Colloidal fouling of membrane filters: Constant transmembrane pressure versus constant permeate flux
Hovinga, Rik Martyn
Wiesner, Mark R.
Master of Science
A previously developed model describing colloidal fouling of membrane filters (Sethi, 1997) predicts that operation under conditions of constant transmembrane pressure should result in less fouling than operation at constant permeate flux. These predictions were tested in a series of laboratory experiments. The influence of particle size and mode of operation on the specific permeate flux performance of a cross-flow flat slit membrane unit, was evaluated using an ultra-filtration membrane mounted in an existing Osmonics SEPA CF membrane module. Experiments of three hours in duration were conducted with polystyrene latex particles (100 nm, 430 nm, and 1000 nm) which resulted in a strong correlation between particle size and specific permeate flux. Consistent with theoretical prediction, less fouling was observed in a constant pressure mode of operation. However difference in between the two modes of operation with different particle sizes were not as great as anticipated. Indications for a strong influence of the flowing layer on the specific permeate flux performance were found for the 1000 nm particles. Future research for a better understanding of the role of the flowing layer and cake resistance in membrane fouling is needed and recommended.
Environmental science; Environmental engineering