Ultraviolet disinfection is the use of appropriate wavelengths of ultraviolet rays to destroy the molecular structure of DNA (deoxyribonucleic acid) or RNA (ribonucleic acid) in microbial cells, causing growth cell death and (or) regenerative cell death to achieve sterilization effect. Ultraviolet disinfection technology is based on modern epidemic prevention, medicine, and photodynamics. It uses specially designed high-efficiency, high-intensity and long-life UVC band ultraviolet light to irradiate flowing water to remove various bacteria, viruses, parasites, algae and algae in the water. Other pathogens are killed directly.
At present, only artificial mercury (alloy) light source can output enough UVC intensity for engineering disinfection. The tube of the ultraviolet germicidal lamp is made of quartz glass. The mercury lamp is divided into three types according to the mercury vapor pressure in the lamp tube after lighting and the difference of the ultraviolet output intensity: low pressure low intensity mercury lamp, medium pressure high intensity mercury Lamps and low-pressure high-intensity mercury lamps.
The sterilization effect is determined by the radiation dose received by the microorganisms. At the same time, it is also affected by the output energy of ultraviolet rays, which is related to the type of lamp, light intensity and use time. As the lamp ages, it will lose 30%-50% of its intensity . Ultraviolet radiation dose refers to the amount of ultraviolet light of a specific wavelength that is required to achieve a certain bacterial inactivation rate: radiation dose (J/m2) = radiation time (s) × UVC intensity (W/m2) The larger the radiation dose, the greater the disinfection efficiency Because of the equipment size requirements, the general irradiation time is only a few seconds. Therefore, the UVC output intensity of the lamp tube becomes the main parameter to measure the performance of the ultraviolet light "g('disinfection equipment');">the disinfection equipment. In the disinfection of urban sewage, the average radiation dose is generally above 300 J/m2. Below this value, the phenomenon of light resurrection may occur, that is, the germs cannot be completely killed. When they flow out of the channel and receive visible light, they will be revived, reducing the sterilization effect. The higher the requirement for sterilization efficiency, the greater the radiation dose required. The main factor that affects the microbes receiving sufficient UV radiation dose is the light transmittance (at 254 nm). When the UVC output intensity and irradiation time are constant, the change in light transmittance will cause the actual dose of the microorganisms to change.
Ultraviolet disinfection is a physical method. It does not add any substance to the water and has no side effects. This is where it is superior to chlorination disinfection. It is usually used in combination with other substances. Common combined processes are UV+H2O2, UV+H2O2 +O3, UV+TiO2, in this way, the disinfection effect will be better.
Precautions:
1. During use, the surface of the UV lamp should be kept clean. Generally, wipe it with an alcohol cotton ball once every two weeks. When dust or oil is found on the surface of the lamp, it should be wiped at any time.
2. When disinfecting indoor air with ultraviolet light. The room should be kept clean and dry to reduce dust and water mist. The temperature should be lower than 20℃ or higher than 40℃, and the relative humidity should be longer than 60%.
3. When using ultraviolet rays to disinfect the surface of objects, the irradiated surface should be directly irradiated by ultraviolet rays, and a sufficient radiation dose should be achieved.
4. Do not irradiate people with ultraviolet light sources to avoid damage.
5. The UV intensity meter is calibrated at least once a year.
Recommend a UV sensor that can be used in UV disinfection lamps. The UV sensor imported from abroad-GUVC-T10GD, the sensor chip size is 0.4mm, TO 46 package, using aluminum gallium nitride material, Schottky photodiode, photovoltaic mode Operation, with good sun blindness. Can be widely used: UV intensity detection and control, UV index detection. Outdoor UV index equipment, etc., can also be used for UV disinfection and UV curing to monitor UV intensity. UV flame detector, etc.
