Which of the following best describes disinfectants used in water treatment?

Disinfectants used in water treatment are crucial for ensuring that the water is safe for consumption and free from harmful microorganisms. The correct choice highlights that disinfectants are employed to kill a wide range of microorganisms, including pathogenic bacteria, viruses, and protozoa. This capability is essential in water treatment processes to prevent waterborne diseases and protect public health.

In water treatment, disinfectants—such as chlorine, ozone, and ultraviolet light—function by targeting the cellular structures and processes of these microorganisms, effectively rendering them inactive and unable to cause harm. The use of disinfectants is a primary barrier in maintaining water quality and safety.

In contrast, the other options do not accurately represent the role of disinfectants. The idea that they can only kill viruses is misleading, as effective disinfectants can target a broader spectrum of microbial life, not just viruses. The statement regarding them being solely based on physical processes overlooks the chemical nature of many disinfectants, which often involve chemical reactions to achieve disinfection rather than being purely physical methods. Lastly, while removing sediments does play a role in water treatment, it is primarily the function of filtration, not disinfection. Hence, disinfectants are specifically aimed at eliminating biological contaminants rather than physical impurities like sediments.