atg UV Technology

UV Technology


Over 100 years ago, German scientists discovered that the top surface of lake-water was sterile when exposed to sunlight. Further Investigation led to the discovery of Ultraviolet (UV) light. Ultraviolet light has many beneficial properties. UV light into four main categories, UV-A, UV-B, UV-C and Vacuum UV. The area between 240 and 280 nanometres (nm) is UV-C, known as the germicidal region. UV-C light has the ability to inactivate chlorine-resistant organisms in water, air and other fluids. For industrial product and process fluids, these organisms can cause spoilage and reduced shelf life. For municipal drinking water, these organisms can be harmful to humans. With regulations becoming more stringent, we have developed some of the leading UV systems for a vast range of applications and industries.

We are committed to continuous innovation and product development. The technical aspects of the business are split into two main sections: Research and Development and Validations/Approvals.

UV light is a physical, nonintrusive method of ensuring that organisms are unable to replicate, and with a typical life of only a few minutes, they are rendered harmless.

Correctly sized UV systems can also be used to de-chlorinate or de-ozonate process water and to assist in the removal of TOC and urea from ultra pure water. The level of a pathogens inactivation depends on the UV dose (UV intensity x exposure time) applied and the pathogens susceptibility to this UV dose and it varies for every pathogen.

UV does not affect the taste, colour, or pH of the fluid being disinfected and, as such, the technique is often used where conventional chlorine disinfection cannot be applied, such as within a brewery, soft drinks plant, pharmaceutical facility or fish farm.

atg UV are committed to providing Ultraviolet disinfection systems that deliver the required amount of UV for a given application. This has become paramount as pressure increases on facilities to provide sufficient treatment. With this in mind, atg have invested in Bio Dose Testing on selected product ranges, enabling atg to offer “Validated” systems.

atg UV Technology have a large number of validated UV systems to ensure UV disinfection performance. Our validation testing has been carried out in accordance with the United States Environmental Protection Agencies (US EPA), Ultraviolet Disinfection Guidance Manual (UVDGM).

The EPA method is one of the most modern and rigorous testing regimes in the world, offering a number of benefits over other existing validation standards, such as an increased flexible operation for validated equipment.

The US EPA UVDGM 2006 uses the mandate of the Safe Drinking Water Act to monitor emerging contaminants, under the Unregulated Contaminant Monitoring Regulation (UCMR2).

Aimed at water supplies originating from lakes, reservoirs, groundwater aquifers and rivers, the purpose of the US EPA UVDGM legislation is to ensure populations are kept safe from emerging pathogens, such as Giardia and Cryptosporidium.

These pathogens are among 17 such species of microorganisms that are resistant to conventional disinfectants, such as chlorine. There are no microorganisms that are resistant to Ultraviolet disinfection.

As an industry leader with considerable experience in supplying US EPA Validated UV systems for Cryptosporidium protection, atg UV Technology are well placed to support and advise all water companies on the application of the validated units into water disinfection strategies.

These include: log reduction, RED Dose, installation into existing infrastructures, upgrades and retrofits, ongoing industry regulation and future product development.

atg UV have designed and developed a large range of fully compliant UV systems, specifically for municipal drinking water and waste water applications.

Additionally, our experience in the US pools market has placed atg UV as an industry leader for validated swimming pool UV systems. For instance, thanks to atg UV’s close work with the New York Department of Health, it is now compulsory in New York State (US) to fit UV on spray-pad type aquatic features.


UV light output at 254 nanometres is known as UVC light (germicidal region). UVC light has the ability to inactivate all known microorganisms, bacteria, pathogens, virus and moulds, including chemically resistant organisms, such as Cryptosporidium and Giardia. UV dose (fluence) is calculated from intensity (UV Power) and time (flow rate) and is typically measured in mJ/cm2.

UV Systems are typically sized in two ways:

  1. To provide a minimum level of UV intensity. This sizing ensures that the UV intensity at all points with the UV chamber, including the points furthest away from the UV lamp (UVC light source) receives a minimum dose set point e.g. 30 mJ/cm². This UV dose is often referred to as wall dose, due to the chamber wall typically being the furthest point from the UV lamp.
  1. An average UV dose takes into account the wall dose (furthest distance from the UV lamp) and the area immediately in front of the UV lamp where the UV output is greatest. The sizing method calculates an average dose for the whole UV chamber.
  2. Validated RED Dose. The term RED – Reduction Equivalent Dose is used for validated UV systems that have undergone independent, 3rd party bioassay testing. The testing uses live surrogate microorganisms e.g. MS2 and T1 to physically test and ascertain ‘real world’ reactor performance.  Validated RED doses take into account UV chamber design, hydraulic flow efficiencies, lamp positioning and intensity zones to guarantee the performance of a UV system at achieving bacterial log reductions of microorganisms e.g. a 40 RED will achieve 99.99% reduction.  Safety factors such as lamp aging and quartz fouling factors are also included in the UV dose equation to provide a conservative and guaranteed performance.

Sizing a UV system is primarily based around water quality. Water quality is measured inUVT (Ultraviolet Transmittance). This measures the clarity of the water to ultraviolet light, relative to that of distilled water (taken to be 100%).  Specifically, this property is measured in a quartz cuvette at a fixed UV wavelength of 254 nm.  If the water is of high quality, e.g. borehole water, the UVT will be high – around 95% UVT, allowing the UV light to easily penetrate the liquid.

If the water is low quality, e.g. river water, the UVT will be low – around 80% UVT, requiring additional power or additional UV lamps to achieve the same UV dose performance.  It is important to note that a fall in just a few % UVT can double the amount of UV intensity required to provide disinfection.

The use of UV light has now become standard practice in a vast range of industries, including municipal drinking water and wastewater treatment, industrial process and manufacturing, offshore and marine and aquatics. Ultraviolet disinfection systems are used to ensure water is free from harmful organisms and is a proven, regulated and environmentally friendly technology.

In order to provide the best Ultraviolet system to suit your needs, the following variables are required to accurately size a UV system for a specific application. The following information is helpful but not essential to providing a quotation:

  • Flow e.g. 150 m3/hr
  • Application e.g. Drinking Water / Waste Water / Swimming Pools
  • Water Source e.g. Borehole / Surface Water / Final Effluent
  • UVT (Ultraviolet Transmittance) e.g. 90% UVT
  • Details of pre treatment e.g. Filtration
  • Intended use e.g. Irrigation / Drinking Water / Process Water
  • Known biological challenge e.g. Cryptosporidium reduction
  • Known dose standard e.g. 30 mJ/cm2 minimum / 60 mJ/cm2 average
  • Treatment Cycle e.g. Single pass treatment or re-circulation

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