It has only taken about 40 years for UV to enjoy its overnight success, as Ashleigh Mackenzie reports…
Offering efficient disinfection, cost savings, quick return on investment and improved bathing quality, it is no wonder that almost half of the UK’s commercial pools have now opted for ultraviolet as their preferred method of water treatment.
Basking in previously unprecedented popularity, it has taken some 40 years for UV to enjoy that overnight success.
In fact, the benefits of using UV have been understood since the early 1900s, it has only become part of a viable mainstream water treatment process in the last 40 years, gaining significant popularity over the past decade.
Recent technological developments in UV use makes its application a very practical proposition for many swimming pools.
“Major improvements in UV technology over the past decade have contributed to its ongoing success and popularity, particularly in our industry,” says Barry Hopton UK sales manager of atg UV Technology.
The use of ultraviolet disinfection was incorporated as part of the aquatic events water treatment strategy at the London 2012 Olympics. Working with one of Europe’s leading filtration and leisure specialists, Euro pools, atg UV Technology was selected to provide a range of UV disinfection systems to protect athletes, and the next generation of elite divers, from the risk of waterborne pathogens including, chlorine resistant pathogens such as Cryptosporidium and Giardia.
The UV technology provided by atg was medium pressure ultraviolet treatment. Importantly, the use of medium pressure UV treatment breaks down problem chloramines, which resulted in a number of key benefits to the swimming pool at the Aquatics Centre.
Barry comments: “As part of the TV coverage, underwater cameras played a huge role in making the aquatic competitions an exciting and atmospheric spectacle.
“By using UV disinfection, problem chloramines that cause swimming pool water to look dull and hazy were removed, leading to bright, crystal clear water that allowed the underwater cameras to catch all of the action in clarity.”
The reduced risk of corrosive condensation was also a major benefit for the Olympic pool operators. With the total cost of the London Aquatics centre standing at £214 million, opting for UV water treatment meant that the vents, piping ducts, poolside furniture and metal fixtures would last longer than other sanitisation systems.
“A major advantage of UV is that it significantly reduces the need for backwashing and dilution, saving hundreds of pounds a month for pool operators,” says Diane White, Hanovia’s European sales manager.
She adds: “Some systems also feature a power switching function, which optimises power use only when it’s actually needed. This too can have a significant impact on a pool operator’s energy bill.”
One of Hanovia’s most high profile UK installations is the Nirvana Spa in Berkshire. A prestigious spa facility, Nirvana has nine pools, each filled with pure spring water. Each pool is treated with a Hanovia UV system, including the ‘Celestial’ floatation pool, the UK’s largest hydrotherapy pool containing salt imported from Israel’s Dead Sea.
The Hanovia UV systems consist of a stainless steel chamber containing a high intensity Hanovia UVLux lamp, which is housed in a quartz sleeve to protect it from the pool water. The chambers were carefully designed by Hanovia engineers using advanced flow calculation methods, ensuring all the water flowing through the chambers receives the correct UV dose.
Neil Phelps, Nirvana’s maintenance director said: “UV allows us to run the chlorine at the right levels and there is no way we’d be able to achieve the level of water purity without it.
“As the water temperature is kept at a constant 35°C, which is higher than in leisure pools, there is an increased risk of infection from microorganisms such as bacteria and moulds which thrive in warm water. Microbiological control is a key aspect of the water quality and UV plays an important part in that control and bacteriological checks are carried out regularly.”
Interestingly, some of England’s most famous football clubs are now also using Hanovia UV technology to purify their hydrotherapy pools. Water of exceptionally high quality is required as the clubs can’t afford for their players to fall ill as a result of water-borne pathogens.
“Running costs are being scrutinized much more by football clubs, as all of them are trying to maximize their profits and minimise unnecessary wastage,” says Diane of Hanovia.
The Pool Water Advisory Group advises that UV works in two ways – as a photo-oxidant and as a biocide. The process by which it breaks down chloramines and other organic pollutants is photolysis. Both medium and low pressure UV lamps are effective against bacteria (as well as the chlorine-resistant parasites Cryptosporidium and Giardia). First it attacks the vital DNA of the bacteria directly. Then the radiation initiates a photochemical reaction that prevents DNA strands recombining during cell division, stopping reproduction. The inactivated microorganisms are not removed from the water, so an effective filtration system is fundamental.
UV is only one part of pool water management and will not compensate for poor filtration and inadequate turnover periods. But for a decently operated and engineered pool it has the potential to provide excellent quality swimming pool water.
Top 10 Benefits of UV Technology
- Reduced consumption of chemicals
- Fewer chlorination by-products in the water and air
- Efficient disinfection
- Reduction of necessary free chlorine concentration
- Improved bathing quality
- Quick return on investment
- Reduced rate of corrosion
- No side effects
- UV cannot be overdosed
- More environmentally friendly
*Provided by LifeTech
Checks And Balances
Basic checks and balances need to be in place though, like effective management of free chlorine and pH and microbiological testing to back up the operation. The free chlorine residual in a well designed, well engineered and well managed pool with UV might be 0.5mg/l at a pH of 7.2.
“It’s important to be clear that ultraviolet generation is not an alternative to chlorine,” emphasises Barry Humphries, sales director at Topline Electronics. “In terms of minimising chlorine use, UV can reduce the amount of free chlorine that is measured in a typical pool by up to 50%, but since UV has no residual effect outside the UV chamber in the plant room the pool requires an additional residual disinfectant to minimise cross infection between bathers.”
Topline supply UV units for numerous local authority pools, hotel and school pools, and theme parks including Legoland, Thorpe Park and Chessington World of Adventure. The Topline ultraviolet treatment system offers a unique full flow design to eliminate dead spots and areas of poor flow within the chamber, and can be configured to treat all types of swimming pools, spas, hydrotherapy pools, interactive play structures and water features.
“The benefits of the Topline low pressure UV, when compared to a medium pressure UV system, are much lower energy consumption and a reduced spares requirements,” says Barry.
“For example, a 7kW medium pressure system will typically use around £6,000 of electricity per year. A Topline low pressure unit will use just £500 of electricity in a year, and requires only a lamp and quartz sleeve change each year, minimising the spares requirements that many UV units require.”