The southern hemisphere’s largest Xylem-manufactured drinking water ultraviolet disinfection and water treatment system has kept pathogens at bay. After more than six months, it has protected the safe, clean drinking water supply for nearly half a million South Australians.
Commissioned in December 2021, the system was retrofitted to SA Water’s Happy Valley Water Treatment Plant as part of a $26 million upgrade to ensure the utility’s continued compliance with Australia’s world-leading drinking water standards while enabling community access to green open spaces.
Four reactors with a combined 624 ultraviolet (UV) lamps enable the system to instantly treat up to 600 megalitres of water each day. It has been designed with an additional treatment capacity to maintain network flexibility and support demand changes.
SA Water’s Senior Manager of Capital Delivery Peter Seltsikas said secondary disinfection with ultraviolet light provides an additional layer of water quality protection against potentially harmful pathogens.
UV water treatment new for South Australia
“Our new UV disinfection system at Happy Valley is another line of defence protecting the quality and safety of our largest drinking water supply to metropolitan Adelaide. It also enables kayaking and fishing at the adjoining reservoir,” said Seltsikas.
“Pathogens come in various forms and can be found naturally in water sources. The catchment area that supplies Happy Valley Reservoir via Mount Bold Reservoir is significant and covers the Mount Lofty Ranges. This particular catchment is challenging given the presence of agriculture from water treatment and quality perspective. There’s an ever-present risk of pathogens, such as cryptosporidium, finding their way into our reservoirs.
“To manage these risks, our Happy Valley Water Treatment Plant adopts a series of conventional treatment processes, including coagulation, flocculation and filtration. They will trap and remove dissolved organic matter or other solid particles. Disinfection of the water with chlorine occurs after filtration to destroy any microorganisms that may not have been captured. However, cryptosporidium can be resistant to chlorine and evade treatment.
“When pathogens like cryptosporidium and giardia are exposed to and absorb the high-powered ultraviolet light, it destroys their structures and inactivates the microorganisms’ cellular function. Each reactor has 13 independent rows of 12 UV lamps. They are automatically operated and can turn themselves off based on the instantaneous treated flow and incoming water quality.
“The latest electronic ballast technology powers the lamps. They harness a sophisticated UV intensity sensor that significantly reduces energy consumption. These two features make it one of the most energy-efficient UV systems. Combined with our solar array at Happy Valley, it can produce more than 17,000 megawatt hours of energy per year to help power the wider plant. That ensures we meet the system’s energy demands and operate sustainably.”
Water treatment projects employ many
More than 200 people worked on the project across SA Water. The construction partner, John Holland Guidera O’Connor joint venture, had 60 full-time employees working on-site at the height of construction.
Seltsikas said the team’s agility and innovation came to the fore amid global shipping delays last year.
“While the impact of last year’s Suez Canal incident sparked delays across the global supply chain, including with our UV system en route inside a shipping container, we initiated swift changes to our project design and condensed the construction schedule to maintain our delivery program,” said Seltsikas.
“Our team reviewed the design of the inlet duct, which required a new weir cut into the existing wall. The initial design included manual concrete demolition and a significant amount of structural steelwork. Harnessing creative thinking, we used a robotic cut saw to remove the concrete more efficiently. We poured a large concrete beam, eliminating the need to install steel to support the new weir structurally.
“We needed to remain on schedule despite the delay in receiving the infrastructure. These design variations removed six weeks of work from the program to ensure we could complete the project on budget and time.”
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