegradation In Wastewater Treatment Plant

Plastic products are widely used in industry and daily life,which makes the plasticizer PAEs enter the industrial wastewater and domestic sewage,and finally flow into the sewage treatment plant for treatment,so the sewage treatment plant is the transit place of PAEs.PAEs in the environment not only endanger the ecological environment,but also easily accumulate in human body through food chain,which interferes with hormone level and affects reproduction and development of human body.Therefore,the treatment of PAEs in sewage treatment plants is very important,while microbial community plays an important role in the degradation process of PAEs in sewage,and its composition and structure are closely related to the efficiency of sewage treatment.Therefore,it is particularly important to study the influence of PAEs pollution on microbial community in sewage treatment plants.At the same time,high-efficiency PAEs degrading strains were screened from activated sludge to provide technical support for bioremediation of PAEs pollution.Therefore,this study collected samples from sewage treatment plants in two different periods(winter and summer),and determined the content of 16 kinds of PAEs in sewage by gas chromatography-mass spectrometry The relationship between PAEs pollution degree and microbial community characteristics was studied by high-throughput sequencing technique.In addition,two strains which can synergistically and efficiently degrade dibutyl phthalate(DBP)were screened from activated sludge of sewage treatment plant,and corresponding DBP degradation experiments were carried out.The main research results are as follows:(1)There are six dominant phyla in the sewage treatment plant,which are Proteobacteria,Bacteroidetes,Chloroflexi,Acidobacteria,Nitrospirae and Firmicutes,among which the most dominant phyla is Proteobacteria The main dominant bacteria are Arcobacter sp.,Aeromonas sp.,Pseudomonas sp.,Nitrospira sp.and Malikia sp.Pearson correlation analysis showed that PAEs were positively correlated with Proteobacteria,Aeromonas sp.and Pseudomonas sp.,which indicated that PAEs could be used as carbon source by these bacteria,that is,these bacteria could be used to degrade PAEs.In addition,in summer,PAEs concentration is negatively correlated with ? diversity of bacterial community,that is,when PAEs concentration increases,?diversity of bacterial community decreases significantly,which may further affect wastewater treatment efficiency.(2)There are five main phyla in the fungal community,which are Ascomycota,Basidiomycota,Chytridiomycota,Zygomycota and Glomeromycota,among which Ascomycota and Basidiomycota are the two most important phyla.Pearson analysis found that PAEs pollution can affect the diversity index(richness)of fungal microbial community.At the same time,Mantel analysis showed that pH,EC,TP,COD,TN,NH3-N,NO3-N and PAEs were significantly positively correlated with the fungal community structure in wastewater treatment plants(P<0.05),among which COD and NH3-N had the strongest correlation.(3)Among the PAEs degrading flora in the sewage treatment plant,the bacterial community composition is also dominant in the sewage treatment plant,that is,the dominant bacteria in the sewage treatment plant can use PAEs as carbon source to achieve the effect of degrading PAEs.Two strains of bacteria were isolated from sewage treatment plant.through substrate broad spectrum test,it was found that one strain(Gordonia sp.)could grow with DBP as the only carbon source and energy,and the other strain(Agrobacterium sp.)could grow with phthalic acid as the carbon source and energy.the two strains could cooperate with each other.the mixed use of these two strains could not only achieve complete degradation of DBP,but also achieve better degradation effect than single strain.The optimal conditions for DBP degradation by mixed bacteria are temperature 30?,pH= 7 and rotational speed 175r/min.Under the optimum conditions,500 mg/L DBP can be completely degraded in3 days.Through this study,it was found that PAEs pollution was related to ? diversity and community composition of microbial community in sewage treatment plant,which would affect the efficiency of sewage treatment.Therefore,two strains which could degrade PAEs synergistically and efficiently were screened through enrichment culture,which provided technical support for bioremediation of PAEs pollution.Figure 27,Table 28,references 108.