AWWA MTC61130

Low-pressure membrane technologies are playing an increasingly important role in the treatment of water sources used for drinking purposes. These membranes are generally classified as either microfiltration (MF) or ultrafiltration (UF). Although it is generally assumed that UF membranes provide effective virus removal and MF membranes do not, these classifications do not accurately describe their capabilities to remove a wide array of microorganisms. As a result of the exponential growth in the membrane market, it is anticipated that new membranes will be developed for water treatment purposes. Membranes have traditionally been characterized based on nominal pore size designations or molecular weight cutoffs (MWCOs). However, assumptions about microbial removal based on these descriptions can be inaccurate. Consequently, an AWWARF-funded study was undertaken to characterize membranes at bench scale based upon their capability to remove specific microorganisms. A previously developed, peer-review protocol was employed to develop a microbial removal rating system for membranes. Materials and methods used include: low-pressure membrane testing unit and membrane modules; disinfection of experimental system; organisms used for bench-scale challenge experiments; microbial challenge experiments; determination of specific flux. Analytical methods are given for: pH; temperature, conductivity; chlorine preparation for membrane cleaning; and, bacteriophages. Includes 6 references, tables, figures.