Three Steps to Control Biofouling in Reverse Osmosis Systems for Water Reuse

The impact of new membrane chemistry, feed spacer thickness and configuration, and the use of non-oxidative biocide upon feed-side pressure drop and membrane flux were presented. On all scales (laboratory, pilot and field scale) the benefits of the individual biofouling control techniques were demonstrated. A suggested path forward is to use an integrated approach for biofouling control and not to rely on stand-alone fouling control strategies. A fouling resistant membrane combined with an optimized feed spacer is recommended whenever a high potential for biofouling is seen. The introduction of targeted biocides upstream of the RO will result in improved fouling prevention and help to ensure long term trouble free operation. This conclusion was supported by an economic evaluation showing that the cost embodied in the initially higher price of a premium RO element or the increased OPEX cost due biocide dosing can be fully recovered when the life cycle cost is considered.