How does a UV reactor work

Every cell of a living organism contains DNA (except many viruses, which only contain RNA), which acts as the ‘’ which allows the cell to function and reproduce. UV-C light is able to penetrate the cells of microorganisms and disrupt the structure of their DNA molecules (Figure 3). This prevents the microorganism from surviving and/or reproducing, rendering it inactive and no longer pathogenic.

While this may seem a very simple principle process, many barriers exist that can potentially stop the UV-C light effectively penetrating the target organism’s cells. For this reason, it is important that a UV reactor system is carefully selected to ensure these barriers do not affect performance.


Figure 3 – UV-C radiation disrupts DNA

UV dose

A UV application requires an average UV dose. UV dose is the amount of UV energy per unit area that falls on a surface. It is calculated as:

Dose = Intensity x Residence Time (mJ/cm²)*

* Intensity is determined by the lamp power and Residence Time by the period of exposure to UV. Berson will recommend the appropriate UV dose for each application, taking into account the lamp ageing and fluid transmittance.

What UV dose is required to achieve validation?

As much as is required to inactivate a given pathogen by a specified log reduction. 40mJ/cm2 reduction equivalent dose (RED). This is based on the principle  that  most common water-borne pathogens will experience at least a 4 log reduction at this dose.
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