USE OF ETHYLENE AND ETHANE AS PRIMARY SUBSTRATES FOR AEROBIC COMETABOLISM OF VINYL-CHLORIDE

A significant problem encountered with anaerobic reductive dechlorinat ion of polychlorinated ethylenes during groundwater remediation is acc umulation of vinyl chloride (VC). Even when reduction of VC proceeds t o ethylene and/or ethane, low levels of VC may persist. The purpose of this study was to examine use of ethylene and ethane as primary subst rates for aerobic cometabolism of VC. Both ethylene- and ethane-grown enrichment cultures (developed with activated sludge inoculum) readily consumed VC. The ethylene culture exhibited an initial preference for VC over ethylene but then switched after several weeks. This culture was unable to use ethane or VC as sole substrates. Although VC inhibit ed ethylene use, growth on ethylene still occurred in the presence of VC. The ethane-grown culture was able to use both VC and ethylene as s ole substrates. When all three compounds were present, ethylene was co nsumed first, followed by VC and ethane. Thus, the presence of ethylen e and/or ethane with VC may eliminate the need to add a primary substr ate (for example, methane, toluene, or phenol) to sustain cometabolism of VC below the regulatory limit.