Estudo da matéria orgânica nos recalques de resíduos sólidos urbanos aterrados.

Abstract

In landfills of municipal solid waste (MSW) the settlements, or reduction of height and volume of the solid waste mass, are a result of the solid mass loss of its organic components or due to rearrangements, distortions and other factors responsible for the solid waste mass and volume reduction. The objective of this work was to study the behavior of the organic matter found in the interior of a municipal solid waste experimental cell (bioreactor) regarding its biodegradability and how this organic matter influences the settlements. For the development of this research, an experimental cell with 9 m3 of capacity of compacted solid waste was built. The investigation was developed in the rooms of the Federal University of Campina Grande, Paraiba state, in order to study the influence of the organic matter in the settlements and for this goal to be reached physical, physicochemical, microbiological and mechanical experiments of the solid waste deposited in the experimental cell were carried out. The solid waste was collected in Campina Grande city in three districts of different social classes. The bioreactor was instrumented in order to monitor the parameters that were being researched. While the study was being conducted, settlements were measured in time and depth through superficial and deep plates. Based on the analyzed results, it was possible to assert that the settlements in municipal solid waste are largely influenced by the present organic matter and by the solid waste self-weight to a lesser extent and the latter contributes almost exclusively in the first 30 days of landfilling while the former after the 30 days of confinement. By means of this study, it was noticed that the quantity of organic matter was largely reduced in all the researched levels, and that the settlements, due to this organic matter and mechanical factors (solid waste self-weight), varied according to the depth. The settlements observed by means of the settlement plates in the upper layer showed a solid waste height reduction due to 93% of organic matter consume and about 40% in the intermediate and lower layers. These data suggest that while the experimental cell was being monitored the solid waste degradation was fast enough if compared to real landfills. Besides, it was noticed that the settlements which are pronounced due to organic matter degradation happen because in the interior of the studied system there are 66% of organic products, what can be understood as large settlements. It can be said that the solid waste upper layer had its content of organic matter degraded quickly and settlements more pronounced because this layer is more influenced by external conditions and this fact can be proved by statistical results. Besides, the settlements that are a result of both the solid waste self-weight and the organic matter degradation are larger in this layer by being influenced by the displacements of the other layers. It was also observed that the value of the biostabilization constant, K, that shows the solid waste biostabilization rate, varied in the three studied layers and in time, and that in the first days of measurements of the vertical settlements, correlation of this constant with the settlements was not found because, initially, the vertical displacements were more influenced by mechanical than biodegradative factors.