Tonnes of microbes get to work at Mangere Wastewater Treatment Plant

08 February 2018


Our Mangere Wastewater Treatment Plant is already one the world’s 20 largest and most advanced facilities—and now it’s even bigger.
  
Construction work on expanding the new Biological Nutrient Removal (BNR) facility at the Mangere Wastewater Treatment Plant began in 2013 and finished late last year and now it’s been commissioned. Over the past seven days, 22 tonnes of microbes have been added to the wastewater, so they can begin “munching” on debris bad bacteria, as part of the primary treatment process.

Watercare wastewater service delivery manager Shane Morgan says it’s a dramatic sight: “The microbes have been added to ‘seed’ the wastewater, so they can get to work and as a result, large foam tracts are appearing on the surface of the water, like mini icebergs.

"Most people don’t realise that treating wastewater is essentially a natural process —and the microbes are a huge part of that.”          

Wastewater flowing through the reactors at the Mangere Wastewater Treatment Plant extension.
Wastewater flowing through the reactors at the Mangere Wastewater Treatment Plant extension.

Wastewater staff are working on a 24/7 staff roster while the new plant starts up. It consists of a new four-stage treatment reactor, two new 52-metre diameter clarifiers and associated pump stations, pipes and blower facilities.  

The new facility will increase Mangere’s BNR capacity as Auckland’s population grows by an estimated one million people over the next 30 years.

BNR project manager Sven Harlos has overseen the design and construction: “The new facility will increase Mangere’s BNR capacity as Auckland’s population grows by an estimated one million people over the next 30 years. It’s hugely satisfying to see the plant up and running, I’m enormously proud of all the work Watercare staff and our contractors have put into it.” 

The plant’s increased capacity will ensure the highest quality treated wastewater continues to be discharged to the Manukau Harbour, even during heavy rainfall, which is good news for the environment. 

Staff at the Mangere Wastewater Treatment Plant.
Staff at the Mangere Wastewater Treatment Plant.

In order for work to take place, a new road linking Ascot Road and Puketutu Island had to be constructed. The public has benefitted too, with the creation of a new pathway between the hugely popular Watercare Coastal Walkway and Greenwood Road Park. 

We have carried out extensive planting in the area as part of the Mangere Coastal Restoration project in early 2000’s. With BNR construction more landscaping and planting of 100,000 native plants was done to shield the facility, which lies to the south of the existing Mangere treatment plant.  

Both Mangere and Rosedale wastewater treatment plants use primary (mechanical), secondary (biological) and tertiary (filtration and ultraviolet radiation) methods to treat wastewater before it’s discharged into the Manukau and Waitemata Harbours. 

Quick facts:
  • The average Auckland household produces 675 litres of wastewater per day
  • Contractor is a joint venture employing many small-medium contractors and suppliers
  • Early earthworks involved moving 450,000m3 of soil to create site area
  • 3000 piles driven into the ground, supporting 13,500m3 concrete poured to create structures
  • Major pipelines constructed to allow process flow connections with existing plant
  • This is one of many major infrastructure projects we will deliver to accommodate Auckland’s growth and other infrastructure drivers in the coming years, include: Central Interceptor project, Hunua 4 Section 11, North Harbour No2 Watermain and Northern Interceptor, a replacement for Huia WTP and Warkworth/Snells Beach wastewater upgrades and Clarks Beach sub-regional upgrades.
  • The BNR project forms part of the $4.9b capital infrastructure investment forecast during the next 10 years.
Give feedback