Biodegradation of trichloroethylene in finished compost materials

Growing interest in the use of biofiltration technology to remove toxic organic compounds from gaseous waste streams has led to the investigation of various solid packing materials to support microbial populations capable of contaminant biodegradation. Finished compost material has been used as a biofiltration packing matrix for the treatment of noxious odors and the removal of several gaseous organic contaminants. Trichloroethylene (TCE), a widespread groundwater contaminant, has been shown to undergo aerobic biodegradation under a variety of environmental conditions. The current investigation focused on the capacities of five different finished compost materials to remove TCE from head space vapors in small reaction flasks. Due to the cometabolic nature of aerobic TCE biodegradation, enrichment of compost materials with propane or methane as primary substrates was tested as a means to stimulate biological TCE removal. Results indicate that all of the materials tested removed at least 85 percent of the added TCE (initial head space concentration = 5.0 ppmv) without enrichment and over 99 percent total removal was observed in samples enriched with propane gas. Rapid adsorption of TCE accounted for up to 77 percent of the removal observed in the reactors. This study suggests that finished compost material from a variety of sources has considerable potential for use as a biofiltration packing material for the treatment of chlorinated solvent vapors in waste gas streams.