Which of the following is not applied/used for disinfection of water?

Correct option is D

Perchlorate is not used for water disinfection. It is a chemical compound commonly found in explosives, rocket fuel, fireworks, and fertilizers. While perchlorate can contaminate water sources, it has no disinfectant properties and poses health risks when present in drinking water.
In contrast, the other options – hypochlorous acid, chlorine dioxide, and ozone – are all widely used disinfectants in water treatment due to their effectiveness in killing bacteria, viruses, and other pathogens.
Explanation:
· Hypochlorous acid (HClO): A powerful disinfectant formed when chlorine dissolves in water, commonly used in drinking water and swimming pool sanitation.
· Chlorine dioxide (ClO₂): A highly effective disinfectant that doesn’t produce harmful by-products like traditional chlorine.
· Ozone (O₃): A strong oxidant used in water treatment to destroy microorganisms and degrade contaminants.
· Perchlorate: A contaminant that can disrupt thyroid function and is not suitable for disinfection.
Information Booster:
1. Hypochlorous acid is produced when chlorine reacts with water.
2. Chlorine dioxide is used to disinfect water and remove biofilms.
3. Ozone is more effective than chlorine but requires specialized equipment.
4. Perchlorate contamination in drinking water can affect thyroid health.
5. Water disinfection ensures safe drinking water by killing harmful pathogens.
6. Disinfectants are regulated to ensure safety and minimize harmful by-products.
Additional Knowledge:
· (a) Hypochlorous Acid:
· Effective against bacteria, fungi, and viruses.
· Used in municipal water treatment and household cleaning.
· Leaves a residual disinfectant to prevent recontamination.
· (b) Chlorine Dioxide:
· Used in water treatment since the 1940s.
· Does not produce trihalomethanes (THMs) or haloacetic acids (HAAs).
· Effective at lower doses than chlorine.
· (c) Ozone:
· A highly reactive gas used for water and wastewater treatment.
· Kills microorganisms more rapidly than chlorine.
· Leaves no chemical residue, making it environmentally friendly.
· (d) Perchlorate:
· An industrial contaminant linked to thyroid dysfunction.
· Found in contaminated groundwater but not used as a disinfectant.
· Exposure can reduce hormone production in the thyroid gland.
Key Points:
1. Hypochlorous acid, chlorine dioxide, and ozone are effective water disinfectants.
2. Perchlorate is a contaminant, not a disinfectant.
3. Disinfection is essential for safe drinking water.
4. Water treatment standards protect public health.
5. Effective disinfection balances pathogen elimination and minimal by-products.