Evaluation of Membrane Fouling in a Pressure Retarded Osmosis System

Abstract

This study evaluated the fouling of a forward osmosis membrane in a pressure retarded osmosis (PRO) system using Aldrich humic acid (AHA) as a model foulant. Fouling behaviour was evaluated quantitatively by observation of the decline in water permeability in the fouling tests: when AHA and CaCl₂ were added to the feed solution (FS), severe fouling (51 ％ decline) occurred; when only AHA was added to FS, moderate fouling (23 ％ decline) occurred. Photographs of the membrane surfaces after fouling tests indicate that the severe fouling is due to the formation of a dense layer of cross-lined AHAs with Ca^2＋ on the membrane surface of the FS side.