AWWA ACE70669

Erie Water Works (EWW) conducted an evaluation of the use of membrane filtration to replace an existing conventional filtration process. EWW's objective was to provide filtration that will reliably produce water exceeding the Safe Drinking Water Coalition requirements and prepare the utility for more stringent drinking water regulations, while providing increased public protection against acute illness caused by Cryptosporidium. EWW conducted a pilot study with two different low-pressure submerged membrane system manufacturers, along with a log removal validation study for each membrane system, using fluorescing microspheres as the surrogate for the pathogenic organisms. The Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) requires that membrane filtration systems used for Cryptosporidium removal undergo a challenge test to establish the maximum log removal value (LRV) that a membrane system can achieve. While a number of third-party challenge tests for both products have been historically conducted, EWW requested that additional testing be conducted at their facility as a demonstration. Following evaluation of various challenge test methods, EWW selected fluorescing microspheres as surrogates for Cryptosporidium for the challenge study. The basic protocol was modeled on guidance provided in the United States Environmental Protection Agency (USEPA) Membrane Filtration Guidance Manual. The microsphere testing concluded that both low-pressure submerged membrane systems achieved LRVs greater than 5.3. These results confirm that low-pressure membrane filtration will meet the requirements of the LT2ESWTR. EWW intends to proceed with full-scale design of a low-pressure submerged membrane filtration system. Includes 6 references, tables, figures.