SEÇÃO IX - POLUIÇÃO DO SOLO E QUALIDADE AMBIENTAL

SUMMARY : CHEMICAL CHARACTERIZATION OF URBAN WASTECOMPOSTS FROM SOME BRAZILIAN PLANTS One of the alternatives to diminish the urban waste volume to be discarded is thecomposting process, whose final product - the compost - can be used in agriculture. However,these composts may present toxic substances for humans, i.e. heavy metals. The aim of thisstudy was to evaluate the chemical composition of waste composts from six Brazilian capitals.Samples of cattle manure, lime, ordinary phosphate, potassium chloride, and urea wereanalysed to compare with the waste compost. Determinations of organic matter, C, N, P, K,Ca, Mg, Cu, Mn, Mo, Zn, Fe, Al, Ba, Cd, Co, Cr, Ni, Pb, Sr, Ti, and V were made. Nutrientcontents in the compost samples were dependent on the composting processes involved.Micronutrient content was variable, some presenting values above the tolerable level of theGerman waste composts. The other elements analyzed, including heavy metals, were at thesame reported levels for sludges in England. Considering the German tables of tolerablelevels in waste compost values for Pb, Cr, Ni, and Cd, some of the samples were very high. Inmost of them, the total content of nutrients was smaller than in cattle manure, while that ofheavy metals was higher. Considering that the content of analyzed elements is the totalcontent, caution is advised on its use until secure results are available on the bioavailabilityto the plants of these elements in the composts.Index terms: Compost analysis, nutrients, heavy metals.