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In the development of tactical water purification systems, the U.S. Department of Defense (DoD) has increasingly used commercial off-the-shelf (COTS) products and components.
Driven by the war on terrorism and the deployments in Afghanistan and Iraq, the DoD has rapidly developed new tactical water purification systems that employ commercially available ultrafiltration (UF) membrane technology, sometimes in conjunction with reverse osmosis (RO).
The new systems can be easily transported to remote locations and quickly set up to produce safe drinking water from almost any available raw water source.
Transportable in a C-130 Plane
The first measurable objective of the Expeditionary Unit Water Purifier (EUWP) program, initiated by Congress in 2003, was to develop a transportable water treatment system that could be airlifted in a single C-130 transport plane and be quickly assembled to produce 100,000 gal per day (gpd) of purified water from seawater.
Two first-generation EUWP demonstration systems have been built by Village Marine Tec of Gardena, Calif. The system can be set up in as little as eight hours and is completely self-contained, requiring only diesel fuel to run power generators.
The 20-ft-long by 8-ft-wide by 8-ft-high skid containing a UF system can produce 200,000 gpd of drinking water from a contaminated water source, enough to support the needs of between 40,000 and 50,000 people. An identical-sized skid containing an RO system can receive pretreated water from the UF skid and purify 100,000 gpd when the source is highly turbid surface water or seawater.
Each EUWP uses 16 TARGA-10 hollow fiber UF cartridges designed and manufactured by Koch Membrane Systems, Inc. The 10-in.-diameter cartridges contain 35-mil hollow fiber membranes.
The EUWP systems were quickly put to the test. When Hurricane Katrina struck, the systems were undergoing final demonstration testing. Within days, a request came from the Mississippi Emergency Management Administration to send the unit to Biloxi, Miss., to provide potable water to the Biloxi Regional Medical Center.
The Expeditionary Unit Water Purifier provided potable water to the Biloxi Regional Medical Center after Hurricane Katrina struck.
The EUWP arrived and was immediately set up on the beach by engineers from the U.S. Department of the Interior’s Bureau of Reclamation and U.S. Army TARDEC. Within hours, it was converting seawater into clean water suitable for use in the hospital.
Transportable in a HMMWV
The DoD has also used state-of-the-art membrane technology for its much smaller and more portable scale lightweight water purifier (LWP). The compact LWP produces 125 gal per hour from fresh or brackish water and 75 gal per hour from saltwater.
The LWP, designed by Mechanical Equipment Company, Inc., is light enough to be carried by four soldiers and simple enough for two operators to set up and begin producing water in 45 minutes. The system can be transported in a high-mobility multipurpose wheeled vehicle (HMMWV) and in a single lift of a helicopter, such as the UH-60 Black Hawk.
By using UF membranes to pretreat water before processing by RO, this design replaces the Army’s previous generation of portable water processing equipment that pretreated the RO feed water with multimedia filters and disposable cartridge filters.
The ultrafiltration process in the new LWPs avoids the need to replace and resupply disposable filters, since the UF cartridges can be cleaned and reused.
The 5-in.-diameter ROMIPURE cartridges contain the same 35-mil hollow fiber polysulfone membranes as the much larger TARGA-10 cartridges used in the EUWP. The UF membrane pores have a 100,000 Dalton nominal molecular weight cutoff, and consistently produce filtrate water with less than 0.1 NTU, a more than tenfold improvement compared to multimedia and cartridge filters.
The U.S. Army awarded the company an exclusive multiyear contract for 400 LWP units. About half have already been delivered and some are being used in Iraq and Afghanistan.
Commercial Off-the-Shelf Membrane Technology
The EUWP and the LWP exemplify the benefits of the COTS procurement process. By incorporating UF hollow fiber membrane technology from the commercial market, the DoD, its collaborators and suppliers were able to design and build high-performance mobile purification systems on an aggressive schedule.