PROBLEM TO BE SOLVED: To provide a deoxidation treatment method of an aqueous liquid containing a hardness component where carbon dioxide gas is dissolved in the aqueous liquid containing the hardness component and carbonated water is obtained, the deposition of a carbonate on the surface of a gas permeation membrane can be effectively prevented when the deoxidation treatment of the carbonated water is performed by gas-liquid gas exchanging using the gas permeation membrane.SOLUTION: Water BT to be treated is converted to carbonated water having a Langelier index of -1.0 or less by dissolving carbon dioxide gas in the water BT to be treated containing dissolved oxygen and a hardness component. A deoxidation treatment method of the water BT to be treated includes that the carbonated water is deoxidized by gas-liquid gas exchanging via a gas permeation membrane 2.SELECTED DRAWING: Figure 4COPYRIGHT: (C)2018,JPO&INPIT【課題】硬度成分を含有する水性液中に炭酸ガスを溶解して炭酸水液を得、この炭酸水液を気体透過膜を用いた気液ガス交換により脱酸素処理するに当たり、気体透過膜表面への炭酸塩の析出を効果的に防ぐことができる、硬度成分を含有する水性液の脱酸素処理方法を提供する。【解決手段】溶存酸素及び硬度成分を含有する被処理水BT液中に炭酸ガスを溶解することにより、被処理水液BTを、ランゲリア指数が-1.0以下の炭酸水液とし、この炭酸水液を、気体透過膜2を介した気液ガス交換により脱酸素処理することを含む、被処理水液BTの脱酸素処理方法。【選択図】図4
