Biogas as a fuel is attractive from a greenhouse standpoint, since biogas is carbon neutral. To be used as such, increasingly stringent emission standards must be met. Current low-emission technologies meet said standards by precisely controlling the air-fuel ratio. Biogas composition can vary substantially, making air-fuel ratio control difficult. This research was conducted as part of a larger project to develop a sensor that accurately measures biogas composition. Biogas was simulated by fuel mixtures consisting of natural gas and CO2; the effects that fuel composition has on emissions and catalyst performance were investigated. Engine-out THC and NOx increased and decreased, respectively, with increasing CO2 in the fuel mixture. Doubling the catalyst residence time doubled the conversion of THC and CO emissions. The effectiveness of the catalyst at converting THC emissions was found to be dependent on the relative proportions of engine-out THC, NOx and CO emissions.

Biogas as a fuel is attractive from a greenhouse standpoint, since biogas is carbon neutral. To be used as such, increasingly stringent emission standards must be met. Current low-emission technologies meet said standards by precisely controlling the air-fuel ratio. Biogas composition can vary substantially, making air-fuel ratio control difficult. This research was conducted as part of a larger project to develop a sensor that accurately measures biogas composition. Biogas was simulated by fuel mixtures consisting of natural gas and CO2; the effects that fuel composition has on emissions and catalyst performance were investigated. Engine-out THC and NOx increased and decreased, respectively, with increasing CO2 in the fuel mixture. Doubling the catalyst residence time doubled the conversion of THC and CO emissions. The effectiveness of the catalyst at converting THC emissions was found to be dependent on the relative proportions of engine-out THC, NOx and CO emissions.

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Esta pesquisa apresenta uma revisão bibliográfica sobre as emissões de metano em aterros sanitários, os conceitos de geração de gases em aterros sanitários, movimentações de gases em aterro, apresenta os métodos de medição de gases in situ, tipos de cobertura finais para aterros e a oxidação do metano na camada de cobertura. A pesquisa também tem como objetivo medir as emissões de gases e avaliar a infiltração das águas pluviais através da camada de cobertura do aterro sanitário da CTR Nova Iguaçu. As medições foram realizadas nos meses de julho a novembro de 2010, na camada de cobertura monolítica existente e em outra construída sobre uma barreira capilar. Sensores para medir temperatura e umidade foram instalados em profundidade nas duas camadas. Foram realizados ensaios de placa de fluxo para medir a composição dos gases e o fluxo através dos dois tipos de camadas, e avaliadas duas situações: com os poços de extração de gás ativos e desligados. Os sensores indicaram que em período de baixa pluviosidade, a barreira capilar apresenta uma eficácia superior à camada monolítica, e com a intensificação das chuvas, as umidades medidas nos dois tipos de camadas aumentam, e na barreira capilar o gradiente estabelecido entre os sensores diminui, indicando uma possível tendência à saturação desta barreira capilar. Porém, com a paralisação das chuvas, recupera e retoma sua condição inicial. Os resultados de medidas dos gases demostraram a eficiência do sistema de extração de gás quando ativado, resultando em emissões quase nulas de metano e gás carbônico nos dois tipos de camadas. No entanto, quando o sistema está desativado, as emissões através da camada monolítica são cerca de 3 vezes maiores do que através da barreira capilar. / This research presents a literature review on methane emissions from landfills, the concepts of landfill gas generation, the landfill internal gas flow, introduces the methods of measurement of gases "in situ", types of final landfill coverage and the methane oxidation in the cover layer. The research also purposes to measure greenhouse gas emissions and to evaluate the infiltration of rainwater through the landfill cover layer of the CTR Nova Iguaçu. Measurements were made in the months from July to November 2010, the existing monolithic cover layer and another built on a capillary barrier. Sensors to measure temperature and humidity were installed in two layers in depth. Plate assays were performed to measure the flow of the gas composition and flow through the two types of layers, and evaluated two situations with the gas extraction wells active and off. The sensors have indicated that in times of low rainfall, the capillary barrier has superior efficacy to the monolithic layer, and with the intensification of rain, the moisture content measured on two types of layers increase, the capillary barrier and the gradient established between sensors decreases, indicating a possible trend to saturation of capillary barrier. However, with the stoppage of rain, recovers and returns to its initial condition. The results of measurements of gases demonstrated the efficiency of extraction of gas when activated, resulting in near zero emissions of methane and carbon dioxide in the two types of layers. However, when the system is off, the emissions through the monolithic layer is about three times larger than through the capillary barrier.

Esta pesquisa apresenta uma revisão bibliográfica sobre as emissões de metano em aterros sanitários, os conceitos de geração de gases em aterros sanitários, movimentações de gases em aterro, apresenta os métodos de medição de gases in situ, tipos de cobertura finais para aterros e a oxidação do metano na camada de cobertura. A pesquisa também tem como objetivo medir as emissões de gases e avaliar a infiltração das águas pluviais através da camada de cobertura do aterro sanitário da CTR Nova Iguaçu. As medições foram realizadas nos meses de julho a novembro de 2010, na camada de cobertura monolítica existente e em outra construída sobre uma barreira capilar. Sensores para medir temperatura e umidade foram instalados em profundidade nas duas camadas. Foram realizados ensaios de placa de fluxo para medir a composição dos gases e o fluxo através dos dois tipos de camadas, e avaliadas duas situações: com os poços de extração de gás ativos e desligados. Os sensores indicaram que em período de baixa pluviosidade, a barreira capilar apresenta uma eficácia superior à camada monolítica, e com a intensificação das chuvas, as umidades medidas nos dois tipos de camadas aumentam, e na barreira capilar o gradiente estabelecido entre os sensores diminui, indicando uma possível tendência à saturação desta barreira capilar. Porém, com a paralisação das chuvas, recupera e retoma sua condição inicial. Os resultados de medidas dos gases demostraram a eficiência do sistema de extração de gás quando ativado, resultando em emissões quase nulas de metano e gás carbônico nos dois tipos de camadas. No entanto, quando o sistema está desativado, as emissões através da camada monolítica são cerca de 3 vezes maiores do que através da barreira capilar. / This research presents a literature review on methane emissions from landfills, the concepts of landfill gas generation, the landfill internal gas flow, introduces the methods of measurement of gases "in situ", types of final landfill coverage and the methane oxidation in the cover layer. The research also purposes to measure greenhouse gas emissions and to evaluate the infiltration of rainwater through the landfill cover layer of the CTR Nova Iguaçu. Measurements were made in the months from July to November 2010, the existing monolithic cover layer and another built on a capillary barrier. Sensors to measure temperature and humidity were installed in two layers in depth. Plate assays were performed to measure the flow of the gas composition and flow through the two types of layers, and evaluated two situations with the gas extraction wells active and off. The sensors have indicated that in times of low rainfall, the capillary barrier has superior efficacy to the monolithic layer, and with the intensification of rain, the moisture content measured on two types of layers increase, the capillary barrier and the gradient established between sensors decreases, indicating a possible trend to saturation of capillary barrier. However, with the stoppage of rain, recovers and returns to its initial condition. The results of measurements of gases demonstrated the efficiency of extraction of gas when activated, resulting in near zero emissions of methane and carbon dioxide in the two types of layers. However, when the system is off, the emissions through the monolithic layer is about three times larger than through the capillary barrier.