A project of reuse of reclaimed wastewater in the Po Valley, Italy: Polishing sequence and cost benefit analysis

The paper presents a study carried out in the environmentally sensitive area of the Po Valley in northern Italy, with the aim of evaluating, from technical and economic perspectives, a project to reuse part of the final effluent from the Ferrara wastewater treatment plant for irrigation and to develop the site for recreational purposes. Although this area features plentiful supplies of surface water, the Ministry of the Environment has declared it to be at risk of environmental crises due to eutrophication and the drought recurring over the last decade. Thus the availability of fresh water, particularly for agricultural purposes, is threatened, and prompt water saving and protection measures are required. Hence, the possibility of reusing reclaimed wastewater from this plant was investigated, with the aim of exploiting the space around the WWTP, situated within a large urban park, to install natural polishing treatment systems and create green spaces for recreational use. Based on experimental investigation on a pilot plant (featuring both natural and conventional treatments), the study outlines the rationale behind the treatment train selected for the project, details the initial and ongoing costs involved, evaluates the benefits deriving from the project, and assesses public acceptance of the project by the contingent valuation method. A cost–benefit analysis completes the study, and various economic indicators (net present value, benefit–cost ratio, pay-back period, and internal rate of return) revealed that the proposed project was financially feasible.