1. Chloramine, an inorganic by-product, includes products generated by the reaction of hypochlorous acid with ammonia, such as monochloramine, dichloramine, trichloroamine or nitrogen trichloride, which is harmless to human health.
2. Organic by-products chlorinated hydrocarbons, such as chloroform and haloacetic acid, have become the main control objects because of their strong carcinogenicity, and also represent volatile and nonvolatile disinfection by-products.
There are four disinfection by-products of trihalomethane, namely chloroform, dichlorobromomethane, monochlorobromomethane and tribromomethane. Experiments show that chloroform has obvious mutagenic effect and a good dose-response relationship. Animal experiments have also confirmed that chloroform can cause kidney tumors in male rats and liver tumors in female rats. Tribromomethane has also been proved to be carcinogenic. A large number of epidemiological surveys show that long-term drinking of chlorinated drinking water will increase the risk of cancer death in digestive system and urinary system, which is statistically related to the mortality of other cancers.
Non-volatile disinfection by-product: Haloacetic acid, another non-volatile disinfection by-product produced in chlorine disinfection of drinking water, has attracted great attention of the US Environmental Protection Agency since the mid-1980s.
Current solution:
One is to minimize the formation of halogenated organic precursors in water;
Second, use other chlorine-free disinfectants such as carbon dioxide, ozone and ultraviolet rays for disinfection;
The third is to remove halogenated organic compounds formed in water after chlorine disinfection.