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The decline in membrane performance due to both biofouling and particulate fouling is a major issue for membranes in the water treatment industry. In spiral wound modules, commonly used in reverse osmosis and nanofiltration, the presence of feed spacers results in an increased potential of fouling. We describe a novel cleaning method to be used in the restoration of membrane module performance. The method described here involves the use of water saturated with dissolved CO 2 at higher pressures and rinsing of the fouled membrane/ spacer channel at a lower pressure. Due to depressurization, bubbles nucleate at spacer filaments and improve the cleaning efficacy significantly. The study compared the cleaning efficacy of three methods in the removal of fouling from a membrane/spacer channel; water rinsing, water/N 2 sparging, and water/CO 2 (dissolved) nucleation. Using water rinsing, 40% of the fouling on the spacer-filled channel could be removed; a water/ N 2 mixture removed 85% of the fouling. With the dissolved water/CO 2 , there was complete removal of the fouling (all measured as restoration of the hydraulic resistance of the clean channels). Such an efficient tool to recover the performance of severely fouled desalination membrane modules could replace or reduce today's expensive, sensitive, and chemically intensive cleaning processes.

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