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ABSTRACT
This work assessed and compared the leaching properties of two types of compost and stabilized waste from a mechanical-biological treatment (MBT) plant. The first type of compost and the MBT waste were produced by aerobic treatments, while the second type of compost was generated from a combination of anaerobic and aerobic biodegradation processes. Both static-batch leaching tests, carried out applying a single liquid to solid (L/S) ratio equal to 10 L kg-1, and dynamic column percolation tests, investigating constituents release as a function of different L/S ratios, were performed. The three materials were also characterized in order to investigate their biological stability degree, organic matter content, and metals total content. As expected, due to the differences in feed input waste or treatment conditions, the three types of samples showed different characteristics and leaching concentrations. However, the leaching behavior of the three types of treated materials presented similar trends of dissolved organic carbon (DOC) and metals (Cu, Ni, Pb, Zn) leaching as a function of the L/S ratio. A screening model proposed and developed for MBT waste in a previous study, which allows the description DOC release as a function of the L/S ratio, was applied and discussed. The comparison of model predictions with the experimental leaching data highlighted that for all three samples the screening model describes quite well the release trends of metals.
Keywords: Compost, MBT waste, leaching properties, modelling.
RESUMO
O estudo atual aprofunda-se e compara o comportamento a lixiviaçao (leaching) de dois tipos de composto, o primeiro produto do tratamento aerobio da fraçao orgánica selecionada (dos mercados ortofrutíferos), o segundo tratamento em conjunto com o anaeróbio/aeróbio de fraçao orgánica de residuos sólidos da cidade, proveniente de seleçao diferenciada, com o resultado da fraçao orgánica estabilizada produzida de planta do tratamento mecánico/biológico. As tres matrizes evidenciaram propriedade e comportamentos diferentes que dependem seja das várias características dos residuos que foram tratados seja dos diferentes processos de tratamentos que foram feitos, com relaçao ao tratamento da lixiviaçâo, foi determinante um desempenho igual para as tres matrizes testadas em todos os tres residuos foram observados uma significativa semelhança entre as cinéticas, de lixiviaçao do carbônio orgánico solubilizado (BOC) e dos metais principais (Cu, Ni, Pb, Zn) em funçao do relacionamento. L/S....