Digital Theses Archive


Tesi etd-11182016-191601

Type of thesis
Analisi delle interazioni acqua-suolo nella fitodepurazione delle acque di drenaggio e nella ricarica delle falde Analysis of water-soil interaction in drainage water phyto-treatment and in aquifer recharge schemes
Scientific disciplinary sector
  • Induced RiverBank Filtration
  • Managed Aquifer Recharge
  • Phyto-treatment
  • Soil Buffer Effect
  • Wetland
Exam session start date
Since the water availability is the nexus between all human socio-economics activities, solutions based on non-conventional water resources may be applied to deal with water scarcity (e.g. wastewater reuse and managed aquifer recharge). Reuse of treated rural drainage water may contribute in preserving aquifers from over-exploitation for irrigation purposes during the summer period, while Managed Aquifer Recharge (MAR) may be used to increase groundwater resources. Phytotreatment and MAR schemes, comprised within the so-called water related agro-ecosystem services, recently gained the interest of the European Commission and national governments. However, although being generally beneficial, non-conventional resources bring along concerns of environmental nature: (a) potential groundwater pollution due to the leaching of nutrients, Pharmaceutical and Personal Care Products (PPCPs) and pesticides; (b) wrong management of the service schemes. This research aims to analyze the soil-water interactions, in order to identify the key factors that can influence the water quality during the provision of two different water related agro-ecosystem services. Two test sites (Sant'Alessio Induced RiverBank Filtration plant, and San Niccolò Phytotreatment plant), were monitored for 3 years, in order to evaluate the water quality during the provision of the services and the influence of each test sites unique meso-scale conditions on the efficiency of the services provided. Additionally, column tests, specifically designed to minimize pharmaceutical adsorption, were run for 6 months in order to evaluate the soil buffer capacity of the two test sites at a lab-scale. The Induced RiverBank Filtration (IRBF) system showed to be strongly influenced by the river water quality. The 80-100% of the water pumped at the IRBF originate from the river, and therefore the surrounding agricultural area does not represent a relevant source of contamination, even if periurban non-collected drainage and treated sewage systems present high concentration of undesirable compounds. No monitored pollutants (nutrients, pathogenic microbes and PPCPs) present in the river water persist after filtration through the riverbank, a process which was estimated to be shorter than 30 days. The evaluation of phytotreatment (PT) plant site hydrodynamics shows potential sources (natural-geogenic) of contamination. Therefore, site characterization prior to the design of eco-engineered solutions is proved fundamental for the efficiency of the PT plant. However, the results of the mass balance show a high capacity of the system to remove nutrients from agricultural drainage water (about 50% and 30% for P and N species respectively). The analysis of the soil characteristics confirmed high differences between the properties of the two test site soils; in particular related to the organic carbon contents (48% and 0.9% for the soil from the PT plant and for the soil from the IRBF plant respectively). During the column test, significant differences between the soil types were detected in the filtrating water quality. The variations are related to the different soil characteristics, which determine the buffer or leaching of different compounds. Furthermore, changes in the buffer effect of the soils were observed during the test, meaning that the soil characteristics were altered. Both the IRBF and the PT plant were found to be very complex and highly dependent on the specific site conditions. Based on the characterizations of the test sites (at meso and lab scale) and the management systems, the safety of the groundwater resource were evaluated. For the detected issues, specific monitoring schemes to assure safe operation also during extreme events are suggested.