Scaling Prediction in Reverse Osmosis Systems: Barium Sulphate

88 89 Barium sulphate scaling in reverse osmosis (RO) causes flux decline and potentially severe membrane damage. Existing methods e.g. Du Pont, predict barite scaling when the RO concentrate is saturated. However, precipitation in supersaturated concentrate may be limited by slow nucleation kinetics, expressed as long induction times. Induction time decreases, hence precipitation is more likely, with supersaturation and temperature. This research aims to develop a more realistic method to predict barite scaling based on the assumption that a threshold induction time can be defined which should not be exceeded to prevent scaling. Induction times were calculated for supersaturation (determined using the Pitzer model) and temperature data from an RO pilot plant from a relationship derived from measured induction times at 25 °C. Safe (μ10 hours) and unsafe (