Bacillus endospores Cryptosporidium Ultrafiltration Membranes

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Abstract

The U.S. Environmental Protection Agency (EPA) Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) allows the use of a Cryptosporidium surrogate for the required product-specific laboratory challenge study, provided the surrogate is conservative. The EPA Membrane Filtration Guidance Manual (MFGM) discusses use of endospores of the bacteria Bacillus subtilis as a surrogate, but states, ﾓBecause there is limited data currently available regarding the use of Bacillus subtilis in membrane challenge studies, a characterization of this organism would be necessary to determine whether it could be used as a Cryptosporidium surrogateﾅﾔ The MFGM also states, ﾓBased on the sizeﾅBacillus subtilis could potentially be considered a conservative surrogateﾅpending a comparison of other characteristics (e.g., shape, surface charge, etc.)ﾅﾔ NSF International conducts ultrafiltration (UF) membrane module laboratory challenge tests for the EPAﾒs Environmental Technology Verification (ETV) Program, and also for NSF performance certification of UF modules. Low-pressure UF membrane modules manufactured by Siemens Water Technologies Corp. (Siemens), Dow Chemical Co. (Dow), and Hyflux Membrane Manufacturing (S) Pte. Ltd. (Hyflux) were tested at NSF Internationalﾒs laboratory in accordance with the EPA LT2ESWTR, and EPA MFGM.

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