Question 139General Subjects - Assistant Engineer

The correct answer is C) An ultraviolet irradiator at the desalinator discharge to the potable water storage tank. This is the correct answer because ultraviolet (UV) irradiation does not provide a residual disinfectant in the potable water, unlike chlorination or bromination. UV disinfection works by disrupting the DNA of microorganisms, but it does not leave behind any disinfecting chemicals in the water. This means that the water could become recontaminated after leaving the UV unit, as there would be no residual disinfectant to maintain the water's purity. The other options, such as chlorinators or brominators, would provide a residual disinfectant in the potable water, which would help prevent microbial regrowth and maintain the water's quality throughout the distribution system.