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Authors
Advisor(s)
Abstract(s)
As águas residuais urbanas são resultado do uso da água para fins domésticos e industriais, que, se não forem tratadas, se tornam um problema ambiental, contaminando solos e recursos hídricos. Para serem devolvidas ao ambiente, estas águas precisam passar por uma série de etapas de tratamento. As Estações de Tratamento de Águas Residuais (ETARs) são responsáveis pela diminuição do potencial poluidor dessas águas residuais e, desta forma, são vistas como infraestruturas que beneficiam o ambiente. Todavia, durante o tratamento, os processos envolvidos transformam os constituintes da água residual em quantidades não negligenciáveis de Gases de Efeito Estufa (GEE) para atmosfera, que acabam por contribuir para as alterações climáticas. Os principais GEE associados às emissões das ETARs são o CO2, CH4 e N2O, os quais são igualmente emitidos em maior quantidade pela atividade antrópica.
Este estudo teve como objetivo principal avaliar a pegada de carbono associada à fase de exploração de uma (ETAR), localizada no norte de Portugal, adotando uma abordagem metodológica de Análise do Ciclo de Vida (ACV). Além disso, com o intuito de propor um conjunto de medidas conducentes à redução das emissões de GEE da ETAR em estudo, procedeu-se também à avaliação de um conjunto de cenários alternativos.
Após a definição dos objetivos e do âmbito de estudo, preparou-se uma ficha de inventário de dados e de informação a obter junto dos responsáveis da ETAR, bem como de um conjunto de outras fontes de informação disponíveis. O inventário foi organizado com base na metodologia adotada pelo Painel Intergovernamental sobre as Alterações Climáticas, a qual separa a contribuição das emissões associadas a 3 âmbitos distintos – emissões diretas, indiretas internas e indiretas externas para a situação atual e para um conjunto de cenários alternativos relacionados com alterações do processo de tratamento, implementação de energias renováveis e gestão das lamas produzidas na ETAR. A pegada de carbono foi depois estimada para todas as situações com recurso a uma ferramenta em Excel, adaptada da aplicação informática “Cálculo da pegada de carbono das estações de tratamento de águas residuais suecas” (SVU 12-120).
A pegada de carbono obtida foi de 1,3 kg CO2e/m3 de água residual tratada. Os resultados mostram que os processos biológicos de tratamento da fase líquida da ETAR constituem a fonte direta mais relevante de GEE, seguindo-se fontes indiretas relacionadas com o uso de energia e com a gestão de lamas. A avaliação dos cenários estudados permitiu obter reduções da pegada até 26%, motivadas sobretudo pela implementação de energias renováveis e pela alteração do tratamento das águas residuais.
Urban wastewater is the result of the use of water for domestic and industrial purposes, which, if left untreated, becomes an environmental problem, contaminating soil and water resources. To be returned to the environment, these waters need to go through a series of treatment steps. Wastewater Treatment Plants (WWTPs) are responsible for reducing the polluting potential of these wastewater and, in this way, are seen as infrastructure that benefits the environment. However, during the treatment, the processes involved transform the constituents of the waste water into non-negligible amounts of greenhouse gases (GHG) into the atmosphere, which end up contributing to climate change. The main GHGs associated with the emissions from WWTPs are CO2, CH4 and N2O, which are also emitted in greater quantities by human activity. This study had as main objective to evaluate the carbon footprint associated with the exploration phase of a (WWTP), located in the north of Portugal, adopting a methodological approach of Life Cycle Analysis (LCA). In addition, in order to propose a set of measures leading to the reduction of GHG emissions from the WWTP under study, a set of alternative scenarios was also assessed. After defining the objectives and the scope of the study, a data and information inventory form was prepared to be obtained from the WWTP managers, as well as a set of other available information sources. The inventory was organized based on the methodology adopted by the Intergovernmental Panel on Climate Change, which separates the contribution of emissions associated with 3 different areas - direct, indirect internal and indirect external emissions for the current situation and for a set of related alternative scenarios with changes in the treatment process, implementation of renewable energy and management of sludge produced at the WWTP. The carbon footprint was then estimated for all situations using an excel tool, adapted from the computer application “Calculating the carbon footprint of Swedish wastewater treatment plants” (SVU 12-120). The carbon footprint obtained was 1.3 kg CO2e / m3 of treated wastewater. The results show that the biological processes of treatment of the WWTP liquid phase constitute the most relevant direct source of GHG, followed by indirect sources related to the use of energy and sludge management. The evaluation of the studied scenarios allowed to obtain footprint reductions of up to 26%, motivated mainly by the implementation of renewable energies and by the change in the treatment of waste water.
Urban wastewater is the result of the use of water for domestic and industrial purposes, which, if left untreated, becomes an environmental problem, contaminating soil and water resources. To be returned to the environment, these waters need to go through a series of treatment steps. Wastewater Treatment Plants (WWTPs) are responsible for reducing the polluting potential of these wastewater and, in this way, are seen as infrastructure that benefits the environment. However, during the treatment, the processes involved transform the constituents of the waste water into non-negligible amounts of greenhouse gases (GHG) into the atmosphere, which end up contributing to climate change. The main GHGs associated with the emissions from WWTPs are CO2, CH4 and N2O, which are also emitted in greater quantities by human activity. This study had as main objective to evaluate the carbon footprint associated with the exploration phase of a (WWTP), located in the north of Portugal, adopting a methodological approach of Life Cycle Analysis (LCA). In addition, in order to propose a set of measures leading to the reduction of GHG emissions from the WWTP under study, a set of alternative scenarios was also assessed. After defining the objectives and the scope of the study, a data and information inventory form was prepared to be obtained from the WWTP managers, as well as a set of other available information sources. The inventory was organized based on the methodology adopted by the Intergovernmental Panel on Climate Change, which separates the contribution of emissions associated with 3 different areas - direct, indirect internal and indirect external emissions for the current situation and for a set of related alternative scenarios with changes in the treatment process, implementation of renewable energy and management of sludge produced at the WWTP. The carbon footprint was then estimated for all situations using an excel tool, adapted from the computer application “Calculating the carbon footprint of Swedish wastewater treatment plants” (SVU 12-120). The carbon footprint obtained was 1.3 kg CO2e / m3 of treated wastewater. The results show that the biological processes of treatment of the WWTP liquid phase constitute the most relevant direct source of GHG, followed by indirect sources related to the use of energy and sludge management. The evaluation of the studied scenarios allowed to obtain footprint reductions of up to 26%, motivated mainly by the implementation of renewable energies and by the change in the treatment of waste water.
Description
Mestrado de dupla diplomação com a UTFPR, Universidade Tecnológica Federal do Paraná
Keywords
GEE Carbono equivalente Metano Óxido Nitroso Impactes ambientais Alterações climáticas