Trace organic compounds in landfill gas at seven UK waste disposal sites

The trace volatile organic compounds (VOCs) in landfill gas were examined at seven U.K. waste disposal facilities. Over 140 compounds were identified, of which more than 90 were common to all seven sites. The groups of compounds and concentrations observed were alkanes, 302-1543 mg m(-3); aromatic compounds, 94-1906 mg m(-3); cycloalkanes, 80-487 mg m(-3); terpenes, 35-652 mg m(-3); alcohols and ketones, 2-2069 mg m(-3); and halogenated compounds, 327-1239 mg m(-3). The observed variations in landfill gas composition were largely attributed to differences in the waste composition and the stage reached in the decomposition processes at each of the sites. Three sites were found to have total chlorine concentrations, derived from the organochlorine compounds in the gas, of above 250 mg m(-3). Chlorine contents of this level were considered to be potentially damaging to landfill gas fueled engines used for electricity generation. Chloroethene (>0.1-87 mg m(-3)) was identified as the most abundant toxic component. Chloroethene levels in the landfill gases from two of the sites studied were found in excess of the U.K. maximum exposure limit by a factor of 5 and 3. Total VOCs emissions from four of the seven sites studied were estimated to be of the order of 10(4) kg/yr.