SPN FEB 2010 COMPLETE EDITION:SPN 2010 21/01/2010 06:29 Page 70
70 SPN FEB 2010 UVSystems
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skin, in hair, noses, and mouths, DNA. It is most powerful in the
intestinal and uro-genital tracts. region of the electromagnetic
“It just makes the swimming experience The vector for transmission is both spectrum between about 210nm
the water and pool surfaces. The and 310nm, the so-called
massively more pleasurable” adoption of UV light should not ‘germicidal’ wavelengths.
be seen either to replace the It is well-known that water-
dosing of chlorine, or indeed to borne microorganisms contain
replace good pool hygiene enzymes that can repair UV-
of their business. Traditionally practices. The UV systems serve a damaged DNA – a process known
chemicals such as chlorine have dual role; primary disinfection of as ‘DNA reactivation’. Some of
been added to pools to provide the waterborne organisms, and these enzymes need visible light
effective disinfectants; this has effective photolysis of the to perform the repairs (‘photo
worked well however organisms combined chlorine species. reactivation‘), while others can do
have started to develop resistance A typical UV system consists of so without light (known as ‘dark
to chlorine, and several outlined a UV lamp in a protective quartz repair’). Both of these phenomena
later in this article cannot be sleeve which is mounted within a pose obvious concerns for pool
killed using chlorine alone. New cylindrical stainless steel owners who are using UV for
developments in pool disinfection chamber. The water to be treated disinfection in addition to
use electrolysis to form chlorine enters at one end and passes chloramine reduction.
by making the entire pool into a along the entire length of the Recent research, however,
very low concentration brine chamber before exiting at the comparing photo reactivation of
solution. This seems to be a safer other end, receiving a dose of UV E.coli DNA after exposure to UV
method of chlorinating the pool, energy along the way. wavelengths emitted by low and
and is gaining acceptance. There are two main types of UV medium pressure lamps shows
“A secondary issue for the pool technology, based on the type of that the DNA underwent
operators are the by-products UV lamps used: low pressure and extensive repair following
formed by the addition of medium pressure. Low pressure exposure to UV from low pressure
chlorine to pool water; combined lamps have a monochromatic UV UV lamps, but virtually none
chlorine species are irritants, output (limited to a single following exposure to UV from
cause corrosion and are wavelength at 254nm), while medium pressure lamps.
increasingly linked by many medium pressure lamps have a The researchers concluded that
research groups to asthma in polychromatic UV output (with it was the broad UV output of
children and elite athletes. an output between 185-400nm). medium pressure lamps that has
“People swimming in pools, UV is a highly efficient natural this desirable effect. By emitting
using splash pads for recreation or disinfectant and kills virtually all UV over a wide range of the UV
visiting indoor or outdoor water known microorganisms, spectrum, these lamps appear to
parks are at risk from waterborne including bacteria, viruses, damage other intracellular
infection. Some of these moulds and their spores, by molecules, such as enzymes, in
infections are naturally present on permanently destroying their addition to DNA. It is this ‘extra’
POOL MANAGERS QUICK TO PRAISE SWITCH TO TRIOGEN UV SYSTEMS
Zero bacteriological testing, user friendly equipment and consistent competition pool and a 408m³, 334m³/h leisure pool with water
noticeable improvements in water quality are three key benefits to fountains, slides and rapids.
come out of two very different pools which have switched to Triogen A UVARAY system, installed by Biwater Leisure to supplement the
UV systems. pre-existing chlorination system, has been serving the leisure pool
The pools – one a 25 metre high usage holiday leisure complex in since 2004. The competition pool uses a chlorination system only.
Sussex, the other in a local authority Northamptonshire pool have Kim Bennett of the Oasis said: “We have found that having the
reacted with complete approval of the move to UV systems. UVARAY 400 chloramine reduction system installed greatly reduces
Triogen prefers medium pressure UV systems for chloramine the need for chlorine use within the leisure pool, compared to that of
reduction in swimming pools since only this method provides all of the competition pool, allowing us to operate with a greatly reduced
the following favourable reactions: free chlorine set point.
“The combined chlorine levels are also extremely low and we definitely
1 Hydroxyl radical production via absorption by chlorine at 254 nm. notice deterioration in this respect if the UV unit is being serviced.
2 Direct photochemical oxidation of chloramine, dichloramine and “The bacteriological standards for our pool are regularly tested by
nitrogen trichloride. the local authority and have constantly come back with better than
3 Hydroxyl radical production by interactions with water at around average results.
230nm. “I find this an excellent form of disinfection consisting of a very
discreet unit providing a more than adequate level of water quality. We
Triogen offer three types of UV systems for commercial pools: have also found the unit to be highly user-friendly and easy to maintain.”
Chris Tye is responsible for pool and plant maintenance at The
• the flagship UVARAY system, featuring stainless steel reactors, Nene Centre, Thrapston, which is operated by Cultural Community
with UV sensors and automatic wiper systems as standard; Partnerships on behalf of East Northamptonshire District Council.
• the similar UVALITE system, including a manual push-rod wiper The centre has a 169m³/h, 25m pool with a small trainer area and uses
for quartz tube cleaning; a UVARAY 210 chloramine reduction system. He said: “Our pool is
• the UVASPA system for smaller commercial pools and spas where the heavily used, for example 45,000 users over a three month period plus
quartz tube is cleaned by a manual wiping process when necessary. 1,000 children per month for swimming lessons.
“However, over this period our combined chlorine has been
Among the users of Triogen equipment, West Sands at Selsey, West consistently in the range of 0.1 – 0.3mg/l. The Environmental Health
Sussex, is the largest park run by Bunn Leisure, providing traditional Officer bacteriological testing of the water has consistently given a
English holidays for mainly UK citizens. The Oasis leisure complex is zero result. Overall, both water and air quality at the Centre has
a multi-million pound facility including a 25 metre, 513m³, 197m³/h been excellent”.
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