Reverse osmosis treatment system for recovering energy generated both at brine and permeate sides during seawater desalination

A reverse osmosis treatment system comprising:

• a reverse osmosis treatment device configured to separate first to-be-treated water into permeate and brine via reverse osmosis;
• a branched portion at which second to-be-treated water is divided into third to-be-treated water and fourth to-be-treated water;
• a first pump configured to pressurize the third to-be-treated water thus divided, thereby to feed fifth to-be-treated water having a higher pressure than to-be-treated water before divided into the third to-be-treated water;
• a first energy recovery device configured to exchange pressures between the fourth to-be-treated water thus divided and the brine thus separated by the reverse osmosis treatment device, thereby to produce sixth to-be-treated water having a higher pressure than the fourth to-be-treated water;
• a merging portion at which the fifth to-be-treated water and the sixth to-be-treated water are merged to produce the first to-be-treated water;
• and
• a second energy recovery device configured to raise a pressure of the third to-be-treated water located at a downstream side of the branched portion with a pressure of the permeate thus separated by the reverse osmosis treatment device.