Reliability analysis as a support tool for projects focusing on non-potable uses of treated wastewater in steel industries ; Análise de confiabilidade como ferramenta de apoio para projetos focando em usos não potáveis de águas residuárias tratadas em indústrias de Siderurgia

Abstract

In a scenario of increasingly frequent water crises, the use of treated wastewater is an important water management tool, with quality standards being developed worldwide to ensure safety in such practices. In this context, it is necessary to guarantee the reliability of wastewater treatment plants (WWTP). Reliability has been used to predict the probability of reaching the established standards or determine the design concentrations required to achieve them. This study associated the reliability concept with the study of WWTP in the steel industry, focusing on water use. The method developed by Niku et al. (1979) and used by Oliveira and Von Sperling (2008) was used to determine the coefficient of reliability, the mean project concentrations, and the percentage of compliance with the parameters required by the legislation of 3 WWTPs that treat industrial effluents and 1 WWTP that treats sanitary effluent. The percentages of compliance with legislation for most parameters were equal to or close to 100%, indicating an excellent performance of the 4 WWTPs, which could even allow the adoption of even higher levels of reliability. Therefore, the reliability studies together with a modeling of the contaminants' dispersion in the soil proved to be a very interesting approach for projects related to non-potable uses of treated wastewater in steel industries. Keywords: reliability, soil disposal, water reuse. ; In a scenario of increasingly frequent water crises, the use of treated wastewater is an important water management tool, with quality standards being developed worldwide to ensure safety in such practices. In this context, it is necessary to guarantee the reliability of wastewater treatment plants (WWTP). Reliability has been used to predict the probability of reaching the established standards or determine the design concentrations required to achieve them. This study associated the reliability concept with the study of WWTP in the steel industry, focusing on water use. The method developed by Niku et al. (1979) and used by Oliveira and Von Sperling (2008) was used to determine the coefficient of reliability, the mean project concentrations, and the percentage of compliance with the parameters required by the legislation of 3 WWTPs that treat industrial effluents and 1 WWTP that treats sanitary effluent. The percentages of compliance with legislation for most parameters were equal to or close to 100%, indicating an excellent performance of the 4 WWTPs, which could even allow the adoption of even higher levels of reliability. Therefore, the reliability studies together with a modeling of the contaminants' dispersion in the soil proved to be a very interesting approach for projects related to non-potable uses of treated wastewater in steel industries. Keywords: reliability, soil disposal, water reuse. ; Em um cenário de crises hídricas cada vez mais frequentes, o uso de águas residuárias tratadas (ART) aparece como uma importante ferramenta de gerenciamento hídrico, sendo desenvolvidos em todo o mundo padrões de qualidade a fim de garantir a segurança na utilização de ART. Nesse contexto, é preciso garantir a confiabilidade das estações de tratamento de esgoto (ETE). A confiabilidade vem sendo utilizada para prever a probabilidade de alcance dos padrões estabelecidos ou para determinar a concentração de projeto necessária para esse atingimento. O presente trabalho teve como objetivo a associação do conceito de confiabilidade ao estudo de ETEs de uma indústria siderúrgica, no tocante à produção de água para reúso. Para tanto, foi utilizado o método desenvolvido por Niku et al. (1979) e utilizado por Oliveira e Von Sperling (2008) para a determinação do coeficiente de confiabilidade, das concentrações médias de projeto e do percentual de atendimento aos parâmetros exigidos pela legislação de 3 ETEs que tratam efluentes industriais e 1 ETE que trata efluente sanitário. Os percentuais de cumprimento da legislação para a maioria dos parâmetros foram iguais ou próximos a 100% indicando um excelente desempenho das 4 ETEs, podendo inclusive permitir a adoção de níveis de confiabilidade ainda mais elevados. Portanto, os estudos de confiabilidade em conjunto com a modelagem da dispersão de contaminantes no solo mostraram-se uma abordagem muito interessante para projetos relacionados ao uso não potável de águas residuárias tratadas em indústrias siderúrgicas. Palavras-chave: confiabilidade, disposição no solo, reúso de água.