Enhanced Biodecolorization Of Azo Dyes Using Immobilized Quinones As Redox Mediators And Bacterial Community Analysis

AQS has been immobilized in polyurethane foam and on ceramsite surface respectively using chemical method. The advantages of AQS immobilization were to effectively avoid secondary pollution and to reduce the operating costs. In order to realize the application of immobilized quinones as redox mediators in the treatment of azo dye wastewater, this paper studied their catalytic properties and analyzed the dynamics of microbial community structure using PCR-DGGE and454high-throughput sequencing technology.The catalytic performance of AQS-ceramsites on the anaerobic bio-decolorization of azo dyes was studied. The results indicated that AQS-ceramsites functioning as redox-mediators exhibited good catalytic activity of accelerating anaerobic bio-decolorization of a series of azo dyes under saline conditions. And when the structures of the azo dyes were different, the accelerated effect was also different. PCR-DGGE method was used to analyze the dynamics of the STAR (salt-tolerant AQS-reducing) community structure. The dynamics of the STAR community structure revealed by PCR-DGGE showed that Halomonas sp. play an important role in the catalytic system. Moreover,454high-throughput sequencing are used to analyze the community structure of STAR community. The results showed that the two methods got similar information. However, compared with PCR-DGGE,454high-throughput sequencing got more abundant information.The accelerating effect of AQS-PUF on anaerobic bio-decolorization of azo dye Reactive Brilliant Red X-3B by activated sludge was investigated. The results showed that the sludge concentration, electron donors and temperature had different effects on AQS-PUF mediated bio-decolorization of Reactive Brilliant Red X-3B. After10repeated experiments using AQS-PUF under the anaerobic conditions (30℃,1.8g·L-1sludge and1.5g·L-1sodium formate), immobilized AQS-mediated bio-decolorization efficiency of Reactive Brilliant Red X-3B retained over90%of their original value. The decolorization efficiencies of Reactive Brilliant Red X-3B were obviously enhanced using AQS-PUF during30days running. Compared with that lacking immobilized AQS, the start-up time of bio-decolorization of Reactive Brilliant Red X-3B was significantly shorter using AQS-PUF under anaerobic conditions.454high-throughput sequencing was used to study the dynamics of bacterial community. The change of the numbers of phylum, class, order, family, and genus were obtained. Moreover, rarefaction curve and Shannon index were also calculated based on nonlinear parameter. It could be concluded that microbial community had good diversity. The changes were further analyzed at different biology classification level of phylum, class and genus. The results showed that Proteobacteria phylum,δ-Proteobacteria class and Desulfovibrio genus were preponderant colonies in the system. In addition, we found the presence of the electrochemical activity of bacteria in the reaction system. The bacteria with electrochemical activity could accelerate the electron transfer, resulting in the increased decolorization of azo dyes by the immobilized quinone.