AWWA JAW49851

Faced with the need for additional treatment of its finished water stored in the Hollywood Reservoirs, the Los Angeles Department of Water and Power evaluated the efficacy of microfiltration (MF) to meet the requirements of the Surface Water Treatment Rule. This evaluation included a pilot test to assess the MF process and to define the design parameters (flux and frequency of chemical cleaning). Finished water turbidity and particle removal were independent of flux in the tested water. This finding allows the utility to operate the MF system at a flux as much as 50 percent higher than the 67-gfd (114-L/m2/h) flux currently allowed by California regulations. Membrane resistance was used to evaluate the system performance under variable operating conditions of temperature, flux, and pressure. A design flux of 67 gfd (114 L/m2/h) was projected to yield more than two months (i.e., 66 days) of filter run before chemical cleaning. A higher flux of 80-100 gfd (136-170 L/m2/h) was acceptable with more frequent chemical cleaning of the MF membranes. Includes 22 references, tables, figures.