Effects of the Membrane Filter Properties on the Fouling Mechanism in Potable Water Treatment

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Many water treatment plants (WTPs) in the Province of Manitoba struggle to meet the latest, rigorous provincial quality standards and have been upgrading their water treatment process to a dual membrane system, which feature microfiltration(MF) and nanofiltration(NF) in series. The raw water in Manitoban Rivers contains high concentrations of manganese, occasionally causing "brown water" in the tap water. Manganese is often bound with the Natural Organic Matter (NOM) present in the water. The NOM is also a pre-cursor to potentially carcinogenic disinfection by-products, trihalomethanes (THMs), therefore, many water systems are motivated to improve their removal of NOM. NOM is well known as the worst foulant in membrane filtration processes. The extent of the organic fouling is determined by the interaction of the particular membrane material with the local mixture of organic compounds in the water. In this research we propose to investigate these interactions. Liquid flow (flux) through four different membrane samples will be tested in the bench scale membrane filtration experiments. The fouling cakes accumulated on the membrane filter will be analyzed. The results of these analyses will allow for identification of the components in the filtered water that have the highest propensity to foul the membrane. These components have to be removed from the water prior to membrane filtration and have to be addressed in the design of the water pre-treatment. The laboratory obtained flux profiles accompanied by the information of the compounds causing fouling will provide WSP with a new tool not only in the selection of an appropriate nanofiltration membrane, but also a strategy for the design of the pre-treatment process. Therefore, the results of this research can ultimately influence treatment design standards for water systems. This project will also contribute to further development of new, bench-scale membrane filtration unit recently built at the University of Manitoba, providing students training both in the lab and at the water treatment plant. This research will result in significant savings to municipalities, as well as provide highly qualified personnel for the industry.