A novel method to control biofouling on the surface of membrane filters using UV irradiation though optical fibers

Membrane processes such as microfiltration, ultrafiltration, nanofiltration and reverse osmosis have been popular subject for researchers interested in water filtration system. One of the main problems with such membrane system is biofouling, which is caused by deposition or growth of microorganisms on membrane surface. One solution to this problem, as it has been used for many years now, is chlorination. However, it has a number of side effects including over chlorination, odor problems, and formation of highly carcinogenic disinfection by-products [1-3]. As an alternative solution to biofouling, UV irradiation has been used to clean the membrane system. However, it is difficult to accomplish complete disinfection with normal UV source because UV cannot be irradiated onto every part of membrane. This research focuses on UV disinfection using optical fibers, which allow the UV ray to be delivered to any site on membrane. Research GE has been developing membrane water filtration system for applications in developing world. Professor Kim’s lab was funded to evaluate the performance of GE’s membrane unit under varying water quality conditions. The student will focus on understanding the biofouling process and developing a novel way to mitigate membrane fouling. More specifically, the student will use UV irradiation process with optical fibers to control membrane biofouling, and explore the optimal configuration and operating conditions based on cell deactivation or growth retardation, water productivity through membrane filtration, and equipment and operation costs. A schematic diagram of a membrane-UV irradiation system is shown in Fig. 1. Microfilatration or ultrafiltration membranes of hollow fiber types are used. Optical fibers are placed among the membrane fibers as Fig. 2. Fig. 1. A schematic diagram of a lab-scale membrane-UV irradiation system. Fig. 2. A hollow fiber membrane module equipped with UV irradiation Experiments will be performed in these manners: i) Comparison of biofouling with and without UV irradiation – During filtration of microorganisms such as E. coli with and without UV irradiation, permeability (water productivity) will be monitored by measuring permeate flow rate. After filtration, degree of biofouing will be investigated by cell counting or cell activity test for cells in retentate and Feed Tank Permeate Reservoir UV source Membrane module Raw water (Retente) Raw water (Feed) Membrane Optical fibers Filtered water (Permeate) UV source