Persistent organic pollutants (POPs) originating from POP waste are playing an increasingly important role in the elevation of regional POP levels. In this study we realized the complete dechlorination of high concentration hexachlorobenzene (HCB) waste in the presence of polyethylene glycol and hydroxide, rather than using conventional high temperature incineration. Here, we demonstrate the do...

Recent field studies have indicated synergistic effects of coupling microbial reductive dechlorination with physicochemical remediation (e.g., surfactant flushing) of dense nonaqueous phase liquid (DNAPL) source zones. This study explored chlorinated ethene (e.g., tetrachloroethene [PCE]) dechlorination in the presence of 50-5000 mg/L Tween 80, a nonionic surfactant employed in source zone reme...

Metabolically stable anaerobic enrichment cultures have been obtained from sediment samples contaminated with chlorophenolic compounds. Enrichment was carried out with esculin, esculetin, naringin, naringenin, fraxin, quercetin, and acetate in media with two sulfate concentrations. These cultures were used to examine the O-demethylation of 4,5,6-trichloroguaiacol and the dechlorination of 3,4,5...

Chlorinated ethenes are among the most frequently detected groundwater contaminants in industrially developed countries. Although their degradation pathways have been understood, assessing the progress of natural attenuation of chlorinated ethenes still remains a challenge. Chlorinated ethenes undergo sequential reductive dechlorination under anoxic conditions; hence, the presence of less chlor...

Anaerobic microbial reductive dechlorination of PCBs is important because it removes the chlorine substituents that block aerobic metabolism and it reduces PCB toxicity. Although this process occurs widely in nature, its extent is often limited to dechlorination of some of the chlorines in the meta positions of biphenyl. In this report we demonstrate the ability to achieve nearly complete meta ...

Microbial reductive dechlorination of commercial polychlorinated biphenyl (PCB) mixtures (e.g., Aroclors) in aquatic sediments is crucial to achieve detoxification. Despite extensive efforts over nearly two decades, the microorganisms responsible for Aroclor dechlorination remained elusive. Here we demonstrate that anaerobic bacteria of the Dehalococcoides group derived from sediment of the Hou...

Most of the 36 billion gal of treated sewage wastewater discharged daily into the environment in the United States is disinfected via chlorination. To minimize toxicity, dechlorination with sulfite or sulfur dioxide is often performed. Although dechlorination is considered instantaneous and complete, several studies have found residual toxicity of chlorinated/dechlorinated effluent to aquatic l...

The application of aqueous film-forming foams (AFFFs) to extinguish chlorinated solvent-fueled fires has led to the co-contamination of poly- and perfluoroalkyl substances (PFASs) and trichloroethene (TCE) in groundwater and soil. Although reductive dechlorination of TCE by Dehalococcoides mccartyi is a frequently used remediation strategy, the effects of AFFF and PFASs on TCE dechlorination ar...

Hydrogen served as an electron donor in the reductive dechlorination of tetrachloroethene to vinyl chloride and ethene over periods of 14 to 40 days in anaerobic enrichment cultures; however, sustained dechlorination for more extended periods required the addition of filtered supernatant from a methanol-fed culture. This result suggests a nutritional dependency of hydrogen-utilizing dechlorinat...

In situ methods are needed to evaluate the effectiveness of chemical amendments at enhancing reductive dechlorination rates in groundwater that is contaminated with the priority pollutant, trichloroethene (TCE). In this communication, a method that utilizes single-well, "push-pull" tests to quantify the effects of chemical amendments on in situ reductive dechlorination rates is presented and de...