Population equivalent

Design and costruction

ACCIONA is the proud process design contractor for the project of Unitywater’s Kawana Sewage Treatment Plant and responsible as a subcontractor to Monadelphous, for aspects of process design, equipment supply and commissioning advice of the AU$56M sewage treatment facility.

Unitywater’s Kawana Sewage Treatment Plant is located in Warana, Queensland serving multiple populations in the region such as Minyama, and Parrearra. The sewage plant was commissioned in 1981 and has had upgrades in 1991, 1997, 2005, and 2013.


The treatment capacity of the existing plant is equivalent to 90,000 of the population, which needs to be initially increased to service a population equivalent to 150,000 persons, the result of anticipated Sunshine Coast population growth and the consolidation of existing smaller wastewater treatment facilities.


ACCIONA, as part of a submission with Monadelphous to Unitywater, undertook the process design and process equipment supply for the Kawana Sewage Treatment Plant upgrade.
The project, which is the first large scale MBBR (Moving Bed BioRector) municipal plant in Australia, design to treated a population equivalent of 200,000 became operation during 2020.
The plant is designed to accommodate imported municipal wastewater sludge, collect methane gas from the anaerobic digester, clean it and uses it to generate electricity, which reduces the imported power consumption of the plant.


  • Location: Warana, Sunshine Coast, Queensland
  • Our role: To provide process design inputs / upgrades through Moving Bed Biofilm Reactor (MMBR) in order to effectively and efficiently enhance production and utilisation of waste water sustainably.
  • Infrastructure: Unitywater’s Kawana Sewage Treatment Plant
  • Project Value: This project is valued at AU$56 million
  • Estimated completion date: Start of construction April 2017, with an estimated start of operations early 2020.
  • Maintenance Period (by Monadelphous): 12 month maintenance starting early 2020.


ACCIONA will be responsible for aspects of process design, equipment supply and commissioning advice of the Kawana Sewage Treatment Plant upgrade.

  • Current treatment capacity of 90,000 PE (population equivalent)
  • Increase treatment capacity to 200,000 PE (150,000 PE specified)
  • 24 months to design and construct
  • Estimated in-service date is early 2020



  • The treatment process of Moving Bed Biofilm Reactor (MBBR) will be introduced which is designed in order for micro-organisms to grow which optimise capacity in quantity and quality of the water and is highly cost efficient.
  • Due to the innovative nature of the MBBR process, the proposal submitted increased the treatment capacity from the specified 150,000 PE to 200,000 PE, without any significant CAPEX cost increase.
  • This project will enhance the utilisation of by-products from wastewater through sustainably promoting co-digestion and generation of methane gas in order to generate electricity to offset the plants power requirements and thus reducing its carbon footprint.

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