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Produção de Hidrogénio Verde via tratamento de Águas Residuais-WasteWater-To-H2
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Abstract(s)
Neste trabalho, foi estudada a eletrólise como forma de tratar a água residual duma estação de
tratamento e produção de H2 e O2 para suporte económico deste serviço. Os ensaios foram
executados recorrendo à eletrólise da água residual da estação de tratamento (ARET), alguns
testes sem e outros com adição de eletrólitos e combinações de elétrodos, realizando uma
comparação destas condições com a água destilada (AD) para perceber o potencial de tratamento das águas e produção de gases. A ARET foi caracterizada quanto à carência química de oxigénio, sólidos totais e dissolvidos, condutividade, pH e análise termo gravimétrica. Foi possível observar que o efluente possui uma alta carga orgânica e quantidade de sólidos totais.Os ensaios de eletrólise foram realizados sem e com a adição de NaCl, para simular a água do mar, e KOH, por ser comercialmente utilizado em eletrolisadores. Para realizar as experiências, selecionaram-se elétrodos de diferentes materiais: grafite (EG) e aço inoxidável A2 (Inox). As combinações de elétrodos (cátodo||ânodo) foram grafite||grafite, inox||grafite e inox||inox. A escolha destes materiais baseou-se em critérios de relevância prática e diversificação de propriedades eletroquímicas. Foi possível observar que o processo de eletrólise com os eletrólitos adicionais embora se produza mais gás H2 e O2 não foi obtido melhoria a nível de tratamento/purificação da água e os ensaios com inox||inox para a ARET + NaCl não foi possível devido à alta corrosão no ânodo. Os ensaios com inox||grafite em ARET apresentaram os melhoresresultados de redução de CQO e ST, 52,4 % e 80 %, respetivamente, sendo considerada a melhor opção para o tratamento e simultaneamente no aproveitamento produção de gases. Foi realizada a avaliação económica para a condição mínima de retorno do investimento em 10 anos e concluído que o processo é viável, possuindo um tempo de retorno de 9,3 anos sem capital financiado alheio, com um CapEx de 1.974.225 € e TIR 3.29 %.
In this study, electrolysis was investigated as a means of treating wastewater from a treatment and production station, generating H2 and O2 for economic support of this service. The experiments were conducted by performing electrolysis on the wastewater from the treatment station (ARET), with some tests conducted without electrolytes and others with their addition, along with variations in electrode combinations. A comparison was made between these conditions and distilled water (AD) to understand the treatment potential of the water and the production of gases. The ARET was characterized in terms of chemical oxygen demand, total and dissolved solids, conductivity, pH, and thermogravimetric analysis. It was observed that the effluent exhibited a high organic load and a significant quantity of total solids. Electrolysis experiments were carried out both without and with the addition of NaCl, simulating seawater conditions, and KOH, commonly used in electrolyzers. For the experiments, electrodes of different materials were selected: graphite (EG) and stainless steel A2 (Inox). The electrode combinations (cathode||anode) were graphite||graphite, inox||graphite, and inox||inox. The choice of these materials was based on practical relevance and diversification of electrochemical properties. It was found that the electrolysis process with additional electrolytes resulted in increased H2 and O2 gas production but did not yield significant improvements in water treatment/purification. Experiments using inox||inox for ARET + NaCl were not feasible due to severe anode corrosion. The inox||graphite tests in ARET exhibited the best results in terms of COD and TSS reduction, with values of 52.4% and 80%, respectively, making it the preferred option for both treatment and gas production. An economic assessment was conducted for a minimum investment return period of 10 years, concluding that the process is feasible. The payback period is 9.3 years without external funding, with a CapEx of €1,974,225 and a TIR of 3.29%.
In this study, electrolysis was investigated as a means of treating wastewater from a treatment and production station, generating H2 and O2 for economic support of this service. The experiments were conducted by performing electrolysis on the wastewater from the treatment station (ARET), with some tests conducted without electrolytes and others with their addition, along with variations in electrode combinations. A comparison was made between these conditions and distilled water (AD) to understand the treatment potential of the water and the production of gases. The ARET was characterized in terms of chemical oxygen demand, total and dissolved solids, conductivity, pH, and thermogravimetric analysis. It was observed that the effluent exhibited a high organic load and a significant quantity of total solids. Electrolysis experiments were carried out both without and with the addition of NaCl, simulating seawater conditions, and KOH, commonly used in electrolyzers. For the experiments, electrodes of different materials were selected: graphite (EG) and stainless steel A2 (Inox). The electrode combinations (cathode||anode) were graphite||graphite, inox||graphite, and inox||inox. The choice of these materials was based on practical relevance and diversification of electrochemical properties. It was found that the electrolysis process with additional electrolytes resulted in increased H2 and O2 gas production but did not yield significant improvements in water treatment/purification. Experiments using inox||inox for ARET + NaCl were not feasible due to severe anode corrosion. The inox||graphite tests in ARET exhibited the best results in terms of COD and TSS reduction, with values of 52.4% and 80%, respectively, making it the preferred option for both treatment and gas production. An economic assessment was conducted for a minimum investment return period of 10 years, concluding that the process is feasible. The payback period is 9.3 years without external funding, with a CapEx of €1,974,225 and a TIR of 3.29%.
Description
Keywords
Eletrólise valorização energética Água residual Sustentabilidade Hidrogénio Oxigénio Electrolysis Energy valorization Wastewater Sustainability Hidrogen Oxigen