Water Pumps & Treatment News

Ultraviolet Disinfection Services

Ultraviolet (UV) has a number of advantages over traditional disinfectants like chlorine or chloramines; however, like anything else, it must be applied properly. At EDS Pumps & Water Treatment Ltd., we see a number of customers who want to treat their water with ultraviolet disinfection services and systems because they are so simple to install, easy to maintain, and relatively cheap to purchase, but without doing the proper checks and tests, you could be buying yourself a lot of problems.

What is Ultraviolet Disinfection?

Ultraviolet light is suitable for residential, commercial, and industrial markets. Surface water from lakes, rivers, or shallow wells is typically exposed to more sources of contamination than deeper wells and they are also subject to wider fluctuations in water quality due to runoff and seasonal affects. These water sources are also a source of waterborne diseases caused by pathogenic bacteria and viruses and these microbes can be easily inactivated by UV disinfection.

The mechanism of UV disinfection is the same for all UV systems. Microbial inactivation is caused by the damaging effect of UV light on the microbe’s DNA. In the case of pathogens, the resulting damage prevents the microbe from multiplying, thus destroying their ability to infect and cause disease such as cholera, typhus, and other gastro-intestinal diseases commonly associated with contaminated water sources.

How Does Ultraviolet Disinfection Work?

UV disinfection has the ability to inactivate bacteria, viruses, and protozoa; however, each type of organism requires a specific dose for inactivation and typically viruses require higher UV doses than bacteria and protozoa. A UV dose is the product of light intensity and exposure time (the time the water resides in the UV reaction chamber).

The UV dose is usually given in units of microWatt seconds per square centimeter. For most residences, a range of 16,000-30,000 mW/cm is acceptable and will inactivate 99.99% of all bacteria, protozoa, and viruses, including cryptosporidium and giardia (beaver fever).

Key factors which impact the performance of a UV system are water quality, pretreatment, and UV design.

UV disinfection is highly effective when the water is low in iron, manganese, hardness, and has a high UV transmittance. UV transmittance is commonly referred to as UVT and refers to the waters ability to transmit UV light. Various organic and inorganic compounds that may or may not be visible can absorb UV and decrease the amount of UV energy for disinfecting. All water should be tested for UVT before it should be considered as a disinfection method. Typically, most water with a UVT of 75% or higher is required. Your water treatment professional can usually perform this test with the proper analyzer.

Ultraviolet Systems and Services

A comprehensive water test is an absolute necessity for sizing a UV system. As mentioned, water quality is paramount for the successful operation of a UV system. As elevated levels of minerals such as iron or hardness can form a film on the UV sleeve, reducing the UV dosage below the kill zone. Again, your water treatment professional can test for these parameters and make any recommendations should pre-treatment be needed. In addition, all UV manufactures require a minimum 5-micron sediment filter before the UV system and they will also recommend a carbon filter to reduce undesirable tastes, odours, and organic compounds.

To determine if UV disinfection is a good fit for your water system, call EDS Pumps & Water Treatment Ltd. at 604-534-1115 and ask to speak with one of our Water Treatment Specialists!  You can also read more about UV on our website.