School swimming pools are a valuable asset, and are now present in the majority of high schools and higher education facilities throughout the UK. Whilst school pools vary in size, shape and usage, many school swimming facilities are facing a common dilemma in their water disinfection strategy. Existing treatment regimes are often badly designed, under sized or simply outdated, which is leading to pool operating and maintenance costs spiralling out of control.
In order to meet these increasing costs, many schools, colleges and universities have been forced to open up their pools to the general public in order to generate extra income. This action has led to increased bather loads beyond the number that existing treatment systems were designed to cope with. As a result combined chlorine levels begin to increase, requiring more chlorine dosing, dilution, backwashing, shock treatments and water disposal, again increasing operational costs.
These factors have seen many independent schools seriously consider closing their swimming facilities. So what is the solution?
Ultraviolet Disinfection treatment
Ultraviolet disinfection is now an established method of water treatment for municipal pools, and has become the preferred treatment choice for a number leading international leisure brands and new-build or renovated swimming pools.
UV systems not only provide disinfection against the 17 known chlorine resistant micro-organisms such as Cryptosporidium and Giardia, which have a thick outer membrane making them highly resistant to traditional Chlorine disinfection, UV also destroys chloramines. Chloramines are formed when free chlorine reacts with organics such as sweat, body fats and urine, brought into the pool environment by bathers.
Trichloramines in particular are powerful irritants which are responsible for ‘burning red eyes', itchy skin, respiratory complaints and the often over powering chlorine smell associated with indoor pools. Additionally chloramines are also the cause of corrosive condensation, which leads to the damage of pool buildings and structures such as ventilation ducts.
With a correctly sized UV system, pool operators can typically reduce chlorine usage down to 1.0ppm, or even less, and vastly reduce the need for backwashing, dilution and shock treatments, with most applications only requiring the need for a residual chlorine level.
Case Study - Franklin and Marshall College
After identifying several flaws in the design of the filtration and disinfection systems, Franklin and Marshall College installed an atg UV Technology UV disinfection system. After just a few days operation, Franklin and Marshall College reported their combined chlorine readings as 0.0 and their air quality as perfect.
Mr Bob Rueppel Head Swim Coach commented; 'Members of my swim team who have chronic breathing problems, asthma etc now have absolutely no problems at all. The transformation has been such a benefit to all who use our facility'.
Significant cost savings
The cost of pool water is ever increasing, taking into account water costs, heating, chemicals and actual discharge costs, and is likely to rise to £4 per cubic metre in 2010. As UV systems can significantly cut chlorine usage, the requirement for backwashing, dilution and shock treatments is greatly reduced. Even pools with outdated dosing and filtration equipment can reduce their operational costs by implementing UV treatment.
UV Systems for Swimming Pools
As UV systems become more popular for swimming pool applications, UV equipment manufacturers such as atg UV Technology in the UK, and ETS in the USA now offer a number of UV systems with pre selected options tailored to the specific requirements of swimming pool operators. Typical swimming pool UV units should include; 316L stainless steel chambers, UV monitoring, automatic wiper systems, strainer baskets and the option for half to full power for energy savings during periods of no/low use.
Additionally UV manufactures should always follow best practise when sizing a UV system, and offer UV equipment capable of providing a 60 mj/cm2 dose (average) at a transmission of 94%, and should always take into account the usage of the pool e.g. typical bather load, additional disinfection technologies such as filtration and pool volume turnover.
There are typically two types of UV systems available; traditional axial UV systems with inlets and outlets at either end of the chamber, and the more modern inline UV systems, which can be installed directly into the pipe work and offer a much smaller foot print and increased efficiency and performance.