Kiwi environmental innovation receives international honours
Contact Energy’s Wairākei bioreactor – a Kiwi innovation – has been awarded honours at the internationally recognised
2014 IWA Asia Pacific Regional Project Innovation Awards in Singapore. Jointly developed by Contact and Beca, the
bioreactor is a unique, world-first solution to improve the quality of water that is discharged from the iconic Wairākei
geothermal power station into the Waikato River.
“I’m immensely proud of our bioreactor,” says Contact Energy CEO, Dennis Barnes. “As a world-first it’s great to see
this example of Kiwi ingenuity recognised at an international level.”
“To work with Contact Energy from the beginning, developing and testing innovative concepts through to the design and
construction of the Wairākei bioreactor has been immensely rewarding for the Beca team”, says Beca CEO, Greg Lowe. “This
is another great example of New Zealand talent delivering world class project outcomes.”
The Wairākei bioreactor was developed to reduce hydrogen sulphide (H2S) discharges from the Wairākei geothermal power
station to the Waikato River. This was identified through a 10-year programme of environmental and technical studies
which examined the environmental impacts from the ongoing operation of the power station. These studies showed that H2S
levels in the Waikato River downstream from the Wairākei power station exceeded accepted water quality guidelines
Harnessing the power of billions of naturally occurring bacteria endemic to the Waikato River, the bioreactor was
developed as a treatment facility for the breakdown of H2S in the cooling water. The bioreactor is designed around a
large network of almost 400 kilometres of pipes that create an environment for the bacteria to live and grow.
To date, the bioreactor is reducing around 85 per cent of H2S in the cooling water discharges, which is equivalent to a
reduction in H2S discharge levels of almost 8,000 kilograms per week. It is also on track to achieving the August 2016
milestone of an overall reduction of 95 per cent.
In creating this solution Beca engineers used several innovative engineering techniques, including:
· A tubular biofilm reactor design consisting of 1900 parallel polythene pipes;
· Excavated soil and pumice from the site was mixed with concrete to hold the 378 kilometre-long polythene pipe field in
place, saving considerable costs; and
· A syphon configuration for the bioreactor hydraulic design lowers the pumping head to minimise power usage and also
contributes to significant cost savings.
The IWA Innovation Awards is a prestigious global competition which recognises and celebrates innovation and excellence
in water engineering projects around the world.
The Wairākei bioreactor was also awarded the ‘Energy Project of the Year’ and ‘Environmental Excellence’ awards at the
2013 Deloitte Energy Excellence Awards (NZ). It received the 2013 New Zealand Engineering Excellence Award in the
Chemical, Bio and Food category and is a current finalist for the INNOVATE NZ Awards of Excellence.