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UV water treatment minimises chemicals

An advanced ultra-violet form of water treatment technology could be trialled in Australia’s harsh climate, after being successfully used on a semi-arid Caribbean island, writes Peter Mills.

Advanced ultra-violet (UV) water treatment technology being introduced to Australia by CST Wastewater Solutions has demonstrated its potential for applications here after being installed on a semi-arid Caribbean island.

Ten of Berson’s InLine UV disinfection systems — distributed in Australia by CST — were installed on the island of Aruba, where eight systems are used to disinfect drinking water and two are used to treat greywater prior to discharge.

The island opted for UV instead of chlorine as part of its ‘non-chemical’ approach to water treatment, says CST Wastewater Solutions managing director, Michael Bambridge.

Five of the Berson UV units are installed at the Balashi water treatment plant, the site of gold mill ruins near Aruba’s capital, Oranjestad. Operated by W.E.B. Aruba N.V., which supplies drinking water and electricity to the island’s residents and businesses, Balashi also houses the world’s second largest desalination plant. Because Aruba has a semi-arid climate, desalination is necessary to supply its growing population with much-needed water.

Chemical-free desal

Following the desalination process, the water passes through the UV systems before being transported to seven storage tanks situated at elevated locations around the island. The UV units, which are installed outdoors and controlled by DGtronic microprocessors, each disinfect 400m3 of water per hour, rising to 600m3/h during peak flow conditions.

No chlorine is used at any stage of the water treatment process. Chlorine was originally considered as an alternative to UV but was rejected after concerns over costs and safety. W.E.B. Aruba also has an anti-chemical policy.

Two of the seven storage tanks situated around the island are also fitted with Berson’s InLine UV systems, providing an additional disinfection step prior to distribution. It is expected that all the tanks will eventually be fitted with UV. One of the storage tanks is situated in the harbour and supplies cruise ships with UV-treated drinking water.

In addition to disinfecting drinking water, two Berson UV systems are also used to treat greywater. One unit is installed at each of the island’s two wastewater treatment plants and the treated greywater is used to irrigate the island’s two golf courses. The Dr Horacio Hospital on the island also uses UV technology.

Berson’s customer service manager Danny van Kuringen says there is a lot of interest in Berson’s UV systems on the island, especially from businesses wanting to use greywater for hosing down buildings. “It is very dusty on Aruba, so keeping the outside of buildings clean is a real concern for many companies. We have also recently supplied one of our new InLine+ UV systems to disinfect drinking water for the airport.”

Re-using wastewater

Berson’s compact InLine medium pressure UV systems use MultiWave lamps, which emit a wide spectrum of UV wavelengths with a very high energy output, causing the total and permanent deactivation of micro-organisms. The small size of the lamps means that they are positioned perpendicularly to the flow of liquid, increasing disinfection efficiency and reducing the overall size of the disinfection unit.

Berson’s InLine+ medium pressure closed vessel UV systems recently became the first in the world to gain formal approval for wastewater re-use applications. They underwent extensive third party testing by Carollo Engineers in the Unites States of America before being formally approved for post-filtration and reverse osmosis applications by the California Department of Public Health (Title-22 validation).

The systems are now validated for wastewater re-use applications in accordance with AwwaRF/NWRI guidelines, which are internationally respected and some of the toughest in the world, says Bambridge. The guidelines are also the only ones offering guidelines on sewage treatment, which is a key factor in Australia.

“The Berson technology used on Aruba clearly has potential in Australia as well, because we not only have the same pressures on water in semi-arid areas, but also are looking increasingly to desalination as an alternative source of water supply,” said Bambridge.

Pure representation

Berson is represented in Australia by CST Wastewater Solutions, formerly known Contra Shear Technology. CST is a member of the Global Water and Energy Alliance, which is a group of select global companies committed to providing solutions in water and wastewater treatment for the recovery of green energy and water.

According to CST, Berson UV is one of the few non-German UV system suppliers capable of providing a complete range of UV systems with capacities between 10—10,000 m3/hour, certified to the latest German DVGW norm, W294, Part 1, 2 & 3, which is the highest standard currently possible in the world. The systems are also fully-validated in accordance with the USEPA UV Disinfection Guidance Manual (UVDGM).

Headquartered in the Netherlands, Berson specialises in providing UV disinfection systems for municipal water and wastewater treatment applications. Its InLine+ range of closed-vessel UV disinfection systems is capable of treating water and wastewater flows as high as 5000 m3/hour. The InLine+ has a unique design where the UV lamps are angled at 90o to the water flow — this not only means a more effective distribution of UV light to the passing fluid, it also means a much smaller footprint, allowing easy installation and servicing, CST says.

[Peter Mills is the managing director of marketing company Peter Mills Pty Ltd.]

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