Drinking and Process Water Treatment

UV is applied in water treatment prior to consumption e.g. for drinking and processwater or afterwards in sewage plants to treat the waste water. Generally, watertreatment is performed in several stages. Usually UV water treatment is used in thesecond-to-last or last stage depending on the specific application (see chapter 3).Stages of water treatment depend on individual water quality and vary from case to case.

UV is applied in water treatment prior to consumption e.g. for drinking and processwater or afterwards in sewage plants to treat the waste water. Generally, watertreatment is performed in several stages. Usually UV water treatment is used in thesecond-to-last or last stage depending on the specific application (see chapter 3).Stages of water treatment depend on individual water quality and vary from case to case.

UV water treatment equipment can generally be classified into two groups:n closed systems for drinking and process water treatmentn open channel configuration for wastewater treatment in sewage plants.






Closed reactor systems are used for drinking and process water treatment, in order to avoid any recontamination. For drinking water, a fluence of 400 J/m² was established as a minimum requirement for effective disinfection. This minimum UVC fluence corresponds to DVGW, ÖNorm and NSF ANSI standard (class A UV system). Please refer to chapter 9 for further information.


UV water treatment is a simple, economic and reliable method, provided a good
water quality in terms of low content of organic compounds is given. Substances like iron and manganese, staining and clouding influence the water condition and the disinfection process. The absorption coefficient or transmittance of the water for UV is critical. To ensure an effective disinfection, the operating conditions must therefore be carefully monitored and controlled. Variations in the transmittance of the water can be compensated for by adjusting lamp power and/or flow rates accordingly. Thus, UV irradiance is monitored with at least one UV sensor at a representative position in the reactor to guarantee proper lamp operation.

Generally two different types are used:

• Longitudinal flow system
• Cross flow system

Typically, the reactor consists in both cases of following components:

• UV lamp
• quartz sleeve
• wiper for mechanical cleaning of quartz sleeves to protect against fouling
• UV sensor to control UV output
• power supply