What is the residual chlorine standard of the national standard water quality (the meaning of maintaining residual chlorine in water quality)

In recent years, many collective accidents caused by water quality problems are caused by the contamination of drinking water by microorganisms, which occurs because the residual amount of disinfectant in the peripheral water is insufficient and the water quality is not regularly monitored. For water disinfection, the most frequently heard test item for drinking water is residual chlorine. So what is residual chlorine? Residual chlorine is the general term for the free chlorine and combined chlorine remaining in the water after the water has been chlorinated and disinfected for a certain period of time. After chlorine is put into water, in addition to consuming a part of the chlorine amount by interacting with bacteria, microorganisms, organic matter, inorganic matter, etc. in the water, there is still a part of the chlorine amount left, and this part of the chlorine amount is called residual chlorine.

What is the significance of maintaining residual chlorine in water quality?

1. Prevent the regrowth of coliform bacteria. The problem of the regrowth of coliforms has received more and more attention, and the use of residual disinfectants is a more effective method.

2. Inhibit the formation of biofilm. Various methods can be used to control the formation of biofilms in the pipeline network, but maintaining the residual chlorine in the pipeline network is still the most effective measure.

3. Keep the water quality of the pipe network free from microbial contamination. The biological stability of water quality in the pipeline network is almost consistent with the biofilm formation and the regrowth of microorganisms in the pipeline network. Therefore, maintaining residual chlorine is conducive to stabilizing water quality.

4. Prevent the occurrence of occasional pathogenic bacteria. Some pathogenic bacteria, such as Legionella and some coliform microorganisms, can survive or even multiply in the biofilm in the pipe network and branch pipes. The residual disinfectant in the water plays an important role in the control of incidental microorganisms.

5. Remaining disinfectant dose as a signal to convey microbial contamination. When the pollutants enter the pipe network system, the remaining disinfectant is consumed, so that the remaining disinfectant in some pipe sections in the pipe network is reduced, and the consumption of the remaining disinfectant can be used as a pollution signal.