In this paper an integrated two-step model was developed based on the fuzzy-AHP and TOPSIS methods. The performance and reliability of the modelwere then evaluated in a realworld case study concerning the selection of the most suitable desalination technology for the treatment of brackish groundwater typical of an area located in north-east of Iran. The desalination technologies included in this study were reverse osmosis, electrodialysis, ion exchange, multistage flash distillation, multi-effect distillation, and vapor compression. The comparison of the technologies was based on various environmental, technical and economical criteria and sub-criteria. The fuzzy-AHPwas used to analyze the structure of the selection process and to determine the weights of the criteria and sub-criteria, and the TOPSIS method was used to calculate the final ranking of the technologies. The outcome results of the two-step model revealed that electrodialysis, with a closeness coefficient value of 0.7547, was the most applicable desalination technology for the study area. Moreover, sensitivity analysis demonstrated that any variation in the criteria weights does not affect the outcome of the model.

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