Metagenomics reveals the influence of advanced wastewater treatment process on microbial community structure and function

In order to explore the influence of advanced treatment process on the structure and function of microbial communities in wastewater, samples of the influent and effluent of each treatment stage of an advanced treatment process were collected. The characteristics of bacterial diversity and distribution, nitrogen metabolism genes and carbohydrate active enzymes along the treatment process were investigated by metagenomics. The results showed that Proteobacteria, Bacteroidetes and Actinobacteria dominated the abundance at phylum level. At the genus level, the dominant bacteria showed obvious seasonal variations. The relative abudance of denitrification bacteria in denitrification filter effluent in summer was 28.6%, but only 14.4% in winter. In addition, species analysis also showed that the stages that had an significant impact on the microbial community structure were the denitrification filter and the cloth filter, while activated carbon filter and ozonation contact reactor exhibited less impact. A total of 23 biological nitrogen removal genes were detected in summer, with nirB, nasA, nosZ, napA and norB being the most abundant genes. A total of 29 biological nitrogen removal genes were detected in winter, and nirB, narZ, nosZ, napA and norB showed high abundance, indicating that the process had good potential for nitrogen removal.Moreover, 406~508 carbohydrate active enzyme families were identified, including 116 glycosyltransferases and 386 glycosidic hydrolases, indicating that the process also had strong degradation capability for organic matters. This study could improve the understanding of the advanced treatment process and provide microbiological support for the transformation and upgrading of the advanced treatment process in wastewater treatment plant.