Evaluation of the effects of bio stabilised waste on soil in terms of heavy metal accumulation and leaching¹

Avaliação dos efeitos da aplicação de resíduos bioestabilizados no solo em termos de acumulação e lixiviação de metais pesados

Abstarct

This work evaluated and compared potential impacts related to the accumulation and/or release of heavy metals resulting from the application of different types of stabilized waste to soil. Namely, the following three types of flows were considered: waste produced by aerobic bio-stabilization of municipal solid waste at a Mechanical Biological Treatment (MBT) plant, and compost produced either from aerobic composting or from a combination of anaerobic and aerobic biodegradation processes. After a preliminary characterization of the materials (organic matter content, volatile solid, and heavy metals content), heavy metal accumulation in soil caused by possible long-term application of these organic materials was evaluated by implementing a discretized mass balance based on the total content of the heavy metals in each type of solid matrix investigated. In addition, results of percolation leaching tests performed on each type of material were presented and discussed. Results highlight that although the total content of heavy metals of the three types of materials differed considerably, with the MBT waste presenting the highest concentrations, the results of the leaching percolation tests were quite similar.

Keywords:
aerobic stabilization; anaerobic digestion; compost; leaching behavior; MBT waste; metal accumulation.