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Authors
Abstract(s)
Um dos resíduos/subprodutos do tratamento de águas residuais é a lama. A gestão deste output mássico dos sistemas de tratamento é altamente complexa e dispendiosa que, se mal realizada, pode comprometer as vantagens ambientais e sanitárias do próprio tratamento. De acordo com a Agenda 21, da ONU, sendo este tipo lamas um problema a resolver pela estrutura de gestão de resíduos sólidos, existe uma necessidade crescente de reduzir a sua produção, de aumentar as suas taxas de reutilização e reciclagem, de promover a sua valorização e de encontrar os locais de deposição mais adequados. Neste estudo, procurou-se construir um modelo computacional do tratamento global de uma ETAR de águas residuais urbanas, incluindo as operações/processos de tratamento das fases líquida e sólida. Além disso, procedeu-se ainda à utilização do modelo para avaliar alguns cenários com vista a reduzir a produção de lamas, sem diminuir a qualidade final da água residual tratada, estimar o incremento de lamas causado pelo atual uso de coagulantes. Para a construção do modelo dinâmico utilizou-se do software SUMO e todos os dados primários foram fornecidos pela empresa gestora da ETAR. A validação do modelo mostrou um desempenho bastante aceitável do mesmo, quer em termos de caracterização da qualidade da água residual tratadas, quer no que respeita à produção de lamas. As simulações realizadas, embora não envolvendo diretamente o coagulante biológico usado na ETAR para a remoção de cor (AMBIFLOC BIOT100), sugere que este agente biológico apresenta uma contribuição média aproximadamente 23% da produção da lama total (o equivalente a aproximadamente a 238 ton/mês), podendo aumentar para 25-30% no caso de a ETAR ter de futuramente cumprir os requisitos legais para o fósforo. O estudo também prevê que a utilização de coagulantes químicos alternativos, em particular o cloreto férrico, apresentam um forte potencial de redução de produção de lamas em comparação com o coagulante biológico, sem comprometerem a qualidade do efluente final; assim há garantia de não alterar de forma negativa o corpo recetor do mesmo. Todavia, importa realçar que o uso de coagulantes químicos em elevadas dosagens poderá apresentar um aumento na concentração de ferro e alumínio, podendo comprometer o tratamento da lama e armazenamento. O estudo realizado é uma demonstração de que os objetivos e a tipologia de tratamento devem assentar num processo multicritério, no qual a componente ambiental não pode apenas cingir-se à qualidade do efluente e à manutenção do equilíbrio ecológico do meio recetor.
One of the waste/by-products of wastewater treatment is sludge. The management of this mass output from treatment systems is highly complex and costly which, if poorly performed, can compromise the environmental and health benefits of the treatment itself. According to the UN's Agenda 21, since this type of sludge is a problem to be solved by the solid waste management structure, there is a growing need to reduce its production, to increase its reuse and recycling rates, to promote its valorization, and to find the most appropriate disposal sites. In this study, we sought to build a computational model of the overall treatment of an urban wastewater treatment plant, including the operations/processes for treating the liquid and solid phases. In addition, the model was also used to evaluate some scenarios to reduce the production of sludge, without decreasing the final quality of the treated wastewater, to estimate the increase in sludge caused by the current use of coagulants. To build the dynamic model the SUMO software was used and all primary data were provided by the WWTP management company. The validation of the model showed a quite acceptable performance of the model, both in terms of characterization of the treated wastewater quality and in terms of sludge production. The simulations carried out, although not directly involving the biological coagulant used at the WWTP for color removal (AMBIFLOC BIOT100), suggest that this biological agent has an average contribution of approximately 23% of the total sludge production (equivalent to approximately 238 ton/month), which could increase to 25-30% in case the WWTP has to meet the legal requirements for phosphorus in the future. The study also predicts that the use of alternative chemical coagulants, in particular ferric chloride, have a strong potential to reduce sludge production compared to the biological coagulant, without compromising the quality of the final effluent; thus there is a guarantee of not adversely altering the effluent receiving body. However, it should be noted that the use of chemical coagulants in high dosages may present an increase in the concentration of iron and aluminum, which may compromise the treatment of the sludge and storage. The study carried out is a demonstration that the objectives and treatment typology should be based on a multi-criteria process, in which the environmental component cannot be limited to the quality of the effluent and the maintenance of the ecological balance of the receiving environment.
One of the waste/by-products of wastewater treatment is sludge. The management of this mass output from treatment systems is highly complex and costly which, if poorly performed, can compromise the environmental and health benefits of the treatment itself. According to the UN's Agenda 21, since this type of sludge is a problem to be solved by the solid waste management structure, there is a growing need to reduce its production, to increase its reuse and recycling rates, to promote its valorization, and to find the most appropriate disposal sites. In this study, we sought to build a computational model of the overall treatment of an urban wastewater treatment plant, including the operations/processes for treating the liquid and solid phases. In addition, the model was also used to evaluate some scenarios to reduce the production of sludge, without decreasing the final quality of the treated wastewater, to estimate the increase in sludge caused by the current use of coagulants. To build the dynamic model the SUMO software was used and all primary data were provided by the WWTP management company. The validation of the model showed a quite acceptable performance of the model, both in terms of characterization of the treated wastewater quality and in terms of sludge production. The simulations carried out, although not directly involving the biological coagulant used at the WWTP for color removal (AMBIFLOC BIOT100), suggest that this biological agent has an average contribution of approximately 23% of the total sludge production (equivalent to approximately 238 ton/month), which could increase to 25-30% in case the WWTP has to meet the legal requirements for phosphorus in the future. The study also predicts that the use of alternative chemical coagulants, in particular ferric chloride, have a strong potential to reduce sludge production compared to the biological coagulant, without compromising the quality of the final effluent; thus there is a guarantee of not adversely altering the effluent receiving body. However, it should be noted that the use of chemical coagulants in high dosages may present an increase in the concentration of iron and aluminum, which may compromise the treatment of the sludge and storage. The study carried out is a demonstration that the objectives and treatment typology should be based on a multi-criteria process, in which the environmental component cannot be limited to the quality of the effluent and the maintenance of the ecological balance of the receiving environment.
Description
Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do Paraná
Keywords
Águas residuais Lama biológica Simulação matemática Produção de lamas