TRACE-ELEMENTS IN MUNICIPAL SOLID-WASTE COMPOST

Composting is a major potential municipal solid waste (MSW) management system. There is a concern that heavy metals in the compost product may be a health concern as a result of the use of compost on land. Several European countries and organizations in the United States are advocating source separation of organics and have recommended the prohibition of mixed MSW composting. This study evaluated the data on heavy metals from mixed MSW and source separated MSW (SOW) for the United States and European facilities. The levels of heavy metals in mixed MSW-compost were considerably lower than levels in sewage sludge and sludge compost that the U.S. EPA has determined to be safe for land application. Although concentrations of heavy metals in SOW are somewhat lower than in mixed MSW compost, there is no evidence that either type poses a risk to human health or the environment. There were no significant differences between MSW and SOW compost for chromium, mercury and nickel. Significant differences at the 5 % level were found for cadmium and at the 1 % level for lead copper, and zinc. The risk analysis showed that the potential health risk even in the worse cases is extremely low. A discussion of the bioavailability of cadmium and lead is presented.