Application of Ultraviolet Technology in Water Treatment—degradation of Residual Chlorine

The advantages of using ultraviolet (UV) light to kill aquatic pathogens causing infectious diseases are widely recognized. In fact, industry was one of the earliest pioneers in using this technology. Today, almost all industries apply UV technology to water treatment systems, including the food and beverage, pharmaceutical, cosmetics, health product, manufacturing, and high-tech industries. Sterilization and disinfection are the primary applications of UV technology in water and wastewater treatment. At the same time, industry also applies this technology to many other areas, including ozone removal, reduction of total organic carbon (TOC), liquid sugar disinfection, chlorine degradation, surface and air disinfection, and cooling tower disinfection. This article will provide a brief overview of some of the industrial applications of UV light.

Residual Chlorine Degradation

In municipal water treatment and supply systems, chlorination disinfection is essential. However, in industrial production processes, removing residual chlorine from water is often a necessary pretreatment to avoid adverse effects on products. Basic methods for removing residual chlorine include activated carbon beds and chemical treatment. The disadvantage of activated carbon treatment is that it requires constant regeneration and often encounters problems with bacterial growth. Ultraviolet light with wavelengths of 185 nm and 254 nm has been proven to effectively break the chemical bonds of residual chlorine and chloramine. Although it requires a large amount of ultraviolet energy to be effective, its advantages include that this method does not require the addition of any chemicals to the water, does not require the storage of chemicals, is easy to maintain, and simultaneously has the effects of sterilization and removal of organic matter.