The germicidal lamp does not need to be converted into visible light. The 250nm-260nm wavelength can play a good sterilizing role. This wavelength range can destroy its chromosomes and play a photochemical role.

Only artificial mercury (alloy) lamp light source can output enough UVC intensity for engineering disinfection. Ultraviolet germicidal lamps are made of quartz glass. Mercury lamps are divided into three types according to the difference in mercury vapor pressure and the intensity of ultraviolet output in the lighted lamp: low-pressure low-intensity mercury lamps, medium-pressure high-intensity mercury Lamps and low-pressure high-intensity mercury lamps. The bactericidal effect is determined by the amount of radiation received by the microorganisms, and it is also affected by the output energy of ultraviolet light, which is related to the type of lamp, light intensity and use time. As the lamp ages, it will lose 30% -50% of the intensity . Ultraviolet irradiation dose refers to the amount of ultraviolet rays of a specific wavelength required to reach a certain bacteria inactivation rate: irradiation dose (J/m²) = irradiation time (s) × UVC intensity (W/m²) The greater the irradiation dose, the greater the disinfection efficiency High, due to the size requirements of the equipment, the general irradiation time is only a few seconds. Therefore, the UVC output intensity of the lamp becomes the most important parameter to measure the performance of the ultraviolet disinfection equipment. In urban sewage disinfection, the average average dose is above 300 J/m². Below this value, there may be a photo-resurrection phenomenon, that is, the pathogen cannot be completely killed. When it flows out of the channel and receives visible light irradiation, it is reactivated and the sterilization effect is reduced. The higher the sterilization efficiency requirements, the greater the radiation dose required. The main factor that affects the microbes receiving sufficient ultraviolet radiation dose is the light transmittance (at 254 nm). When the UVC output intensity and irradiation time are fixed, the change in light transmittance will cause the microbes to actually receive a change in dose.

Most ultraviolet installations use traditional low-pressure ultraviolet lamp technology, and some large water plants use low-pressure high-intensity ultraviolet lamp systems and medium-pressure high-intensity ultraviolet lamp systems. Due to the generation of high-intensity ultraviolet light, the number of lamps may be reduced by more than 90%, thus The floor space is reduced, installation and maintenance costs are saved, and the ultraviolet disinfection method is also applicable to effluent with poor water quality.