As the operators in the water industry gather in Bendigo for the WIOA conference and exhibition, the town’s water reclamation plant is celebrating a significant milestone: 25 years of continuous operation, utilising a unique and innovative technique for treating wastewater.
The current Bendigo Water Reclamation Plant at Epsom began treating Bendigo’s wastewater 25 years ago, when a bigger and better plant was needed to meet the needs of the city’s growing population and new environmental regulations.
The plant was planned when the Bendigo Water Board was still in existence, the water authority in place before Coliban Water was established.
At the time a biological nutrient removal (BNR) process called Modified UCT had been developed by the University of Cape Town for the removal of phosphorus.
BNR involves using naturally occurring bacteria, often referred to as ‘bugs’, to consume the excess nutrients, nitrogen and phosphorus. The bugs are then removed as sludge, which after further treatment can be reused as biosolids.
BNR is more cost effective and environmentally friendly than using chemicals to remove nutrients.
The project’s Chief Engineer was Neil Burns, who still works for Coliban Water as its Community Infrastructure Development Specialist.
Mr Burns said, “We could see the process was working successfully at plants where it had been retro-fitted but we wanted to conduct our own tests.
“We worked with staff and students from the Bendigo College of Advanced Education (now La Trobe University) to set up a pilot plant, which produced good results.
“It was decided our new Epsom plant would have BNR treatment tanks which made it one of the first purposebuilt BNR plants in Australia,” said Mr Burns.
Construction work started in 1990 and the plant commenced operation in May 1991. It was officially opened on 26 July 1991 by the Labor Minister for Conservation and Environment, the Hon Steve Crabb MP.
“When the plant commenced operation in May 1991, Bendigo’s population was around 62,000 and there were 25,000 connections to our sewer network.
“Bendigo’s population is now around 108,000 and there are almost 43,000 connections, as well as an increase in local industries and commercial customers,” said Mr Burns.
The new BNR plant was also capable of treating wastewater to a higher standard to bring it in line with new environmental regulations at the time.
“Some of the water treated at the Epsom plant can be discharged into Bendigo Creek under license from the Environmental Protection Agency (EPA).
“The new plant met the new EPA regulations at the time, removing the harmful nutrients which could destroy flora and fauna and cause algal growths,” said Mr Burns.
The plant has had further developments in its 25 years to improve the treatment process.
In 2003, a tertiary plant was added to treat the water to Class B for irrigation for non-food crops, some livestock drinking and in road construction.
In 2007, during the Millennium Drought, the Recycled Water Factory was built along with a 14.5km pipeline from the plant to the Spring Gully Reservoir.
This enabled recycled water to be used for public gardens, sporting facilities and irrigation in the Bendigo area, and by some new residential developments for toilet flushing and watering gardens.
Coliban Water can also supply recycled water to its rural customers along its Ascot, Axe Creek and Cockatoo Hill channels, and supplies two standpipes in the Bendigo area.
A project is nearing completion at the plant to replace the original submersible mixers in the BNR treatment tanks.
Diving specialists were used to replace the mixers as the tanks are in constant use so taking the plant offline to empty the tanks was not an option.
The new mixers are more reliable and energy efficient and will enable the plant to continue to treat on average around 19 million litres of wastewater per day.
As well as an increase in the amount of wastewater treated, there has been an increase in the rubbish that needs to be collected and taken to landfill.
Everything from false teeth to mobile phones have ended up at the end of the sewer network, and recently flushable wet wipes have been causing blockages, jamming pumps and increasing clean up costs and landfill.
When the Epsom plant was built 25 years ago the major issue was the biological removal of phosphorous from wastewater, with the principal source being soaps and detergents.
The industry responded with phosphate-free soaps and detergents. Hopefully a long-term solution can be found to the flushable wipes issue.