Some economic considerations on wastewater reclamation for irrigation, with reference to the Italian situation

The purpose of this work is to check construction and operation costs for simplified post-treatment trains able to produce water displaying a quality suitable for different agricultural uses. Having in mind the quality of most of surface waters in Italy, the main parameters to control for a general purpose reclaimed water supply are microbial quality and TSS content. Therefore a contact filtration followed by disinfection is to be considered the minimum option, while the use of polishing ponds can be strictly limited in many Italian regions due to the area requirements and to the need to provide a full lining of bottom and levees. Some data referring to surface waters quality and to the Italian epidemiological situation are given. On the basis of the current Italian situation, the construction and operation cost increases due to a polishing section, downstream a standard municipal WWTP, are evaluated and the impact of different technical choices is shortly discussed (disinfection options, chemicals, etc.). Some considerations about the link existing in Italy between the cost of water for irrigation and the agricultural economy are made.