ABSTRACT
The industrial reuse of existing municipal wastewater treatment plant (WWTP) effluent can play a major role in improving water security in urbanized regions facing scarcity. As the complexity of engineered direct water reuse is related to various economic, technical, legal, social, environmental, and public health aspects, multi-criteria analysis (MCA) is a feasible decision-making tool in this context. The present work aimed to establish the relevant key factors for the application of MCA, wherever plant planning, design, and construction did not previously consider reuse practices. The adopted methodology considers the proposition and valuation of key criteria, based on the existing literature, expert consultations, statistical analysis, and the application of MCA to a real municipal WWTP located in Campinas city (São Paulo State, Brazil). The 13 proposed criteria encompass multiple categories, and their relevance is demonstrated, given the high significance frequencies assigned. The best values are related to effluent quality, health risks, and treatment reliability, in addition to environmental costs and benefits. The application of those criteria in Cooperative Game Theory (CGT) and Compromise Programming (CP) methods is proved to be suitable, considering the characteristics of the studied area (i.e., highly urbanized with a history of water scarcity). Among nine surveyed end-users, the first position in the hierarchy corresponds to the largest industries with the shortest distance from the WWTP.