Ultrapure Water System UV Digestion System Principle and Introduction

Ultraviolet (UV) light is an invisible light wave located at the ultraviolet end of the spectrum, hence the name. Based on different wavelength ranges, it is divided into three bands: A, B, and C. The C band, with wavelengths between 240-260 nm, is the most effective sterilization band, with the strongest wavelength at 253.7 nm. The sterilization principle of UV disinfection in ultrapure water systems utilizes the energy of UV photons to disrupt the DNA structure of various viruses, bacteria, and other pathogens in the water. This primarily involves breaking various structural bonds in DNA or causing photochemical polymerization reactions, such as dimerization of THYMINE in DNA, thereby preventing viruses, bacteria, and other pathogens from replicating and multiplying, achieving a sterilization effect. UV light with a wavelength of 185 nm reacts with air to produce ozone. Ozone is a strong oxidant with bactericidal effects and the ability to decompose organic matter, effectively reducing TOC (Total Organic Carbon).

UV sterilizers are commonly found in low-flow-rate pure water equipment. As an effective sterilization device, it can treat bacteria and viruses in the solution passing through the flow chamber. The efficiency of sterilization is related to the contact time between the 253.7nm wavelength ultraviolet light and the liquid, as well as the irradiation intensity. Ultraviolet lamps have a limited lifespan; prolonged use reduces their irradiation intensity, affecting sterilization effectiveness, and they should be replaced.

Common ultraviolet sterilizers are divided into flow-through and immersion types. The flow-through type used by UPU typically consists of a flow-through chamber (made of 304 stainless steel with a polished inner wall), ultraviolet lamps, a sleeve (quartz glass that does not block ultraviolet light), and a power supply. High-end flow-through ultraviolet sterilizers also include a timer and light intensity monitoring, allowing for the observation of the ultraviolet lamp's usage time and the ultraviolet irradiation intensity.