Avaliação da aplicabilidade de cinzas de fundo de resíduos de serviço de saúde para uso em cobertura final de aterros sanitários

Abstract

In alignment with the global trend of comprehensive waste mapping and identification before final disposal, and the practice of landfilling only after exploring all potential avenues for reuse, coupled with recent amendments in Brazilian legislation mandating thorough awareness of by-products emanating from production processes for consideration of alternative destinations prior to landfilling, this study proposes the judicious application of incineration ash derived from Healthcare Waste (HW) as a functional component in the final cover of landfills. The objective is to achieve a purposeful and effective disposal. To realize this objective, the study delves into the properties of bottom ash resulting from the incineration of HW at a facility in Paraíba. The aim is to evaluate its suitability for deployment in impermeable barrier layers. The experimental program encompasses geotechnical analyses, as well as assessments of chemical and mineralogical composition, to ascertain whether the material possesses the requisite characteristics for the intended use. Mixtures were prepared by combining the soil typically employed in the final cover of landfills (S) with varying proportions of HW ash (C), with substitutions expressed in terms of mass percentage (S95C5, S92.5C7.5, S90C10, S85C15, S80C20). The results revealed that the primary chemical constituents of the ash are Calcium and Chlorine, accompanied by the presence of fibrous particles composed of Carbon. Physically, the ash exhibits similarities to municipal solid waste ash, commonly classified as sand, with specific gravity of solids lower than typical sand values. The outcomes of compaction tests on soil and mixtures demonstrated a slight variability in optimum moisture content, ranging between 8.3% and 11.9%, and maximum dry density, varying from 1.8 to 2.1 g/cm³. In contrast, the ash curve displayed an optimum moisture content of 37.2% and maximum dry density of 1.01 g/cm³. Importantly, all mixtures exhibited a saturated permeability coefficient in the order of 10-7 m/s, closely aligning with the recommended values of hydraulic conductivity coefficient found in the literature. This substantiates their suitability for the proposed application.