Photo/ UV Oxidation
What is it?
This decomposition takes place in two ways:
- Photolysis: compounds such as VOCs, NH3 H22 and amines are directly broken down by the radiation;
- Oxidation by reactive oxygen radicals: the presence of highly reactive oxygen radicals oxidises compounds that are not broken down by direct photolysis and reaction products from the photolysis.
Design, maintenance and efficiency
Besides spent UV lamps (expected lifespan of about 8000 hours), no waste is created. The energy consumption is in the range of 0.3–1.5 kWh/1000 Nm3.
The first use of photo oxidation in air purification on an industrial scale dates back to the late ‘90s. Applications can be found in the following sectors:
- Coating installations;
- Wastewater treatment;
- Waste sorting/ processing installations;
- Fermentation processes, breweries;
- Foodstuffs industry (meat, fish);
Table 1 shows application limits and restrictions associated with photo/ UV oxidation (adapted from EIPPCB, 2016, Table 3.218).
Table 1. Application limits and restrictions associated with photo/ UV oxidation.
|Gas flow (Nm3/h)||2000-58000 (in theory not very critical)|
|Temperature (°C)||< 60|
|Pressure drop (mbar)||NI|
|Relative humidity (%)||Dust removal should preferably be carried out|
|Dust concentration||Dust removal should preferably be carried out|
|Energy||Ionisation is primarily suited for gas streams with low concentrations of VOCs because of the low energy consumption compared to thermal oxidisers|