Adaptation of a Constructed Wetland to Simultaneous Treatment of Monochlorobenzene and Perchloroethene

Abstract

Mixed groundwater contaminations by chlorinated volatile organic compounds (VOC) cause environmental hazards if contaminated groundwater discharges into surface waters and river floodplains. Constructed wetlands (CW) or engineered natural wetlands provide a promising technology for the protection of sensitive water bodies. We adapted a constructed wetland able to treat monochlorobenzene (MCB) contaminated groundwater to a mixture of MCB and tetrachloroethene (PCE), representing low and high chlorinated model VOC. Simultaneous treatment of both compounds was efficient after an adaptation time of 2 1/2 years. Removal of MCB was temporarily impaired by PCE addition, but after adaptation a MCB concentration decrease of up to 64% (55.3 micromol L(-1)) was observed. Oxygen availability in the rhizosphere was relatively low, leading to sub-optimal MCB elimination but providing also appropriate conditions for PCE dechlorination. PCE and metabolites concentration patterns indicated a very slow system adaptation. However, under steady state conditions complete removal of PCE inflow concentrations of 10-15 micromol L(-1) was achieved with negligible concentrations of chlorinated metabolites in the outflow. Recovery of total dechlorination metabolite loads corresponding to 100%, and ethene loads corresponding to 30% of the PCE inflow load provided evidence for complete reductive dechlorination, corroborated by the detection of Dehalococcoides sp.

Isolation and Characterization of Volatile Organic Compounds-Degrading <i>Bacillus</i> Strains from Loess

“…Therefore, the laws and policies pertaining to environmental regulations such as REACH, WEEE, and RoHS have been continually updated and developed. In addition, there has been a trend toward replacing the existing chemical purifying processes with more environmentally friendly biological processes [7,8]. In particular, the bioremediation of VOCs using a biofilter with microorganisms has a lower cost and is more environmentally friendly than physical and chemical processes.…”