Anaerobic Conversion of Chlorobenzene and Benzene to CH4 and CO2 in Bioaugmented Microcosms

• Published in: Environmental science & technology Vol. 47; no. 5; pp. 2378 - 2385
• Main Authors: Liang, Xiaoming, Devine, Cheryl E, Nelson, Jennifer, Sherwood Lollar, Barbara, Zinder, Stephen, Edwards, Elizabeth A
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 05-03-2013
• Subjects: Anaerobiosis; Applied sciences; Bacteria, Anaerobic - metabolism; Benzene - chemistry; Benzene - metabolism; Biodegradation, Environmental; Biological and medical sciences; Biological treatment of waters; Biotechnology; Carbon Dioxide - chemistry; Chlorobenzenes - chemistry; Chlorobenzenes - metabolism; Earth sciences; Earth, ocean, space; Electrons; Engineering and environment geology. Geothermics; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Groundwaters; Halogenation; Industrial applications and implications. Economical aspects; Methane - chemistry; Natural water pollution; Pollution; Pollution, environment geology; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - metabolism; Water treatment and pollution; Dehalogenation; Metabolite; Mutagen; Bioaugmentation; Organic chlorine compounds; Organic halogen compounds; Carcinogen; Dechlorination; Halogenated hydrocarbon; Decontamination; Methanogenic bacteria; Benzene; Greenhouse gas; Chlorocarbon; Aromatic compound; Water pollution; Bioremediation; Degradation product; Organic compounds; Ground water
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es3043092

Chlorobenzene is a widespread groundwater contaminant found at many industrial sites. Reductive dechlorination of chlorobenzene requires input of electron donor and results in problematic accumulation of benzene, which is more toxic than chlorobenzene. We hypothesized that coupling a culture capable of reductive dechlorination of chlorobenzene to benzene with a second benzene-degrading methanogenic culture would completely detoxify chlorobenzene. To this end, active chlorobenzene-dechlorinating microcosms that were producing benzene were inoculated with a previously described enriched methanogenic benzene-degrading consortium. The combination resulted in the transformation of chlorobenzene via benzene to the nontoxic degradation products, CO2 and CH4. Sustainable degradation of chlorobenzene and benzene was observed in the microcosms and was further confirmed by shifts in the carbon isotopic ratios of chlorobenzene and benzene during degradation. Moreover, we could show that benzene derived electrons fueled chlorobenzene dechlorination removing the need to provide exogenous electron donor. The results have promising implications for sustainable bioremediation of sites contaminated with chlorinated benzenes and benzene.