The graphic illustrates the flow paths in a continuous, feed and bleed membrane filtration plant configuration in spiral-wound membrane format. The feed product typically enters into a feed balance tank. The product is picked up by a feed pump and transferred from the feed balance tank into the first recirculation stage. The stage recirculation pump is responsible for providing adequate flow and pressure conditions for optimal membrane performance. Product is pumped through the vessel, or through multiple vessels in parallel, and across the membrane surface. The permeate is withdrawn from the vessel while simultaneously retentate exits the opposite end of the vessel in a more concentrated state. The retentate flow is split between that which is needed to satisfy the stage recirculation requirements while the remainder progresses forward to the next stage in series. This step-wise concentration progresses throughout a number of stages in series until the final retentate is eventually withdrawn from the plant at the desired concentration and composition.
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