Experimental Batch Counterflow Reverse Osmosis for Brine Concentration

A pilot-scale osmotically assisted reverse osmosis (OARO) system is evaluated for high-salinity brine concentration beyond the limits of conventional RO. The batch counter-flow RO configuration with separate concentrate and diluate streams achieves theoretical dewatering of synthetic RO brine (70 g/kg salinity) to 102.4 g/kg concentrate with specific energy consumption of 1.63 kWh/m³. Cyclic operation including permeate production, flushing, and refilling steps is employed with LabView-controlled valves and pumps. Sensitivity analysis demonstrates that recovery ratio optimization balances cross-flow friction losses against longitudinal salinity gradient effects. The experimental setup validates OARO viability for treating high-osmotic-pressure streams in resource recovery and zero liquid discharge applications.