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Basic Technical Requirements for Ultraviolet Disinfection Units and Key Points for UV Disinfection Construction and Installation

2021-03-12

Basic Technical Requirements for Ultraviolet Disinfection Units and Key Points for UV Disinfection Construction and Installation

Ultraviolet disinfectors are highly valuable in water treatment because they primarily work by exposing water to ultraviolet light, which damages and alters the internal structures of certain microorganisms, leading to bacterial death and preventing their reproduction—thus achieving the goal of sterilization. Ultraviolet disinfection is a physical disinfection method characterized by its simplicity and convenience, broad-spectrum effectiveness, absence of secondary pollution, and ease of management and automation. So, what are the basic technical requirements for ultraviolet disinfectors? Let’s find out together below!


　　Basic Technical Requirements for Ultraviolet Sterilization Lamps and Ultraviolet Disinfectors for Water Treatment

　　1. The design of the ultraviolet disinfection device shall comply with the requirements of GB 8988, “Safety Requirements for Electronic and Related Equipment Powered by Mains Electricity for Household and Similar General-Purpose Applications.”

　　2. Manufacturing shall be carried out in accordance with drawings and technical documents approved according to the procedures stipulated in the technical management regulations.

　　3. The components of the same model of sterilizer shall ensure interchangeability;

　　4. Surfaces exposed to ultraviolet radiation should be polished.

　　5. The working pressure of the pressurized cylinder shall not be less than 0.60 MPa, and the test pressure shall not be less than 0.90 MPa.

　　6. It is advisable to install flow guide plates inside the simplified structure or enclosure.

　　7. The installation requirements for straight-tube quartz ultraviolet low-pressure mercury lamps and lamp tubes shall comply with YY/T0160 “Straight-Tube Quartz Ultraviolet Low-Pressure Mercury Disinfection Lamps.”

　　8. When higher environmental requirements apply, it is advisable to prioritize the use of low-ozone lamps to minimize ozone pollution to the environment.

　　9. The arrangement of the lamps should ensure a uniform distribution of UV intensity on the surface exposed to ultraviolet radiation.

　　10. A lamp ignition indicator, a cumulative ignition time indicator, or a relative indicator of ultraviolet irradiance intensity shall be provided.

　　11. The lamp tube is equipped with a quartz glass sleeve that is isolated from water. The quartz sleeve should have a UV transmittance of over 85% at 253.7 mm.

　　12. The low-voltage electrical appliances selected shall meet the technical requirements of the corresponding products.

　　13. The ultraviolet disinfection unit should be equipped with inlet and outlet pipes, a drain pipe, and a sampling pipe. If it is inconvenient to install a drain pipe directly on the disinfection unit itself, it may instead be installed on the connecting pipeline at a location equivalent to that of the disinfection unit.

　　14. The specifications of the disinfectant and the diameters of its inlet and outlet pipes should be selected according to the table provided.

　　15. According to the inspection requirements specified in this standard, for disinfectors equipped with new lamps, the measured ultraviolet irradiance dose shall not be less than 12,000 micro Ws/cm² (with water filled). For disinfectors operating normally, the measured ultraviolet irradiance dose shall not be less than 9,000 micro Ws/cm².

　　16. Under the operating conditions specified in this standard and when operating at the rated disinfection water volume, the bacteriological indicators of the effluent shall meet the requirements of GB 5749, “Hygienic Standard for Drinking Water.”

　　17. The materials shall comply with the requirements of GB/T 17219, “Safety Evaluation Standard for Water Supply and Distribution Equipment and Protective Materials for Domestic Drinking Water.” The disinfectant should preferably be made of 304 stainless steel.

　　18. The head loss under the rated disinfection water flow rate shall be less than 0.005 MPa.

　　 Ultraviolet sterilization The principle involves treated water entering the chamber of the flow-through ultraviolet disinfection unit through the inlet. The ultraviolet light waves exert cavitation, mixing, cleavage, oxidation, flow-promotion, bactericidal, and algaecidal effects on the water, thereby achieving auxiliary sterilization and degradation of organic substances. The localized shock waves generated in the process induce turbulent flow in the treated water, ensuring more thorough and uniform contact between the water and ultraviolet light, thus delivering a highly efficient sterilization effect. Meanwhile, the ultraviolet light waves, combined with strong ultraviolet C (UVC) radiation at a wavelength of 254 nm, further enhance broad-spectrum sterilization, enabling the treated water to achieve effective sterilization within a very short time.

　　Key Points for the Construction and Installation of Ultraviolet Disinfectors

　　1. It is not advisable to install it directly on the outlet pipe adjacent to the pump, to prevent water hammer caused by pump shutdown from damaging the quartz glass tube and lamp tube.

　　2. Install strictly according to the direction of water inflow and outflow.

　　3. There should be a foundation that rises above the building’s ground level; the height of the foundation above the ground should not be less than 100 mm.

　　4. The ultraviolet disinfection unit, along with its connecting pipes and valves, shall be securely fixed and must not allow the UV generator to bear the weight of the pipes and accessories.

　　5. The installation should facilitate easy disassembly, inspection, and maintenance; all pipe connections must not use materials that could compromise water quality and hygiene.

　　The ultraviolet disinfection commonly referred to in water supply and drainage projects is, in fact, UVC disinfection. UV disinfection technology is based on modern epidemiology, medicine, and photodynamic principles. It employs specially designed, high-efficiency, high-intensity, and long-life UVC ultraviolet light to irradiate flowing water, directly killing various bacteria, parasites, algae, and other pathogens present in the water, thereby achieving the purpose of disinfection.

　　Environmental requirements for UV sterilizers:

　　Iron content: Not more than 0.3 ppm (0.3 mg/L)

　　Hydrogen sulfide: Not more than 0.05 ppm (0.05 mg/L)

　　Solid suspended matter: Not more than 10 ppm (10 mg/L)

　　Manganese content: Not more than 0.5 ppm (0.5 mg/L)

　　Water hardness: Not exceeding 120 mg/L

　　Chroma: Not more than 15 degrees

　　Water temperature: 5℃～60℃

　　Applications of Ultraviolet Disinfectors

　　Disinfection for reclaimed water reuse; disinfection of water used in aquaculture and processing; disinfection of secondary water supply in residential communities; disinfection of water used in the food and beverage industry; disinfection of municipal wastewater treatment effluent; disinfection of municipal landscape water; disinfection of water at tap water, purified water, and mineral water plants; small-scale household drinking water disinfection; disinfection of water used in aquatic facilities (such as swimming pools); disinfection of water used in large-scale poultry and livestock farming.

The above is a compilation of the basic technical requirements for ultraviolet disinfectors. To learn more about ultraviolet disinfectors, stay tuned to Guangzhou Weigu Environmental Protection.

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