FATE OF VOLATILE ORGANIC-COMPOUNDS AND PESTICIDES IN COMPOSTED MUNICIPAL SOLID-WASTE

Composting of municipal solid waste (MSW) has many advantages includin g volume reduction, reduced atmospheric emissions of methane from land fills, and the potential for beneficial use of the end product. Inform ation about the fate of volatile organic chemicals (VOCs) which are co mmonly present in MSW is needed to protect the environment from undesi rable emissions. To achieve this goal, the present study was undertake n to evaluate the fate of four VOCs (benzene, carbon tetrachloride, di chlorobenzene, and xylene) and two pesticides (Captan and Lindane) add ed to simulated MSW. Volatile organic chemicals were added at three co ncentrations while pesticides were tested at a single concentration. A ll of the treatments were replicated three times and composted in 200 L aerated static pile composters. The composters were specially equipp ed with pumps and flow meters to aerate the feedstock at 1.12-1.68 m(3 )/hr, sorption filters to collect volatile organic chemicals from the exiting air stream, and leachate collection vessels. The feedstock was selected to be representative of MSW after the majority of recyclable metal and glass had been removed and was spiked with organic chemical s known to commonly occur in MSW. The results showed that the majority of VOCs present in the feedstock were lost via volatilization in the initial 48 hours of composting. Concentrations of VOCs were below dete ction limits after one week of composting in both the leachate and com post. Thus, while aerated pile composting is effective in removing VOC s from the feedstock, the exiting air stream will need to he monitored for approximately one week and possibly treated to meet environmental quality standards. Aerobic composting reduced the initial concentrati ons of 275 mg/kg each of Captan and Lindane to final concentrations of 53.8 and 158.9 mg/kg, respectively, after five weeks of composting. T his corresponded to half Lives of 1.5 and four weeks during composting for Captan and Lindane respectively. All concentrations of both pesti cides were below detection limits in all samples of air, condensate an d leachate, indicating that none of the pesticides were volatilized an d all were retained by the MSW until they biodegraded.