atg 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 systems to ensure UV disinfection performance. Our validation testing has been carried out in accordance with the United States Environmental Protection Agencies, 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 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, ground water 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.
DNA, or deoxyribonucleic acid, is a long polymer made from repeating units called nucleotides. The DNA chain is 66 to 78 x 10-10 feet wide and 10 x10-10 feet long.
Information in the DNA is stored as a code made up from 4 chemical bases: adenine (A), guanine (G), cytosine (C) and thymine (T). Human DNA consists of 3 billion bases and more than 99% of these bases the same in all people. The largest human chromosome, chromosome number 1, is approximately 220 million bases long.
The order or sequence of these bases determines the information available for building and maintaining an organism. DNA bases pair up with each other; A with T and C with G to form units called base pairs. Each base pair is also attached to a sugar molecule and a phosphate molecule. Together, the base, sugar and phosphate are called a nucleotide.
The nucleotides are arranged in 2 long strands that form a spiral or double helix. The double helix is like a twisted ladder; the base pairs forming the ladders rungs and the alternating sugar and phosphate forming the vertical sides of the ladder. Each strand of DNA in the double helix can serve as the pattern for duplicating the patterns of the bases
The base pairs are linked together by hydrogen bonds. These bonds are responsible for all of the interactions between the complimentary base pairs, and this link is critical for all of the functions of living organisms.
These hydrogen bonds are ruptured by UV light in the 260nm light region, and when the cross bonds are broken, new bonds called dimers form between adjacent bases. This process is almost instantaneous, taking approximately 1 Pico second to occur. Once the cross bond is broken, normal cell function, including replication, assimilation of food and respiration cease. The organism is rendered non viable and it poses no further infectious threat.
A number of research groups have shown that this phenomena can be reversed for very low doses of UV light; this makes both the design of the UV system and regular maintenance very important. Photo- repair does not occur at a normal disinfection dose.
Healthy organisms can replicate and quickly spread infection or cause product spoilage. UV light effectively prevents cell replication and routine cell functions. Equipment design needs to ensure that the delivery of UV dose is uniform, that the optical path is not blocked and that inlet bends or baffles used to overcome poor hydraulic designs do not permit breakthrough or cause shadows.
The majority of organisms have been studied and their susceptibility to UV, known as their D10, value has been determined. This value indicates the dose in mJcm-2 that is required to achieve a 90% (or 1 log) reduction of a challenge species. Typical UV doses can achieve 99.9999% reduction of the target species. Certain species demonstrate higher resistance to UV, molds and yeasts for example require a higher UV dose than many common waterborne species.
If you are concerned about a particular nuisance organism or would like to review our research database, contact our sister company, ETS UV Technology.
atg UV Technology systems utilise two key lamp technologies: -
1. Low Pressure Amalgam lamps offer unparalleled electrical efficiency, long and predictable lamp life (generally 12000 hours), and are unaffected by changes in water temperature. A correctly run Amalgam lamp is 38-42% efficient, therefore a 320watt lamp is capable of delivering 134 watts of UV at 254nm. These lamps produce a monochromatic output at 254nm, the germicidal region for effective disinfection of all known micro-organisms.
2. Medium pressure lamps offer the same disinfection properties as low pressure lamps at much greater levels. Additionally, medium pressure lamps have the ability for TOC reduction, De- ozination, and chlorine removal.
For a number of applications, medium pressure lamps are incorporated due to their small footprint and short arc length, for example Retrofits into existing small footprint facilities. Our UV monitors can be offered as NIST traceable devices and fit into dry ports that permit reference monitors to be inserted without breaking a water seal to validate the lamp output. In all cases, the sensor technology we use is specific to germicidal UV and blind to visible light and IR.