Long-Term Testing of the RALEX® Membranes in the Chlorine Dioxide Solution

Abstract

Electrodialysis is widely used for whey desalination. Cleaning-in-place (CIP) is required in order to remove fouling from the membranes and to eliminate microorganisms in the equipment. CIP usually consists of rinsing with cleaning agent solutions (e.g. NaOH and HNO₃), which is not always effective enough for the microorganism control. In this case, additional disinfection steps may be necessary. Unfortunately, most of the disinfectants widely used in the food industry damage ion-exchange membranes. As ClO₂ appears to be a promising candidate, membranes were exposed to various concentrations of ClO₂ (0.15–3.0 ppm) for 10 weeks in order to evaluate its influence on membrane properties. Although there was a small decrease in ion exchange capacity after exposure to 3.0 ppm, there was no significant effect on membrane specific resistance, permselectivity or overall membrane performance in desalination tests.