Reverse osmosis treatment apparatus and reverse osmosis treatment method

A reverse osmosis treatment apparatus comprising

• a membrane unit including one or more reverse osmosis membrane modules to perform reverse osmosis treatment on water to be treated, wherein
• the membrane unit includes a plurality of banks connected in series, each bank including the one or more reverse osmosis membrane modules disposed in parallel,
• at least one of the banks includes
• a treatment water pipe for supplying the water to be treated to the bank,
• a concentrated water pipe for discharging concentrated water separated by the bank, from the bank,
• a treatment water pipe valve capable of closing the treatment water pipe, and
• a concentrated water pipe valve capable of closing the concentrated water pipe,
• a bypass pipe is connected between an upstream side of the treatment water pipe valve and a downstream side of the concentrated water pipe valve, the bypass pipe being capable of diverting the water to be treated, which is to be supplied to the bank, around the bank and draining the water to be treated, and
• a chemical cleaning pipe is connected between a downstream side of the treatment water pipe valve and an upstream side of the concentrated water pipe valve, the chemical cleaning pipe being capable of supplying the reverse osmosis membrane modules disposed in the bank with chemical cleaning water for cleaning the reverse osmosis membrane modules.