Overview of the Development of Ultraviolet (UV) Disinfection

Currently, water supply and drainage disinfection methods can be divided into two main categories: chemical disinfection and physical disinfection. Chemical disinfection methods include chlorination and ozone disinfection; physical disinfection methods include ultraviolet (UV) disinfection. Chemical disinfection methods generally produce disinfection byproducts, while UV disinfection is unique in that the bactericidal and disinfecting effects of ultraviolet light from sunlight were discovered as early as 1878. The application of UV disinfection technology in urban wastewater treatment began in the mid-1960s, with extensive early research conducted in the 1970s and early 1980s. This was primarily because it was recognized that residual chlorine in the widely used chlorination process was toxic to fish and other organisms in the receiving water, and that chemical disinfection methods such as chlorination produced carcinogenic, genotoxic, and teratogenic byproducts such as trihalomethanes (THMs). These discoveries prompted the search for a better disinfection method that would not produce disinfection byproducts or cause secondary pollution. Thus, the application of ultraviolet light in disinfection began to attract attention. Ultraviolet (UV) disinfection was first applied in the United States (the U.S. Environmental Protection Agency completed the first demonstration project of UV disinfection for wastewater in 1970) and is now widely used in the United States and Canada. UV disinfection is a physical disinfection method with broad-spectrum bactericidal capabilities and no secondary pollution. After more than 30 years of development, it has become a mature, reliable, efficient, and environmentally friendly disinfection technology, widely used in various fields abroad. In my country, due to limited understanding of the technology, its application in wastewater treatment is limited. The Shanghai Municipal Engineering Design Institute has conducted extensive research in this area and has already applied it in wastewater treatment plants such as Minhang and Changqiao in Shanghai. Entering the 21st century, with increasing emphasis on wastewater effluent disinfection and the accumulation of operational experience, UV disinfection technology will be promoted. It is estimated that in the future, 50% of wastewater treatment plants with the necessary conditions will adopt UV disinfection, making it the mainstream technology to replace traditional chemical disinfection methods.