Anaerobic Degradation Of Tetrabromobisphenol-a By Sludge Bacterial Agent

Tetrabromobisphenol-A (TBBPA) is widely used as a brominated flame retardant (BFR) in the market. So far, it has been detected in environmental samples owing to its widely use.TBBPA could be biodegradated under anaerobic-aerobic conditions., Howevre, the reaction rate of TBBPA under anaerobic conditions was rather low, and the reductive transformation process generally acts as the rate-limiting steps in the overall biodegradation, and its high hydrophobicity also increased the difficulty of biodegradation.In addition, there were a large number of nutrients and humic acids in activated sludge. They could be used as carbon sources and redox mediators during the biodegradation, but they were not fully used in actual processes. Base on this, we proposed to use sludge bacterial agent to solve the above problems. To the best of our knowledge, it is the first report that enhanced the debromination of TBBPA using sludge bacterial agent under anaerobic conditions was investigated. In this paper we investigated the characteristics of TBBPA degradation by sludge bacterial agent under anaerobic conditions. In addition, this paper discussed the microbial remediation of TBBPA contaminated soil under anaerobic conditions which provided theoretical support for the remediation of TBBPA contaminated soil.Firstly, the properties of three types of sludge-lysis liquids from three different sludge treatment processes and the characters of Shewanella sp.XB which cultivated by sludge-lysis liquid were compared. The results showed that the best sludge bacterial agent which used to degradate TBBPA was cultivated by Heat-Alkaline-Treatment sludge-lysis liquid.Secondly, TBBPA degradation by sludge bacterial agent under anaerobic conditions were investigated, after72h,45.1%of TBBPA (initial concentration of30mg/L) degradation efficiency was observed in the presence of sludge bacterial agent with OD660=1-2. The effects of sludge-lysis liquid, humic acids and other substances in agent were also investigated. The results showed that a certain amount of sludge-lysis liquid (60%, v:v) and humic acids (90mg/L) could accelerate the transformation of TBBPA, the protein and polysaccharide secretion of strain XB might have beneficial effects on anaerobic TBBPA biotransformation. The cyclic voltammogram of humic acids showed its good redox activity, the apparent solubility of TBBPA was increased in the presence of humic acids. And these beneficial effects of humic acids could accelerate the degradation of TBBPA.In addition, this paper discussed the profermance of microbial remediation of TBBPA contaminated soil using sludge bacterial agent under anaerobic conditions. TBBPA degradation in soil under different conditions were investigated, after15d anaerobic cultivation, approximately90%TBBPA degradation efficiency was obtained with60mL sludge bacterial agent per30g soil. And sludge bacterial agent could improve the soil dehydrogenase activity about57%, thus enhanced the biodegradation of TBBPA in soil.