P33

SEQUENTIAL ANAEROBIC/ AEROBIC TRANSFORMATION OF CARBON TETRACHLORIDE, PERCHLOROETHYLENE, AND 1,1,1- TRICHLOROETHANE

With a sequential anaerobic/aerobic column process, the feasibility for complete mineralization of CT, PCE, and 1,1,1-TCA is greater. The capabilities of a sequential methanogenic-methanotrophic system to transform mixtures CT, PCE, and 1,1,1-TCA are being investigated. Three anaerobic-aerobic column systems containing glass beads or steel wool (Fe0) as support media have been established. Anaerobic glassbead reactors were seeded with acetate enrichment cultures and are being fed acetate as an electron donor; H2 produced from Fe0corrosion serves as an electron donor in the anaerobic steel-wool column. Methanotrophic, aerobic columns are supported by methane produced from the anaerobic columns, and fed hydrogen peroxide as an oxygen source.

Disappearance of parent compounds and appearance of transformation products before and after anaerobic and aerobic treatment are measured using gas chromatography. Methane production and acetate utilization are also measured to determine the impact of exposure to chlorinated aliphatics. Abiotic controls are operated to assess volatilization and sorption losses and the effect of H2O2 on transformation of the CAHs.

Key words: chlorinated aliphatics, biotransformation, mixtures, sequential anaerobic-aerobic