Anaerobic bioventing of unsaturated zone contaminated with DDT and DNT

Initial degradation of highly chlorinated compounds and nitroaromatic compo unds found in munition waste streams is accelerated under anaerobic conditi ons followed by aerobic treatment of the degradation products. The establis hment of anaerobic environment in a vadose zone can be accomplished by feed ing appropriate anaerobic gas mixture, i.e., "anaerobic bioventing". The ga s mixture contains an electron donor for the reduction of these compounds. Lab scale study was conducted to evaluate potential of anaerobic bioventing for the treatment of an unsaturated zone contaminated with 1,1,1-trichloro -2,2-bis (p-chlorophenyl)ethane (DDT) and 2,4-dinitrotoluene (DNT). Hydrog en was used as the electron donor. Using the soil columns innoculate with a naerobic microorganisms, it was observed that by feeding a gas mixture of 1 % hydrogen. 1 % carbon dioxide and nitrogen, methanogenic conditions were established and DDT was reductively dechlorinated. 1,1-dichloro-2, 2-bis(p- chlorophenyl)ethane (DDD) accumulated as the intermediate product. The half life of DDT was calculated to be 8.5 months. DNT completely disappeared af ter six months of operation and no intermediates could be detected.