The bactericidal and algal killing agent can effectively control the growth and reproduction of microorganisms in the circulating cooling water system, thus controlling the microbial corrosion and microbial slime in the circulating cooling water system. The commonly used bactericides and algicides can be divided into two categories: oxidizing bactericides and non oxidizing bactericides, which are generally used alternately. The selection of bactericidal and algal killing agents in each system of circulating cooling water shall be based on the characteristics of the system, and the agents used shall not affect the operation of the system. In the circulating cooling water of iron and steel enterprises, bactericidal and algicidal agents should be added to the indirect cooling circulating water, while some systems that directly cool the circulating water, such as blast furnace gas washing water, steel making turbid circulating water and other highly polluted water quality systems, do not need to add bactericidal and algicidal agents without bacteria and algae breeding, but some systems that connect the casting turbid circulating water, steel rolling turbid circulating water and indirect cooling circulating water systems must be added with bactericidal and algicidal agents, Otherwise, the interaction of microbial sludge and oil sludge will block the pipes and equipment of the circulating water system. This year, the chemical chlorine dioxide generator has also been used in the circulating water treatment of iron and steel enterprises. The generated chlorine gas and chlorine dioxide compound gas are added to the water to prevent bacteria and algae from breeding. The application of chlorine dioxide generator can realize the continuity of sterilization and algae killing, especially suitable for the turbid circulating water containing oil such as the turbid circulating water for continuous casting and steel rolling.

The application of bactericidal and algicidal agents in the treatment of circulating water in iron and steel enterprises should pay attention to the following matters:

1. During the period of adding bactericidal and algal killing agents, the system shall try to reduce the sewage discharge, so as not to reduce the concentration of the agents and affect the bactericidal and algal killing effect.

2. The dosing point shall be selected according to the process conditions, based on the principle that the agent is easy to mix and dissolve.

3. The selection of bactericides and algaecides depends on the system. For example, the direct cooling water system shall not be added with medicaments that are easy to produce foam such as Jielming, otherwise the product quality will be affected; The indirect cooling water should be regularly added with chemicals such as Jiermei which have the function of slime stripping.

4. In a certain system, several agents should be added alternately to avoid the complementary advantages of system resistance and agents. Oxidizing and non oxidizing should also be used alternately.

5. Generally, the bactericidal and algicidal agents are added by impact, that is, the excessive bactericidal and algicidal agents are added periodically at one time to produce a relatively high concentration in the circulating water to quickly and effectively kill microorganisms.