Fouling of Nanofiltration Membranes by Natural Organic Matter

Nanofiltration membranes (with pore sizes on the order of 10 -9 m) have been shown in pilot plant studies to provide a very effective means of removing natural organic matter (NOM). Removal of NOM from product water results in accumulation of rejected species which may foul the membrane. Frequency and intensity of cleaning, as well as the useful life of membranes, are important process optimization issues which cannot be resolved until membrane fouling by NOM is better understood. In this research we report that the concentration and composition of NOM and cross flow velocity are important factors in affecting the rate of fouling; in addition, fouling must be measured not only by permeate flux decline but also by permeate water quality.