Bactericidal effect is determined by the microorganisms received by the irradiation dose, at the same time, but also by the output energy of ultraviolet light, and the type of lamp, light intensity and use of time related to the lamp, with the aging of the lamp, it will lose 30% -50% of the intensity. UV irradiation dose is to achieve a certain bacterial inactivation rate, the amount of a specific wavelength of ultraviolet light is required: irradiation dose (J/m2) = irradiation time (s) × UVC intensity (W/m2) The larger the irradiation dose, the higher the disinfection efficiency, 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 has become a measure of UV onclick = "g (disinfection) equipment);">Disinfection equipment performance is the most important parameter. In urban wastewater disinfection, the average irradiation dose is generally above 300 J/m2. Below this value, there is a possibility of light revival phenomenon, that is, the germs can not be completely killed, when the outflow from the channel to receive visible light irradiation, re-animation, reducing the sterilization effect. The higher the sterilization efficiency requirement, the larger the required irradiation dose. The main factor affecting the microorganisms to receive enough UV irradiation dose is the transmittance (254 nm), when the UVC output intensity and irradiation time is certain, the change of transmittance will cause the microorganisms to receive the dose of the actual change.
Advantages
Most ultraviolet devices utilize traditional low-pressure ultraviolet lamp technology, there are some large water plants using low-pressure high-intensity ultraviolet lamp system and medium-pressure high-intensity ultraviolet lamp system, due to the production of high-intensity ultraviolet light may make the number of lamps to reduce the number of more than 90%, which reduces the footprint, saving the cost of installation and maintenance, and so that ultraviolet disinfection of poorer quality of water of the effluent water is also applicable.
Research and use of the status quo
Currently domestic research, production and application of sewage ultraviolet sterilizer is still very little. Tianjin University, such as Gu Ping people to Tianjin Jizhuangzi wastewater treatment plant depth treatment of effluent as the object of study, static and dynamic tests, to determine the relationship between the ultraviolet dose and bacterial survival rate, and designed to produce turbulent flow of ultraviolet disinfector, Duoyuan water environmental protection technology industry (China) Co., Ltd. developed and produced a closed-type disinfector can be handled by the amount of water 100 ~ 500m3 / h, and in the onclick="g(swimming pool);"> swimming pool circulating water disinfection has been applied, modular open-type sterilizer can be designed and installed according to user needs. Yantai City, sets of Bay sewage plant depth treatment using open UV disinfection process, can provide the city with 4 × 104m3 / d of industrial water reuse, the current operating conditions are good.
Ultraviolet disinfection scope of application:
2.3.1 Scope of application:
Used for indoor air, object surfaces and water and other liquids disinfection.
2.3.2 Ultraviolet disinfection lamps and ultraviolet sterilizers
2.3.2.1 Disinfection of ultraviolet light is the C-wave ultraviolet light, the wavelength range is 200-275nrn, the strongest bactericidal effect of the band is 250-270nrn, disinfection of ultraviolet light source must be able to produce irradiation value of the national standard of sterilization of ultraviolet lamps.
2.3.2.2 Preparation of ultraviolet disinfection lamps, quartz glass tubes should be used grades, in order to obtain satisfactory ultraviolet irradiation intensity.
2.3.2.3 Ultraviolet disinfection lamps can be equipped with reflectors made of materials with high reflection coefficients of ultraviolet light (e.g., polished aluminum).
2.3.2.4 Requirements for disinfection of ultraviolet lamps in the voltage of 220V, relative humidity of 60% of the environment, the temperature of 20 ℃, the radiation of the 253.7nm ultraviolet intensity shall not be less than 7ouW/cm2 (ordinary 30W straight tube ultraviolet lamps in the distance from the tube at the 1-meter determination, special ultraviolet lamps in the use of distance determination, the use of ultraviolet intensity meter must be calibrated. calibration.)
2.3.2.5 The use of ultraviolet lamps in the process of its irradiation intensity gradually decreased, it should be determined frequently disinfection of ultraviolet intensity, once the intensity of the requirements of the drop below; should be replaced in a timely manner.
2.3.2.6 The service life of ultraviolet disinfection lamps, that is, the intensity of the new lamp reduced to 70Uw/cm2 time (power ≥ 30w) lamps, or reduced to 70% of the original intensity of the new lamps (power & lt; 30w = time, should not be less than 1,000h.
2.3.2.7 Currently used in China's ultraviolet disinfection lamps are the following < /p>
(1) the intensity of the lamp should be replaced in a timely manner. /p>
(1) ordinary straight hot cathode low-pressure mercury ultraviolet disinfection lamp: quartz glass or other lamps made of glass with a high transmittance of ultraviolet rays, the power of 40W, 30W, 20W, 15w and so on. Requirements for factory new lamp radiation 253.7nrn ultraviolet intensity (measured at a distance of 1 m, without reflector) for: power & gt; 30W lamps, ≥ 90Uw/cm; power & gt; 20w lamps, ≥ 60Uw/cm2; power 150 lamps, ≥ 20Uw/cm2. As such lamps radiate 253.7nrn ultraviolet radiation at the same time, but also radiate a part of the 184.9nm ultraviolet. Therefore, it can produce ozone.
(2) high-intensity ultraviolet disinfection lamp: the intensity of radiation 253.7nrn ultraviolet (measured at a distance of 1 m) for: power 30W lamps, & gt; 180uW/CM2; 11w lamps, & gt; 30 uW/CM2.
(3) low-ozone ultraviolet disinfection lamp: also hot cathode low-pressure mercury lamp, can be straight or H-type; due to the use of special processes and lamp materials. The use of special processes and lamp materials, so the ozone production is very low, the ozone production requirements <1mg/h.
(4) high ozone ultraviolet disinfection lamps: due to the adoption of a special process, this lamp produces a larger proportion of the wavelength of 184.9nrn ultraviolet light, so the ozone production is greater.
2.3.2.8 Ultraviolet sterilizer
(1) Ultraviolet air sterilizer: low ozone ultraviolet germicidal lamps are used to manufacture, can be used for indoor air disinfection under manned conditions.
(2)UV Surface Sterilizer: manufactured with low ozone high-intensity ultraviolet germicidal lamps so that it can achieve satisfactory disinfection effect in an instant.
(3)Ultraviolet disinfection box: high ozone high-intensity ultraviolet germicidal lamp manufacturing, on the one hand, the use of ultraviolet light and ozone synergistic sterilization, on the other hand, the use of ozone on the ultraviolet irradiation can not be parts of the disinfection.
2.3.3 Scope and conditions of application
2.3.3.1 Ultraviolet light can kill a variety of microorganisms, including bacterial propagules, germ cells