Removal of biofilms formed on ion-exchange membranes in ultrafiltration permeates of secondary dairy raw materials

Abstract

The modelling of biofilm development on MK-40 and MA-41Π ion-exchange membrane coupons was conducted in skim milk, sweet whey and acid whey ultrafiltration permeates. The membranes were suspended in permeates for up to five days at the room temperature. The incubation was followed with cleaning procedure including water rinsing, acidic, enzymatic and alkaline steps. The efficiency of each step was estimated by the optical densities of waste cleaning solutions relative to original values prior to cleaning. Cleaning efficiency was influenced by the growth medium, type of membrane and incubation time. The biofilms formed in acid whey permeate showed the highest resistance to the introduced cleaning procedure. Moreover, no increase in the optical density of cleaning solutions was observed for 24-h-old biofilms formed in acid whey permeate. Generally, biofilms demonstrated better attachment to MA-41Π membranes. The acidic cleaning step appeared to remove the highest amount of biofilm material from the membrane. However, in some cases, the full cleaning procedure was insufficient to remove a biofilm.