Industry Applications
Intrinsic germicidal efficiency (ideal clean‑water laboratory condition)
Low‑pressure UV (LP‑UV)：Monochromatic output at 254 nm, which matches the maximum DNA absorption wavelength of microorganisms. Under clean‑water conditions, LP‑UV delivers higher germicidal efficiency per unit UV energy. At the same UV dose (J/m²), LP‑UV achieves slightly better inactivation for most bacteria and viruses.
Medium‑pressure UV (MP‑UV)：Broad‑spectrum output ranging 200‑400 nm. Only part of the energy falls on the optimal 254 nm germicidal band. Given the same total UV energy, its pure germicidal photon utilization is lower than LP‑UV. However, the 185 nm emission generates hydroxyl radicals to support oxidation‑assisted disinfection.
Conclusion for ideal clean water: LP‑UV has higher intrinsic disinfection efficiency at equal UV dose.
2. Practical on‑site disinfection efficiency (real‑world engineering conditions)
Low‑pressure UV
High electro‑optical conversion efficiency; more 254 nm UV output per watt of electric power.
Limitation: Low irradiance per lamp. In turbid or colored water, UV penetration drops rapidly, and the actual delivered UV dose decreases significantly. Best for low‑turbidity clean water.
Medium‑pressure UV
Extremely high irradiance per lamp. Better penetration in moderately turbid or colored water, ensuring effective UV dose throughout the water stream. Combined broad‑spectrum UV and advanced oxidation effect enhance inactivation of tough pathogens.
Limitation: Lower electro‑optical conversion efficiency; part of input power converts into heat instead of effective UVC.
Conclusion for field application: MP‑UV often shows better practical disinfection efficiency for turbid water, colored water and high‑flow projects.
3. Performance against typical microorganisms
Common bacteria such as E. coli: Both perform well in clean water; LP‑UV is slightly superior.
Cryptosporidium, Giardia: LP‑UV requires sufficient retention time and dose. MP‑UV achieves high inactivation rate within short retention time, widely used for swimming pool and drinking‑water projects.
UV‑resistant microorganisms: MP‑UV benefits from broad‑spectrum radiation plus oxidation synergy and delivers better overall inactivation.
4. External factors affecting efficiency
Quartz sleeve fouling: Fouling reduces efficiency for both types, even for high‑irradiance MP‑UV.
Hydraulics: Turbulent flow and adequate retention time are critical for both systems.
Lamp aging: LP‑UV has mild light decay. MP‑UV suffers greater light decay due to high operating temperature; lamps shall be replaced on schedule.
