A 20-tonne steel cover for the new anaerobic digester has been craned in place at SA Water’s Port Lincoln Wastewater Treatment Plant at Billy Lights Point, South Australia, marking a milestone for the $18 million upgrade project.
A 20-minute lift was required to get the 10m diameter cover on top of the 8m digester, which caps off the majority of the digester’s construction, including the structure’s round walls and installation of internal pipework.
SA Water Senior Manager Production and Treatment, Lisa Hannant, said, “The lid is actually a floating cover and sits comfortably in voids, controlled by guide rails and rollers – moving up and down depending on capacity within the digester, which is also sealed by water to prevent the escape of biogas generated during the digestion process.
“Our biogas is then extracted and burnt to provide a source of heat for the digester, helping to hold waste at a constant 38 degrees to create an optimal environment for the bacteria inside.”
Anaerobic digesters are large, sealed concrete tanks that heat the solid organic waste from sewage – known as sludge – in an oxygen-free environment, to promote the natural bacterial metabolic processes that break it down.
The new infrastructure will reduce methane emissions, and improve odour management and the long-term operability of the treatment plant.
“With a state-wide network and continuous focus on sustaining our infrastructure, there’s often opportunities to work together and support local businesses and communities,” Ms Hannant said.
“Keeping it local, where possible, can lead to a positive economic and social impact for the community we’re working within, while enabling us to tap into their expertise and knowledge for the benefit of our wider project.”
As part of the wider program, SA Water invested $6 million to increase the capacity of the sewerage pipe network, which included the upgrade of a wastewater pumping station and 4km of new sewer main around the Port Lincoln Marina.
The upgrade of SA Water’s Port Lincoln Wastewater Treatment Plant marks the final stage of the program, and is expected to be complete by December 2020.