UV-C disinfection · 30–40 mJ/cm² · no chemical residual
Commercial UV Water Sterilizer — 254 nm Disinfection for Drinking Water
Quick answer
A commercial UV water sterilizer exposes water to 254 nm light at 30–40 mJ/cm², inactivating bacteria, viruses and protozoan cysts without adding chemicals or leaving a residual. It needs clear water, a 5 µm prefilter and a clean quartz sleeve. Lamp output and UV transmittance determine the real dose, so reactors are sized at end of lamp life.
- Typical UV dose
- 30–40 mJ/cm² Typical UV dose
- Wavelength
- 254 nm Wavelength
- Lamp life
- 8,000–9,000 h Lamp life
- Feed turbidity
- <1 NTU Feed turbidity
01
What is a commercial UV water sterilizer and how does it work?
A UV sterilizer is a stainless chamber containing one or more mercury lamps inside quartz sleeves. Water flows through the annular gap around the sleeves, and 254 nm light damages microbial DNA and RNA so the cells cannot replicate. Nothing is added to the water, and no residual remains. Dose is the product of UV intensity and residence time, so lamp output, sleeve cleanliness and water clarity decide what the reactor actually delivers.
A commercial unit adds a UV intensity sensor, flow meter, temperature switch, drain and inspection ports, and a control panel that alarms on low dose. Low-pressure lamps suit small and medium flows; amalgam lamps pack more output into the same footprint.
02
How much UV dose does drinking water need?
Industry practice for drinking water is 30–40 mJ/cm² at 254 nm, stated at the end of lamp life and after a fouling allowance. Bacteria need less, viruses generally need more, and protozoan cysts such as Cryptosporidium are inactivated at comparatively low UV doses but still require a validated reactor. Regulated supplies may demand a specific log credit and a defined validation protocol.
Dose is not a fixed property of a lamp. A 40 W lamp rated at 1 m³/h and 30 mJ/cm² will not deliver that dose if the water is at 70% UV transmittance or the sleeve is coated. Size the reactor at end-of-lamp-life output and state the UVT, turbidity and temperature used for the calculation.
03
Which flow rate can one UV chamber treat?
Capacity is quoted at a defined dose, UV transmittance and water temperature. The table gives typical combinations for 30–40 mJ/cm² with filtered water above 90% UVT. Treat it as a starting point: a reactor selected for 10 m³/h at 30 mJ/cm² needs more lamps or a larger chamber to reach 40 mJ/cm².
| Flow (m³/h) | Lamps | Lamp power | Installed power | Typical use |
|---|---|---|---|---|
| 0.5 | 1 | 25–40 W | 0.04 kW | Drinking point, café |
| 1 | 1 | 40 W | 0.05 kW | Clinic, office pantry |
| 2 | 2 | 40 W | 0.09 kW | Restaurant, small hotel |
| 3 | 2 | 55 W | 0.12 kW | Hotel, school |
| 5 | 3 | 55 W | 0.18 kW | Resort, food service |
| 10 | 4 | 100 W | 0.45 kW | Bottling, food plant |
| 20 | 6 | 100 W | 0.65 kW | Beverage line, loop |
| 30 | 8 | 100 W | 0.90 kW | Industrial process water |
| 50 | 8 | 150 W | 1.30 kW | Large plant, booster |
Typical industry values, not a model list. Lamp count rises with lower UVT, higher dose, colder water and the end-of-life factor.
04
What water quality does UV need before the lamp?
UV treats only what the light reaches. Particles shield microorganisms, and iron, manganese and scale coat the sleeve; the sensor can read normal intensity while the water receives less than the design dose. A 5 µm cartridge before the reactor and turbidity below 1 NTU are the usual minimum, and many target below 0.5 NTU.
| Parameter | Typical requirement | Why it matters |
|---|---|---|
| Turbidity | Below 1 NTU | Particles shield microorganisms from UV |
| UV transmittance at 254 nm | Above 90% (1 cm path) | Low UVT needs more lamps for the same dose |
| Suspended solids | 5 µm nominal prefilter | Protects the sleeve and keeps the water clear |
| Iron | Below 0.3 mg/L | Stains the quartz sleeve |
| Manganese | Below 0.05 mg/L | Stains the sleeve and reduces output |
| Hardness and scale | No visible scale on the sleeve | Scale blocks UV and needs frequent cleaning |
Typical values for filtered drinking water; confirm the UVT and turbidity assumptions with the reactor supplier.
05
How long do UV lamps and quartz sleeves last?
Low-pressure mercury lamps are rated 8,000–9,000 hours, roughly twelve months of continuous operation. Output falls gradually, so replace at the rated hours or when the sensor can no longer hold the setpoint, not when the lamp stops glowing. Keep a log of running hours and sensor readings.
Quartz sleeves are chosen for high 254 nm transmittance, typically above 90% when new, but scale, iron and biofilm reduce it. Clean every 3–6 months, more often on hard or iron-bearing water. Replace a sleeve when cleaning no longer restores output or when scratches scatter light. Calibrate the UV sensor at commissioning and annually; a fouled sensor can hide a low dose.
06
Is UV a residual disinfectant, and how is it different from ozone?
No. UV inactivates microorganisms only while they pass the lamp; it leaves nothing in the water to protect the pipework downstream. A tank, a long distribution loop or a dead leg can reintroduce bacteria after the reactor. UV is therefore a barrier at the point of use, or one stage in a loop that also has a residual disinfectant.
Ozone works differently: it is a dissolved oxidant with a measurable residual, so it protects the tank and oxidises iron, manganese, colour and taste. Ozone needs contact time and off-gas destruction; UV needs clarity and a 5 µm prefilter. Choose UV for a clean point-of-use barrier, ozone for storage and oxidation, and combine them when both duties exist.
| Criterion | UV at 254 nm | Ozone |
|---|---|---|
| Mechanism | Photochemical damage to DNA and RNA | Oxidation of cell components and organics |
| Residual | None | Measurable, decays in minutes |
| Contact time | Seconds | 5–15 minutes typical |
| Colour, taste, iron | No removal | Oxidises and aids filtration |
| By-products | None at 254 nm | Bromate possible with bromide present |
07
What installation and certification points matter?
Install the reactor with the service clearance needed for lamp changes, provide a drain and a sample point after the chamber, and wire the intensity alarm to the plant control system. Keep the upstream filter and flow meter sized for peak flow, and confirm that the reactor cannot run dry. Allow a bypass with isolation valves so the chamber can be serviced without stopping the plant.
HydroWorks manufactures under ISO 9001 and holds CE certification; the company is a national high-tech enterprise with several water-treatment patents. These are quality and safety certificates, not UV validation for a regulated supply. Where validation is required, it must be obtained for the exact reactor and dose.
08
Can UV treat borehole, rainwater or stored water?
Yes, after the water is clarified and iron is removed. Borehole and rainwater usually carry turbidity, iron and colour that must be settled or filtered first; UV then polishes the clear water at the point of use. For stored rainwater, recirculate the tank through the reactor or treat at the outlet, and clean the tank on schedule.
UV does not remove chemicals, metals or dissolved salts, and it does not repair a contaminated distribution system. Test the source, treat the cause, and use UV as the final barrier rather than the only step.
Specifications
Delivery and service — typical ranges
| Item | Typical range |
|---|---|
| Standard skid lead time | 15–30 days after drawing approval |
| Containerized / turnkey lead time | 30–60 days after drawing approval |
| Warranty | 12–18 months from shipment |
| Factory testing | Hydrostatic pressure test and trial run with water before packing |
| Documentation | General arrangement drawing, P&ID, test record, O&M manual and spare-parts list |
| Packaging | Seaworthy plywood crate, or container for containerized plants |
| Installation support | Remote guidance as standard; on-site engineer available on request |
| Operator training | 1–2 days at commissioning, covering operation, CIP and consumables |
| Spare parts | Recommended two-year list quoted separately with the equipment |
| Payment terms | Typically 30% deposit and 70% before shipment; confirmed in the quotation |
| Minimum order | 1 unit |
| Loading port | Guangzhou or Shenzhen, China |
| Power supply | 220/380/415/440 V, 50/60 Hz; confirmed on order |
| Ambient temperature | 5–40 °C |
| Enclosure protection | IP54 for indoor skids; higher IP available on request |
| Certification | CE and ISO 9001; model-specific test reports on request |
Typical industry ranges for planning. Final scope, commercial terms and lead time are confirmed in the quotation.
FAQ
Frequently asked questions
Questions buyers actually ask during sizing and quotation. Answers match the specifications above.
01 Does UV remove chlorine, taste or colour?
02 Does UV kill Cryptosporidium and Giardia?
03 Can UV be installed before the storage tank?
04 What flow can one UV lamp treat?
05 Why does UV need a 5 µm prefilter?
06 Do UV lamps run continuously?
07 Is UV light safe in a plant room?
08 How often are lamps and sleeves replaced?
Next step
Send your water analysis, get a factory quotation
Tell us the source water, TDS, hardness, iron and daily demand. Factory engineers reply with a flow rate, process train and budget range within one working day.