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Crystal Clear

It can be a minefield for operators looking to select the right element for disinfecting and reducing organic loading of swimming pool water at their facility. Karen Maxwell talks to experts in water treatment about some of the options available

Published in Sports Management 2012 issue 2
Water treatment methods should account for health and safety, environmental influences and cost effectiveness / photo: shutterstock.com
Water treatment methods should account for health and safety, environmental influences and cost effectiveness / photo: shutterstock.com

Jim Kenyon,

Managing Director,

JAK Water

Jim Kenyon
Jim Kenyon

Over the last 30 years, there have been many changes in the way swimming pool water has been treated and disinfected.

In the ‘old days’ virtually all commercial swimming pools would have had a manually operated gas chlorine system for disinfection with pH controlled by the addition of soda ash/sodium bicarbonate and aluminium sulphate flocculants – often dosed by hand.

How things have changed. With the introduction of relatively inexpensive automatic control systems, sodium hypochlorite, calcium hypochlorite, ultra violet (UV), PAC flocculants and pH correction – using either CO2, hydrochloric acid or sodium bisulphate – are all now at the forefront of modern pool treatment systems.

Chemical treatment today comes in several forms – from bulk, tank and mixer and UV to, more recently, automatic calcium hypochlorite feeder systems.

The need for chemical dosing to be simpler with health and safety in mind, has led to several feeder systems being developed which utilise calcium hypochlorite, and are widely accepted. The quality of calcium hypochlorite varies enormously and consideration should be given to the product’s chlorine, moisture (hydrated or anhydrous) and insoluble content, to establish value, safety and purity.

JAK developed the FlowTab (calcium hypochlorite tablet dosing system) several years ago. FlowTab has evolved over the years but we still have units in industry working from those early days. An automatic preparation system suitable for both municipal and potable water, it provides a constant strength solution, requires little maintenance and is compatible with all automatic control.

Today, choosing products and treatment techniques can be confusing to the buyer and can become an expensive decision if made incorrectly. Deciding on the best treatment methods must take into account several factors – including environmental influences, heath and safety and especially in today’s climate, cost effectiveness. A challenging task for even the most experienced pool operator where impartial advice may need to be sought.

www.jakwater.co.uk

Barry Humphries,

Leisure Sales Manager,

Siemens Water Technologies

Barry Humphries
Barry Humphries

The key to effective water treatment is integration. By effectively integrating systems, facilities will be able to increase energy and operational efficiency, which ultimately reduces operating costs.

Many operators of sports and leisure centres are unaware of the levels of savings that can be achieved through adopting an integrated solution, which will optimise energy, water and chemical usage, while maintaining optimal water quality conditions – a key performance indicator for customer satisfaction.

In the case of swimming pools, Siemens offers an innovative energy and water optimisation system (EWO), which has a modular design so operators can select the right elements for their facility. The DEPOLOX® Pool controller by Siemens sits at the heart of this system. It continuously monitors all of the critical water quality parameters, automatically controlling the addition of disinfectant and pH correction to reflect the changes in the pool.

The controller can be offered with options to measure the combined chlorine, TDS and redox value on an ongoing basis. This means that if the pool water is within the user defined limits, the DEPOLOX® Pool controller can signal to the pool’s flow meters and the variable speed drives to reduce their speed.

Should this quality deviate, the controller does the reverse and normal circulation levels resume. Crucially, this is where significant energy savings are to be made and water quality can be maintained – even as bathing loads fluctuate.

Through the installation of SED2™ variable speed drives, facilities can save up to 50 per cent on the energy consumption of circulation pumps.

Further savings can be made by using a UFOX sludge water recycling system. It can reduce water consumption by safely recovering 80 per cent of backwash water to the highest standards, so it can be reused for functions including pool filling or toilet flushing.

For ultimate efficiency, integration should span a facility’s complete water system. These should also use low footprint technologies for the best use of space and ensure a safe environment for customers.

At Siemens we can offer a total water treatment solution, from rainwater harvesting through to cooling towers and sterile cleaning to meet these objectives.

www.siemens.co.uk

The DEPOLOX Pool Controller can signal to flow meters and speed drives
The DEPOLOX Pool Controller can signal to flow meters and speed drives

Paul Hennessey,

Sales and Marketing Manager,

atg UV

Paul Hennessey
Paul Hennessey

The use of ultraviolet (UV) disinfection for swimming pool applications is growing fast. From small swimming pools, spas and hydro pools to large municipal leisure facilities and full-scale water theme parks, this treatment is now becoming standard practise in many UK leisure facilities.

As water features, wave machines, flumes and splash pads raise the fun factor in swimming pools, the traditional method of disinfecting water by using chlorine is causing problems for operators and customers alike. Higher water temperatures and increased turbulence in leisure pools requires increased dosages of chlorine, leading to pool users complaining of burning eyes, red or itchy skin and an over- powering chlorine smell throughout the facility. In some cases the fabric of the building has also been attacked through corrosive condensation.

The main reason for these problems is the production of chloramines in the water caused by the reaction of free chlorine residuals with organic materials, such as bacteria brought into the environment by pool users. While ozone can be successful at reducing chloramine levels, both the installation and operation could be expensive and may require skilled personnel to operate the plant, again driving up operating costs.

UV treatment provides another option. UV wavelengths between 240 and 280 nanometres deactivate all micro-organisms, particularly Pseudomonas (SP) and Ecoli. Manufacturers such as atg UV can incorporate UV systems into existing control strategies to protect against micro-organisms, including chlorine-resistant pathogens such as cryptosporidium.

A correctly-sized UV treatment system also reduces chloramines, the compound responsible for skin irritations, red eye and the often overpowering chlorine smell. The result is safe, glacier-clear sparkling water, fresh air and a more inviting bathing environment. Typically, following the installation of this treatment, operators report a significant drop in combined chlorine levels, chlorine smell and a large reduction in the need for taxing back washing and shock treatments.

Systems such as atg UV’s ECF system offer pool operators a flexible and cost effective solution, treating up to 2000 m3/hr in a single high-output, small footprint system.

www.atguv.com

Keith Glass
,

Sales Engineer,

Triogen

Keith Glass
Keith Glass

Chlorine is the most common method employed to treat pool water as it’s a fairly effective disinfectant and eliminates a large number of bacteria, as well as some viruses. It’s also a fairly strong oxidising agent that reacts with organic matter in the swimming pool water.

However, chlorine does have its limitations and has several disadvantages. These include the fact that potentially harmful micro-organisms such as cryptosporidium parvum and giardia lamblia remain unaffected, and the chloramine by-products can irritate the bathers’ nose, eyes, respiratory system and skin.

Ozone has proved to be a viable option over the past 30 years. It’s a gas that can be loosely described as a concentrated form of oxygen and is responsible for the ‘fresh air’ smell that’s experienced after a thunderstorm.

Generated by passing a stream of air through an electric arcor by passing air over a specially-dosed UV lamp, ozone is not a stable compound and quite rapidly decomposes to oxygen. It has a half-life of only about 20 minutes at room temperature, which means it can’t be manufactured and stored; it must be generated at the location where it is used.

Ozone gas, when used to treat water, is a strong oxidising agent while offering a strong biocidal effect: it kills or renders harmless micro-organisms unaffected by chlorine, which means that it’s a powerful disinfectant when applied at the correct dose. When ozone is used in conjunction with chlorine, the undesirable chloramines are destroyed and their undesirable effects are largely eliminated.

Ozone gas is generated in an ozone generator. This gas is then mixed with water from the pool filter, and the water/ozone mixture is held in a tank for a predetermined time.

This allows the ozone to react with the impurities in the water and also allows any excess ozone to separate from the water.

The excess gaseous ozone is converted back to oxygen and discharged to the atmosphere. The cleaned water is returned to the pool. The flocculating effect of the ozone collects small particles to form larger particles that can easily be removed by the filter and the pool water is clearer, bluer and more sparkling.

www.triogen.com

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