The purpose of water treatment is to improve water quality and make it reach a certain water quality standard. According to the different treatment methods, there are a variety of physical water treatment, chemical water treatment, biological water treatment and so on. According to the treatment object or purpose, it can be divided into water treatment and wastewater treatment. Water treatment includes domestic drinking water treatment and industrial water treatment; Wastewater treatment is divided into domestic sewage treatment and industrial wastewater treatment. Among them, boiler feed water treatment, recharge water treatment, steam turbine main condensate water treatment and circulating water treatment belong to the category of industrial water treatment and thermal technology is particularly close. Water treatment is of great significance to the development of industrial production, the improvement of product quality, the protection of human environment and the maintenance of ecological balance.