Chlorine is the most widely used chemical for water disinfection, usually as sodiumhypochlorite (liquid) or chlorine gas.

When chlorine gas or hypochlorite is added to water, hypochlorous acid (HOCl) is formed. The hypochlorous acid dissociates in water into H+ and OCl (hypochlorite ion). The degree of dissociation depends on the water characteristics. In certain situations mainly HOCl is present in other situations mainly OCl.

To protect the membranes of food stuff from free chlorine in the water the manufacturer needs a water source with extremely low levels of free chlorine.

The process of reducing the amount of free chlorine in water is called “dechlorination”. It is often used in water to reduce the amount of free chlorine.

UV light is able to dechlorinate water by direct action (photolysis) on both HOCl and OCl. The effect of UV light on HOCl and OCl is different, due to the difference in UV absorption. The consequence is that different wavelengths and UV doses must be applied to dissociate ‘chlorine’ with direct UV photolysis.

The applied UV dose can differ from hundreds to several thousands of mJ/cm2 to create the required effect in the dechlorination process.

The advantage of using UV light instead of chemical dosing or filtration techniques is that it requires no chemicals and results in no residuals.

bestUV offers the know-how to design the right UV system for the water characteristics at a specific site.

Contact the ‘experts in ultraviolet light’ to fully optimise your new or existing water treatment system with bestUV technology.