Complete remediation of PCE contaminated unsaturated soils by sequential anaerobic-aerobic bioventing

Bioventing principles have been applied to completely dechlorinate tetrachl oroethylene vapors in the unsaturated zone in a sequential anaerobic-aerobi c pattern. The aerobic step yields trans-DCE and VC as PCE reductive dechlo rination byproducts, while TCE and cis-DCE are observed as intermediates. T he aerobic step results in rapid oxidation of the VC and trans-DCE to carbo n dioxide. Hydrogen was delivered in the gas phase as a reducing agent for the anaerobic step at levels of 1%, and oxygen at 4.2% was used as an elect ron acceptor in the aerobic step. PCE and VC half lives in the anaerobic an d aerobic steps respectively, where less than 10 min.