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Waste 2 Gold

05 Apr, 2012

The Rotorua District Council and Scion are testing new technologies to reduce waste and create valuable products.

Listen to audio: Waste 2 Gold

Duration: 21:06

High level of biosolids produced in wastewater treatment

Rotorua District Council (RDC) is looking at ways to reduce the amount of sludge going from their wastewater treatment plant to landfill. They currently have about 9000 tonnes of solid organic waste going to landfill annually, at a cost of nearly $1 million per year.

RDC has one of the highest standards of wastewater treatment in the country because it is an inland catchment. This means it discharges into a lake rather than a river or ocean. For this reason, the level of biosolids removal is very high – about 90%.

New process trialled to reduce biosolids

RDC is hopeful that a new process developed by Scion will help significantly reduce the volume of waste and at the same time produce energy and valuable byproducts.

Scion has experience in dealing with organic waste disposal at pulp and paper mills and has been developing its expertise with wet oxidation, creating a new process of hydrothermal deconstruction. The process uses high temperature and high pressure together to minimise waste volumes by up to 90% and produce valuable byproducts at the same time.

Scaling up the process

Scion is in the process of scaling up from the lab bench to a pilot plant. At the pilot stage, they look at optimising the process and integrating it with chemical and biological processes to extract value.

The next stage is to design and cost a full-scale treatment facility, which would save $1.5 million dollars per year as well as reducing the impact on waterways and air discharges.

In this programme, Scion’s Dr Robert Lei shows Alison Ballance the lab where the initial testing was done and then the town’s wastewater treatment plant where the Waste 2 Gold pilot plant is working.

Get news story: Scion turns sewage into $4m savings

Programme details: Our Changing World

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