Challenge

Unpleasant effects of chloramines irritated staff and patrons' eyes, skin and breathing at the Kilmore Leisure Centre in Mitchell Shire, an hour north of Melbourne in the heart of Victoria, Australia. Traditionally, reducing chloramines meant increased backwashing, which required using more freshwater to dilute the disinfectant. With prolonged drought and water restrictions in the region, though, that wasn't a sustainable option for the facility. It needed an alternative that didn't use more water and held operational costs in check.

Solution

Centre officials proposed to improve the pool's water quality by installing a Barrier® M UV System, a medium pressure ultraviolet (UV) light system manufactured by Siemens Water Technologies. These systems emit a broad polychromatic light spectrum in the range of 200-350 nanometers (nm) – the level required to remove mono-, di- and trichloramines from pool water.

The M Series medium pressure UV system also provides effective control of waterborne pathogens such as bacteria, viruses, and parasites, including Cryptosporidium or Giardia, which can be resistant to conventional chemical disinfection. In addition, it does so without forming harmful disinfection by-products.

Due to its compact, in-line design, the system was easy to install directly into a straight 200-mm vertical or horizontal filter line without affecting plant flow or filter performance. This was important, as the leisure facility required minimal interruption to its operations. The entire project was accomplished within three days.

Results

During the six month period after commissioning the Siemens Barrier M UV System, Kilmore Leisure Centre recorded a reduction in chloramine levels of 75-80%. The facility now boasts a consistent 0.2-0.3 mg/L chloramine range – much lower than the maximum standards set by the State Health pool guidelines for public pools.

In addition to staff and patron health, another benefit of lower levels of chloramines in the atmosphere is reduced corrosion of the facility's steel roof structure and air handling systems.

Automation also enables the newly installed system to save on energy and maintenance costs. Automatic wipers keep the UV lamps and sensors clean, which is crucial for monitoring UV output levels. The unit's "auto disinfection control" system pushes up UV lamp output to a higher setting to compensate for lower water quality. As water quality improves through higher UV output levels, or perhaps, reduced bathing periods at night, the system automatically reduces UV output to its lowest setting. Likewise, maintenance costs are less with servicing required only yearly and replacement of UV lamps at a considerably lower cost compared to alternative systems.

Above all, the new UV system has enabled a reduction in the centre's pool filter backwashing program. Now only completed weekly, this reduced backwashing program is saving nearly 1 million liters of water a year, well in line with the facility's targeted water reductions.