Assessment of wastewater reuse for sustainable crop irrigation: technical, agronomic, environmental, and economic perspectives

The increasing scarcity of freshwater resources poses a major challenge for agriculture, particularly in regions facing climate variability and high-water demand. Wastewater reuse represents a sustainable strategy to supplement irrigation supply while promoting circular nutrient management. This doctoral research investigates the potential of treated wastewater (TWW) as an alternative irrigation source, assessing its agronomic, environmental, and technological implications across multiple levels. The study combines experimental and analytical approaches to evaluate the integration of wastewater reuse within conventional irrigation systems. Field trials conducted at the Smart Fertigation Platform of Cesena (Italy) explored the performance of automated fertigation systems using secondary and tertiary treated wastewater for different crops, focusing on nutrient balance, soil response, plant physiology and crop productivity. Parallel investigations examined irrigation system durability and the occurrence of contaminants of emerging concern, assessing both safety and long-term sustainability of this practice. At the irrigation-district scale, the research assessed the integration of treated wastewater reuse into existing distribution networks through the Cesena WWTP case study. This district-level approach linked effluent quality, crop requirements, and management practices to evaluate environmental and economic co-benefits of wastewater reuse. The study emphasizes that wastewater reuse can simultaneously support nutrient recycling, reduce pollutant loads to surface waters, and enhance the efficiency of irrigation infrastructures, providing an evidence base for regional planning under the EU Regulation 2020/741 framework. Overall, this work advances understanding of the technical and environmental feasibility of wastewater reuse in agriculture and provides practical insights for the design of sustainable, data-driven fertigation and water management systems. Further research should extend towards long-term field validation, the assessment of contaminant fate in different crops edible tissues, and the integration of quaternary treatment technologies and their validation in field conditions.