Brine Recirculation RO System


Brine recirculation is a concentrate reduction approach that has been tried in various forms to improve RO recovery. In certain forms, this approach has now been licensed and commercialised by several technology providers. Some technology providers have partnered with membrane suppliers to develop RO projection software to allow engineers and consultants to develop brine recirculation designs and models. Brine recirculation RO designs can achieve in excess of 95% recovery in a single stage configuration under favourable feed water conditions.

The brine recirculation approach operates the RO as a semi batch process. In the production mode, the RO operates as a dead-end filter with the concentrate being recycled back to the RO inlet by a low head pump. The recirculating concentrate and reduced membranes per pressure vessel increase the cross fl ow and provide improved fl ux rates across the pressure vessel. As the salinity of the feed water increases through the production cycle until the desired recovery is achieved, the pressure is gradually increased to maintain permeate flow. In the fl ush mode, the brine fl ush valve opens and discharges concentrate for a pre-set time based on volume of the system. Permeate is still created in this mode.

The routine fl ushing, along with higher salinity achieved in the production mode, disrupts biofouling and scaling mechanisms. Brine recirculation RO systems use traditional RO components such as membranes, pumps, pressure vessels, etc.

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