一, what is the main way of disinfection and sterilization of tap water at present?

China's current tap water purification methods: chlorine gas sterilization; The world's developed countries and regions tap water purification methods: ultraviolet and ozone technology sterilization.

二，Why should chlorine be added to tap water?

Tap water should be a kind of hygienic and safe drinking water, but due to the pollution of the environment, resulting in a large number of harmful substances such as bacteria in the water, in order to inhibit and kill the bacteria in the water, chlorine is added in the water treatment process.

Chlorine disinfection is the most common disinfection method in the water treatment process, and the World Health Organization stipulates that the residual chlorine concentration in drinking water should not exceed 5 mg/L. In the process of transmission and distribution of tap water, disinfection by-products are produced and the excessive concentration of residual chlorine affects the taste. Water supply enterprises generally ensure the residual chlorine at the end of the pipe network by increasing the amount of chlorine injected into the factory water. With the increase in the amount of chlorine injected into the factory water, the generation of disinfection by-products in the pipe network also increases, and excess residual chlorine at the front end of the pipe network will also produce odor.

三, the significance of maintaining residual chlorine

1. Stop the regrowth of coliform bacteria: The problem of the regrowth of coliform bacteria has received more and more attention. The measure to prevent the growth of microorganisms is to choose a disinfectant that is stable in nature, convenient in transportation, does not produce harmful by-products and can penetrate into the biofilm to kill epiphytic bacteria. Under the condition that no special measures are adopted at present, the use of residual disinfectants is a more effective way.

2. Inhibit the formation of biofilm: A variety of methods can be used to control the formation of biofilm in the pipe network, but maintaining the residual chlorine in the pipe network is still the most effective measure.

3. Water quality of pipe network water: the biological stability of water quality of pipe network water is almost consistent with the biofilm formation and microbial regrowth in pipe network. Therefore, maintaining residual chlorine is conducive to stable water quality.

4. Prevent the occurrence of accidental pathogens: Prevent the occurrence of accidental pathogens and microorganisms in some user branches. Residual disinfectant in water plays an important role in the control of sporadic microorganisms.

5. As a signal to convey microbial pollution: When pollutants enter the pipe network system and consume the remaining disinfectant, the remaining disinfectant in some pipe sections of the pipe network will be reduced, and the consumption of the remaining disinfectant can be used as a pollution signal.