Low pressure multi-stage RO system developed in “Mega-ton Water System” for large-scaled SWRO plant

A new RO system for large-scaled SWRO plant has been developed in the project named “Mega-ton Water System” with private–public cooperation in Japan. The characteristic of the newly developed RO system to increase the recovery rate is to use the short vessel that contains 2–4 elements for the first stage, and to use relatively long vessel for the second stage after inter-booster pump in order to reduce the pressure and the flux of the lead element The new RO system used by low pressure new SWRO element studied by this project is capable of the high recovery rate (under 65%) and allows the scale of the intake and pretreatment equipment to reduce compared to conventional system. Considering also to new isobaric ERD that has been developed in this project, the energy consumption was estimated and compared the results with that of conventional system. It is suggested that the reduction of energy consumption is to be about 20% compared with a conventional system. •New RO system for large-scaled SWRO plant is developed.•The system is developed in the Mega-ton Water System project.•The system reduces the pressure and the flux of the lead element.•The system enables the recovery rate to increase.•Conventional and new system's costs are compared.