NZ Herald
  • Home
  • Latest news
  • Video
  • New Zealand
  • Sport
  • World
  • Business
  • Entertainment
  • Podcasts
  • Quizzes
  • Opinion
  • Lifestyle
  • Travel
  • Viva
  • Weather forecasts

Subscriptions

  • Herald Premium
  • Viva Premium
  • The Listener
  • BusinessDesk

Sections

  • Latest news
  • New Zealand
    • All New Zealand
    • Crime
    • Politics
    • Education
    • Open Justice
    • Scam Update
    • The Great NZ Road Trip
  • On The Up
  • World
    • All World
    • Australia
    • Asia
    • UK
    • United States
    • Middle East
    • Europe
    • Pacific
  • Business
    • All Business
    • MarketsSharesCurrencyCommoditiesStock TakesCrypto
    • Markets with Madison
    • Media Insider
    • Business analysis
    • Personal financeKiwiSaverInterest ratesTaxInvestment
    • EconomyInflationGDPOfficial cash rateEmployment
    • Small business
    • Business reportsMood of the BoardroomProject AucklandSustainable business and financeCapital markets reportAgribusiness reportInfrastructure reportDynamic business
    • Deloitte Top 200 Awards
    • CompaniesAged CareAgribusinessAirlinesBanking and financeConstructionEnergyFreight and logisticsHealthcareManufacturingMedia and MarketingRetailTelecommunicationsTourism
  • Opinion
    • All Opinion
    • Analysis
    • Editorials
    • Business analysis
    • Premium opinion
    • Letters to the editor
  • Sport
    • All Sport
    • OlympicsParalympics
    • RugbySuper RugbyNPCAll BlacksBlack FernsRugby sevensSchool rugby
    • CricketBlack CapsWhite Ferns
    • Racing
    • NetballSilver Ferns
    • LeagueWarriorsNRL
    • FootballWellington PhoenixAuckland FCAll WhitesFootball FernsEnglish Premier League
    • GolfNZ Open
    • MotorsportFormula 1
    • Boxing
    • UFC
    • BasketballNBABreakersTall BlacksTall Ferns
    • Tennis
    • Cycling
    • Athletics
    • SailingAmerica's CupSailGP
    • Rowing
  • Lifestyle
    • All Lifestyle
    • Viva - Food, fashion & beauty
    • Society Insider
    • Royals
    • Sex & relationships
    • Food & drinkRecipesRecipe collectionsRestaurant reviewsRestaurant bookings
    • Health & wellbeing
    • Fashion & beauty
    • Pets & animals
    • The Selection - Shop the trendsShop fashionShop beautyShop entertainmentShop giftsShop home & living
    • Milford's Investing Place
  • Entertainment
    • All Entertainment
    • TV
    • MoviesMovie reviews
    • MusicMusic reviews
    • BooksBook reviews
    • Culture
    • ReviewsBook reviewsMovie reviewsMusic reviewsRestaurant reviews
  • Travel
    • All Travel
    • News
    • New ZealandNorthlandAucklandWellingtonCanterburyOtago / QueenstownNelson-TasmanBest NZ beaches
    • International travelAustraliaPacific IslandsEuropeUKUSAAfricaAsia
    • Rail holidays
    • Cruise holidays
    • Ski holidays
    • Luxury travel
    • Adventure travel
  • Kāhu Māori news
  • Environment
    • All Environment
    • Our Green Future
  • Talanoa Pacific news
  • Property
    • All Property
    • Property Insider
    • Interest rates tracker
    • Residential property listings
    • Commercial property listings
  • Health
  • Technology
    • All Technology
    • AI
    • Social media
  • Rural
    • All Rural
    • Dairy farming
    • Sheep & beef farming
    • Horticulture
    • Animal health
    • Rural business
    • Rural life
    • Rural technology
    • Opinion
    • Audio & podcasts
  • Weather forecasts
    • All Weather forecasts
    • Kaitaia
    • Whangārei
    • Dargaville
    • Auckland
    • Thames
    • Tauranga
    • Hamilton
    • Whakatāne
    • Rotorua
    • Tokoroa
    • Te Kuiti
    • Taumaranui
    • Taupō
    • Gisborne
    • New Plymouth
    • Napier
    • Hastings
    • Dannevirke
    • Whanganui
    • Palmerston North
    • Levin
    • Paraparaumu
    • Masterton
    • Wellington
    • Motueka
    • Nelson
    • Blenheim
    • Westport
    • Reefton
    • Kaikōura
    • Greymouth
    • Hokitika
    • Christchurch
    • Ashburton
    • Timaru
    • Wānaka
    • Oamaru
    • Queenstown
    • Dunedin
    • Gore
    • Invercargill
  • Meet the journalists
  • Promotions & competitions
  • OneRoof property listings
  • Driven car news

Puzzles & Quizzes

  • Puzzles
    • All Puzzles
    • Sudoku
    • Code Cracker
    • Crosswords
    • Cryptic crossword
    • Wordsearch
  • Quizzes
    • All Quizzes
    • Morning quiz
    • Afternoon quiz
    • Sports quiz

Regions

  • Northland
    • All Northland
    • Far North
    • Kaitaia
    • Kerikeri
    • Kaikohe
    • Bay of Islands
    • Whangarei
    • Dargaville
    • Kaipara
    • Mangawhai
  • Auckland
  • Waikato
    • All Waikato
    • Hamilton
    • Coromandel & Hauraki
    • Matamata & Piako
    • Cambridge
    • Te Awamutu
    • Tokoroa & South Waikato
    • Taupō & Tūrangi
  • Bay of Plenty
    • All Bay of Plenty
    • Katikati
    • Tauranga
    • Mount Maunganui
    • Pāpāmoa
    • Te Puke
    • Whakatāne
  • Rotorua
  • Hawke's Bay
    • All Hawke's Bay
    • Napier
    • Hastings
    • Havelock North
    • Central Hawke's Bay
    • Wairoa
  • Taranaki
    • All Taranaki
    • Stratford
    • New Plymouth
    • Hāwera
  • Manawatū - Whanganui
    • All Manawatū - Whanganui
    • Whanganui
    • Palmerston North
    • Manawatū
    • Tararua
    • Horowhenua
  • Wellington
    • All Wellington
    • Kapiti
    • Wairarapa
    • Upper Hutt
    • Lower Hutt
  • Nelson & Tasman
    • All Nelson & Tasman
    • Motueka
    • Nelson
    • Tasman
  • Marlborough
  • West Coast
  • Canterbury
    • All Canterbury
    • Kaikōura
    • Christchurch
    • Ashburton
    • Timaru
  • Otago
    • All Otago
    • Oamaru
    • Dunedin
    • Balclutha
    • Alexandra
    • Queenstown
    • Wanaka
  • Southland
    • All Southland
    • Invercargill
    • Gore
    • Stewart Island
  • Gisborne

Media

  • Video
    • All Video
    • NZ news video
    • Business news video
    • Politics news video
    • Sport video
    • World news video
    • Lifestyle video
    • Entertainment video
    • Travel video
    • Markets with Madison
    • Kea Kids news
  • Podcasts
    • All Podcasts
    • The Front Page
    • On the Tiles
    • Ask me Anything
    • The Little Things
    • Cooking the Books
  • Cartoons
  • Photo galleries
  • Today's Paper - E-editions
  • Photo sales
  • Classifieds

NZME Network

  • Advertise with NZME
  • OneRoof
  • Driven Car Guide
  • BusinessDesk
  • Newstalk ZB
  • What the Actual
  • Sunlive
  • ZM
  • The Hits
  • Coast
  • Radio Hauraki
  • The Alternative Commentary Collective
  • Gold
  • Flava
  • iHeart Radio
  • Hokonui
  • Radio Wanaka
  • iHeartCountry New Zealand
  • Restaurant Hub
  • NZME Events

SubscribeSign In
Advertisement
Advertise with NZME.
Home / New Zealand

$30m bioreactor a world first

By Laurilee McMichael
Rotorua Daily Post·
19 Sep, 2012 12:10 AM3 mins to read

Subscribe to listen

Access to Herald Premium articles require a Premium subscription. Subscribe now to listen.
Already a subscriber?  Sign in here

Listening to articles is free for open-access content—explore other articles or learn more about text-to-speech.
‌
Save

    Share this article

The new bioreactor facility at the Wairakei Power Station near Taupo. Photo / Jeremy Bright

The new bioreactor facility at the Wairakei Power Station near Taupo. Photo / Jeremy Bright

A one-of-a-kind new water treatment facility near Taupo is using gas-gobbling bacteria and 378km of underground pipes to clean Waikato River water.

While it may make a fabulous water feature, Wairakei Power Station's new bioreactor is a serious piece of industrial plant, and a world first.

It uses sulphur-oxidising bacteria to reduce the levels of hydrogen sulphide in the power station's cooling water.

The $30 million bioreactor was commissioned in July and formally opened yesterday at Wairakei with a blessing from Rev Sonny Garmonsway of Te Pihopatanga o Aotearoa (the Maori Anglican Church) and Ngati Tuwharetoa.

The bioreactor's follows years of trials and a 12-month construction project.

Advertisement
Advertise with NZME.
Advertisement
Advertise with NZME.

The power station draws water from the Waikato River and uses it to cool geothermal fluid extracted to generate electricity.

Hydrogen sulphide occurs naturally in geothermal fluid, but due to the power station's cooling process, some of it also gets into the cooling water.

The new bioreactor pumps the used cooling water through 378km of pipes under a field next to the power station at the rate of 13,000 litres per second. Inside the pipes, the bacteria gobble the hydrogen sulphide from the water, removing up to 80 per cent of the toxic compound. The cleaned water is then returned to the Waikato River.

Advertisement
Advertise with NZME.

The new bioreactor helps ensure Contact Energy, which operates the Wairakei Power Station, can meet strict new cooling water discharge resource consent conditions, which came into effect last month.

The underground pipes provide an environment where the naturally-occurring bacteria colonise and grow to form a thin whitish film to remove the hydrogen sulphide as the cooling water flows through the bioreactor. Water takes about four minutes to travel the 378km of pipes, which equates to over three million litres of treated water being returned to the river every four minutes.

The bioreactor is thought to be unique internationally because the Wairakei Power Station was one of the first geothermal power plants in the world, and used the-then acceptable solution of discharging the cooling water directly back into the river.

It took Contact three years of trials to find the ideal conditions for sulphur-oxidising bacteria to grow. Scientists tried growing the bacteria using strings and mesh, but eventually discovered that they were best grown on smooth surfaces in a dark environment with the right conditions.

Project manager Peter Hewett said the bacteria used in the bioreactor occur naturally in the Waikato River water, so once the right conditions were provided, the bacteria began growing in the pipes.

Contact is delighted with the success of the bioreactor, which is currently removing around 80 per cent of the hydrogen sulphide in the water, 10 per cent more than is required in the power station's resource consent.

"As far as we know, this is the first time it's been done anywhere in the world."

Contact Energy chief executive Dennis Barnes said after many years of trialling different mediums to grow and house the bacteria, the eureka moment came when they discovered the bacteria would flourish in pipes, but it was still a leap of faith for the company to invest so much money into something that was "absolutely unique" in the world.

Save

    Share this article

Latest from New Zealand

New Zealand

Watch: Major highway blocked by slip, Auckland flights delayed as intense storm strikes

09 May 08:09 AM
Crime

Man's 11-day crime spree targets police by spitting and threatening to kill staff

09 May 08:00 AM
New Zealand

Auckland War Memorial Museum closed to public after asbestos discovery

09 May 07:49 AM

One tiny baby’s fight to survive

sponsored
Advertisement
Advertise with NZME.

Latest from New Zealand

Watch: Major highway blocked by slip, Auckland flights delayed as intense storm strikes

Watch: Major highway blocked by slip, Auckland flights delayed as intense storm strikes

09 May 08:09 AM

Motorists are being warned to expect hazardous driving conditions.

Man's 11-day crime spree targets police by spitting and threatening to kill staff

Man's 11-day crime spree targets police by spitting and threatening to kill staff

09 May 08:00 AM
Auckland War Memorial Museum closed to public after asbestos discovery

Auckland War Memorial Museum closed to public after asbestos discovery

09 May 07:49 AM
'We've had enough': Red Square protest opposes pay equity changes

'We've had enough': Red Square protest opposes pay equity changes

09 May 07:21 AM
Connected workers are safer workers 
sponsored

Connected workers are safer workers 

NZ Herald
  • About NZ Herald
  • Meet the journalists
  • Newsletters
  • Classifieds
  • Help & support
  • Contact us
  • House rules
  • Privacy Policy
  • Terms of use
  • Competition terms & conditions
  • Our use of AI
Subscriber Services
  • NZ Herald e-editions
  • Daily puzzles & quizzes
  • Manage your digital subscription
  • Manage your print subscription
  • Subscribe to the NZ Herald newspaper
  • Subscribe to Herald Premium
  • Gift a subscription
  • Subscriber FAQs
  • Subscription terms & conditions
  • Promotions and subscriber benefits
NZME Network
  • The New Zealand Herald
  • The Northland Age
  • The Northern Advocate
  • Waikato Herald
  • Bay of Plenty Times
  • Rotorua Daily Post
  • Hawke's Bay Today
  • Whanganui Chronicle
  • Viva
  • NZ Listener
  • What the Actual
  • Newstalk ZB
  • BusinessDesk
  • OneRoof
  • Driven CarGuide
  • iHeart Radio
  • Restaurant Hub
NZME
  • About NZME
  • NZME careers
  • Advertise with NZME
  • Digital self-service advertising
  • Book your classified ad
  • Photo sales
  • NZME Events
  • © Copyright 2025 NZME Publishing Limited
TOP