Emergency Response Water Treatment Systems
When natural disasters such as hurricanes, floods and earthquakes strike, safe drinking water can be compromised, limited or unavailable. During these situations, there is a need for emergency response water treatment systems (ERWTSs) that can treat water of unknown quality to safe drinking water levels. ERWTSs can be used by utilities and states to provide potable water to critical infrastructure (hospitals and fire and police stations), or to provide non-potable water for showering, etc.
An ERWTS can be composed of many components to form a skid-mounted treatment train designed to provide enough water for a small community or a single building, or it can be a handheld device to treat water for one individual. Almost all ERWTSs use more than a single treatment process, including the handheld individual water purification (IWP) devices. Most ERWTSs use a combination of mechanical filtration, absorptive media, and chemical or ultraviolet radiation (UV) disinfection processes.
ETV DWS Center
The U.S. EPA Environmental Technology Verification (ETV) Drinking Water Systems (DWS) Center is presently evaluating an ERWTS developed by the U.S. Army, called the Expeditionary Unit Water Purifier (EUWP). The EUWP was used to provide potable water to a hospital in Biloxi, Miss., in the aftermath of Hurricane Katrina while the water system was being repaired. The EUWP is a skid-mounted system designed to fit into a C-130 transport aircraft. The system can produce potable water from almost any freshwater or seawater source. The EUWP uses a bank of ultrafiltration (UF) membranes, followed by a bank of reverse osmosis (RO) membranes, to treat the raw water. The treated water can be chlorinated and stored in 20,000-gal storage tanks prior to distribution.
For the EUWP ETV testing, existing ETV protocols are being applied with a four-week testing period emphasizing reduction of microorganisms and chemicals naturally present in the water source. The EUWP is being tested on three different water sources: secondary wastewater, seawater and a freshwater lake.
The EPA ETV DWS Center is also verifying three point-of-entry (POE) treatment systems that could be used in cases where a water supply is intentionally or accidentally contaminated. The systems are being tested for their ability to reject or reduce microorganisms and common, but acutely toxic, chemicals. The three POE systems use combinations of UF membranes, RO membranes, activated carbon, ozone and UV in their treatment processes. The results are expected to be published in October 2006.
If a point-of-use (POU) or IWP ERWTS uses a chemical for disinfection, the device must be registered as a pesticide with the EPA’s Office of Pesticide Programs. The use of antimicrobial chemicals is regulated under the Federal Insecticide, Fungicide and Rodenticide Act. One element of registration is submission of antimicrobial efficacy data to the EPA for review. To satisfy this requirement, the EPA requires testing according to the U.S. EPA Guide Standard and Protocol for Testing Microbiological Water Purifiers (1987).
NSF offers two certification protocols to test an ERWTS’s ability to remove, kill or inactivate disease-causing bacteria, viruses and cysts. Both protocols are based on the EPA microbiological purifiers guide standard. NSF Protocol P231 Microbiological Water Purifiers (P231) applies primarily to POU devices, and in addition to performance testing, incorporates the material safety and structural integrity criteria present in the NSF/ANSI drinking water treatment unit standards. NSF Protocol P248 Emergency Military Operations Microbiological Water Purifiers (P248) applies to handheld IWP devices, and was written primarily for military end use. P248 includes ease-of-operation requirements, in addition to performance testing.
The Air Force Field Water Medic Program conducted a market survey in 2004 that identified commercially available IWP devices with possible applications for military use. NSF Protocol P231 was identified as the preferred test approach to evaluate the performance of IWP devices. NSF, in turn, was selected as the organization of choice to conduct the third-party, independent testing.
The U.S. Army Center for Health Promotion and Preventative Medicine, in conjunction with NSF International, developed a protocol that addressed the specific needs of the military. The resulting effort was P248. The Army concluded that IWP devices certified as compliant with NSF P248 could be used by deployed personnel with a greater measure of assurance that the treated water would be of acceptable quality and would not cause acute illness or disease.
In summary, there are many publicly available protocols that address ERWTSs. These protocols were developed with assistance from the EPA and Army, and involved many experts and stakeholders from the drinking water community. Evaluation of ERWTSs will help the public and military personnel in the selection of treatment equipment to address the challenge of safe drinking water when source quality is compromised or unknown.