DEGRADABILITY OF CHLORINATED ALIPHATIC-COMPOUNDS IN METHANOGENIC LEACHATES SAMPLED AT 8 LANDFILLS

The degradability of chlorinated aliphatic compounds (tetrachlorometha ne (TeCM); 1,1,1-trichloroethane (1,1,1-TCA); 1,1,2-trichloroethane (1 ,1,2-TCA); tetrachloroethene/perchloroethylene (PCE); and trichloroeth ene/trichloroethylene (TCE)) was studied under methanogenic conditions in batch reactors with leachate from eight landfills in Denmark. All landfill leachates showed fast abiotic degradation of TeCM and 1,1,1-T CA, while 1,1,2-TCA seemed unaffected during the methanogenic incubati on. PCE and TCE were degraded biologically by reductive dehalogenation , but only in three of the eight leachates. The conversion rates of th e chlorinated ethenes (PCE, TCE, dichloroethene (DCE)) and monochloroe thene/vinyl chloride (VC) varied significantly between the three landf ill leachates transforming chlorinated ethenes. In one leachate, compl ete conversion of all ethenes, including conversion of VC, was observe d within 40 days, while another leachate during the same period showed only about 50% conversion of PCE. This indicates that transformation of these common solvents in the landfill environment may vary substant ially between landfills.