Chlorine is widely utilized in water treatment as a disinfectant to eliminate harmful bacteria and other microorganisms.

As a strong oxidizing agent, chlorine reacts with organic matter when added to water, resulting in the formation of compounds known as disinfection by-products. The most prevalent method of chlorination involves the application of chlorine gas, which is highly effective at eradicating bacteria, viruses, and other pathogens that can lead to diseases. This initial phase of disinfection is referred to as primary disinfection.

During the treatment process, chlorine gas is injected into the water under carefully controlled conditions. It reacts with water to produce hypochlorous acid (HOCl) and hydrochloric acid (HCl). Among these, hypochlorous acid serves as the active disinfectant, effectively killing microorganisms by penetrating their cell walls and disrupting essential metabolic processes.

Beyond primary disinfection, chlorine is also employed for secondary disinfection. In this stage, a small residual amount of chlorine is maintained in the water after it leaves the treatment facility. This ensures that the water remains safe for consumption as it travels through the distribution system to consumers’ taps. The presence of residual chlorine continues to eliminate any microorganisms that may enter the water after it has departed from the treatment plant.

Despite its effectiveness, the use of chlorine in water treatment presents certain challenges. The disinfection by-products generated when chlorine interacts with organic matter can pose health risks if consumed in significant quantities over extended periods. Therefore, water treatment facilities must meticulously regulate the amount of chlorine used to strike a balance between effectively killing microorganisms and minimizing the production of harmful disinfection by-products.

In summary, chlorine is essential in water treatment as a disinfectant that eliminates harmful microorganisms, thereby ensuring the water remains safe for drinking.