Seawater intrusion and infiltration modelling coupled to digital tools to avoid high saline concentrations in reclaimed water: application in coastal central Italy.

Industrial symbiosis approach was established between an industrial company and a water utility to prioritize the reuse of urban wastewater for industrial purposes. This requires low-salinity water, but this area is frequently affected by saline intrusion, thus creating water-related conflicts between the different economic activities. This study proposes a digital solution that combines dynamic simulation model (that predicts seawater intrusion and runoff) with digital tools, i.e., smart equalization (control algorithm) and matchmaking platform (decision support system). The models aim to predict the periods where significant peaks of salinity occurs, whereas the tools aim to distribute the wastewater and reclaimed water streams to diverse applications (industrial, agricultural) and/or treatments (conventional treatment, reverse osmosis) to maximize the amount of wastewater reused in efficient and sustainable way. During the 2D simulated period, wastewater conductivity was in range of 2100-2700 µS·cm^-1. Although this conductivity was over the limit required for industrial reuse, the digital solution implemented in this study enabled to recover 71% of the total wastewater produced for industrial purposes and 10% for irrigation, only discharging 19% of the total. The approach implemented in this study would be very useful to be replicated in coastal areas where saline intrusion is relevant.