Kawana Sewage Treatment Plant Upgrade

Project summary

Unitywater is undertaking a major upgrade of Kawana Sewage Treatment Plant, which is one of the key sewage treatment facilities in our service area.

The upgrade will expand the plant’s capacity, taking the current treatment capacity from approximately 90,000 people to 200,000 people.

As part of this upgrade, Unitywater is constructing a new anaerobic digester to produce methane from the sewage biosolids. This is our first step towards a sustainable waste-to-energy solution to reduce our operating costs and dependence on electricity.

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Kawana Sewage Treatment Plant aerial view

As one of Unitywater’s largest facilities, the Kawana Sewage Treatment Plant (STP) plays an important role in keeping our coastal waterways healthy. Located at Main Drive, Warana, it currently serves Sunshine Coast communities from Pelican Waters to Buddina.
As the population of the Sunshine Coast grows, the volume of sewage treated by Kawana STP will also increase from its present rate of 20 million litres a day. The facility must therefore be upgraded to maintain its high treatment standards as it handles increased sewage loads.
The upgrade, which started in 2017, will be the fifth enhancement to the 35-year-old STP. Its capacity is currently the equivalent of 90,000 people and this is forecast to be exceeded within the next few years.
In addition to population growth, Unitywater has identified the Kawana STP as the future central sewage treatment plant for the Sunshine Coast. Areas such as South Buderim, Chancellor Park and Sippy Downs, which are currently connected to the Maroochydore STP, are planned to be serviced by the Kawana STP in the near future.
Looking to the long term, Unitywater is considering the requirement for treating sewage on the Sunshine Coast and believes that Kawana STP may ultimately need to treat the sewage for an equivalent of 600,000 people – over six times its current capacity.

Treating sewage to a standard that meets community expectations and environmental standards is a complex process involving large concrete structures, mechanical equipment and a lot of biotechnology. As such, STPs are expensive to build and operate.
Unitywater is always looking for ways to treat sewage more economically without compromising standards.
Since May 2015, Unitywater has been working with industry partners to identify the best design for the current upgrade that is compatible with a larger scale plant for the future. In December 2016, we selected Australian engineering group Monadelphous to design and build the upgraded Kawana STP.

Monadelphous has teamed up with other leading engineering and industrial companies including Acciona Australia, a global leader in the water sector. Incorporating Acciona’s biotechnical processes, which have been used extensively in Europe, will mean the upgraded plant will require less infrastructure than would otherwise need to be built.
Design work on the upgraded Kawana STP began in December 2016.

Traditionally, the treatment of sewage has been considered an ongoing and necessary cost. Unitywater is turning this concept around by exploring ways to generate energy from sewage. The key is anaerobic digestion where special bacteria turn sewage into methane-rich biogas.
As part of the upgrade of Kawana STP, Unitywater is constructing a new anaerobic digester to produce methane from the sewage biosolids.
Beyond this first step, Unitywater is considering the next stages of a waste-to-energy future, where even more methane-rich biogas can be produced through the controlled introduction of other liquid organic waste products to the anaerobic digester. This would enable Unitywater to produce sustainable energy from both our sewage biosolids but also other organic waste materials, reducing liquid waste disposal from the region and offsetting our electricity dependence and impact on our operating costs.

Location	Main Drive, Warana
Current treatment capacity	90,000 equivalent persons
Next stage treatment capacity	200,000 equivalent persons
Construction commenced	April 2017
Forecast in-service date	December 2019
Investment value	$74m