Which chemical agent used for water disinfection is known for not providing a residual effect?

Ozone is a powerful oxidizing agent commonly used in water disinfection due to its effectiveness in killing bacteria, viruses, and other pathogens. One of its key characteristics is that it does not leave a residual disinfectant in the water after treatment. This means that once the ozone has been used to purify the water, it rapidly decomposes back into oxygen, leaving no residual agents to continue providing antimicrobial protection in the distribution system.

In contrast, other disinfectants such as chlorine, iodine, and bromine remain in the water and provide a residual effect, which can help to maintain water quality as it travels through pipes to reach consumers. This lack of a residual effect is significant in considering the choice of disinfectant, especially in systems where ongoing disinfection is crucial to prevent recontamination of the water supply after treatment. Therefore, the nature of ozone as a non-residual disinfectant differentiates it from the others listed.