Discharging the wastewater

To deliver high-quality wastewater treatment solutions that support the health of our growing communities, Council combined Western science with mātauranga Māori [knowledge] during the design of the new plant.

Guided by Te Ture Whaimana o Te Awa o Waikato (The Vision and Strategy for the Waikato River), and supported by advanced technology, we undertook a detailed assessment to determine the most appropriate location and method for discharging treated wastewater.

Investigations confirmed the current Rapid Infiltration Beds were no longer viable, due to groundwater levels, geotechnical challenges, and construction risks at the site.

Following advice from the Kaitiaki Group, the preferred solution was a gabion wall and riprap (rock) structure on the bank of the Waikato River. This approach honours the Mātauranga Māori Framework by reconnecting the water with the land before it returns to the river, and has become an eye-catching landmark.

The discharge structure is located within the treatment plant site.

The wastewater treatment process

The wastewater is treated in several stages, combining biological treatment with membrane filtration to remove pollutants and suspended solids, producing high quality treated wastewater.

Here's how it works

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  • Biological treatment

    An activated sludge (with bugs) breaks down the organic matter and nutrients in the wastewater.

  • Membrane bioreactor filtration

    Treated water is pumped from the bioreactor tank and filtered through membranes, typically made of specialty plastic. (For engineers out there, this is called polyvinylidene difluoride, or PVDF).

  • Solid liquid separation

    The membranes act as a physical barrier, allowing only purified water to pass through while retaining the suspended solids, bacteria, and pathogens.

  • UV disinfection

    Treated wastewater is passed through the disinfection system. The light damages the DNA of the microorganisms, preventing them from replicating and causing harm.

  • Discharge

    The highly treated wastewater is discharged through the gabion wall and riprap (rock) structure on the bank of the Waikato River.