environmental and health concerns associated with compost products in iran

in this research, health, safety, and environmental risks were studied for the final compost products in iran. municipal solid waste (msw) is the major feedstock for composting plants and the main users are farmers. according to the objective of this research program three factors including heavy metal concentrations, foreign matter content, and maturity degree were identified as important parameters. the values were measured in the ready-for-sale compost produced in the active iranian composing plants. this results showed that the amount of foreign matters and the stone of all compost samples were less than the standard values and the samples were either practically free from the above mentioned matters or had a very little amount. in all compost samples the maturity grade, which is very important with respect to the pathogens removal, was in comply with epa-503 standard, except for saleh abad with the maturity grade of iii, which needs further fermentation. but the major problem for iranian compost goes with the heavy metal concentrations in the final product which makes it unsuited to the agricultural applications. the concentrations of copper, cadmium, and zine had the highest differences with the standard values, respectively. for example, copper concentrations had a difference about 4.5 to 8 times by comparing the compost samples with a german standard (which is 100 mglkg). for other heavy metals (cr, ni, pb), except for a few cases, the concentrations at the compost exceeded the standard levels e.g., chromium values, except for one of compost plants, were at least 2 to 2.5 times greater than the standard values.