Condições intervenientes nas emissões fugitivas de biogás em camada de cobertura de solo compactado em aterros sanitários.

Abstract

The performance of final cover layers of landfills can be affected by both geotechnical and meteorological conditions. In regions with a semi-arid climate, the cover layers, which use soils with low permeability, may have their performance reduced due to the wetting and drying cycles, resulting in a loss of efficiency in retaining the flow of liquids and gases and increasing the emissions of these gases to the atmosphere. One way to improve the performance of cover layers in terms of fugitive biogas emissions in landfills is to determine factors that influence the functionality of these layers. Thus, this work has the objective of verifying the influence of the main intervening factors in the fugitive emissions of biogas in the final cover layer of compacted soil of sanitary landfill. The experimental field for the development of this research comprises an area of 40,000 m2 of the cover layer of the Landfill located in Campina Grande-PB. In this layer, static flux chamber tests were carried out for the mapping of fugitive biogas emissions, characterization and mapping of the layer's soil and verification of correlations between biogas emissions and geotechnical and meteorological conditions through statistical analysis. The

results showed CH4 emissions ranging from 0 to 386.7g.m-2.day-1, with an average of 22 gm- 2

.day-1, and CO2 emissions ranging from 0 to 965.90 gm-2.day-1, with an average of 103.73 gm- 2

.day-1. The mapping of biogas emissions indicated a non-homogeneous behavior and with more accentuated emissions occurring in more peripheral areas of the Cell, with values of more than 17 times the average emissions. In this location, a reduced degree of soil compaction and thickness below the recommended was observed. With respect to local meteorological conditions, higher fugitive emissions of biogas were observed occurring with higher temperatures. As for the geotechnical conditions, although there were low correlations, an influence of low humidity on higher emission values was observed, which contributed to the need for studies of soil permeability to air in the unsaturated condition. The analysis of the fit models indicated that, under the saturation conditions verified in the cover layer of the sanitary landfill, the permeability of the soil to air approached the maximum, which constitutes a more favorable condition for the passage of gases.