**History of Water Chlorination:**
– Proposal to add chlorine to water for germ-free rendering in 1894.
– Early water chlorination attempts in Hamburg, Germany in 1893.
– Maidstone, England was the first town with the entire water supply treated with chlorine in 1897.
– Permanent water chlorination started in Lincoln, England in 1905 due to a typhoid fever epidemic.
– The first continuous use of chlorine for disinfection in the U.S. was in 1908 at Boonton Reservoir.
**Biochemistry of Water Chlorination:**
– Chlorine is added to water supplies as a disinfectant.
– Chlorine kills disease-causing pathogens like bacteria and viruses.
– The majority of chlorine is manufactured from table salt by electrolysis.
– Chlorine kills via oxidation of organic molecules.
– Chlorine easily penetrates pathogens’ surfaces and disrupts cell structure.
**Principles of Water Chlorination:**
– Chlorine in water converts to an equilibrium mixture of chlorine, hypochlorous acid, and hydrochloric acid.
– Major species in an acidic solution are Cl and HOCl.
– In an alkaline solution, only ClO (hypochlorite ion) is present.
– Very small concentrations of ClO, ClO, ClO are also found.
**Chlorination Methods and Drawbacks:**
– Shock chlorination is used in swimming pools, water wells, and other water sources to reduce bacterial and algal residue.
– Chlorination can produce disinfection by-products (DBPs) like trihalomethanes (THMs) and haloacetic acids (HAAs).
– Effects of DBPs depend on exposure duration and amount ingested.
– High doses of bromoform, a THM, can slow down brain activity.
**Importance of Dechlorinators and Chemicals Used:**
– Dechlorinators remove chlorine or chloramine from water.
– Common compounds in dechlorinators include sodium thiosulfate.
– Sodium thiosulfate, sodium hydroxymethanesulfonate, and sodium hydroxymethane sulfinic acid are chemicals used in dechlorinators.
– These compounds effectively neutralize chlorine and play a crucial role in making water safe for fish.
Water chlorination is the process of adding chlorine or chlorine compounds such as sodium hypochlorite to water. This method is used to kill bacteria, viruses and other microbes in water. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, and typhoid.
.jpg)