title: Benzene and toluene biodegradation down gradient of a zero-valent iron permeable reactive barrier.
abstract: This study simulated benzene and toluene biodegradation down gradient of a zero-valent iron permeable reactive barrier (ZVI PRB) that reduces trichloroethylene (TCE). The effects of elevated pH (10.5) and the presence of a common TCE dechlorination by product [cis-1,2-dichloroethene (cis-1,2-DCE)] on benzene and toluene biodegradation were evaluated in batch experiments. The data suggest that alkaline pH (pH 10.5), often observed down gradient of ZVI PRBs, inhibits Fe(III)-mediated biotransformation of both benzene and toluene. Removal was reduced by 43% for benzene and 26% for toluene as compared to the controls. The effect of the addition of cis-1,2-DCE on benzene and toluene biodegradation was positive and resulted in removal that was greater than or equal to the controls. These results suggest that, at least for cis-1,2-DCE, its formation may not be toxic to iron-reducing benzene and toluene degrading bacteria; however, for microbial benzene and toluene removal down gradient of a ZVI PRB, it may be necessary to provide pH control, especially in the case of a biological PRB that is downstream from a ZVI PRB.
authors.affiliation: Beijing Key Laboratory of Water Resources and Environmental Engineering, China University of Geosciences, Beijing 100083, PR China. chenliangqingdao@163.com
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.forename: Fei
authors.initials: F
authors.lastname: Liu
authors.forename: Yulong
authors.initials: Y
authors.lastname: Liu
authors.forename: Hongzhong
authors.initials: H
authors.lastname: Dong
authors.forename: Patricia J S
authors.initials: PJ
authors.lastname: Colberg
mesh_terms: D001554:Benzene / Q000378:metabolism*; D001673:Biodegradation, Environmental; D006863:Hydrogen-Ion Concentration; D007501:Iron; D014050:Toluene / Q000378:metabolism*; D014241:Trichloroethylene
chemical_list: D014241:Trichloroethylene; D014050:Toluene; D007501:Iron; D001554:Benzene