Study On Functional Flora Of Different Biochemical Units In Urban Sewage Treatment Plants

The improvement of urban sewage discharge standards is one of the key reasons for the rapid development of society.Some special river basins and regions have implemented higher local discharge standards.Activated sludge process is the most widely used method in urban sewage treatment and the main carrier for pollutant removal in sanitary sewage.The relationship between its physical and chemical properties and microbial community structure,dominant strains and functions is worth further to study and research.54 activated sludge samples were collected from 16 rural sewage treatme nt stations and 2 urban sewage treatment plants in Baoding.The results show that:(1)the urban sewage treatment plants and five rural sewage treatment stations have better remove rates of total nitrogen,ammonia nitrogen and total phosphorus,and four rural sewage treatment stations have better treatment effective for ammonia nitrogen and total phosphorus,but the total nitrogen remove rate is not very ideal.(2)Illumina high-throughput sequencing technology was used to analyze the composition of microbial communities,class and genus.It was found that there was not significantly different in the level of phylum for different element,however the dominant class was different.The dominant class of most sewage treatment plants(stations)is ?-Proteobacteria.The dominant class of rural sewage treatment stations D and N was gamma-proteobacteria.(3)The results showed that the species diversity of Q urban sewage treatment plants was the largest,and that of eight rural sewage treatment stations had better diversity.(4)Through RDA analysis,it is concluded that TN and NH4-N have a great influence on the composition of microorganisms in the activated sludge of sewage treatment station.(5)The functional identification of the dominant strains in the activated sludge was carried out by the method of separation and culture.The effective degradation strains were screened out as K102,E002,G103 and B103,respectively.The maximum removal rates of COD,TN,TP and ammonia nitrogen were 49.58%,44.39%,48.58% and 21.95%,respectively.These strains were obtained from rural sewage treatment stations K,E,G and B,respectively,except for ammonia nitrogen,the removal rates were all above 40%.In conclusion,there are significant differences in the quality of the inlet and outlet water and the supernatant of activated sludge in rural and urban sewage treatment plants.The species diversity of urban sewage treatment plants was higher than that of rural sewage treatment stations.The community composition at phylum level was not significantly different,but at class level was slightly different.In rural sewage treatment stations,there are some strains with high degradation function to pollutants.In addition,the physical and chemical properties of activated sludge should also be monitored and managed.