Flux Restoration of Reverse Osmosis Membranes by Intermittent Lateral Surface Flushing for Orange Juice Processing

A newly developed method for washing membranes and the adhesive strength of mandarin orange juice fouling on reverse osmosis membranes were studied. When the permeation rate decreased, it was restored to more than 90% of its original value by a lateral surface flushing of highly accelerated mandarin orange juice driven by the expansion force of compressed gas. For runs of 4–5 hr duration with 10° Brix feed, the normal operating cycle was 45 min of reverse osmosis concentration followed by a 10‐sec wash. Membranes treated at higher temperature have a more condensed surface from which deposits are easily removed. However, high axial flow rates, which are useful for preventing the fouling on the membrane, actually promote permanent fouling.