Estudo da degradação dos resíduos sólidos urbanos através dos parâmetros físico-químicos em um biorreator de escala experimental.

Abstract

Solid waste has been a matter of strong discussion between environmentalists and the community that emphatically try to reduce its impacts. It is known that the production of waste and its subsequent elimination without treatment can cause several environmental and public health problems. The purpose of this study is to evaluate the degradation procedure of municipal solid waste (MSW) deposited in a bioreactor in experimental scale, located in Campina Grande / PB. The research will be conducted through physical and physical-chemical properties of the residues. The MSW used in the bioreactor was composed by the residue of three different districts of the city of Campina Grande. The bioreactor, which was constructed at the Federal University of Campina Grande (FUCG), has a 2.0 m diameter, is 3.0 m in height and approximate 9m3 of volume. It also has three holes along its height that allow the collection of waste at different levels of depth. It has a system for sealing the bottom and coverage of the bioreactor and another system for draining liquids and gases. There are also liquid level measurement equipment and settlement and temperature measurement equipment. In this study physical (gravimetric composition, volumetric composition and moisture content) and physicochemical analyzes (pH, alkalinity, volatile acids, volatile solids, COD, BOD, Chloride, TKN and ammonia nitrogen) were performed. The results of physicochemical analyzes were tabulated for the execution of the statistical analysis. The results of gravimetric and volumetric composition showed that the largest portions of the material were of organic and plastic elements. The humidity percentage did not vary significantly in the monitoring period, remaining in a 40-60% range, except for the top layer. The evolution of chlorides concentration indicated that the levels of contaminants are concentrated at the bottom of the bioreactor, process mainly due to leaching. Initially the pH had acid characteristics. During the rest of the experiment it was alkaline, which confirm that the bioreactor is in a methanogenic stage. The COD and BOD results demonstrate that the degradation stage of the MSW is consistent with the waste disposal period. The COD was reduced by over 50%, whereas the BOD reduced more than 80%, a pattern similar to the volatile solids that declined significantly over the monitoring. The alkalinity increased for all depth levels while volatile acids decreased over time. Both TKN and ammonia nitrogen were initially at high values that tended to decrease during the period of monitoring. These results corroborate with the technical literature because the current phase the bioreactor presents is a methanogenic stage.