Water Pumps & Treatment News

Ultraviolet Treatment

At EDS Pumps & Water Treatment Ltd., we offer a selection of water treatment services, including ultraviolet treatment, for ensuring the safety of your home’s drinking water supply.

What is Ultraviolet Treatment?

Typical Ultraviolet (UV) disinfection systems involve the flow of water through a vessel containing a UV lamp. As the water passes through this vessel, microorganisms are exposed to intense ultraviolet light energy, which causes damage to genetic molecules (i.e. nucleic acids: DNA or RNA) needed for reproductive functions. This damage prevents the microorganism from multiplying or replicating in a human or animal host. Since the microorganism cannot multiply, no infection can occur. Disinfection of water is achieved when UV light causes microbial inactivation.

Advantages of Ultraviolet Treatment

The advantages of UV disinfection over other disinfection methods include:

  • No use of chemicals (or a reduced amount of chlorine chemical when it is combined with UV disinfection)
  • No known production of chemical by-products
  • Simple to install, operate, and maintain
  • Inline process requiring no contact tanks
  • Inexpensive to operate

Primary Disadvantages of Ultraviolet Treatment

The disadvantages of UV disinfection include:

  • No residual disinfecting ability in storage (as there is with chlorine)
  • No residual disinfecting ability in the distribution system (as there is with chlorine)
  • Water quality can seriously affect disinfection ability
  • Very high UV doses are required to inactivate viruses
  • May require pre-treatment or pre-filtration to reduce turbidity of the raw water

These limitations must be considered whenever UV disinfection is incorporated into a system design. It may be advantageous to use a secondary disinfection method, such as chlorination, that will provide a disinfecting residual, depending on the system and the desired level of protection.

Ultraviolet System Sizing

Determining the proper capacity of an ultraviolet system is based on three variables: maximum flow rate, dose required, and UV transmittance of the water. Not all UV Systems are created equal.

Ultraviolet Applications

Water treatment systems can incorporate ultraviolet as a useful method of disinfecting treated water for safe use. Many other applications of this technology are possible, depending on the desired outcome. For instance, UV disinfection used in conjunction with chlorination can be a very effective disinfection system. UV is a cost-effective method for treating bacteria, viruses and protozoa, while chlorine provides a chemical residual offering additional protection in the event of contamination being introduced in the distribution system or plumbing.

For surface water systems and ground water under the direct influence of surface water, filtration pre-treatment and other processes are required. After pre-treatment, it is desirable to install another polishing filter such as a 1-micron (1μm) sediment filter, which can exclude small organisms. If water is suspected to contain viruses, ultraviolet dosage and contact time may need to be increased and/or used in combination with chlorine disinfection (effective virus inactivation occurs by maintaining a concentration of 0.25 mg/L free chlorine for 1 minute of contact time).

Sometimes, small point-of-use reverse osmosis devices (installed at one dedicated tap) utilize a very small UV lamp at the last stage of treatment. This ultraviolet is used to disinfect the water before use. Small UV devices function in the same manner as larger UV devices, and require similar maintenance and replacement practices.

Ultraviolet Maintenance

UV units operate at a low cost. The bulb gradually loses its disinfecting capabilities over time. It should be changed by you at least once a year — even if it is still operating. The quartz sleeve surrounding the bulb must be kept clean in order for the unit to function safely. It should be examined once a month; if it becomes cloudy, it should be cleaned. Note: that no one system can treat water 100 per cent and without proper maintenance it should not be considered 100 per cent reliable.

In cases where you suspect the water is unsafe due to a malfunction of the unit, you should boil water for one minute before using the water for drinking and brushing teeth. Should your plumbing become contaminated, it is recommended that you contact your local public health unit for the proper clean-up procedures.

Sleeve Replacement

Quartz sleeves, just like UV lamps, wear out over time. Quartz will lose its ability to transmit UV rays into the reactor chamber. To maximize the optimal performance of any UV unit, manufacturers recommend that the quartz sleeves be replaced with each lamp replacement. Most system operators typically replace their quartz sleeves every three to five years in disinfection applications and replace them once every one to three years in TOC-reduction, ozone-destruction, and UV de-chlorination applications.

EDS Pumps & Water Treatment Ltd. carries a wide variety of ultraviolet treatment systems for every application and budget. Contact one of our Water Treatment Specialists at 604-534-1115 to find out which one is right for your water treatment system.