Application of energy efficient reverse osmosis system for seawater desalination

A performance of an energy-efficient reverse osmosis (RO) system for seawater desalination was evaluated. The evaluation focused on energy saving performance of the RO system. The strategy adopted was to induce high recovery (50%) through the pressure increase. For this purpose, a pilot-scale RO plant (5 m3/h) was built and installed in a southern port of Korea. The study showed that energy saving was possible by application of high pressure. The 50% recovery was achieved at 8.3 MPa, but the operation led to water quality degradation. The water quality problem was solved by the operation of two-stage mode. Under this condition, the target recovery was achieved at lower pressure (6.6~7.5 MPa), which resulted in the saving of power consumption. No water quality degradation was observed. Further saving was possible by adding energy recovery turbine (ERT) and inverter system. When the RO system was operated for 50% recovery at two-stage mode while equipped with energy saving devices of ERT and inverter system, 44% of saving in power consumption was possible.

This study found that BMF could be a good candidate for pretreatment of RO system. It successfully reduced SDI values less than 2 without chemical cleaning, which was not possible with sand filter. This study showed that high recovery (50%) was possible through the pressure increase. The currently available membrane could not tolerate the pressure of 8.3 MPa. The consequence of the intolerance was reflected by