Strategic Assessment of Treated Wastewater Reuse Potential in Brazilian Watersheds Using Analytic Hierarchy Process

This study assesses the potential for water reuse from treated wastewater in the Rio dos Sinos and Rio Sapucaí watersheds in Brazil, applying the Analytic Hierarchy Process (AHP). The criteria evaluated include treatment efficiency, proximity to demand, supply capacity, and legal and institutional frameworks. A pairwise comparison and consistency ratio were applied to validate the methodology (CR < 0.01). Results showed that in the Rio dos Sinos watershed, 21 WWTPs were identified, with high biochemical oxygen demand (BOD) removal (> 80%) allowing up to 46% of industrial demand to be supplied, and three WWTPs classified as high potential. In the Rio Sapucaí watershed, 13 WWTPs were identified, with most classified in the 60%–80% BOD removal range; reuse could meet up to 68% of irrigation demand, though only one WWTP was ranked as high potential. Esteio (Rio Grande do Sul—RS), São Leopoldo (RS), and Pouso Alegre (Minas Gerais—MG) were identified as hotspots for water reuse opportunities. An interactive decision‐support dashboard was developed to visualize results and support watershed management. Future research should expand criteria and integrate economic feasibility.