Methods to Reduce Membrane Fouling

There are three main factors that contribute to membrane fouling:
  1. Feed stream properties. This includes characteristics such as concentration, pH and ionic strength, dissolved solid content, suspended solid content, etc.
  2. Membrane material and its physical-chemical properties. Membrane pore size, porosity and pore distribution, and membrane surface charge and hydrophobicity in certain pH and ionic strength conditions can contribute to fouling.
  3. Processing variables. Transmembrane pressure, temperature, and cross-flow velocity have a big impact on membrane fouling.
With a better understanding of these factors, several approaches can be taken to minimize membrane fouling:
  • Optimize pH and ionic strength of the feed solution to minimize the adsorption or deposition of the feed materials.
  • Select an appropriate pre-filtration procedure or other means to remove large molecules, since the presence of larger molecules or particles could cause a steric hindrance to the passage of smaller molecules through the membrane.
  • Select a membrane with an optimum pore size to result in good separation performance as well as optimized permeate flux.
  • Optimize the operating conditions. This includes increasing transmembrane pressure to maximize flux without introducing more fouling potential.
  • Increase the cross-flow velocity, which generally results in an improvement in permeate flux.