Feasibility of tertiary treated wastewater reuse in the irrigation of grapes and olives

The increased global water demand is causing strong stress on natural water resources, and implies the need of alternative ones. In this view, treated wastewater is increasingly considered a potential source of water, rather than a waste. In recent years, several studies about treated wastewater reuse for irrigation confirmed the feasibility of this practice. Nevertheless, water reuse still meets hesitation in potential users, mainly for incomplete information about the characteristics and potential benefits of reclaimed water. The project MeProWaRe (WaterWorks2014, Water JPI cofunded call) was aimed at encouraging treated wastewater reuse through an integrated strategy for the irrigation of vineyards and olives groves. MeProWaRe introduces an innovative methodology towards water reuse specifically addressing well defined types of crops, agronomic practices, and water constraints that are typical of Mediterranean countries. The idea is to highlight the positive relationships between water reuse, plants growth and crops productivity with specific reference to the Mediterranean area. To obtain this, reuse practices were made more easily acceptable to stakeholders through their direct participation in the implementation of the proposed methodology. Experimental activities were carried out at three demonstration sites in Portugal, Spain, and Italy. The present study focuses of the Italian case study of Acquaviva delle Fonti (Puglia, South-Eastern Italy), where the adoption of tertiary treated effluents from the local municipal wastewater treatment plant was evaluated by monitoring their quality over time. The proposed strategy included the possibility of blending the treated effluent with the conventional source (well water), and the results showed the effectiveness of the tertiary treatment based on gravity disk microfiltration and UV disinfection to obtain water suitable for unrestricted irrigation. The possibility of adjusting the dilution ratio of the two water sources according to the nutrient content of the treated effluent and the phenological needs of the crops was also evaluated.