Reuse of wastewater: a feasible option, or not? A decision support system can solve the doubt

A wide debate on wastewater reuse has been turning on within the scientific community (and also at the legislative level) for several years. Beyond the undeniable advantages linked to the recovery of a material resource, the typical question plaguing water managers sounds like: “Is this practice feasible, in terms of both technical and economic sustainability?”. To answer their query, we have developed an innovative tool that rates the three actors of the reclamation process (the wastewater treatment plant WWTP, the hydraulic system, and the final user) by means of a waterfall framework based on the following: (i) the definition of meaningful input factors, (ii) the calculation of robust indices, and (iii) the synthesis process up to a final evaluation (numerical values). The model has been successfully applied to several case studies, where the reuse is either already practiced or under study: As a result, the most suitable scenario for reuse (i.e. #1 WWTP), together with the main opportunities (e.g. a crucial increase in water availability for the final user: #1 WWTP) and threats (e.g. the worst quality of the effluent compared to the current source) has been identified. In summary, this tool represents a useful technical support for decision-makers whenever a judgment on reuse feasibility is required.