PURPOSEThis information paper provides an in-depth review of filtration (including adsorption and ion exchange) as a pathogen and particulate reduction mechanism when treating natural waters. This paper is intended to assist the reader in evaluating the capabilities of Individual Water Purification Devices (IWPDs) using size exclusion, adsorption, and/or ion exchange to reduce disease-causing bacteria, virus, and protozoan cyst populations, as well as turbidity causing particulate matter.
REFERENCESAppendix A contains a list of references.
INTRODUCTION
BackgroundUnderstanding the ability of filtration to reduce disease-causing microorganisms is important in protecting Soldiers, who are considering using this technology, from acute health threats posed by these microorganisms. Soldiers deployed beyond traditional field drinking water supplies must have access to potable water. Using IWPDs is one way to provide microbiologically safe water in these situations. These IWPDs must protect the Soldier from acute microbial health threats. The U.S. Environmental Protection Agency (EPA) Guide Standard and Protocol for Testing Microbiological Water Purifiers (reference 1) provides performance standards by which an IWPD using filtration can be evaluated. The performance standards are a minimum 6-log reduction/inactivation of bacteria, 4-log reduction/inactivation of viruses, and 3-log reduction/ inactivation of protozoan cysts (typically Giardia or Cryptosporidium). IWPDs meeting these standards are considered effective at reducing disease causing bacteria, viruses, and protozoan cysts. Some IWPD manufacturers test their devices using this protocol. This is considered the best way to evaluate the IWPDs pathogen reduction capabilities. In the absence of that testing data, this information paper can be used to gain an understanding of the advantages as well as limitations of filtration and help determine if an IWPD using filtration could successfully meet the EPA Guide's minimum performance standards.
Origin of Filtration for Water TreatmentFor the purpose of this paper, filtration will be used broadly to incorporate separation by (1) granular media, (2) size exclusion (e.g., membranes), (3) electrochemical adsorption (e.g., activated carbon), and (4) ion exchange (e.g., anion, cation exchange). Filtration is a well-
Report Documentation PageForm Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subje...