Legislative, economical and technical aspects of irrigation with reclaimed wastewater in Italy

The reuse of polished municipal wastewaters for irrigation is becoming an important topic in many Italian regions, especially in the South. This practice can be beneficial - from different points of view - for the whole environment, but it is not encouraged by the present legislation. Therefore no full scale authorized plant is yet in operation. This paper deals with preliminary information on present situation and, on the basis of current studies in the field of wastewater reclamation in agriculture. Tentative quality criteria are proposed, with reference to the usual quality of surface waters extensively used for irrigation and the quality standards set for recreational waters and treated effluents. Information on appropriate process units and suitable process schemes is given, also on the basis of preliminary tests carried out at the Politecnico di Milano. Referring also to the Italian market situation, a comprehensive study was carried out to evaluate cost-effectiveness of different process schemes for different quality levels of the reclaimed effluents. Results show that substantial savings can be obtained if reference microbiological quality standard is raised by two orders of magnitude, with respect to the present situation; further extensions (still acceptable from a hygiene point of view) are not likely to give appreciable extra savings. In any case operation costs to produce good quality reclaimed waters - often better than surface waters - appear to be quite reasonable, being on average below 0.05 US $/m3. © 1994.