Technology Assessment of Water Treatment Devices for Small-Scale Production

Potable water supply is a long-standing challenge for military missions and critical to maintaining warfighter performance. The U.S. Armed Forces currently rely on large, centralized reverse-osmosis (RO) water-treatment systems for production of potable water, which must then be distributed to its point-of-use. Delivering water to remote expeditionary operations is logistically demanding, dangerous, and expensive. The Navy and DoD have recently developed RO desalination systems that adequately scale to the platoon level (45 warfighters), but further down-scaling to squad level (13 warfighters) or below is a challenge for RO. Other drawbacks of RO include maintenance and lifetime issues associated with the membranes and a high consumables burden. Because of increasing global concerns about civilian drinking water supplies, many alternative desalination/purification technologies are under development, including various electrochemical methods(e.g., capacitive deionization) that are electrically driven, thermal processes that use solar input, and atmospheric-water harvesting techniques that bypass the need for direct desalination. Herein, we summarize performance requirements for small-scale (squad-level to individual) water-treatment systems, recount recent development and demonstration of RO technologies for Navy and DoD uses, and highlight more nascent investments in alternative (non-RO) approaches at the time of this report. We provide an assessment of emerging desalination/water-generation techniques, noting particularly their advantages and disadvantages interims of scalability, energy efficiency, and throughput. Electrochemical approaches that borrow materials and mechanisms from aqueous battery chemistry are projected to be the most relevant for direct desalination needs with such requirements, while atmospheric-water generation should also have utility to meet potable water needs in certain environments and missions.