Cobertura final de aterro sanitário de resíduos sólidos urbanos avaliada sob o enfoque da oxidação microbiológica de metano

Abstract

The landfill is considered an appropriate method for the treatment and disposal of Municipal Solid Waste (MSW). In Brazil, about 60% of the municipalities dispose their waste in inappropriate locations, without any kind treatment, causing damage to the environment. The high proportion of biodegradable organic matter present in the mass of wastes, associated with high rates of percolating water into the landfill, creates ideal conditions to originate the main byproducts of their degradation: leachate and gases (CO2, CH4, NH3, N2O ). Of these, methane is the one with the greatest potential to cause global warming. The final cover system of waste is the main structure to prevent air pollution due to gases generated in solid waste landfills because it?s the barrier between the internal environment and the atmosphere. The cover system must prevent the infiltration of rain water and release gases into the atmosphere. This research aimed to verify the occurrence of organisms with potential to oxidate methane in the cover of municipal landfill of São Leopoldo. The presence of these microorganisms may assist in reducing the emission of greenhouse gases. The study was conducted at Unisinos University in the Laboratory of Environmental Sanitation. The soil samples collected from the landfill cover were used to perform tests of geotechnical characterization. Two soil types were identified in the landfill cover, sandy-clay and sandy-silty soil. The thickness of the cover layer of the points presented values between 30 cm and 90 cm high. There were also essays of methane consumption control and microscopic observation of the growth of microorganisms present in vials with specific culture medium for growth of methanotrophic bacteria. Chromatographic analysis of the control vials suggests that the percentage reduction of methane during the incubation period. However, there wasn?t turbidity of the culture in any of the bottles examined during the incubation period (20 days). After the incubation period the vials of samples P7 and P8 were kept in an oven at a temperature of 30 degrees. It was found 13 days later that the control flasks became turbid. Probably longer periods of enrichment and cultivation are need for the acclimatization of these microorganisms.