Effect of Hybridization of Nanofiltration and Reverse Osmosis Membrane on Inorganic Fouling Potential of Groundwater

This paper presents the effect of hybridization of nanofiltration and reverse osmosis membrane on inorganic fouling potential of groundwater. A comparative assessment of three RO plants (using brackish groundwater) located in Delhi region (India) having permeate water flow rates as 12,000 L/h (RO-I), 3,000 L/h (RO-II), and 3,000 L/h (RO-III), respectively. The comparative assessment was performed on the basis of trans-membrane pressure (T1VIP), water recovery, pure water flux, salt rejection, and specific energy consumption (SEC). Samples were characterized as per Indian Standards for drinking water. RO-I showed overall better performance in comparison to other membranes. Inorganic fouling tendency of feed water of all the three RO plants was examined after employing ROIFA (RO inorganic fouling assessment) software. The results predicted by the software showed that the chemical nature of feed water causing scaling in all the three RO plants is sulphate type (with lesser amounts of silicates and phosphates). Lab scale experiments were performed to investigate the effect of hybridization of nanofiltration (NF) and RO membrane in different permeate and concentrate configuration on inorganic fouling potential of the feed water. Based on these experiments, it was suggested that hybrid membrane configuration will help to minimize the effect of inorganic fouling and improve the performance of the membrane system.