1、 The core principle of ultraviolet water treatment technology
The ultraviolet water treatment technology uses ultraviolet light with a wavelength of 200-300nm (with 254nm having the strongest bactericidal effect) to destroy the nucleic acid (DNA/RNA) structure of microorganisms (bacteria, viruses, algae, etc.), causing them to lose their reproductive ability and achieve the purpose of sterilization and disinfection. Its core advantages lie in:
Physical disinfection: No need to add chemical agents, no by-products are produced (such as chloroform for chlorine disinfection);
Instantly effective: Microorganisms can be inactivated by exposure to ultraviolet radiation (usually 0.5-2 seconds);
Easy to operate: The modular design of the equipment makes it easy to integrate into various water treatment systems.
2、 Changes in water quality caused by ultraviolet treatment
UV treatment mainly targets microbial indicators and some organic pollutants, and the specific changes to water quality are as follows:
Core mechanism of water quality indicators before treatment (typical value) and after ultraviolet treatment (standard value)
Total bacterial count 10 ³ -10 ⁶ CFU/mL ≤ 10 CFU/mL (drinking water standard) destroys thymidine dimers in bacterial DNA, inhibits reproduction
Viruses (such as E. coli bacteriophages) with a concentration of 10 ² -10 ⁴ PFU/mL cannot detect the protein synthesis chain that destroys viral RNA
Algae (such as blue-green algae) can be seen in eutrophic and turbid water bodies. Algae cells become inactive, and the transparency of the water increases, damaging algal chlorophyll and preventing photosynthesis
Organic pollutants (partially) containing chlorophenols, pesticide residues, etc. are partially degraded (such as reducing chloroform by 30%). The combination of ultraviolet and ozone (UV/O3) produces hydroxyl radicals (· OH), which oxidize organic matter
After disinfection with residual chlorine/chemical agents, there is no significant change in residual chlorine levels between 0.5-1mg/L (which does not affect chemical indicators). Only physical disinfection is performed and does not react with chemical substances
Note: Ultraviolet radiation has no removal effect on heavy metals, salts, turbidity, etc., and should be used in conjunction with pretreatment methods such as sand filtration and reverse osmosis.
3、 Key parameters of ultraviolet water treatment technology
Ultraviolet dose:
Unit: mJ/cm ², calculated as dose=UV intensity (μ W/cm ²) x irradiation time (s).
Sterilization requirements:
Drinking water: ≥ 40 mJ/cm ² (inactivates 99.99% of Escherichia coli);
Industrial water: 20-30 mJ/cm ² (to control microbial growth);
Medical wastewater: ≥ 60 mJ/cm ² (inactivated spores, viruses).
Equipment type:
Low pressure ultraviolet lamp: wavelength 254nm, low energy consumption (suitable for small-scale water supply);
Medium voltage ultraviolet lamp: broad-spectrum wavelength (200-400nm), capable of degrading organic matter simultaneously, suitable for industrial wastewater treatment;
UV reactor: It is necessary to ensure uniform water flow (such as using turbulent design) to avoid “dead corners” that may cause incomplete disinfection.
4、 Applicable fields and typical application scenarios
Ultraviolet water treatment technology is widely used in the following scenarios due to its non secondary pollution, high efficiency, and convenience:
Drinking water purification
Municipal tap water terminal disinfection: to compensate for the by-product problem of chlorine disinfection, especially suitable for high organic matter water quality (such as lake water), to avoid excessive trichloromethane;
Rural decentralized water supply: Small ultraviolet equipment (with a processing capacity of 0.5-5m ³/h) is directly installed at the well water and river water terminals, replacing traditional boiling disinfection;
Direct drinking water system: Combined with RO reverse osmosis, the treated water quality meets the GB 5749-2022 “Sanitary Standards for Drinking Water”, with a total bacterial count of ≤ 10 CFU/mL.
Food and beverage processing
Bottled/barreled water: UV disinfection before filling (dosage 50-80 mJ/cm ²) to ensure product shelf life (such as 12 months for mineral water);
Dairy processing: Disinfect raw water (such as cleaning water for milk production lines) to avoid contamination by thermophilic bacteria that can cause product spoilage.
Medical and pharmaceutical water
Disinfection of hospital sewage: treatment of wastewater containing pathogens (such as drainage from infectious wards), inactivation of hepatitis B virus, tubercle bacillus, etc., and replacement of chlorine containing disinfectants (to avoid corrosion of medical equipment);
Pharmaceutical purified water: compliant with GMP standards, used for injection and oral liquid production, with a microbial limit of ≤ 10 CFU/100mL.
industrial circulating water
Cooling tower water: Control the growth of Legionella bacteria (UV dose of 30 mJ/cm ² can inactivate 99.9% Legionella bacteria), replace killing agents (such as chlorine), and reduce pipeline corrosion;
Ultra pure water for the electronics industry: terminal disinfection to avoid microbial contamination of chip production lines (water quality requirement: bacteria<1 CFU/mL).
Wastewater treatment and reuse
Municipal wastewater effluent: combined use of ultraviolet radiation and chlorine dioxide, with a fecal coliform count of ≤ 1000/L in the effluent, discharged into natural water bodies in compliance with standards;
Reclaimed water: Water used for flushing and greening in residential areas and hotels, disinfected with ultraviolet radiation to prevent odor and microbial transmission.
Special fields
Swimming pool water: Replace chlorine disinfection, reduce the irritation of chlorine to the skin and eyes, and control algae growth;
Special fields
Swimming pool water: Replace chlorine disinfection, reduce the irritation of chlorine to the skin and eyes, and control algae growth;
Aquaculture: Disinfect the aquaculture water (such as changing water in fish ponds), inactivate Vibrio and mold, and improve the survival rate of fish fry (dose 20-30 mJ/cm ²).
5、 Technical advantages and limitations
Advantages and limitations
No chemical residue, does not change the pH and taste of water, has poor effect on water with high turbidity (particles block UV rays)
Fast sterilization speed (in seconds), suitable for continuous treatment without sustained sterilization ability (possible secondary pollution after water storage)
Equipment maintenance is simple (regular replacement of lamp tubes is sufficient), and energy consumption increases with processing capacity (medium voltage lamps consume more power)
6、 Practical application cases
Case 1: Deep treatment of water supply plant in a certain city
Original process: coagulation sedimentation → sand filtration → chlorine disinfection;
After upgrading: coagulation sedimentation → sand filtration → * * ultraviolet radiation (40 mJ/cm ²) * * → chlorine disinfection (reducing chlorine dosage by 50%);
Effect: The concentration of trichloromethane was reduced from 0.06mg/L to 0.02mg/L, meeting the limit of GB 5749-2022 (0.06mg/L).
Case 2: Purified water system of a pharmaceutical factory
Process: RO reverse osmosis → EDI → * * ultraviolet (60 mJ/cm ²) * * → terminal filter;
Water quality: Conductivity ≤ 0.1 μ S/cm, total bacterial count<1 CFU/100mL, in compliance with USP (United States Pharmacopeia) standards.
summarize
UV water treatment technology is an efficient and environmentally friendly physical disinfection method, with the core value of quickly inactivating microorganisms and no secondary pollution, but it needs to be used in conjunction with pre-treatment (reducing turbidity) and subsequent protection (such as water storage and antibacterial). Its application areas cover drinking water, food, medical, industrial and other scenarios, especially in fields with strict requirements for water quality and chemical indicators (such as no residual chlorine, no by-products), it has irreplaceable advantages. With the improvement of ultraviolet lamp efficiency (such as LED ultraviolet technology) and intelligent control (such as online dose monitoring), its application cost will be further reduced, and its scope of application will continue to expand.
Post time: Jul-08-2025