Multi-criteria decision making for a holistic assessment of sustainable alternatives in SWRO desalination: A case study

Water authorities have been constructing an increasing number of small-scale desalination treatment plants to provide drinking water for remotely located communities. Each location has a different situational context and community priorities, meaning that the treatment solutions should be selected considering a range of criteria and sub-criteria covering technical, economic, environmental, and health aspects. In this study, a comparison of three possible desalination alternatives was made using a multi-criteria decision-making (MCDM) tool in a rural area of Queensland, Australia. The studied alternatives encompassed standalone reverse osmosis (RO); forward osmosis (FO) coupled with RO (FO–RO), and ultrafiltration coupled with RO (UF–RO). The hybrid alternatives have the potential to significantly reduce energy consumption and environmental impact and to increase the efficiency of pathogenic removal and contaminations. The weights for the criteria were developed by integrating a multi-criteria feasibility assessment with a new survey that was responded by SWRO experts. Following this, the desalination alternatives were ranked using the TOPSIS method (technique for ordering preference by similarity to ideal solutions). A sensitivity analysis was conducted to see how the results would vary by changing the weights of preferences. The resulting MCDM framework ranked the UF-RO hybrid system as the best performing alternative with consistently high efficiency levels for stakeholders. The results showed that the performances of the FO-RO hybrid system and of the RO standalone system were similar, with FO-RO showing a marginal superiority in most of criteria. •MCDM was used to score the osmotic and mixed dilution desalination.•TOPSIS method was used to calculate the final ranking.•Hybrid UF-RO ranked as the best alternative in dilution desalination process.•The weight of health and quality analysis was the first priority in all evaluation criteria.