What is the role of ultraviolet (UV) radiation in the water purification systems? 1. It inactivates/kills the harmful microorganisms in water. 2. It removes all the undesirable odours from water. 3. It quickens the sedimentation of solid particles, removes turbidity and improves the clarity of water. Which of the statements given above is/are correct?

Ultraviolet (UV) radiation in water purification acts primarily as a disinfectant by damaging the genetic material (DNA or RNA) of microorganisms [1]. This process inactivates or kills bacteria, viruses, and protozoa, rendering them unable to reproduce. Statement 1 is therefore correct. However, UV radiation does not remove undesirable odors, which typically requires activated carbon filtration or chemical treatment. Furthermore, UV light does not quicken sedimentation or remove turbidity; in fact, high turbidity and suspended particles can shield pathogens from UV rays, reducing the system's effectiveness. Consequently, pre-treatment steps like filtration are often required to improve water clarity before UV exposure. Thus, statements 2 and 3 are incorrect, making '1 only' the correct choice.

Sources

1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 19: Ozone Depletion > OTSNE $$FUETION > p. 267