water Article How to Overcome Barriers for Wastewater Agricultural Reuse in Sicily (Italy)? Delia Ventura 1, Simona Consoli 1 , Salvatore Barbagallo 1, Alessia Marzo 2,*, Daniela Vanella 1 , Feliciana Licciardello 1 and Giuseppe L. Cirelli 1 1 Dipartimento di Agricoltura, Alimentazione e Ambiente (Di3A), Università degli Studi di Catania, Via S. Sofia 100, 95123 Catania, Italy; [email protected] (D.V.); [email protected] (S.C.); [email protected] (S.B.); [email protected] (D.V.); fl[email protected] (F.L.); [email protected] (G.L.C.) 2 Centre for the Conservation and Management of Nature and Agroecosystems (CUTGANA), University of Catania, Via S. Sofia 100, 95123 Catania, Italy * Correspondence: [email protected]; Tel.: +39-095-6139253 Received: 15 November 2018; Accepted: 13 February 2019; Published: 16 February 2019 Abstract: This study reports an up-to-date summary of the principal barriers still limiting reclaimed water use for agriculture in Italy, and particularly in Sicily. Moreover, it provides a geographic informative system (GIS)-based procedure for evaluating the potential treated wastewater (TW) reuse in the Sicilian region as a decision support system for its management. The survey, based on possible economic, morphologic, and design solutions, evidenced a feasible integration of several wastewater treatment plants (WWTPs) with irrigation areas, allowing the water availability enhancement. Overall, the potential volume of TW by WWTPs (connected to irrigation districts) is 163 × 106 m3 year−1, while the water deficit is 66 × 106 m3 year−1. The feasibility of TW reuse in Sicily was also analysed at the light of the World Health Organization microbial risk assessment. Escherichia coli (E. coli) analyses mostly accomplished these guidelines while conflicting with the restrictive Italian standards. Despite several limiting factors (restrictive legislations, high distance and unfavourable slope between WWTPs and irrigable areas, high monitoring and distribution costs) still hamper the exploitation of reclaimed water use in Sicilian agriculture, some solutions were identified to implement this practice. Keywords: agricultural reuse; barriers; GIS-based management; irrigation districts; Risk assessment; treated wastewater 1. Introduction Worldwide, arid and semiarid areas have increasingly experienced water scarcity. Such regions mostly use water for agriculture and crop irrigation (up to 70% of total water extracted), relying in particular on groundwater and surface water sources [1]. To reduce stress on limited freshwater resources, non-conventional water like urban wastewater (TW), constitute an important solution for promoting and enhancing the sustainable use of the available water, as evidenced by [2]. The same authors also highlighted the great potential of TW for irrigation of agricultural fields close to urban centres, also providing a considerable input of required nutrients for plants and reducing their net discharge on sensitive surface waters. As reported by [3], among institutional and socioeconomic causes, a key drawback for agricultural TW reuse practice advancement and its public acceptance is the absence of an adequate international legislation, leading in many cases inhomogeneous quality standards and fairness issues. In fact, as mentioned by [2], and discussed in other studies [3,4], the suitability of reclaimed water for specific applications depends on its quality and usage requirements. Generally, in irrigation practices water quality controls should mainly Water 2019, 11, 335; doi:10.3390/w11020335 www.mdpi.com/journal/water Water 2019, 11, 335 2 of 12 Water 2019, 11, x FOR PEER REVIEW 2 of 12 consider factors such as salinity, heavy metals, and pathogens for minimizing any detriment to salinity,human, plants,heavy metals, and soils. and Beyond pathogens the normative for minimizi barriers,ng any more detriment general to factors human, related plants, to wastewater and soils. Beyondtreatment the plants normative (WWTPs) barriers, siting more have general to be consideredfactors related [5]. to Among wastewater those, treatment some authors plants [6 (WWTPs)] reported sitingthe following: have to be long considered distances [5]. between Among treatment those, some facilities authors and [6] agricultural reported the demand following: areas; long construction distances betweenand maintenance treatment costs facilities of conveying and agricultural pipe systems; demand necessity areas; construction to store TW duringand maintenance fall-winter periods,costs of conveyingsince TW arepipe continuously systems; necessity produced to store throughout TW duri theng fall-winter year, whereas periods, irrigation since TW demand are continuously is generally producedconcentred throughout during crops the growing year, whereas season ofirrigation dry-summer demand periods. is generally Moreover, concentred the controversy during oncrops the growingpossibility season to estimate of dry-summer the true costs periods. of freshwater Moreover, supply, the controversy with respect on to the possibility intrinsic value to estimate of water the [7], truemay costs consequently of freshwater result supply, in economic with disadvantagerespect to the for intrinsic the production value of ofwater recycled [7], may water. consequently resultIn in the economic attempt disadvantage to develop their for ownthe production recycling and of recycled reuse criteria, water. usually proceeding by the most advancedIn the onesattempt (e.g., to Californiadevelop their and own Australia), recycling Mediterranean and reuse criteria, member usually states, proceeding like Italy, by Greece, the most and advancedSpain, enforced ones (e.g., “semiscientific” California and and Australia), too stringent Mediterranean regulations member to be really states, applied like Italy, [3]. Greece, In light and of Spain,this the enforced EU (European “semiscientific” Union) recognized and too stringent the need regu to implementlations to be a really common applied water [3]. reuse In light regulatory of this theinstrument EU (European at the international Union) recognized level and the it isneed working to implement towards botha common minimum water quality reuse requirements regulatory instrumentand health andat the environmental international risk-basedlevel and it policies is working [8]. On towards 28 May both 2018 minimum a “Proposal quality for a requirements Regulation of andthe Europeanhealth and Parliament environmental and of risk-based the Council policies on minimum [8]. On requirements 28 May 2018 for a “Proposal water reuse” for was a Regulation issued [9]. ofHowever, the European in the perspectiveParliament toand adopt of the the Council new EU on guidelines minimum for requirements reclaimed water for usewater at thereuse” national was issued [9]. However, in the perspective to adopt the new EU guidelines for reclaimed water use at level, many constraints will probably remain for a long time, mostly referring to physical and economic the national level, many constraints will probably remain for a long time, mostly referring to physical ones. In Italy, all previously described issues strongly limit the agricultural use of reclaimed water and economic ones. In Italy, all previously described issues strongly limit the agricultural use of (RW). Several studies already evidenced the need to enhance TW sustainable reuse and to promote reclaimed water (RW). Several studies already evidenced the need to enhance TW sustainable reuse management plans for available water resources in Sicily [10–12]. The same authors in fact discussed and to promote management plans for available water resources in Sicily [10–12]. The same authors how, in Sicily, relevant irrigation demand [12] is not satisfied mainly because of the increasing drought in fact discussed how, in Sicily, relevant irrigation demand [12] is not satisfied mainly because of the periods, the impairment of water body quality, and the rising civil demand. increasing drought periods, the impairment of water body quality, and the rising civil demand. Among the aforementioned legislative limitations, the restrictive Italian standards [13] lack of Among the aforementioned legislative limitations, the restrictive Italian standards [13] lack of quality guidelines for diversified agricultural reuse sectors and a microbiological risk-assessment quality guidelines for diversified agricultural reuse sectors and a microbiological risk-assessment approach in line with the World Health Organization [14], but present a list of overabundant approach in line with the World Health Organization [14], but present a list of overabundant water water quality parameters (e.g., chemical and microbiological compounds) to be analysed [15], with quality parameters (e.g., chemical and microbiological compounds) to be analysed [15], with consequent high monitoring costs, mainly for small treatment facilities (Figure1). Additionally, total consequent high monitoring costs, mainly for small treatment facilities (Figure 1). Additionally, total costs for developing TW reuse in agriculture are not sustainable and user-friendly when considering costs for developing TW reuse in agriculture are not sustainable and user-friendly when considering the construction, operation, and maintenance of “additional” processes for tertiary and disinfection the construction, operation, and maintenance of “additional” processes for tertiary and disinfection treatments and RW distribution networks. treatments