離子交換是指采用離子交換樹脂，與水溶液中的各種離子之間發生等物質的可逆交換，從而使水質改善，而離子交換樹脂的結構并不發生實質性變化的水處理方式。用來裝載離子交換樹脂的設備稱為離子交換器。根據所裝載的樹脂種類不同，其去除的例子種類和實現的功能也不同。離子交換法是早期最常使用，最普及的水處理方法，無論是鍋爐用水得軟化，脫堿軟化，除鹽水，純水，超純水的設備，還是工業廢水處理，重金屬及貴重金屬回收等場合均可采用的離子交換法來進行。離子交換設備是一種傳統的、工藝成熟的脫鹽處理設備，其原理是在一定條件下，依靠離子交換劑(樹脂)所具有的某種離子和預處理水中同電性的離子相互交換而達到軟化、除堿、除鹽等功能。用于深度脫鹽處理，產水電阻率動態可達到18MΩ·cm。
Ion exchange refers to the use of ion exchange resin, and a variety of ions in the water solution between the reversibility of material exchange, so as to improve the water quality, and the structure of ion exchange resin does not change substantially.The equipment used to load ion exchange resins is called an ion exchanger.Depending on the type of resin loaded, the types of examples removed and the functions implemented vary.Ion exchange method is the most commonly used and the most popular water treatment method in the early days, whether it is boiler water softening, alkali softening, demineralization, pure water, ultra-pure water equipment, or industrial wastewater treatment, heavy metals and precious metal recovery occasions can be used for ion exchange method.Ion exchange equipment is a traditional and mature desalination treatment equipment, its principle is that under certain conditions, the ion exchange agent (resin) has a certain ion and the pretreatment water with the same electrical ion exchange to achieve softening, alkali, salt and other functions.For deep desalting treatment, water resistivity can be up to 18 m dynamic Ω · cm.