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Avaliação da Implementação do Tratamento Primário Avançado na ETAR do Barreiro/Moita
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O tratamento de água tem um papel importante no que toca à preservação da qualidade das massas de água, sendo este um recurso cada vez mais importante. O estudo e otimização de novos processos de tratamento de água residual deve ser um tópico recorrente, considerando igualmente a redução da pegada de carbono associada a estes processos.
Assim, o presente estudo teve como objetivo entender qual o impacto da implementação de um Tratamento Primário Avançado (TPA) na Estação de Tratamento de Água Residual (ETAR) do Barreiro/Moita. Entendendo esse impacto, procurou-se estender o estudo às operações unitárias a jusante. Inicialmente, avaliou-se qual seria a melhor formulação de reagentes de coagulação/floculação, considerando ainda a possível recirculação de lamas em excesso ao TPA com o objetivo de auxiliar o processo. Para isso, foram realizados ensaios Jar-Test onde foram determinadas as eficiências de remoção para os parâmetros em estudo. Após os ensaios Jar-Test, foram selecionados 3 cenários que apresentaram melhores eficiências de remoção para diversos parâmetros.
O cenário 1 reflete a conjunção de coagulante/floculante que demonstrou melhores eficiências de remoção ao longo dos ensaios, 40 ppm de Cloreto Férrico como coagulante e 2 ppm de polímero líquido como floculante. Neste cenário obteve-se 79% de remoção de Sólidos Suspensos Totais (SST) e 39% de remoção de Carência Química de Oxigénio (CQO). O cenário 2 considera a utilização da mesma conjugação de coagulante/floculante que no cenário 1, mas com a adição de lamas em excesso em conjunto com o coagulante no sentido de simular a recirculação ao TPA de 50% das lamas em excesso produzidas na ETAR do Barreiro/Moita. No cenário 2 obteve-se 80% de eficiência de remoção de SST e 40% de eficiência de remoção de CQO. O cenário 3 espelhou o cenário 2, mas simulando uma recirculação de 100% de lamas em excesso. No cenário 3 obtiveram-se eficiências de remoção de 84% e 45% para SST e CQO, respetivamente.
Realizou-se um estudo comparativo entre o cenário de referência da ETAR do Barreiro/Moita ao longo do ano de 2021 e os 3 cenários escolhidos. No cenário de referência as eficiências de remoção de SST e CQO foram 60% e 34% respetivamente. Deste modo, foram analisados e comparados os impactos da adoção destes cenários no tratamento primário, no tratamento biológico e na produção de biogás da estação. Procurou-se entender quais os benefícios energéticos, económicos e processuais associados à exploração de cada cenário em estudo.Através dos resultados obtidos foi possível constatar que a adoção de um TPA pode contribuir para a redução dos consumos energéticos na ETAR do Barreiro/Moita. Contudo, existe um aumento dos custos operacionais. Em todos os cenários estudados existiram melhorias a nível energético e a nível ambiental, sendo o cenário 3 o que apresentou melhores resultados.
Assim, a utilização do TPA demonstrou ser uma boa alternativa ao tratamento primário convencional, representando um passo importante na caminhada até à neutralidade carbónica.
Water treatment plays an important role in water conservation, which is an increasingly important resource. The study of new ways to optimize wastewater treatment processes should be a recurring topic, also considering the reduction of the carbon footprint associated with these processes. The aim of this study was therefore to understand the impact of implementing a Chemically Enhanced Primary Treatment (CEPT) at the Barreiro/Moita Wastewater Treatment Plant (WWTP). Understanding the impact on the Primary Treatment, the objective was to extend the study to downstream treatment stages. Initially, the best formulation of coagulation/flocculation reagents was studied, also considering the possible recirculation of biological sludge of the CEPT in order to assist the process. Thus, Jar-Test trials were made to determine the removal efficiencies for the parameters under study. After the Jar-Test trials, three scenarios were selected which showed the best removal efficiencies for the various parameters. The first scenario reflects the coagulant/flocculant combination that showed the best removal efficiencies throughout the tests, 40 ppm of Ferric Chloride as a coagulant and 2 ppm of liquid polymer as a flocculant. This resulted in 79% removal of Total Suspended Solids (TSS) and 39% removal of Chemical Oxygen Demand (COD). The second scenario considers the use of the same coagulant/flocculant combination as first scenario, but with the addition of biological sludge together with the coagulant to simulate the recirculation to the CEPT of 50% of the biological sludge produced at the Barreiro/Moita WWTP. The second scenario achieved 80% TSS removal efficiency and 40% COD removal efficiency. The third scenario mirrored the second scenario but simulating 100% recirculation of biological sludge. The third scenario achieved removal efficiencies of 84% and 45% for TSS and COD, respectively. A comparative study was carried out between the Barreiro/Moita WWTP reference scenario throughout 2021 and the 3 chosen scenarios. In the reference scenario, the TSS and COD removal efficiencies were 60% and 34% respectively. The impacts of adopting these scenarios on the plant's primary treatment, biological treatment and biogas production were analyzed and compared. The objective was to understand the energy, economic and process impacts associated with the operation of each scenario under study.The results obtained show that the adoption of a TPA can help reduce energy consumption at the Barreiro/Moita WWTP. However, there is an increase in operating costs. In all the scenarios studied, there were improvements in terms of energy and the environment, with scenario 3 showing the best results. Thus, the use of CEPT has proved to be a good alternative to conventional primary treatment, and an important step on the road to carbon neutrality.
Water treatment plays an important role in water conservation, which is an increasingly important resource. The study of new ways to optimize wastewater treatment processes should be a recurring topic, also considering the reduction of the carbon footprint associated with these processes. The aim of this study was therefore to understand the impact of implementing a Chemically Enhanced Primary Treatment (CEPT) at the Barreiro/Moita Wastewater Treatment Plant (WWTP). Understanding the impact on the Primary Treatment, the objective was to extend the study to downstream treatment stages. Initially, the best formulation of coagulation/flocculation reagents was studied, also considering the possible recirculation of biological sludge of the CEPT in order to assist the process. Thus, Jar-Test trials were made to determine the removal efficiencies for the parameters under study. After the Jar-Test trials, three scenarios were selected which showed the best removal efficiencies for the various parameters. The first scenario reflects the coagulant/flocculant combination that showed the best removal efficiencies throughout the tests, 40 ppm of Ferric Chloride as a coagulant and 2 ppm of liquid polymer as a flocculant. This resulted in 79% removal of Total Suspended Solids (TSS) and 39% removal of Chemical Oxygen Demand (COD). The second scenario considers the use of the same coagulant/flocculant combination as first scenario, but with the addition of biological sludge together with the coagulant to simulate the recirculation to the CEPT of 50% of the biological sludge produced at the Barreiro/Moita WWTP. The second scenario achieved 80% TSS removal efficiency and 40% COD removal efficiency. The third scenario mirrored the second scenario but simulating 100% recirculation of biological sludge. The third scenario achieved removal efficiencies of 84% and 45% for TSS and COD, respectively. A comparative study was carried out between the Barreiro/Moita WWTP reference scenario throughout 2021 and the 3 chosen scenarios. In the reference scenario, the TSS and COD removal efficiencies were 60% and 34% respectively. The impacts of adopting these scenarios on the plant's primary treatment, biological treatment and biogas production were analyzed and compared. The objective was to understand the energy, economic and process impacts associated with the operation of each scenario under study.The results obtained show that the adoption of a TPA can help reduce energy consumption at the Barreiro/Moita WWTP. However, there is an increase in operating costs. In all the scenarios studied, there were improvements in terms of energy and the environment, with scenario 3 showing the best results. Thus, the use of CEPT has proved to be a good alternative to conventional primary treatment, and an important step on the road to carbon neutrality.
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Palavras-chave
Tratamento Primário Avançado Reagentes Impactos Económicos Consumos Energéticos Pegada de Carbono