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Authors
Abstract(s)
A contaminação de águas por compostos químicos orgânicos, provocada pelo homem,
tem-se tornado uma questão cada vez mais crítica, uma vez que a água é um recurso
essencial para a existência de vida humana. Um dos principais responsáveis pela
poluição de águas são os efluentes industriais, uma vez que é necessária uma elevada
quantidade de água para os processos industriais e após a sua utilização, é despejada em
rios, lagos, bacias, mar, entre outros locais. Estes efluentes vêm contaminados e podem
colocar em risco a saúde humana, pois possuem uma variedade de poluentes de águas
residuais, por exemplo, metais e fluoretos, minerais de argila, corantes, metais pesados
entre outros.
O objetivo deste trabalho consistiu em estudar a eficácia da utilização de um processo
eletroquímico, neste caso a eletrocoagulação, utilizando elétrodos de ferro como ânodo
e aço como cátodo, no tratamento de um efluente industrial real e otimizar as melhores
condições para uma futura utilização deste processo numa indústria. Estudou-se ainda a
combinação da eletrocoagulação com a oxidação anódica, utilizando como ânodo um
elétrodo de diamante dopado com boro.
Primeiramente, começou-se por caracterizar o efluente em diversos parâmetros:
carência química de oxigénio, carbono total, pH, teor em ferro, condutividade, turbidez,
entre outros. Após essa caracterização, estudou-se as melhores condições para a melhor
eficiência do processo de eletrocoagulação. As melhores condições para tratar um
volume de 250 mL foram as seguintes: 2 V, 2 h, agitação a 100 rpm, efluente centrifugado
no final do ensaio de eletrocoagulação com estas condições, foi possível atingir uma
remoção de 68 % de carência química de oxigénio .
Infelizmente a eletrocoagulação não foi suficiente para tornar a concentração da carência
química de oxigénio inferior ao limite legal de descarga, então colocou-se a opção de
combinar o processo de eletrocoagulação com o processo de eletrooxidação, com duração
de 2 h + 6 h, para uma intensidade de corrente aplicada de 0,1 A, agitação a 300 rpm,
efluente centrifugado no final do ensaio combinado (eletrocoagulação seguido de
eletrooxidação) foi possível obter uma remoção de CQO de 92 %, atingindo-se um valor
inferior ao limite de descarga legal e com um custo energético de 49 Wh/g CQO
removido.
Man-made contamination of water by organic chemical compounds has become an increasingly critical issue, since water is an essential resource for human life. One of the main contributors to water pollution is industrial effluents, since a large amount of water is required for their activity and after use, it is discharged into rivers, lakes, basins, the sea, among other places. These effluents are contaminated and can pose a risk to human health, as they contain a variety of wastewater pollutants, such as metals and fluorides, clay minerals, dyes, heavy metals, among others. The aim of this work was to study the effectiveness of using an electrochemical process, in this case electrocoagulation, using iron electrode as anode and steal as cathode, to treat a real industrial effluent and to optimize the best conditions for future use of this process in an industry. The combination of electrocoagulation with anodic oxidation was also studied, using a boron-doped diamond electrode as the anode. First, the effluent was characterized in terms of various parameters: chemical oxygen demand, total carbon, pH, iron content, conductivity, turbidity, among others. After this characterization, the best conditions for the best efficiency of the Electrocoagulation process were studied. The best conditions to treat 250 mL were as follows: 2 V, 2 h, agitation at 100 rpm, effluent centrifuged at the end of the EC test. With these conditions, it was possible to achieve 68 % of chemical oxygen demand removal. Unfortunately, electrocoagulation wasn't enough to bring the concentration of chemical oxygen demand below the legal limit of discharge, so the option was taken of combining the electrocoagulation process with the electrooxidation process, lasting 2 h + 6 h, with an applied current intensity of 0,1 A, agitation at 300 rpm and effluent centrifuged at the end of the combined test, it was possible to achieve chemical oxygen demand removal of 92 %, which was below the legal discharge limit and at an energy cost of 49 Wh/g chemical oxygen demand removed.
Man-made contamination of water by organic chemical compounds has become an increasingly critical issue, since water is an essential resource for human life. One of the main contributors to water pollution is industrial effluents, since a large amount of water is required for their activity and after use, it is discharged into rivers, lakes, basins, the sea, among other places. These effluents are contaminated and can pose a risk to human health, as they contain a variety of wastewater pollutants, such as metals and fluorides, clay minerals, dyes, heavy metals, among others. The aim of this work was to study the effectiveness of using an electrochemical process, in this case electrocoagulation, using iron electrode as anode and steal as cathode, to treat a real industrial effluent and to optimize the best conditions for future use of this process in an industry. The combination of electrocoagulation with anodic oxidation was also studied, using a boron-doped diamond electrode as the anode. First, the effluent was characterized in terms of various parameters: chemical oxygen demand, total carbon, pH, iron content, conductivity, turbidity, among others. After this characterization, the best conditions for the best efficiency of the Electrocoagulation process were studied. The best conditions to treat 250 mL were as follows: 2 V, 2 h, agitation at 100 rpm, effluent centrifuged at the end of the EC test. With these conditions, it was possible to achieve 68 % of chemical oxygen demand removal. Unfortunately, electrocoagulation wasn't enough to bring the concentration of chemical oxygen demand below the legal limit of discharge, so the option was taken of combining the electrocoagulation process with the electrooxidation process, lasting 2 h + 6 h, with an applied current intensity of 0,1 A, agitation at 300 rpm and effluent centrifuged at the end of the combined test, it was possible to achieve chemical oxygen demand removal of 92 %, which was below the legal discharge limit and at an energy cost of 49 Wh/g chemical oxygen demand removed.
Description
Keywords
Bdd Carência Química de Oxigénio Efluente Têxtil Eletrocoagulação Eletrooxidação Ferro