(706c) Ceramic Ultrafiltration Membranes for Water Treatment Applications: Effect of Operating Parameters and Water Quality On Permeate Flux

The use of low pressure membrane filtration, microfiltration (MF) or ultrafiltration (UF), is becoming more widely practiced as a pretreatment for desalination of drinking water (AWWA 1996; Jacangelo, Trussel et al. 1997; Adham, Chiu et al. 2005). Polymeric membranes are currently the most commonly used material for low pressure membrane pretreatment, however, they have a number of disadvantages when compared to ceramic membrane materials. Unlike polymeric membranes, ceramic membranes are chemically and thermally resistant, which has important implications for membrane cleaning and operation because ceramic membranes will not degrade when exposed to oxidants, organic acids, strong acids or bases, and high temperatures. Additionally, ceramic membranes have a longer life-span and higher water productivity than polymeric membranes(AWWA 1996). Polymeric membrane MF/UF has been intensively studied and is well established, however, operational experience for ceramic membranes for municipal water treatment is limited and there is little guidance available for system design and operation for ceramic membranes. In the limited published information on ceramic membrane treatment of surface and groundwater, there is conflicting information regarding the values of different operating parameters used for treatment. Understanding the impact of each operating parameter on permeate flux will allow us to realize the full potential of ceramic membranes as a brackish water treatment technology. This study investigated the effects of tubular ceramic membrane channel hydrodynamics, trans-membrane pressure, in-line coagulation, and backwash volume on permeate flux for a ceramic ultrafiltration membrane with a nominal pore size of 0.01ìm. Factorial experimental design was used to construct a controlled set of experiments in which the values of the operating parameters were systematically varied. The measured responses of the system were flux, flux decline, and degree of irreversible fouling. Ceramic membranes are very flexible with regard to the possible values of the operating parameters: channel diameter, TMP, CFV, coagulant dose, and backwash volume. From the factorial experimental design analysis, it was found that in general, when operating at high pressure or with a large diameter membrane channel, high CFV is important to maintain high flux. Using a lower coagulant dose is sufficient if backwash is employed. Backwash volume was the most important factor in reducing the amount of irreversible flux decline in the membrane.