① Chlorine-containing preparations: There are many kinds of chlorine-containing drinking water disinfectants, such as bleaching powder, calcium hypochlorite, chloramine and sodium dichloroisocyanurate. Due to the different quality of source water, the chlorine dosage should be determined according to the chlorine requirement test. The chlorine consumption of water or clean groundwater filtered by coagulation precipitation is 0.5 ~ 65438 0.5 mg/L. If the water quality is poor, add 1.0 ~ 2.5 mg/L (or 1 ~ 4 mg/L). Whether the amount of chlorine added is appropriate, you can ask the local centers for disease control and prevention for help.
② Chlorine dioxide: Chlorine dioxide, known as the fourth generation disinfectant, is the safest chemical recommended by WHO to treat drinking water, and it is an updated product of disinfectant. It is superior to chlorine in disinfection, deodorization, iron removal and many other aspects, and does not produce chloroform carcinogen. When it disinfects water, it is less affected by water temperature, and its bactericidal effect on inferior water is better than chlorine.
③ Ozone disinfection: Ozone is a broad-spectrum and efficient strong oxidant. Its sterilization speed is 600~3000 times faster than chlorine. At present, it is mainly used for drinking water disinfection, air disinfection and food preservation. Ozone disinfection usually uses dry air or oxygen to prepare ozone through high voltage electric field in ozone generator. During disinfection, the absorption liquid with dissolved ozone is fully mixed with water. Under normal circumstances, the dosage of ozone is 0.5 ~ 1.5mg/L, and the residual ozone concentration in water should be 0.1~ 0.5 mg/L. For seriously polluted water, the dosage of ozone should be 3 ~ 6 mg/L. In recent years, someone has developed an electrolyzed water ozone generator, which has the advantages of simple structure and simple structure.
The historical research of extended data shows that the Egyptians first used alum to remove suspended solids from water. It is estimated that at the beginning of civilization, people recommended boiling water to drink. An ancient Indian document 4,000 years ago gave the earliest drinking water standard, stating that before drinking unclean water, the water should be boiled, exposed to the sun, soaked in a hot copper for several times, and filtered and cooled in a soil container. According to historical records, Persian laws and regulations stipulate that drinking water must be stored in bronze or silver.
The Greek doctor Hippocrates pointed out the importance of water to health, but he paid more attention to choosing a better water source than treating it. In the 8th century, Arab chemist Gerber purified water by distillation. In the 1 1 century, Persian doctor Avicenna advised travelers to drink water filtered with cloth or boiled water. 1627, British scientist F. Bacon published many methods to purify water, including percolation, boiling, distillation and condensation.
Before the establishment of bacterial pathogenicity theory in the mid-1980s from 65438 to 2008, people thought that odor was the medium of disease transmission, and based on this assumption, the practice of water and sewage disinfection was developed.
/kloc-in the second half of the 0/9th century, many reports and patents appeared in Britain and America, mostly involving the treatment of water with voltage, magnetic field, current, chlorine, potassium permanganate and hypochlorous acid. Humans have been actively using chemical agents for sterilization and disinfection since the beginning of the19th century. At first, chlorine compounds were mainly used.
For example, after 1820 invented bleaching powder, people used it to disinfect drinking water and treat infected wounds, and the effect was good. This is the first milestone of chemical sterilization. Since then, people have developed the second generation disinfectant dichloroisocyanuric acid and the third generation disinfectant trichloroisocyanuric acid, which are only used for small-scale disinfection at present. Chlorine dioxide is called the fourth generation disinfectant.
References:
Baidu Encyclopedia-Drinking Water Disinfection Technology