WATER TREATMENT METHOD AND WATER TREATMENT SYSTEM

• Main Authors: MIURA YUKI, KUMANO ATSUO, YASUKAWA MASAHIRO
• Format: Patent
• Language: English; Japanese
• Published: 03.07.2023
• Subjects: CHEMISTRY; METALLURGY; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; SEPARATION; TRANSPORTING; TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE

To further reduce energy cost in a water treatment method and a water treatment system in which water is collected from sea water by forward osmosis treatment using temperature responsive draw solute.SOLUTION: A water treatment method includes: a forward osmosis step of causing one surface of a forward osmosis membrane to contact with first sea water and causing the other surface of the forward osmosis membrane to contact with a draw solution including draw solute that lowers in solubility with a temperature change, thereby causing water included in the first sea water to move into the draw solution through the forward osmosis membrane, to obtain a diluted draw solution being a draw solution that has been diluted and concentrated sea water being the first sea water that has been concentrated; a solubility lowering step of changing the temperature of the diluted draw solution through heat exchange between second sea water having a different temperature from the first sea water, and the diluted draw solution, thereby lowering the solubility of the draw solute in the diluted draw solution; and a water collecting step of collecting water from the diluted draw solution after the solubility lowering step and obtaining a reproduced draw solution being the diluted draw solution that has been concentrated.SELECTED DRAWING: Figure 1 【課題】温度応答性ドロー溶質を用いた正浸透処理によって海水から水を回収する、水処理方法および水処理システムにおいて、さらにエネルギーコストを低減すること。【解決手段】正浸透膜の一方の面を、第１海水に接触させると共に、正浸透膜の他方の面を、温度変化により溶解度が低下するドロー溶質を含むドロー溶液に接触させることで、第１海水中に含まれる水を正浸透膜を通してドロー溶液に移動させて、希釈されたドロー溶液である希釈ドロー溶液と、濃縮された第１海水である濃縮海水と、を得る、正浸透工程と、第１海水とは異なる温度を有する第２海水と、希釈ドロー溶液と、の熱交換によって、希釈ドロー溶液の温度を変化させることで、希釈ドロー溶液中のドロー溶質の溶解度を低下させる、溶解度低下工程と、溶解度低下工程の後に、希釈ドロー溶液から水を回収し、濃縮された希釈ドロー溶液である再生ドロー溶液を得る、水回収工程と、を含む、水処理方法。【選択図】図１