Cleaning efficiency and impact on production fluxes of oxidising disinfectants on a pes ultrafiltration membrane fouled with proteins

The cleaning step in the ultrafiltration of skim milk is not always complete before the following disinfection start, raising concerns about the effect of disinfectants on any protein remaining. For a Koch polyethersulfone (PES) UF membrane [model HFK131], the fouling in skim milk UF is exclusively due to proteins. Used in right quantity, hypochlorite well finishes the cleaning and can also be used alone as a cleaner [removing 95% of the proteinaceous fouling]. However, if the amount of hypochlorite is not sufficient to end the cleaning, this can lead to large reductions production flux [a 13% decrease on skim milk flux was observed]. Other oxidants such as PVP-iodine, hydrogen peroxide, peracetic acid and sodium perborate do not achieve hydraulic cleanliness [90% of flux recovery]. Oxidants based on hydrogen peroxide and PVP-iodine, when used on a membrane which was still fouled by protein, yielded flux recovery worse than for a single rinsing.