AWWA WQTC69386

The Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) was promulgated to reduce the incidence of acute illness as a result of pathogens in drinking water. One tool to achieve this goal is the implementation of low-pressure membrane technology, such as microfiltration and ultrafiltration. In order to be granted appropriate log-removal credit under the provisions of the rule, U.S. Environmental Protection Agency (USEPA) requires that low-pressure membrane systems conduct a direct integrity test at least once each day that the system is in operation. While the LT2ESWTR provides a frame-work for calculation of the log-removal, latitude is provided to permit vendor specific calculations. The most prevalently utilized membrane technologies in North America utilize a direct integrity test consisting of a pressure hold test. To calculate the system log removal based upon the pressure hold test results, a number of variables are incorporated, including viscosity, temperature, system filtrate volume, atmospheric pressure, system flow rate. Each of these parameters are subject to a degree of uncertainty. In order to evaluate the cumulative impact of the uncertainty, Monte Carlo simulation was performed. Monte Carlo simulation is a numerical method frequently utilized to develop numerical solutions to problems incorporating uncertainty in the input variables. The authors evaluated the calculated log-removal for a membrane filtration plant to quantify the degree of uncertainty that exists in each measurement. Includes 3 references, tables, figures.