Bactericide and algaecide can effectively control the growth and propagation 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 bactericide and algaecide 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, bactericide and algaecide shall be added to the indirect cooling circulating water, while bactericide and algaecide shall not be added to some systems of direct cooling circulating water, such as blast furnace gas washing water, steel-making turbid circulating water and other systems with high pollution water quality. However, bactericide and algaecide shall be added to some systems such as continuous casting turbid circulating water and steel rolling turbid circulating water as well as indirect cooling circulating water systems, Otherwise, the microbial slime and oil sludge interact to 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 the growth of bacteria and algae. The application of chlorine dioxide generator can realize the continuity of sterilization and algae elimination, and it is especially suitable for such oily turbid circulating water as continuous casting turbid circulating water and steel rolling turbid circulating water.

The application of bactericide and algaecide in circulating water treatment of iron and steel enterprises should pay attention to the following matters:

1. During the period of adding bactericide and algaecide, the system shall try its best to reduce the sewage so as not to reduce the concentration of the agent and affect the effect of bactericide and algaecide.

2. The selection of dosing point shall be determined according to the process conditions and shall be based on the principle of easy mixing and dissolution of chemicals.

3. The selection of bactericide and algaecide depends on the system. For example, the direct cooling water system shall not add such agents that are easy to produce foam, otherwise the product quality will be affected; And the indirect cooling water should be regularly added with such agents as jieermin that have the effect of slime stripping.

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

5. Generally, impact dosing is adopted for bactericide and algaecide, that is, excessive bactericide and algaecide are added in a periodic manner to produce a relatively high concentration in the circulating water to quickly and effectively kill microorganisms.