In 1998 Alameda County Water District (ACWD) embarked upon a plant redesign project with the goal of reducing disinfection by-products, improving plant reliability and reducing reliance on chemical treatment. Ultrafiltration membranes seemed to be the answer, because the understanding at the time was that the process is primarily ?physical? in nature rather than chemical. Twelve years later ACWD has learned that the nature of the ultrafiltration membrane filtration process is indeed driven by chemistry, possibly more than conventional filtration. At ACWD chemical reactions have been the main drivers involved in membrane fouling, membrane performance, backwashing efficiency and chemical cleanings. Operation of the ultrafiltration membrane involved a much more complex interrelated group of variables than originally anticipated by the District. While ACWD was able to resolve some of the issues with the plant, the variable raw water quality and its associated impacts on the membrane fouling has significantly limited the production capacity of the plant. For those water agencies looking at ultrafiltration as a new treatment process, it would be recommended that they give consideration to the following: the variability of the source water, extended pilot testing of the specific membrane material and plant configuration, membrane cleaning regimes, fiber repair techniques and experiences of other agencies using the same raw water source and/ or membrane vendor.
This presentation is available to AMTA Members only.
- Anntoinette Lyons, PE
- Alameda County Water District
- AMTA Annual Meeting, San Diego, CA
- San Diego Biennial
- UF, surface water