Effect of feed spacer thickness on the fouling behavior in reverse osmosis process — A pilot scale study

• Long term pilot test with RO modules applied different feed spacers was conducted.
• Membrane fouling mitigation effect of thicker feed spacer was validated.
• Fouling load distribution effect of thicker feed spacer case was investigated.
• Fouling intensities were compared by instrumental analysis of membrane coupons.

The performance deterioration of RO membrane processes caused by the accumulation of rejected solutes on membrane surface is an inevitable phenomenon in membrane processes. The feed spacer in spiral wound reverse osmosis (RO) membrane modules can provide the structural support to keep feed channel open and also allow turbulent flow to mitigate solute concentration build-up at the vicinity of membrane surface. The objective of this study was to investigate the effect of feed spacer thickness on both membrane fouling behavior and cleaning efficiency in a pilot test during a 659 h operation. Furthermore, fouling load distribution was studied by measuring normalized differential pressure of individual elements in pressure vessels. Foulant analysis according to feed spacer thickness was also conducted to compare fouling propensities. This study showed that a thicker feed spacer could reduce membrane fouling and subsequently decrease membrane cleaning frequency and allow an even fouling load distribution along the modules installed in a pressure vessel.