Optimizing the Nonconventional Water Supply across the Water-Energy-Food Nexus for Arid Regions Using a Life Cycle Assessment

Abstract

The escalating global water scarcity crisis has propelled an increasing dependence on nonconventional water sources, particularly desalination and treated wastewater. Assessments of the United Nations’ water-related sustainable development goals on a global scale have brought to light a paradoxical trend of localized water decisions that have exacerbated long-term water scarcity issues. This study employs a water-energy-food (WEF) nexus framework to evaluate nonconventional water resources, fostering an understanding of interconnected water dynamics and promoting enhanced resource utilization and sustainability. Utilizing a multicriteria mathematical model grounded in life cycle assessment (LCA), this study optimizes water usage across the WEF nexus. The augmented simplex lattice mixture (ASLM) design is employed to identify WEF optimal frontiers under varying priorities within the hyperarid region of Kuwait. The findings underscore the significant influence of hidden virtual water on overall outcomes. Specifically, for wastewater permeate treated by reverse osmosis (WWROP), each cubic meter of permeate utilizes 1.78 m3, with 90% consumed virtually for chemical production. Within the water-for-food nexus, the results reveal that tertiary-level treated wastewater (WWTTE) contains 67% of the required phosphate for fodder cultivation, leading to an additional 24.89 t/ha of fodder compared with WWROP and desalinated water. An evaluation of the energy-for-water nexus indicates that WWTTE and WWROP exhibit the lowest cumulative energy demand. Consequently, these results advocate for the utilization of WWTTE over WWROP and desalinated water to enhance the overall WEF nexus. Research suggests that a misrepresentation of the local context in WEF solutions may contribute to the slow adoption of WEF concepts in governance and political reform. This study addresses the pressing issue of water scarcity through the application of LCA. This analysis involves the evaluation of commercially available nonconventional water technologies concerning demand requirements across municipal, agricultural, and industrial sectors. A mathematical model is employed to assess and optimize the demand and supply assignment problem considering various impacts associated with WEF frontier priorities. The primary focus of this research is on the critical water scarcity challenges faced by hyperarid regions. Specifically, this study delves into the interrelationships among water, energy, and food consumption and their collective impact on these precious resources. Employing LCA, sensitivity analysis, and optimization models, this research scrutinizes the existing state of water, energy, and food in Kuwait. The aim is to provide specific recommendations that contribute to enhancing the equilibrium among these three vital resources.