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UV Water Disinfection Treatment

Ultra-violet water disinfection is a proven, non-chemical treatment system. UV light kills waterborne disease-carrying organisms upon exposure. Advantages of UV systems include the lack of consumables (no chemicals are used up treating water), lack of residuals (no chemicals are left in the water) and relatively low cost for installation. Disadvantages include a dependency on water clarity,. Effectiveness also requires direct exposure, which limits the volume of water which can be treated.

  1. What is Ultra-Violet Light?

    • UV light has a wavelength above the violet end of the light spectrum, in the range of 10 nanometers to 400 nanometers. UV light is very energetic and tends to break chemical bonds. This attribute of UV light is deadly to microscopic organisms.

    What Does UV Do in Water Treatment?

    • UV disinfection is a late-treatment process. This means sedimentation and filtering steps preceed the UV step so the water is as clear as possible before being exposed to the UV step.

      Water flows around UV light tubes, exposing the greatest possible volume of clear water to the light rays coming from the UV tubes.

      Any microscopic organisms carried by the water are exposed to the UV light. The chemical bonds within the organisms are broken up by the high-energy light waves, disrupting and killing these pathogens.

    UV versus Chemical Disinfection.

    • Since UV light passes through the clear water, killing pathogens along the way, there are dead pathogens, but no other chemical components left in the water after disinfection.

      In chemical processes, a compound (chlorine, chloramines, ozone) is added to the water. These disinfectants kill the pathogens, but they or their residuals remain in the water.

    Advantages of UV Treatment

    • Since UV treatment is non-chemical, there are no chemicals added to the treated water and no residuals remain in the water after treatment.

      UV treatment is done by exposure. There are no mixing errors, and the reaction is not dependant upon the water's pH level or temperature.

      Since clear water passing around UV tubes constitutes the disinfection process, the physical equipment is less expensive than most chemical disinfection treatments.

    Disadvantages to UV Treatment

    • UV treatment is line-of-sight. Anything which disrupts or limits direct exposure of the water to the UV rays will reduce its disinfectant value.

      UV arrays have high energy requirements. This is an unavoidable expense.

      Unlike chemical disinfection, where any disruption of the flow of disinfectant into the treated water might be made up by prior or later applications of disinfectants to the standing water, a disruption of UV light means that unexposed water is not disinfected.

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