Differential pressure in membrane channel caused by foulant capture onto spacers

Feed spacers in spiral-wound reverse osmosis membrane modules are highly susceptible to deposition or attachment of suspended particulates and organic matters in the feed stream. This type of fouling can cause a significant pressure drop along the membrane channel (differential pressure) without much effect on the average permeate flux. In practical applications, membrane cleaning is often triggered when the differential pressure in a membrane channel exceeds a threshold value. A mathematical model was developed to simulate the development of differential pressure in the feed channel resulting from foulant capture by the feed spacers. Simulations were carried out to investigate and demonstrate the effect of various parameters on differential pressures in the membrane channel. Differential pressures observed in a two-stage reverse osmosis water reclamation plant were simulated with the model, and the results showed that the model could adequately describe the increase of differential pressure with operating time in the reverse osmosis plant.