AWWA WQTC58930

In the practical operation of MF/UF processes, membrane integrity is critical to assure the consistent production of high-quality finished water. However, there is currently a lack of availability of detailed assessment knowledge bases and selection methodologies for recommended integrity monitoring methods, especially those derived from full-scale testing. Previous work in this area has focused mostly at pilot scale assessment. While this provides useful information, there is a critical need to perform and present a more detailed, realistic, and systematic assessment of integrity monitoring methods derived from full scale testing. Full-scale testing is essential to capture the realistic dilution effects that are not available through pilot testing. This project focused on assessment of existing and improved integrity monitoring methods for MF/UF processes from full-scale testing. Testing of several direct and indirect monitoring methods was performed at six membrane plants. Four of the participating plants are located in the U.S., while the remaining two are located internationally. These plants range in capacity from about 7 to 24 mgd and represent a range of design and operational parameters characterizing available MF/UF systems. Full-scale microbial challenge testing with Bacillus subtilis spores was also included at two MF/UF plants to validate the monitoring methods. The testing was performed at one full-scale membrane rack at each plant. Experiments were performed with integral and artificially compromised membranes to monitor, analyze, and compare integrity monitoring signals at various levels of breach. Indirect monitoring methods tested include particle counting, particle monitoring, turbidity monitoring, laser turbidity monitoring, multisensor laser turbidity monitoring, and a "particle amplifier" approach. Includes 5 references, tables, figures.