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Eletrocoagulação de lixiviados de aterros sanitários
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Neste trabalho estudou-se a aplicação de técnicas eletroquímicas de eletrocoagulação para a remoção de carga orgânica de lixiviados de aterros sanitários. As amostras de lixiviado usadas foram recolhidas em fevereiro, na Estação de Tratamento de Águas Lixiviantes da Resiestrela, na Capinha, Fundão, à entrada do sistema biológico. Usaram-se ânodos consumíveis de ferro e a intensidade de corrente aplicada foi de 2,5 A. O volume usado em cada ensaio foi de 0,5 L e foram testadas diferentes condições experimentais, nomeadamente, o pH inicial do lixiviado, a existência de agitação durante os ensaios de eletrocoagulação e o efeito da diluição da amostra inicial de lixiviado. Os parâmetros de controlo usados para seguir a evolução dos ensaios foram a carência química de oxigénio (CQO), o carbono orgânico filtrado (COf), o azoto total, a condutividade e o pH.
Os resultados obtidos permitiram concluir que, ao fim de duas horas a eficiência da eletrocoagulação começa a diminuir, começando a remoção da CQO a apresentar diminuição na taxa de remoção. Os melhores resultados para a remoção absoluta da carga orgânica foram obtidos nos ensaios realizados a pH inicial de 6, logo seguidos pelos ensaios realizados a pH natural. Foram também os ensaios realizados a pH inicial 6, em particular durante a primeira hora de ensaio, que apresentaram uma maior remoção específica da CQO, quer por massa de Fe consumido quer por energia elétrica gasta. Contudo, os ensaios realizados a pH natural apresentaram também resultados muito promissores, tendo a vantagem de não necessitarem da correção inicial do pH.
In this work, the application of electrocoagulation techniques for the removal of organic load from sanitary landfill leachates was studied. The leachate samples used were collected in February, at the entrance of the biological treatment, in the Leachate Treatment Plant of Resiestrela, in Capinha, Fundão. Iron consumable anodes were used in the electrocoagulation assays and the intensity of the applied current was 2.5 A. The volume used in each assay was 0.5 L and different experimental conditions were tested, namely, different initial pH of the leachate, existence of stirring during the tests and effect of leachate samples dilution. The control parameters used to monitor the progress of the tests were chemical oxygen demand (COD), filtered organic carbon (COf), total nitrogen, conductivity and pH. The results showed that, after two hours of electrocoagulation, efficiency decreases, with the consequent decrease in the COD removal rate. The best results for the complete removal of the organic load were obtained in tests carried out at an initial pH of 6, immediately followed by tests at natural pH. Tests run at an initial pH of 6 have also shown, particularly during the first hour, higher specific removal of COD, per mass of Fe and per electrical energy consumed. However, tests conducted at natural pH also showed promising results, with the advantage of not requiring initial pH adjustment.
In this work, the application of electrocoagulation techniques for the removal of organic load from sanitary landfill leachates was studied. The leachate samples used were collected in February, at the entrance of the biological treatment, in the Leachate Treatment Plant of Resiestrela, in Capinha, Fundão. Iron consumable anodes were used in the electrocoagulation assays and the intensity of the applied current was 2.5 A. The volume used in each assay was 0.5 L and different experimental conditions were tested, namely, different initial pH of the leachate, existence of stirring during the tests and effect of leachate samples dilution. The control parameters used to monitor the progress of the tests were chemical oxygen demand (COD), filtered organic carbon (COf), total nitrogen, conductivity and pH. The results showed that, after two hours of electrocoagulation, efficiency decreases, with the consequent decrease in the COD removal rate. The best results for the complete removal of the organic load were obtained in tests carried out at an initial pH of 6, immediately followed by tests at natural pH. Tests run at an initial pH of 6 have also shown, particularly during the first hour, higher specific removal of COD, per mass of Fe and per electrical energy consumed. However, tests conducted at natural pH also showed promising results, with the advantage of not requiring initial pH adjustment.
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Palavras-chave
Aterro sanitário - Lixiviados - Electrocoagulação Aterro sanitário - Tratamento de lixiviados