How are halogens used in water treatment processes?

Halogens, particularly chlorine and iodine, are used in water treatment processes to kill harmful bacteria and viruses.

In more detail, halogens are a group of elements that include fluorine, chlorine, bromine, iodine, and astatine. They are known for their strong disinfecting properties, which make them ideal for use in water treatment. The most commonly used halogens in water treatment are chlorine and iodine.

Chlorine is often used in the form of a gas or a liquid in large-scale water treatment plants. It is a powerful oxidising agent that kills bacteria, viruses, and other microorganisms by breaking down their cell walls and disrupting their metabolic processes. Chlorine also reacts with organic matter in the water to form compounds known as disinfection by-products, some of which can be harmful if consumed in large quantities. Therefore, the amount of chlorine used must be carefully controlled to ensure that it is effective in killing microorganisms but does not pose a risk to human health.

Iodine, on the other hand, is typically used in portable water purification tablets or solutions, which are often used by campers, travellers, and in emergency situations where access to clean water is limited. Like chlorine, iodine kills microorganisms by disrupting their metabolic processes. However, iodine is less commonly used than chlorine because it can give water an unpleasant taste and can be harmful if consumed in large quantities.

In addition to chlorine and iodine, other halogens such as bromine and fluorine can also be used in water treatment. Bromine is often used in hot tubs and swimming pools because it is more stable at high temperatures than chlorine. Fluorine, in the form of fluoride, is added to drinking water in some areas to help prevent tooth decay.

In conclusion, halogens play a crucial role in water treatment processes due to their strong disinfecting properties. However, their use must be carefully controlled to ensure that they do not pose a risk to human health.