Análise prática e legal sobre micropoluentes emergentes com foco no reúso potável de água no Brasil

Abstract

The present research work was developed based on an intense bibliographical review (a 5-year temporal scope, from 2018 to 2023), divided into two parts. Part 1: a comprehensive understanding of the most pronounced concerns related to micropollutants in the practical and legal context of potable water reuse worldwide. Part 2: a comparison of this scenario with the main micropollutants studied in Brazil. Part 1 involved an integrative review to study legal documents related to concerns about emerging micropollutants in the context of potable water reuse worldwide; and a systematic review for a general understanding of potable water reuse plants in operation worldwide. Part 2 involved a systematic review of the most studied micropollutants in Brazil (in Portuguese and English) in different aquatic matrices (water and sewage). As main results, it was observed that in Part 1, there are currently in force worldwide, 19 regulatory documents (including legal and guiding documents), of which 6 address direct potable reuse (DPR) and indirect potable reuse (IPR) jointly, 11 only IPR, and 2 only DPR. Standards for micropollutants are defined only in documents regulating IPR. Regarding operational plants, 39 units were studied, of which 6 are DPR and 32 are IPR. In terms of legal aspects, the compounds that raised the most concern were: 1,4-dioxane, 17-β-estradiol, gemfibrozil; perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), sucralose, and triclosan. The absence of specific standards for micropollutants in DPR regulations is concerning and highlights the importance of establishing rigorous guidelines that consider efficient micropollutant removal. In Part 2, the results showed that 17α-ethinylestradiol, diclofenac, caffeine, 17-β-estradiol, and ibuprofen are the most studied micropollutants in Brazil, highlighting them as the chemicals of greatest interest in environmental and public health studies. Of the total compounds regulated in specific documents for potable water reuse worldwide, 33 are already standardized in Brazil by MS 888/2021 Potability Ordinance. Of the 418 compounds investigated in the Brazilian context, only 43 are covered by the regulation established in MS 888/2021 Ordinance. In general, the work has elucidated important scientific gaps related to concerns about emerging micropollutants in the context of potable water reuse. Additionally, the implementation of the indication of the main micropollutants and their protective standards for future regulation on potable water reuse in Brazil is a subject for future work, based on the conclusions of this study. It is concluded that the study, besides demonstrating the safe viability of the practice, paved a more assertive path for future regulation of potable water reuse in Brazil.