What is the Chemical Most Used in Water-Treatment Plants?

Water is essential for human life, but not all water sources are safe for consumption. To ensure that drinking water is clean and safe, it must undergo treatment, such as disinfection and filtration, before it reaches our homes. Chemicals play a crucial role in many water treatment processes, and the chemical most used in water-treatment plants is chlorine.

What is Chlorine?

Chlorine is a chemical element with the symbol Cl and atomic number 17. It is a gas at room temperature and is highly reactive. Chlorine is commonly used as a disinfectant in water treatment because it is effective at killing harmful bacteria, viruses, and other microorganisms that can cause waterborne diseases.

How is Chlorine Used in Water Treatment?

Chlorine is added to water in different forms, including chlorine gas, sodium hypochlorite, and calcium hypochlorite. These chemicals react with water to form hypochlorous acid, a strong oxidizing agent that kills microorganisms in the water. Chlorine is effective at eliminating many waterborne pathogens, such as E. coli, Salmonella, and Giardia.

Chlorine is also used in water treatment facilities as a secondary disinfectant to prevent the growth of harmful bacteria that can form in pipelines or storage tanks after the water has been treated.

What are the Disadvantages of Using Chlorine?

Although chlorine is an effective disinfectant, it has some disadvantages that can pose health risks. Chlorine can react with natural organic matter in water to form disinfection byproducts (DBPs), such as trihalomethanes (THMs) and haloacetic acids (HAAs). Exposure to high levels of DBPs over an extended period can be harmful to human health and may increase the risk of cancer and other diseases.

The taste and odor of chlorine can also affect the acceptability of drinking water. Many people find the strong smell and taste of chlorine unpleasant, which can lead to a decrease in water consumption and, in some cases, an increased risk of dehydration.

What are the Alternatives to Chlorine?

Given the potential health risks associated with chlorine, water treatment facilities have been exploring alternative disinfection methods. Some of the alternatives include:

Ozone: A powerful oxidizing agent that can effectively kill microorganisms in water without producing harmful DBPs. Ozone is used in conjunction with other disinfectants to achieve optimal results.

Ultraviolet (UV) radiation: UV radiation is used to destroy the DNA of microorganisms, rendering them unable to reproduce or spread disease. UV radiation is a chemical-free disinfection method that does not produce harmful byproducts.

Chloramine: A chemical compound formed by combining chlorine and ammonia. Chloramine exhibits a lower reactivity than chlorine and produces fewer DBPs.

Conclusion

Chlorine is the most commonly used chemical in water treatment, and for good reason. Chlorine is effective at killing harmful microorganisms and preventing the spread of waterborne diseases. However, the potential health risks associated with chlorine and its DBPs have led to the exploration of alternative disinfection methods.

Ultimately, the most effective water treatment process will depend on the specific characteristics of the water source and the needs of the community. At present, chlorine remains the most widely used disinfectant in water treatment worldwide.