Recycle array with concentrate

Figure 5.6 shows an RO array with concentrate recycle. A concentrate recycle is generally used in smaller RO systems, where the cross-flow velocity is not high enough to maintain good scouring of the membrane surface. The return of part of the concentrate to... 

REJECT RECYCLE Figure 5.6 Two-by-one array with concentrate recycle. 

The recovery of the BRO unit increased from 50% to 70% when a small portion (<20%) of the BRO reject stream was recycled to the BRO unit inlet, as shown in Figure 3.40 [69]. Reject recycle provides additional fluid flow above the membrane, thereby reducing concentration polarisation and achieving higher flow. Thus, the overall water recovery was 92.5%. The BRO unit was a two-stage, 3 2 parallel pressure vessel array with three elements per pressure vessel (15 elements total). The RO elements were Hydranautics ESPA2+ (20 cm dia.). The average flux was 17—20 Imh. 

Like OCTI, OCTI generally accepts a wide array of monovalent organic cations with molecular weights of <400. OCTI is also present in neuronal tissues and may play a housekeeping role in neurons, taking up excess concentrations of neurotransmitters and recycling neurotransmitters by taking up breakdown products that then reenter monoamine synthetic pathways. 

Figure 2.24 Block-flow diagram of the single-pass RO membrane design given in Table 2.11 with reject recycling. Stream 1 is feed, 2 is blended feed, 3 is membrane array pressurised feed, 4 is reject, 5 is reject/concentrate recycle, 6 is reject-to-drain, and 7 is permeate.

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