Abstract: The inventive system and method comprises one or more batch closed circuit desalination (CCD) unit(s) linked by conducting lines and valves means to a pressure exchange (PE) means, such that each said CCD can be engaged periodically with said PE means for brine replacement by fresh pressurized feed, thereby, enable a continuous consecutive sequential batch desalination under fixed flow and variable pressure conditions of low energy and high recovery of unchanged flux. The inventive system and method opens the door to large scale CCD systems operated by predetermined fixed set points of pressurized feed low, cross-flow or module recovery, and system recovery, independent of each other, of infinite operational combinations and high flexibility for effective process optimization. The inventive system and method overcome former volume requirement limitations of large scale SWRO CCD installations.

Abstract: An inventive apparatus for closed circuit batch-RO desalination comprising a RO-skid with membrane elements and circulation means for the recycling of RO concentrate through membranes and a designed hydraulic-arm with a disc separating between a section of pressurized hydraulic fluid created by a high pressure hydraulic pump under fixed flow and variable pressure conditions and a section of RO recycled concentrates. The batch desalination sequence is completed when the entire hydraulic-arm volume is filled with hydraulic fluid and thereafter, desalination is stopped, said apparatus decompressed, brine removed and hydraulic-arm recharged with fresh feed before the initiation of a new batch sequence. The inventive apparatus enables RO desalination under the lowest energy and highest recovery prospects not possible by any other RO technique.

Abstract: The retrofit technology utilizes pressurized brine of convention RO to feed a Closed Circuit Desalination (CCD) unit; wherein, further desalination takes place to a desired recovery level. The application exemplified in FIG. 4 is of a retrofit unit comprising a Booster Pump (BP2) for raising pressure of inlet feed; a Circulation Pump (CP) for creating cross flow over membranes (E) in the pressure vessel (M), thereby enable efficient RO desalination; an Actuated Valve (AV) in line with a partially open Manual Valve (MV) to enable periodic replacement of high salinity concentrates with fresh feed without stopping desalination; No Return (NR) valve means to control the direction of flow in the system; and monitoring means such as of electric conductivity (CM) and flow (FM). Periodic replacement of high salinity concentrates by fresh feed initiated at desired high system electric conductivity and terminated at a desired low system electric conductivity, while desalination continued.

Abstract: A inventive two-stage batch-CCD RO system includes two separate batch-CCD units of a different number of modules per stage with more modules in the first-stage—N(1)>N(2). A two-stage batch-CCD process proceeds when both units execute parallel fixed flow variable pressure desalination sequences of same operational set-points [flux, module recovery and batch sequence recovery (R)], with brine of a former first-stage used as second-stage feed. In two-stage batch CCD RO systems of high N(1)/N(2) ratio whereby the relative production of permeates of the two stages complies to: ?(1)>>?(2), most of the permeates are produced in the first-stage under mild conditions and contribute to the low energy and salinity of permeates of the entire process. Compared with the performance of a single-stage batch-CCD RO unit, a two-stage system of the same module-number will render a performance of super RO characteristics, unmatched by any existing RO methods.