TERAX: Hydrothermal deconstruction - Waste 2 Gold

Rotorua-based Scion has developed the TERAX™ hydrothermal deconstruction technology that converts municipal sewage or wastewater into energy and useful products. A large-scale pilot plant trial of the TERAX™ technology is being tested at Rotorua District Council’s Wastewater Treatment facility. This innovative technology allows recovery of valuable chemicals in addition to reducing waste.

This page describes the TERAX™ hydrothermal deconstruction technology and opportunities for district councils, regional councils and primary producers such as forestry, dairy and horticulture to reduce sewage waste and other biosolids. Updates from the Scion-Rotorua District Council TERAX™ pilot plant are included. The Waste 2 Gold Biosolids research programme which underlies this technology is outlined. 

This technology will interest city and district councils, industrial organic waste producers, primary industry and chemical companies wishing to recover chemical intermediates as alternatives to fossil-fuel sources. 

TERAX™ Hydrothermal Deconstruction

Scion's TERAX™ Hydrothermal Deconstruction technology reduces the volume of biological solids, such as sewage waste, that go to landfills and produces valuable energy and products. While this technology (which falls under the heading of thermal deconstruction or wet oxidation) is in limited use around the world, TERAX™ is different. 

The unique advancement in TERAX™ is the controlled deconstruction process allowing recovery of valuable chemicals rather than complete breakdown to CO2 and water. These chemicals can be sold to industry and used as fertilisers, as well as biopolymers in industrial processes, bioplastics and biofuels. This waste disposal process provides cost saving plus revenue generation.

terax process

Briefly, the process involves both an anaerobic fermentation and a hydrothermal oxidation stage. Before entering the hydrothermal oxidation plant, wastes are treated with bacterial cultures in an anaerobic fermentation plant (Stage 1). This dramatically reduces (by 90%) the volume of solids that enter the hydrothermal oxidation plant. The hydrothermal oxidation plant (Stage 2) uses high pressure, temperature and oxygen to break down waste solids into carbon dioxide, water, and small organic compounds. In the later value recovery stage, biological nutrients are removed (e.g. carbon or complex biopolymers) which can be used to make valuable products.

Treating organic waste benefits city and regional councils and primary industries

Diverting organic wastes away from landfills is a worldwide challenge. New Zealand's organic wastes can be a valuable, high volume source of energy, biomaterials, and fertilisers. A sustainable way to deal with organic waste is the driver behind the TERAX™ technology.

The challenge is that New Zealand sends 2.5 million tonnes of organic waste to landfills each year, a major cost for territorial authorities and industries like pulp and paper, dairy, horticulture, and meat processing. Landfilling is strongly discouraged by the New Zealand Waste Strategy 2000 and the Waste Minimisation Act 2008.

The opportunity was to create a waste minimisation technology that reduces cost (capital and running), eliminates harmful toxins, minimises landfill demand, and generates value. Such a technology, if adopted by territorial authorities and primary industries, will provide markedly reduced landfill requirements plus cost savings, improved environmental performance and the licence to operate by meeting national and international standards.

In response to this strategic challenge, Scion’s six-year-old Waste 2 Gold research programme has addressed the current limitations to organic waste diversion by developing processes which:

  • Achieve substantial volume reductions - effectively eliminating the need for landfilling or downstream marketing of partially converted waste products.
  • Maximise embodied energy and chemical recovery - providing compelling, positive economic returns from waste.
  • Ensure recalcitrant/harmful contaminants are destroyed or segregated.

The TERAX™ technology has the potential to reduce biological volumes that end up in landfill 30-fold. The volume of greenhouse gases can be reduced by approximately 70%.


The Scion and Rotorua District Council TERAX™ Hydrothermal Deconstruction Pilot Plant

In 2008, Scion and the Rotorua District Council (RDC) joined forces to develop the TERAX™ hydrothermal deconstruction technology. RDC has contributed funding and facilities at its Wastewater Treatment Plant for the TERAX™ pilot plant to operate using municipal wastes.

Rotorua has approximately 8,500 tonnes of waste going to landfill every year, at a current cost of around $920,000. Lifecycle analysis shows that the RDC can save approximately $1.4 million per year in landfill and associated environmental costs by using this technology. This economic benefit does not include the sale of potentially valuable chemicals. There have been a number of significant milestones in this programme. Some recent highlights are listed.
  • 31 August 2010:  The Minister for the Environment Hon Dr Nick Smith announces that the Scion-based Waste 2 Gold biosolids programme will receive $1million from the Ministry's Waste Minimisation Fund.
  • 31 May 2011: The Minister for the Environment Hon Dr Nick Smith opened the TERAX™ hydrothermal oxidation pilot plant at Rotorua's municipal waste facility. This pilot plant is a collaboration between Scion and the Rotorua District Council. 
  • The purpose of the pilot plant is to trial the hydrothermal deconstruction technology at a level that will provide sufficient data to determine if the technology can work at a full commercial scale. 
  • October 2011: The Anaerobic Fermentation Pilot Plant was installed and became operational in November. 
  • Jan-March 2012: Data from the TERAX™ pilot plant will be analysed to evaluate if this technology can be applied at a full commercial scale.
  • June 2012: Design of and costing a full demonstration-scale plant at the Wastewater Treatment Plant is due to be completed. This demonstration-scale plant will be able to handle all the biosolids from Rotorua's wastewater. 

Results from the pilot plant together with technical, economic and sustainability assessments, demonstrated that the TERAX™ technology platform could achieve:

  • 96% reduction in landfilling volume.
  • 76% reduction in greenhouse gas emissions.
  • 40% reduction in eutrophication potential.
  • 90% reduction in photochemical ozone creation potential.

In addition, the TERAX™ technology detoxifies the sludge waste stream, kills pathogens and produces essentially sterile output streams. The successful national implementation of the TERAX™ technology platform would reap benefits to:


  • An ability to substantially reduce the costs associated with current municipal sewerage and industrial waste treatment and, more broadly, organic waste disposal.
  • The potential to reduce their environmental footprint through reduction in waste transportation, landfill leachates and greenhouse gas emissions.
  • The ability to develop new revenue streams through sales of industrial chemicals, energy and fertilisers.

New Zealand community

  • Reduced environmental impacts through reduced waste to landfill, reduced greenhouse gas emissions, reduced eutrophication and reduced ozone depletion.
  • Improved capacity to move towards the NZ Waste Strategy Targets.
  • Ability to develop new TERAX™ technology manufacturing opportunities for domestic and export development.
  • Enhanced environmental reputation for New Zealand.

Waste 2 Gold biosolids programme

The TERAX™ hydrothermal deconstruction technology arose as part of Scion's Waste 2 Gold biosolids waste programme that began in 2006. The original research aimed to find solutions for handling waste generated by the forestry industry. This research was funded by the Foundation for Research, Science and Technology, now the Ministry for Science and Innovation.  Between 2006 and 2008 Scion had tested the thermal deconstruction process to for processing this forestry waste. While the results were extremely encouraging, the forestry industry was not yet able to take the project to the next step.

In 2008, the Rotorua District Council became a partner in this research. This RDC-Scion partnership greatly expanded the scope of the laboratory-based studies and laid the foundation for the current pilot plant to become a working reality.

The Waste 2 Gold biosolids programme contains a suite of environmental technologies developed and implemented by Scion. Other examples include the N-Viro Tech technology that uses nitrogen fixing bacteria to treat wastewater. The Titrimetric-Off-Gas Analysis (TOGA) apparatus was further developed under the Waste 2 Gold programme.

Key people involved in the Waste 2 Gold programme

Robert Lei, Waste 2 Gold Project Leader.
For Technical Enquiries. Robert.Lei@scionresearch.com  

Daniel Gapes, Science Leader.
For Technical Enquiries. Daniel.Gapes@scionresearch.com  

TERAX™ Hydrothermal Deconstruction technology resources