CHARACTERIZATION OF ORGANIC SOLID URBAN WASTE COMPOSTS FROM THE RECYCLING AND COMPOSTING PLANTS OF S O PAULO AND S O JOSé DOS CAMPOS MUNICIPALITIES = CARACTERIZA O DE COMPOSTOS DE RESíDUOS SóLIDOS URBANOS ORG NICOS DE UNIDADES DE RECICLAGEM E COMPOSTAGEM DOS MUNICíPIOS DE S O PAULO E DE S O JOSé DOS CAMPOS

Composting of solid urban waste has an important role for sustainable environmental management of solid waste generated in cities by reducing the load and volume of waste sent to landfills. The objective of this study was to evaluate the quality of the urban waste composts produced in the units of recycling and composting plants (URC) of S o Matheus, Vila Leopoldina and S o José dos Campos, SP. During nine months, samples were collected from the original materials given by the pretreatment DANO system of each URC. In order to evaluate the maturation grade and quality of the composts, a fraction of the original samples was composted for 150 days. The concentrations of organic carbon, nutrients and heavy metals were compared between the original and maturated composts. The composts produced in the S o Matheus and Vila Leopoldina URCs had a low maturation grade, in other words, they represented their own municipal solid wastes. However, when these wastes were properly composted, they provided composts with organic carbon concentrations (> 150 g kg 1) suitable to be registered as class C organic fertilizers. All composts presented wide temporal variability in the chemical composition, with minimum concentrations of Ca and Fe enough to be declared as the source of these nutrients, and the Cr concentration below the maximum limit allowed by legislation. Nevertheless, only the S o José dos Campos URC compost, coming from a selective collection, presented concentration of Cd, Ni and Pb suitable for classification as an organic fertilizer. It was concluded that the selective collection of organic solid urban waste and composting based on technical criteria are essential procedures for obtaining composts with appropriate properties to frame it as organic fertilizer. These procedures give economic value to the process, and make the management of solid urban waste economically viable. = A compostagem de resíduos sólidos urbanos é importante para uma gest o ambiental sustentável. Tal prática reduz o volume e a carga de resíduos que s o enviados para os aterros sanitários. Objetivou-se, com este estudo, avaliar a qualidade de compostos de resíduos urbanos produzidos nas usinas de reciclagem e compostagem (URC) de S o Matheus, Vila Leopoldina e S o José dos Campos, SP. Durante nove meses, foram coletadas amostras dos compostos originais oriundos do sistema DANO de pré-tratamento de cada URC. Para se avaliar o grau de matura o e qualidade dos compostos, uma fra o das amostras originais foi compostada por mais 150 dias. Foram comparados os teores de carbono organico, n