Biofouling is the major fouling type occurring in reverse osmosis (RO) plants treating surface water or effluent from a waste water treatment plant. Severe biofouling can result in operational problems, higher energy and chemical consumption and premature membrane replacement. There are different methods to control biofouling. One method is removal of nutrients in the pre-treatment of the membrane filtration plant, another method is periodic removal of biofouling by chemical cleanings or the use of chemicals to prevent biological growth in the RO systems. In this paper the results of experiments with peracetic acid on three different full scale plants are presented. Two of the plants are operated by Evides Industriewater, the third one by Bètawater, a subsidiary company for industry water of Waterleidingmaatschappij Drenthe (WMD).
One of the main outcomes is that biofouling can be controlled fully on reverse osmosis (RO) plants with the applied method with a peracetic acid based product (Divosan Activ). If the proper measures are taken to avoid oxidation damage due to transition metals, this method with the environmental friendly product results in a stable process and savings by a significantly reduced CIP interval.