Views: 0 Author: Site Editor Publish Time: 2021-02-02 Origin: Site
Principle of disinfection
Why does ultraviolet light have a disinfecting effect?
Ultraviolet rays with a wavelength range of 200 to 300 nm have a disinfecting effect, such as 275nm uv light, 222nm far uvc light. They are absorbed by the DNA of microorganisms, destroying its structure and inactivating living cells.
Therefore, ultraviolet rays can make viruses, bacteria, yeasts and fungi harmless in a few seconds.
If the radiation intensity is high enough, ultraviolet disinfection is a reliable and environmentally friendly method because no chemicals are required.
In addition, microorganisms cannot be resistant to ultraviolet radiation.
How does ultraviolet light affect bacteria?
Air, water and surfaces usually contain a lot of bacteria. Some are harmless, while others may pose serious health risks to people.
Microorganisms present in the air (such as viruses, bacteria, yeasts and molds) especially occur in high-frequency populations such as airports, doctors' offices, hospitals and industries. They endanger human health, contaminate raw materials or destroy food.
Ultraviolet radiation can reliably reduce bacteria and improve hygiene and storage conditions. In order to reduce the bacterial content for a long time, the air contaminated by bacteria has been disinfected in the air supply duct.
Short-wave ultraviolet radiation in particular has a strong bactericidal effect. It is absorbed by the DNA of microorganisms and destroys its structure. In this way, living cells are inactivated.
How effective is UV light against viruses, bacteria and bacteria?
Ultraviolet rays can inactivate up to 99,9999% of microorganisms, which is equivalent to a log 6 reduction.
Since viruses have the simplest cell structure, they are inactivated first. In addition, they cannot produce resistance to ultraviolet light. Independent research has proved that UV-C radiation can inactivate SARS-CoV-2 (coronavirus).
In a recent study, Boston University concluded that ultraviolet-C light can reduce the log 6 of the SARS-CoV-2 virus by 99,9999%. This is achieved with a dose of 22 mJ/cm2 and an exposure of 25 seconds.
According to Boston University, depending on the UV-C dose, the exposure time can be reduced up to 6 seconds.
What are the current application areas of UV for disinfection?
Ultraviolet disinfection technology is widely used in various applications and industries.
Microorganisms in the air, such as viruses, bacteria, yeasts, and molds, are especially present in crowded areas such as airports, hospitals and theaters.
They endanger people’s health, contaminate raw materials, and cause food to deteriorate.
Ultraviolet radiation can reliably reduce the bacterial load and improve hygiene and storage conditions.
Sterilizing the air in the supply air duct ensures long-term effective reduction of microorganisms.
Especially short-wave ultraviolet radiation has a strong bactericidal effect. The radiation is absorbed by the microbe's DNA, destroying its structure. This inactivates living cells.
The food packaging process needs to completely remove harmful bacteria such as bacteria, yeasts and fungi. UVC disinfection is a dry and chemical-free method that can reduce the bacterial load by 99.9% (the bacterial reduction rate reaches the third stage).
In just a few seconds, strong ultraviolet light is enough to spoil the harmless food on the sealing foil and yogurt cup, such as bacteria, yeast or fungi.
In order to effectively inactivate even more UVC-resistant molds, it is recommended to use UVC radiation after disinfection with a low percentage of hydrogen peroxide (1% to 3%).
This combination uses two mechanisms: UVC radiation inactivates microorganisms that are sensitive to hydrogen peroxide, such as Bacillus subtilis spores; hydrogen peroxide destroys microorganisms that require high UVC doses, such as Aspergillus niger spores.
This can achieve an effective and extensive sterilization effect and reduce the bacterial load by up to 99.99% to provide the bacterial reduction rate required for logarithmic level 4 (super clean).
This means longer shelf life and less return of spoiled food.
Environmental protection and energy-saving water treatment and disinfection with ultraviolet rays include ballast water, industrial production water, drinking water, municipal sewage, and water treatment for aquaculture, agriculture and horticulture.
UV water treatment and water disinfection
Water treatment and disinfection with high-energy ultraviolet radiation is an environmentally friendly method established more than 100 years ago. It does not use any chemicals, such as chlorine or ozone.
Special UV lamps can destroy microorganisms including bacteria, viruses and parasites, and help decompose harmful chemicals.
UV treatment does not affect the smell or taste of water.
This UV solution can be used to treat ship ballast water, industrial processes and drinking water, urban sewage, industrial waste, aquaculture and agricultural water treatment and recycling processes.