Study On The Mechanism Of Microbial Degradation In 1,4-dioxane,Chloroform And Toluene Mixed Pollution System

1,4-dioxane was widely used as a solvent in paints, lacquers and cosmetics, as well as a stabilizer for chlorinated solvents such as 1,1,1-trichloroethane. Because of its widespread use and stable structure, its pollution problem has provoked people’s attention. Chloroform and toluene, which were combined pollutions, were also common pollutants in daily life, and they often coexisted with 1,4-dioxane in domestic sewage. Therefore,1,4-dioxane, chloroform and toluene were target pollutants of this paper, high-throughput sequencing of 16S rRNA and metagenomic sequencing were used to analyze the changes of microbial community structure and function in degradation systems, and then clarify the microbial removal mechanism of compound pollutions, provides a theoretical basis for the repair of environment in 1,4-dioxane, chloroform and toluene compound pollution. The main results of this study were as follows:(1) When tetrahydrofuran as co metabolism substrate, activated sludge can cometabolic degradation of 1,4-dioxane. Then 1,4-dioxane has begun to degrade after tetrahydrofuran resolved. When tetrahydrofuran was degraded to below the detection limit,1,4-dioxane was no longer degraded, subculture and continue adding tetrahydrofuran,1,4-dioxane can continue to be degraded and can be reduced to below the detection limit.(2) When added chloroform as co contaminants, the tetrahydrofuran degraded, but 1,4-dioxane and chloroform did not appear obvious degradation.(3) When added toluene as co contaminants, toluene degradation was prior to tetrahydrofuran and 1,4-dioxane, which can be degraded to below the detection limit. Then subculture and continue adding toluene, toluene still can be degraded, but 1,4-dioxane and tetrahydrofuran were not degraded clearly.(4) After analyzed the 16S rRNA and metagenomic sequencing, we could infer that because of the high concentration of chloroform in chloroform pollution system, inhibiting the growth of bacteria which can degrade 1,4-dioxane; in toluene pollution system, the continuous addition of toluene may cause the loss of a series functions of the microorganism in the activated sludge.