Life cycle-based evaluation of environmental impacts and external costs of treated wastewater reuse for irrigation: A case study in southern Italy

Treated wastewater (TWW) reuse is a practice involving a series of life cycle environmental and socio-economic benefits and trade-offs. This raises a fundamental question: Is this practice sustainable from the life cycle perspective? In a first of its kind study, using physical and monetized life cycle assessment (LCA) we assessed environmental impacts and external costs of reuse of TWW for irrigation in Trinitapoli, Southern Italy. The release of secondary effluent in the sea and water supply from groundwater was modeled as a baseline scenario. The life cycle impact (LCIA)-model ReCiPe 2016 was applied for analysis. The results at the midpoint level revealed the immanent trade-off between the benefits of reduced water consumption and nutrient pollution and additional impacts for energy and infrastructure for tertiary treatment. The endpoint-based LCA evaluation shows that TWW reuse can bring environmental benefits to human health and ecosystems, even though it is connected to higher damage to resources. Finally, both the physical and economic weighting of LCA results indicated that TWW reuse delivers a lower total environmental impact and total external cost as benefits of reduced water consumption and marine eutrophication counterbalance the reclamation detrimental impacts. A sensitivity analysis using three life cycle methods (IMPACT World+, Environmental prices, and Environmental footprint) provided essentially similar conclusions by portraying TWW as a more advantageous option in a water-scarce region like Trinitapoli. Renewable-based energy mix and energy efficiency can drive the net benefit higher. Overall this analysis delivered two main research thrusts: one detailed environmentally extended LCA profile and the other integrating a financial axis in the LCA-based impacts allowing for a new sustainability-oriented perspective of the TWW reuse in the Mediterranean environment. The model framework can be expanded further to include microbial and chemical risk assessment and impacts of substituted products for more robust, comparative assessments