A power recovery system is used for reducing the total energy consumption in a process such as an industrial treating process or a fluid refining process including the delivery of a fluid under a high pressure. The power recovery system includes a high-pressure pump for pressuring raw water, a reverse osmosis membrane cartridge for treating high-pressure water discharged from the high-pressure pump with a reverse osmosis membrane to produce treated water, a positive-displacement piston pump for pressuring raw water under the pressure of concentrated water which is discharged from the reverse osmosis membrane cartridge without being treated by the reverse osmosis membrane, and a power recovery pump turbine for boosting the pressurized raw water discharged from the positive-displacement piston pump and adding the boosted water to the high-pressure water discharged from the high-pressure pump. The power recovery pump turbine is actuated by pressurized water generated in the power recovery system.