AWWA MTC61213

Membrane fouling is a major problem for surface water filtration by low-pressure membrane systems. This is partially due to the lack of understanding of a very complicated phenomenon that relates to multiple factors. The microfiltration (MF) system at the N.E. Bakersfield Water Treatment Plant experienced rapid trans-membrane pressure (TMP) rise and short runs compared with the initial piloting test and membrane cleaning difficulties, an indication that membranes have experienced serious fouling. Facing a challenging schedule and the difficult task to identify the cause of membrane fouling and to find the solution, technical teams were formed by engineers and scientists from the membrane supplier, consultants and the owner. Through teamwork and cooperation, the teams successfully identified that the membrane fouling was caused by the formation of iron-organic complex. Following the recommendation of changing the coagulant from FeCl₃ to polyaluminum chloride, the plant performance changed dramatically and successfully passed full-flow performance tests meeting all the design criteria. Since then, the plant has been running smoothly with low rate of TMP rise. As a result, both the cost for operating the plant (energy and chemical consumption) and the usage of product water for plant operation were reduced by more than 60%. Includes tables, figures.