This paper discusses the quality of MSW compost produced in the composting plants in operation in Sao Paulo State/Brazil, in regard to their physical and chemical aspects. Samples were collected twice (Winter/2003 and Summer/2004) in fourteen plants. The evaluated plants had different structure, therefore it was necessary a previous separation of the data in similar groups, so that they would make statistical sense. The groups were: Dano plants; plants with rounding sieves; plants with grounders or mills; and plants without post-treatment of the composted material. It was possible to observe that there is a direct relation between the structure of the composting plants and the quality of the compost, the nutrients rate, the levels of heavy metals and the percentage of contaminants.
Compost quality; composting plants; physical and chemical aspects; compost standard
