Study On Degradation Of Tribromophenol In Sediment Microbial Fuel Cell Enhanced By Zero-valent Iron

Sediment is an important part of urban ecosystem and a major accumulation place of pollutants.The release of pollutants in the sediment will lead to secondary pollution of the water body.2,4,6-TBP is a typical brominated flame retardant used in epoxy resin,polyurethane and other polymer materials.Previous studies have shown that like most brominated flame retardants,TBP causes developmental neurotoxicity,embryonic toxicity,and fetal toxicity,with properties similar to estrogen.Tribromophenol has been detected in environmental media such as soil,river sediments,marine life and human body.Therefore,it is important to study the degradation of tribromophenol in sediment.In this study,the sediment microbial fuel cell was constructed by adding zero-valent iron into the sediment to promote the degradation of tribromophenol in the sediment,the change of overburden water quality,the current of microbial fuel cell and the change of microbial community in the sediment were studied.The enrichment and selection of zero-valent iron on microorganisms in sediment were found and the degradation mechanism of tribromophenol and other organic compounds in sediment was analyzed from the perspective of microbial community.The anaerobic biodegradation of TBP firstly involves the reduction of microorganisms to remove bromine atoms from tribromophenol,and the final product is phenol,which is difficult to be further mineralized under anaerobic conditions.At 30 days,the debromination efficiency of microorganisms in the sludge with zero ferric iron reached nearly 100%,and the debromination rate was 0.6 times higher than that of the control group,realizing the debromination of tribrominated phenol enhanced by zero ferric iron.The addition of zero-valent iron to the SMFC reactor promoted the debromination and degradation rate of tribrominated phenol,and enhanced the degradation of phenol,petroleum hydrocarbon,polycyclic aromatic hydrocarbon and other organic compounds in the sediment.During 100 days,degradation rate of phenol in SMFC+5% iron powder group reached 89%,degradation rate of various organic compounds such as petroleum hydrocarbon and polycyclic aromatic hydrocarbons ranged from 13.40% to 93.38%.Adding zero-valent iron to the sediment can effectively inhibit the TOC concentration of the overburden water.The addition of zero iron increased the current in the SMFC reactor,and the addition of 5% zero iron increased the current by 80% to 0.45 mA.The addition of zero-valent iron enriched some bacteria related to phenolic degradation in the bottom sludge: the proportion of Clostridium was 14.90%,while the proportion of the bacteria in the SMFC system alone was 7.95%.In addition,the Desulfovibrio was significantly enriched,with the proportion reaching 3.25%,and the proportion of the bacteria in the SMFC alone was only 0.04%.Meanwhile,the content of Desulfovibrio is significantly positively correlated with the current and the degradation rate of organic matter in the bottom sludge.