The Role of Chlorine in Industrial Water Treatment

Water is a critical resource for many industries, but the presence of contaminants can pose a significant problem to its usability. One of the most common treatments for such impurities is the addition of chlorine, which has been used for centuries to purify water.

Chlorine is a highly effective disinfectant that can neutralize bacteria, viruses, and other harmful microorganisms. This chemical element is available in various forms like gas, liquid, and solid, making it adaptable to numerous applications.

In industrial water treatments, chlorine application is popularly used to control biological fouling and sterilize water. Here's a closer look at the different ways chlorine is employed in water treatment processes.



Chlorination involves the treatment of water with chlorine or chlorine-containing substances. This technique has become an industrial standard due to its effectiveness in destroying a broad range of bacteria and viruses found in water.

In water treatment plants, chlorine is typically added before or during filtration to achieve effective chemical decontamination processes. Industrially, sodium hypochlorite is often favored since it has a more extended shelf life than pure chlorine gas.

Chlorine is very reactive, and once added to water, it quickly reacts with organic matter and reduces its solubility. Once it reacts with contaminants, the resulting chemical compounds harm bacteria, parasites, and viruses in water. Consequently, this leads to the destruction of these infectious agents, making water safer to use for industrial purposes.

One drawback of chlorination in water treatment processes is that it produces the widely reported chlorine odor and taste in treated water. Additionally, when used in higher concentrations, chlorine can react with other water components to form harmful byproducts like trihalomethanes.


Chlorine Dioxide

Another form of chlorine used in industrial water treatment is chlorine dioxide. Chlorine dioxide is a yellowish-green gas that can also be found in liquid and powder form. Chlorine dioxide exhibits potent disinfectant properties and is a popular choice for treating potable water in water treatment plants.

Chlorine dioxide is more effective against bacteria, viruses, and other microorganisms than other chlorine compounds like chlorine gas. Additionally, chlorine dioxide leaves no residual taste or odor in water, making it a preferred chlorine compound in water treatment processes. Its use is particularly popular in industrial water treatment processes that require high levels of water disinfection.

Once applied to water, chlorine dioxide oxidizes organic matter while also damaging the cell walls of bacteria and viruses, ultimately killing them. Chlorine dioxide is thus widely used to disinfect water in various industrial water treatment processes, ranging from cooling towers to food processing applications.


Calcium Hypochlorite

Calcium hypochlorite is often referred to as "cal hypo" and is a stable white solid that contains approximately 65% to 73% available chlorine. Like other chlorine compounds, calcium hypochlorite produces a chlorine scent when applied to water.

Calcium hypochlorite is an effective shock treatment used after a prolonged period of water stagnation. This is crucial in water treatment plants where stagnant water is a health hazard. It is also a highly effective algaestat that helps prevent the growth of algae in processes like cooling towers.

The US Environmental Protection Agency(FPA) recommends using calcium hypochlorite in treating drinking water used by travelers and hikers since it maintains stable levels of available chlorine for long periods.



Chlorine is an essential chemical compound in industrial water treatment. It is a highly effective disinfectant that helps neutralize bacteria, viruses, and other harmful microorganisms. Chlorine is found in various forms and is thus versatile in its applications.

The drawbacks of using chlorine in industrial water treatment requires considerable attention to its processing concentration levels. Additionally, some treatment plant systems may require the development of a residual concentration chemical filtration process, due to existing reactions that may occur upon adding chlorine into the water. However, the importance of safe, clean, and abundant water for industrial use suggests that the application of chlorine in water treatment processes is here to stay.

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