FEASIBILITY OF IN-SITU BIODEGRADATION OF CHLORINATED ETHENES IN CONTAMINATED AQUIFERS

THE CHLORINATED ETHENES, VINYL CHLORIDE, VINYLIDINE CHLORIDE, TRICHLOROETHYLENE, AND TETRACHLOROETHYLENE HAVE BEEN DETECTED IN GROUNDWATER THROUGHOUT THE UNITED STATES. VINYL CHLORIDE AND VINYLIDINE CHLORIDE ORIGINATE FROM INDUSTRIAL WASTE DISPOSAL SITES AS WASTE PRODUCTS OF PLASTIC MANUFACTURING AND TRICHLOROETHYLENE IS WIDELY USED AS AN INDUSTRIAL SOLVENT. SINCE THESE COMPOUNDS ARE HIGHLY TOXIC, IT IS NECESSARY TO DEVELOP METHODS FOR THEIR REMOVAL FROM CONTAMINATED DRINKING WATER AQUIFERS. THE CONTAMINATION CAUSED BY THESE COMPOUNDS IS FREQUENTLY EXTENSIVE AND THEREFORE NOT ABLE TO BE TREATED COST-EFFECTIVELY BY EXISTING TECHNOLOGIES. THE INVESTIGATORS PROPOSE TO EVALUATE THE FEASIBILITY OF IN-SITU BIOLOGICAL TREATMENT OF THESE CONTAMINATED AQUIFERS. THEY HAVE IDENTIFIED THREE MICROBIOLOGICAL PROCESSES WHICH HAVE A HIGH PROBABILITY OF ACHIEVING THE COMPLETE BIODEGRADATION OF CHLORINATED ETHENES AND PROPOSE TO DEMONSTRATE THIS USING 14(C) LABELED VINYL CHLORIDE AND 14(C) TRICHLOROETHYLENE. TWO TYPES OF MICROORGANISMS, AEROBIC AND ANAEROBIC, WILL BE ISOLATED FROM SEDIMENTS TAKEN FROM A DISCHARGE AREA OF A CONTAMINATED AQUIFER. TEST COMPOUNDS AT CONCENTRATION FROM 10 TO 1000 UG/1 WILL BE INCUBATED INDIVIDUALLY WITH AEROBIC AND ANAEROBIC ORGANISMS AND WITH A SEQUENTIAL COMBINATION OF THOSE CULTURES. CHEMICAL INTERMEDIATES WILL BE IDENTIFIED BY GC AND GC/MS (14)CH4 AND (14)CO2 WILL BE MEASURED BY LIQUID SCINTILLATION COUNTING. THE RESULTS SHOULD ENABLE THEM TO DESIGN SPECIFIC AQUIFER RESTORATION PLANS IN WHICH THE SUBSURFACE ENVIRONMENT IS MODIFIED TO CREATE A MICROBIOLOGICAL BARRIER ACROSS THE PATH OF AN APPROACHING CONTAMINANT PLUME.