The best way to clean 3M Liqui-Cel membranes is to use 4 to 5% of NaOH solution in the water at 30 to 40ºC, circulate the cleaning solution counter current of the original process for 2 hours. Water flush the module, and use 2% HCl acid in the water at room temperature for one hour. Water flush, then run N2 or CO2 in the gas side to flush any condensation. This dries the gas side of the membrane. We have a simplified cleaning procedure for the beverage industry. Please don’t use H2O2 for a long time, in order to avoid any oxidation of the membrane.  3M provides Cleaning Guidelines for typical maintenance and more challenging cleaning procedures – however, if fouling is substantial, it may be necessary to replace the contactor(s).   Consider the source of fouling and install prefiltration/treatment to prevent future fouling.