Membrane Product Specific Challenge Test Results under the LT2ESWTR with Endospores as Cryptosporidium Surrogate

The challenge testing of four low pressure membranes manufactured by two companies, Siemens and DOW Chemical, was performed in a laboratory in accordance with the Membrane Filtration Guidance Manual (MFGM) developed for the Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR). Direct integrity testing (DIT) was performed before and after challenge tests to assure module integrity. Based on the literature review findings, and the challenge tests of three different membrane products representing two membrane fiber materials, it was concluded that endospores of the acterium B.atrophaeus can serve as a conservative surrogate for Cryptosporidium oocysts.