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Authors
Abstract(s)
As Estações de Tratamento de Águas Residuais Urbanas (ETARs) têm como função eliminar
ou diminuir a carga de matéria orgânica, sólidos, nutrientes e microrganismos patogénicos.
Apesar de contribuírem para reduzir o impacte no corpo hídrico, as ETARs causam outros
problemas ambientais, relacionados com a transferência de poluição de um meio para outros.
Para quantificar os impactes associados e avaliar o desempenho ambiental de uma
infraestrutura desta natureza, a Avaliação do Ciclo de Vida (ACV) é uma das metodologias
mais usadas. O objetivo principal desta pesquisa foi avaliar a performance ambiental de uma
ETAR situada no Norte de Portugal, utilizando a metodologia de ACV (ISO 14040). A
implementação da metodologia foi apoiada pelo software GaBi 6.0 Professional database da
Thinkstep. A fronteira escolhida para o sistema em estudo abrangeu a delimitação física da
ETAR, produção e transporte dos químicos, transporte dos gradados e das lamas. Os cenários
criados abrangeram a aplicação direta da lama como adubo, a troca do coagulante e o
descarte direto do efluente sem tratamento no corpo hídrico, todos de forma isolada. A
metodologia de análise utilizada foi a CML, onde as categorias de impacte foram os
potenciais de aquecimento global (PAG), eutrofização (PE), acidificação (PA) e toxicidade
(PTH, PET, PEAD). A unidade funcional aplicada foi 1 m3 de afluente. Os resultados obtidos
foram PAG com 5,44 kg CO2-eq., PE com 43,65 g PO4
3--eq., PA com 8,55 g SO2-eq, PTH,
PET e PEAD, estes últimos expressos em g 1,4 DCB-eq, com magnitudes de 601,45, 2,39 e
7,11, respectivamente. A linha líquida apresentou um contributo superior a 95% do impacte
global da ETAR. Desse total de impacte, em quase todas as categorias, a atividade que mais
se destacou pela negativa foi a produção de químicos, seguida de transporte de materiais de
entrada e de saída da ETAR e o uso de energia elétrica. Em relação à categoria PE, a descarga
da água tratada assume-se como o principal contribuidor para essa categoria, devido à
presença de alguma matéria orgânica que ainda persiste no efluente tratado. Apesar da ETAR
em estudo, apresentar uma elevada eficiência de tratamento, contribuindo para redução de
impactes como a eutrofização e acidificação, a sua exploração gera impactes de outra
natureza. Para se conseguir atingir o melhor tratamento com o mínimo de impacte, é preciso
que se procure constantemente tecnologias com baixo impacte direto ou indireto, podendo
recorrer-se à ACV para realizar essas avaliações. A utilização de um novo coagulante com
alto desempenho e baixo impacte no ambiente foi avaliado e os resultados foram
encorajadores.
Urban Wastewater Treatment Plants (WWTPs) have the function of eliminating or reducing the load of organic matter, solids, nutrients and pathogenic microorganisms. Although there is the least impact on the water body, the Wastewater Treatment Plants cause other environmental problems, related to the transfer of pollution from one environment to others. To quantify the associated impacts and to assess environmental performance of such infrastructure, Life Cycle Assessment (LCA) is one of the most widely used methodologies. The main objective of this research was to evaluate the environmental performance of a wastewater treatment plant located in Northern Portugal, using the LCA methodology (ISO 14040). The implementation of the methodology was supported by the GaBi 6.0 Professional database software from Thinkstep. The system boundary was defined by the physical delimitation of the WWTP, including also the production and transport of chemicals, transport of screenings and sludge. The current situation was also compared with future scenarios involving the direct application of the sludge as fertilizer, the exchange of the coagulant and the direct disposal of the effluent without treatment in the water body. The analysis methodology used was the CML, where the impact categories were global warming (PAG), eutrophication (PE), acidification (PA), toxicity (PTH, PET, PEAD) potentials. The functional unit applied was 1 m3 of inffluent. The results obtained were PAG with 5.44 kg CO2-eq., PE with 43.65 g PO4 3--eq., PA with 8.55 g SO2-eq., PTH, PET and HDPE, the latter expressed in g 1.4 DCB-eq, with magnitudes of 601.45, 2.39 and 7.11, respectively. The water treatment line had a contribution of more than 95% of the overall impact of the WWTP. the activity with the most negative impact was the production of chemical products, followed by the transport of materials to and from the WWTP and the use of electricity. Regarding the PE category, the discharge of treated water is the main contributor to this category, due to the presence of some organic matter that still persists in the treated effluent. Although the Wastewater Treatment Plant under study has a high treatment efficiency, contributing to the reduction of impacts such as eutrophication and acidification, its exploitation generates impacts of another nature. In order to increasingly achieve the best treatment with minimal impact, it is necessary to constantly seek technologies with low direct or indirect impact, and LCA can be used to perform these assessments. The use of a new coagulant with high performance and low impact on the environment was evaluated and the results were encouraging.
Urban Wastewater Treatment Plants (WWTPs) have the function of eliminating or reducing the load of organic matter, solids, nutrients and pathogenic microorganisms. Although there is the least impact on the water body, the Wastewater Treatment Plants cause other environmental problems, related to the transfer of pollution from one environment to others. To quantify the associated impacts and to assess environmental performance of such infrastructure, Life Cycle Assessment (LCA) is one of the most widely used methodologies. The main objective of this research was to evaluate the environmental performance of a wastewater treatment plant located in Northern Portugal, using the LCA methodology (ISO 14040). The implementation of the methodology was supported by the GaBi 6.0 Professional database software from Thinkstep. The system boundary was defined by the physical delimitation of the WWTP, including also the production and transport of chemicals, transport of screenings and sludge. The current situation was also compared with future scenarios involving the direct application of the sludge as fertilizer, the exchange of the coagulant and the direct disposal of the effluent without treatment in the water body. The analysis methodology used was the CML, where the impact categories were global warming (PAG), eutrophication (PE), acidification (PA), toxicity (PTH, PET, PEAD) potentials. The functional unit applied was 1 m3 of inffluent. The results obtained were PAG with 5.44 kg CO2-eq., PE with 43.65 g PO4 3--eq., PA with 8.55 g SO2-eq., PTH, PET and HDPE, the latter expressed in g 1.4 DCB-eq, with magnitudes of 601.45, 2.39 and 7.11, respectively. The water treatment line had a contribution of more than 95% of the overall impact of the WWTP. the activity with the most negative impact was the production of chemical products, followed by the transport of materials to and from the WWTP and the use of electricity. Regarding the PE category, the discharge of treated water is the main contributor to this category, due to the presence of some organic matter that still persists in the treated effluent. Although the Wastewater Treatment Plant under study has a high treatment efficiency, contributing to the reduction of impacts such as eutrophication and acidification, its exploitation generates impacts of another nature. In order to increasingly achieve the best treatment with minimal impact, it is necessary to constantly seek technologies with low direct or indirect impact, and LCA can be used to perform these assessments. The use of a new coagulant with high performance and low impact on the environment was evaluated and the results were encouraging.
Description
Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do Paraná
Keywords
Tratamento águas residuais Avaliação de impacte ACV GaBi