Water disinfection can be divided into two methods: chemical and physical methods. Water disinfection is the use of chemical and physical methods to kill pathogens in water, in order to prevent disease transmission and maintain population health.
Physical water disinfection methods include heating method γ Radiation method and ultraviolet irradiation method, etc;
Chemical disinfection methods include the addition of heavy metal ions (such as silver and copper), the addition of alkali or acid, the addition of surface active chemicals, and the addition of oxidants (chlorine and its compounds, bromine, iodine, ozone). Among these methods, oxidant disinfection is the most widely used, with chlorine and its compounds being particularly common for disinfection, followed by ozone disinfection.
The ultraviolet irradiation method and the method of adding bromine, iodine, and their compounds are used for disinfection of water in small-scale water plants or special facilities such as swimming pools.
The Biological Principles of Ultraviolet Water Disinfection
1. Application analysis of ultraviolet disinfection technology for drinking water
Chlorine disinfection can produce chlorinated disinfection by-products with carcinogenic effects. In recent years, the discovery of Giardia and Cryptosporidium has posed serious challenges to existing chlorine disinfection processes. People have begun to search for new alternative disinfection technologies to effectively improve disinfection effectiveness and reduce the potential harm of by-products generated during the disinfection process to human health, while ensuring the microbiological and chemical safety of drinking water. Among the numerous alternative disinfection technologies, ultraviolet disinfection has attracted people's attention due to its advantages of not adding any chemicals, good disinfection effect, and no generation of disinfection by-products. The history of ultraviolet disinfection is very long. In Europe, ultraviolet disinfection of drinking water has a history of nearly a hundred years.
In 1910, a water plant in Marseille, France was the first to install a UV disinfection system to disinfect drinking water. So far, developed Western countries have installed nearly 4000 large-scale UV water disinfection systems in sewage treatment plants, with approximately 10% of the total number of sewage treatment plants using this technology. At the same time, by the end of 2001, more than 2000 water plants had adopted UV disinfection technology, accounting for more than 10% of the total number of water plants, and a large number of UV disinfection technology transformation projects are underway. Due to the outstanding advantages of ultraviolet disinfection in terms of environmental protection and personal safety, many countries in Europe and North America have listed ultraviolet disinfection as the preferred method for water terminals, user inlet ports, and small water supply systems. Especially after discovering the presence of Cryptosporidium in tap water, the United States has incorporated the UV disinfection process as the best method for tap water disinfection into its water supply regulations.
2. The inactivation effect of ultraviolet water disinfection on microorganisms in water. Ultraviolet disinfection has a high inactivation effect on various microorganisms in water, and the sterilization speed is fast, most of which is within 1 second. In addition, ultraviolet disinfection technology also has good inactivation effects on pathogenic microorganisms such as Giardia and Cryptosporidium discovered in recent years. Cryptosporidium oocysts are discharged into the environment through human and animal feces, and they can survive for a long time in the environment. Cryptosporidium oocysts and giasporidium cysts have a longer Time to live than other water-borne pathogenic microorganisms, which can cause multiple disease outbreaks. The disease caused by cryptosporidium is very serious. Its common symptoms are diarrhea, vomiting, low fever, and flu like symptoms. For patients with immune deficiency, such as AIDS patients, the disease is more serious, leading to death.
For example, in 1994, Cryptosporidiosis broke out in Las Vegas, the United States, and 20 AIDS patients died. Recent studies have shown that when the Radiation exposure of low-pressure mercury lamp and medium pressure mercury lamp is 30J/m2, cryptosporidium can be inactivated by more than 99.9%, and a large number of experiments have proved that both low-pressure mercury lamp and medium pressure mercury lamp can effectively inactivate cryptosporidium. UV disinfection also has a good effect on Legionella. Muraca compared the inactivation of Legionella by ozone, UV, chlorine, and heating. UV and heating (60 degrees Celsius) produced 5 logs of inactivation within 1 hour, while chlorine and ozone took 5 hours to achieve the same inactivation effect.
c. Comparison between UV water disinfection and other disinfection methods: A comparison of five commonly used disinfection methods in terms of disinfection effectiveness, cost, and safety. From the table, it can be seen that several chemical disinfectants require a longer time to inactivate microorganisms, while UV disinfection only takes a few seconds to achieve the same inactivation effect. Chemical disinfectants can produce some disinfection by-products that are harmful to human health, and the operation and management are also relatively complex. UV disinfection does not produce disinfection by-products during the sterilization process, and the operation is simple. Its infrastructure investment and operating costs are also lower than other chemical disinfection methods.
d. The advantages and disadvantages of ultraviolet water disinfection application: The ultraviolet disinfection process has advantages that other disinfection processes cannot compare, overcoming the shortcomings of existing traditional disinfection technologies. Many countries in Europe, as well as Canada and the United States in North America, have respectively revised environmental legislation in the 1990s, recommending the use of ultraviolet disinfection technology for disinfection of wastewater treatment and drinking water.
Compared with traditional mercury lamps, UVC LED has obvious advantages.
The high-power lamp beads equipped with the deep ultraviolet UVC-LED water disinfection kit can kill a variety of common pathogens in a confined small space within a period of ten seconds to three or five minutes. Moreover, because of the small size of the UVC-LED lamp beads, the disinfection kit has low requirements for the adaptability of the power line, and ordinary charging pads can be opened, and can be used outdoors or for travel and commuting, with high daily portability. However, the ultraviolet mercury lamp usually needs more than 10 minutes to more than half an hour to achieve a good sterilization effect. However, due to its high pressure, ozone, large power consumption, long sterilization time, bulky equipment and other reasons, the mercury lamp is limited in daily use and will eventually be eliminated by history.
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Shenzhen Hechuang Hitech CO., LTD. is a National High-tech Enterprise, which has won a number of invention patent technology awards. We focuses on the Research, Development, Production and Application of UVC-LED Technology. It adopts innovative technologies of revolutionary optics and fluid science, which can kill bacteria and viruses in 0.2 seconds, with a killing rate of 99.9999%. Hechuang Hitech provides safer, more efficient and more humanized sterilization module design for Water Air and Surface Disinfection products.
