The Efficacy of Ultraviolet Light in Water Treatment Systems

In many on-site wastewater treatment systems, UV disinfections have been accepted as a standard feature. Moreover, many in the drinking water industry have also accepted it as an effective means of combating chlorine resistant organisms like Giardia and Cryptosporidium. It is also popular in wastewater treatment because it does not use any chemicals and it also negates the need for dechlorination as well as its inherent trait to disinfect anything it comes into contact with.

How It Works

According to activated carbon adsoption experts, UV light disinfects by causing permanent damage to the DNA of any living species. Once the DNA is destroyed, the organism is no longer able to function and dies.  How can this effectiveness be measured? The introduction of UV system validation using bioassay methods shows excellent evidence of its effectiveness.


In order to perform a bioassay, pathogenic organisms are introduced into the fluid stream before the UV system. The operation is done under very controlled conditions and some system variables are measured like: flow, transmittance, power loads and lamp intensity before and after the procedure.

Once all the data has been collected, it is then sent to the analyzing laboratory so as to compare to the estimation of the manufacturer. It goes without saying that these bioassays need to be carried out under the supervision of a credible third party.

Virtually all-ultraviolet systems have to del with differences in flow rates and normally an operating flow range is necessary when conceptualizing an ultraviolet system. It is therefore vital to install a UV system for wastewater disinfection into a closed pipe setup so as to ensure not only optimal hydraulics but more importantly to prevent anyone from operating the system to be exposed to the UV light and the wastewater.

Chlorination is no longer the only solution when disinfecting wastewater. UV systems are now in the forefront of wastewater treatment not only for its effectiveness but more importantly its non-chemical nature.