Wastewater reuse potential for agricultural irrigation in Sicily

In Mediterranean countries, water shortage is becoming a problem of high concern affecting the local economy, mostly based on agriculture. In addition, often the problem is not only the scarcity of water in terms of average per capita, but the high cost of making water available at the right place, at the right time with the required quality. In these cases, an integrated approach for water resources management including wastewater is required. The management should also include wastewater (WW) reclamation and reuse, especially for agricultural irrigation, that is becoming a common and rapidly increasing practice in Mediterranean regions, notwithstanding law restrictions and local acceptance. In Italy, WW reuse is regulated by a quite restrictive approach (Ministry Decree, D.M. n. 185/03), especially for some chemical compounds and microbiological parameters; this approach has led some difficulties in promoting WW reuse. On the other hand, at international level, the Guidelines for the safe use of wastewater, excreta and greywater, issued by the World Health Organization in 2006, can be used as a basis for the development of standards and regulation to managing the health risk from hazards associated with wastewater use in agriculture. The main aim of the present paper is the evaluation of the potential of the WW reuse in Sicily. In order to achieve the objective, a Territorial Information System (TIS) at regional level was built to quantify and locate the available WW volumes. In particular, the characteristics of the wastewater treatment plants (WWTPs) (location, altitude, equivalent inhabitants, treatment level, working state, treated volume …) were integrated, through the TIS, with data on irrigation district areas (surface, location, altimetry, potential evapotranspiration, water needs, available water resources, distance to the nearest WWTP…). Moreover, in order to evaluate the Italian approach to the WW reuse for agricultural irrigation, the water quality of different WW treatment effluents, were analysed on the basis of both the Italian law and the WHO guidelines. The microbiological quality standards of the D.M. n. 185/03 were too restricted. A specific national legislation on acceptable maximum concentration of microorganisms, especially for vegetable crops eaten raw, is desirable.