Banca de DEFESA: LARISSA APARECIDA GOES DAMASCENO
Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.DISCENTE : LARISSA APARECIDA GOES DAMASCENO
DATA : 28/08/2019
HORA: 14:00
LOCAL: PROGRAMA DE PÓS-GRADUAÇÃO EM ENGENHARIA CIVIL
TÍTULO:
FUGITIVE EMISSION OF METHANE THROUGH THE COVER SYSTEM OF A SANITARY LANDFILL CONSIDERING THE OCCURRENCE OF CRACKED AREAS
PALAVRAS-CHAVES:
Keywords: Sanitary landfills; Cover systems; Methane fugitive emission; Static flux chamber tests
PÁGINAS: 159
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Civil
RESUMO:
The cover system of a sanitary landfill is one of the mechanisms to avoid or minimize the emission of biogas produced in landfills to the atmosphere. However, its long term efficiency can significantly decrease due to the weathering wetting/drying cycles over time. Fugitive emissions are influenced by some parameters of the cover layer such as dry density and moisture content, presence of preferential flow paths (shrinkage tension cracks) as well as operational techniques of the landfill. In disposal units that reuse methane, the quantification of fugitive emissions allows to evaluate the efficiency of the cover systems and optimize the extraction of biogas. This paper evaluated the fugitive emissions of methane by the cover system of a large sanitary landfill located in a tropical region, by means of static flux chamber tests carried out in cracked and non-cracked zones. Tests were performed in periods with high and low rainfall. The study area was delimited in a cell of the Metropolitan Center Sanitary Landfill (MCSL - Salvador - BA), which is the largest final disposal unit of municipal solid waste (MSW) in the state of Bahia. Cover characterization tests, a survey of the cracks in the area, data collection about the waste disposition history, daily precipitation, applied gas suction and biogas flow in the drains have also been carried out. Through a statistical analysis were obtained correlation coefficients between fugitive emission and the associated independent variables (precipitation, moisture content and dry density of the soil, daily average gas suction in the drains, daily suction applied to the nearest drain and distance between the point tested and the nearest drain) and proposed models for the estimation of fugitive emissions considering the occurrence of cracked and non-cracked areas. The application of waste disposition history in first-order decay model and the surveying of methane flow in biogas drains allowed to calculate the methane generation and methane recovered in the area, respectively, during the period of analyses. The fugitive emissions of methane measured in the tests ranged from 0 to 355 g/m2.day. These values are comparable with the range of values found for similar cover layers in another landfills. During the rainy season, there was an increase in emissions in points located in cracked areas. This was caused by the increase in the soil moisture and the fact that soils cracks act as preferential flow paths. Considering a linear model, the correlations between the variables did not explain the emissions behavior in field, since few presented values with significance. Exponential models explained the variation of emissions in cracked and non-cracked areas, with adjusted R2 of 0.86 and 0.82, respectively. For which a large number of independent variables were required. According to these models, the fugitive emissions accounted for, on average, 12% of the methane produced (sum of fugitive emissions and recovered gas) in the area during the period of analysis. In this period, the production of methane in the study area accounted for 56% of the predicted value by first-order decay model, indicating that the fugitive emissions are not the only factors that have been causing the reduction of productivity in the MCSL thermoelectric plant.
MEMBROS DA BANCA:
Externo à Instituição - ELISABETH RITHER
Presidente - 665.373.396-34 - MIRIAM DE FÁTIMA CARVALHO MACHADO - USP
Interno - 1219972 - SANDRO LEMOS MACHADO