Mediated Bioreduction Of Tetrabromobisphenol-A

Brominated flame retardants (BFR) are a diverse group of chemicals used to protect materials against ignition Tetrabromobisphenol A(TBBPA) is a high production quantity chemicals used as flame retardants in plastics for products.he environmental safety of brominated flame retardants is a controversial topic.TBBPA has primarily been detected in air soil, water, sewage sludge,sediment and human serum samples.A multistage treatment process involving both anaerobic and aerobic stages may be the best solution for biodegradation of TBBPA,and reductive dehalogenation has been shown to be an important mechanism under anaerobic degradation.Anaerobic degradation in sediments, soils and sewage sludge has been frequently reported for TBBPA,but reports on biodegradation of TBBPA by single-strain are few.In this paper we investigated TBBPA was degraded by Shewanella sp.XB,which was isolated from the quinone-reducing microbial community. In addition, This paper preliminarily discussed the metabolic pathway for microbial degradation of TBBPA under anaerobic conditions.Effects of exogenous redox mediator AQDS, AQS. HNQ and DHNQ on the TBBPA degradation by strain XB were studied. It was demonstrated that degradation of TBBPA was promoted by addition of0.12mM HNQ and DHNQ, degradation rates of TBBPA were68.29%and71.89%,respectively.However, added synthetic mediator is usually cost-ineffective, refractory and toxic,which results in secondary pollution. Effects of the supernatant from anaerobic culture in inorganic medium by strain XB were also investigated. The experiment result indicated that externally the addition of the supernatant accelerate the degradation of TBBPA.The best experiment was the one adding40mL of supernatant and degradation efficiency of TBBPA reached76.70%. Supernatant contained flavins were analyzed by fluorescence spectrophotometry and cyclic voltammetry and had electrochemical activity, which could enhance TBBPA degradation by strain XB.In addition,the humic acid extracted from activated sludge and added to the experimental system lias redox activity that could improve the solubility of TBBPA in water.It was demonstrated that humic acid could also promot the degradation of TBBPA.Analysis of metabolic intermediate and possible reaction pathways was performed with HPLC/MS technique.In this study,the final metabolite was identified by asbisphenol A under the experimental conditions of this study.