UV Sterilizers
Ultraviolet germicidal irradiation (UVGI) is a disinfection method that uses ultraviolet (UV) light at sufficiently short wavelength to killmicroorganisms.It is used in a variety of applications, such as food, air and water purification. UVGI utilises short-wavelength ultraviolet radiation (UV-C) that is harmful to microorganisms. It is effective in destroying the nucleic acids in these organisms so that their DNA is disrupted by the UV radiation, leaving them unable to perform vital cellular functions.
Inactivation Of Microorganisms
The degree of inactivation by ultraviolet radiation is directly related to the UV dose applied to the water. The dosage, a product of UV light intensity and exposure time, is usually measured in microjoules per square centimeter, or alternatively as microwatt seconds per square centimeter (µW•s/cm2). Dosages for a 90% kill of most bacteria and virus range from 2,000 to 8,000 µW•s/cm2. Dosage for larger parasites such as Cryptosporidium require a lower dose for inactivation. As a result, the US EPA has accepted UV disinfection as a method for drinking water plants to obtain Cryptosporidium, Giardia or virus inactivation credits. For example, for one-decimal-logarithm reduction of Cryptosporidium, a minimum dose of 2,500 µW•s/cm2 is required based on the US EPA UV Guidance Manual published in 2006.
Aquarium And Pond
Ultraviolet sterilizers are often used in aquaria and ponds to help control unwanted microorganisms in the water. Continuous sterilization of the water neutralizes single-cell algae and thereby increases water clarity. UV irradiation also ensures that exposed pathogens cannot reproduce, thus decreasing the likelihood of a disease outbreak in an aquarium. UV irradiation can also have a positive impact on an Aquariums Redox balance Aquarium and pond sterilizers are typically small, with fittings for tubing that allows the water to flow through the sterilizer on its way from a separate external filter or water pump. Within the sterilizer, water flows as close as possible to the ultraviolet light source. Water pre-filtration is critical so as to lower water turbidity which will lower UVC penetration. Many of the better UV Sterilizers have long dwell times and limit the space between the UVC source and the inside wall of the UV Sterilizer device.
