Technoeconomic feasibility of decentralized desalination in the Navajo Nation

Abstract

The Navajo Nation, located in the southwest United States, faces a significant water stress issue, with approximately 30% of households lacking access to piped water. For many, connection to a piped network is infeasible and decentralized solutions, like desalination, have encountered barriers to adoption. This study evaluates the Navajo Nation’s geography, environment, and infrastructure to justify decentralized desalination. A diverse group of stakeholders were interviewed to gain comprehensive insights into the underlying challenges and possible value-added solutions. Analyzing these interviews revealed a cultural aversion to wastewater, a strong sensitivity to operating costs, and two potential system sizes: home and community. With financial sustainability being an important requirement for several stakeholders, a first-order economic analysis of both system sizes was conducted. Home systems present strong potential for economic viability but community systems struggle to compete in this region due to low population density. Using the elucidated design requirements for home systems, electrodialysis (ED) and reverse osmosis (RO) were evaluated for technical feasibility. While RO systems, unlike ED, are commercially available at this scale, RO wastes 50-80% of the feedwater while ED wastes < 30%. Both technologies have strong technical feasibility for this region and both will be field tested to understand long-term maintenance requirements and user perception of wastewater.