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Pilot-scale studies of advanced wastewater treatment for direct potable water reuse
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A sustentabilidade da água é crucial, contudo enfrenta desafios relacionados com as mudanças climáticas e o crescimento populacional. A reutilização da água é uma abordagem para uma gestão mais viavél da água. Especificamente, a reutilização potável direta já é uma realidade em países como os Estados Unidos da América, Namíbia e Austrália. No entanto, em Portugal, apenas a reutilização não potável é permitida. Para aumentar a confiança na reutilização segura da água, este estudo combina tecnologias, como ultrafiltração, ozonização e osmose inversa, para demonstrar a sua eficácia e as suas limitações.
Este estudo foi desenvolvido numa ETAR, comparando a água resultante de processos em grande escala, como a ultrafiltração, com água adicionalmente tratada através de uma combinação em escala piloto de ozonização e osmose inversa, ou apenas osmose inversa. O sistema foi configurado para produzir 1,25 m3/h, com uma recuperação de 70 % pela osmose inversa.
Foi realizada uma demonstração a longo prazo, com variação de temperatura e salinidade, e diferentes doses de ozono. O desempenho do sistema foi avaliado, juntamente com múltiplos parâmetros de qualidade da água.
Ao longo do processo, houve adversidades como o crescimento de algas, que o ozono degradou, mas resíduos ainda atingiram as membranas, levando a biofouling. Assim, soluções foram estudadas e postas em prática.
Como resultados, a ozonização, com uma dosagem de 5,3 mg/L, mostrou-se capaz de reduzir a concentração de vários contaminantes emergentes (CEs), como o composto farmacêutico diclofenac (em 75 %). A osmose inversa foi eficaz na redução de micropoluentes orgânicos como as substâncias perfluoroalquiladas (PFAS), outros CEs, como o NDMA registando uma redução de 50 %, e subprodutos de oxidação, como o bromato, reduzido em > 50 %.
Water sustainability is crucial, yet it is facing challenges related to climate change and population growth. Water reuse is an approach for a more viable water management. Specifically, direct potable reuse is already a reality in countries like the United States of America, Namibia and Australia. However, in Portugal, only non-potable reuse is allowed. To build confidence on safe water reuse, this study combines technologies, such as ultrafiltration, ozonation and reverse osmosis to demonstrate their effectiveness and limitations. This study was developed at a WWTP, comparing water resulting from full scale processes, like ultrafiltration, with water further treated through a pilot-scale combination of ozonation and reverse osmosis, or reverse osmosis alone. The system was set to produce 1.25 m3/ h, with an RO recovery of 70 %. A long-term demonstration was carried out, with varying temperature and salinity, and different ozone doses. The system performance was evaluated, along with multiple water quality parameters. Throughout, there were adversities as algae growth, which ozone broke down, but remnants still reached the membranes, leading to biofouling. Thereby, solutions were studied and put into practice. As results, ozonation, with a dosage of 5.3 mg/L, showed to reduce the concentration of several contaminants of emerging concern (CECs), such as the pharmaceutical compound diclofenac (by 75 %). RO was effective for the reduction of organic micropollutants such as perfluoroalkylated substances (PFAS), other CECs, like NDMA registering a 50 % reduction, and oxidation-byproducts, as bromate reduced > 50 %.
Water sustainability is crucial, yet it is facing challenges related to climate change and population growth. Water reuse is an approach for a more viable water management. Specifically, direct potable reuse is already a reality in countries like the United States of America, Namibia and Australia. However, in Portugal, only non-potable reuse is allowed. To build confidence on safe water reuse, this study combines technologies, such as ultrafiltration, ozonation and reverse osmosis to demonstrate their effectiveness and limitations. This study was developed at a WWTP, comparing water resulting from full scale processes, like ultrafiltration, with water further treated through a pilot-scale combination of ozonation and reverse osmosis, or reverse osmosis alone. The system was set to produce 1.25 m3/ h, with an RO recovery of 70 %. A long-term demonstration was carried out, with varying temperature and salinity, and different ozone doses. The system performance was evaluated, along with multiple water quality parameters. Throughout, there were adversities as algae growth, which ozone broke down, but remnants still reached the membranes, leading to biofouling. Thereby, solutions were studied and put into practice. As results, ozonation, with a dosage of 5.3 mg/L, showed to reduce the concentration of several contaminants of emerging concern (CECs), such as the pharmaceutical compound diclofenac (by 75 %). RO was effective for the reduction of organic micropollutants such as perfluoroalkylated substances (PFAS), other CECs, like NDMA registering a 50 % reduction, and oxidation-byproducts, as bromate reduced > 50 %.
Descrição
Palavras-chave
Direct potable reuse Reverse osmosis Biofouling Ozonation Organic micropollutants Contaminants of emerging concern