Preliminary studies for the water-smart utility-industry symbiosis Horizon2020 ULTIMATE project: the case of ARETUSA in Tuscany

This study has been done for providing resolutions to the problem of the saline intrusion regarding the wastewater treatment plant and the sewer network of two cities in Tuscany: Rosignano Solvay and Cecina. The aim has been pursued by implementing a dynamic rainfall-runoff simulation model called SWMM (Storm Water Management Model). The first step of the study has been about the preliminary study and the elaboration of the flowrates and concentrations exiting the two plants, comparing the values with the restriction provided by national and regional laws. During the first phase, different problematics had emerged, in particular concerning the high quantity of COD, electrical conductivity and chlorides detected. For the resolution of such problematics, two different methods had been proposed. The first regards the resolution for the COD removal directly in the plant, enhancing the adsorption process by the use of different by-product taken from local industries. The second regards the resolution for the high salinity problem by an investigation on the sewer network by the implementation of the model following two steps: the first, which concerns the construction of the hydraulic pattern and the second, which regards the implementation of the quality properties. The calibration was done both for the hydraulic model and for the qualitative model and finally, the simulation were launched analysing only the winter scenario. In terms of precipitation, three events with specific return time were analysed, while for the qualitative model, the wet and dry events were compared. In the end, it was found that considering different return period, several points on the network were flooding and so not all the flowrate could release on the spillways.