Rotorua Wastewater Treatment Plant upgrade
Finding a solution to prepare for the future
Rotorua's Wastewater Treatment Plant needs to be upgraded to cater for future growth as well as ensuring we manage our waste responsibly, in a way that:
- Protects people's health
- Is environmentally sustainable; and
- Is culturally appropriate
The objectives have been inspired by the Lakes Water Quality programme as well as aligning to the Council Vision 2030 goals of creating a vibrant and sustainable future for Rotorua and its residents.
Rotorua's current plant has to date been the most successful initiative in reducing nitrogen going into Lake Rotorua. Our treatment plant is among the best in the country, treating wastewater to a very high standard. But it is in need of future-proofing to meet higher projected demand and to continue to reduce and maintain nutrient levels below the targets agreed under the Lakes Water Quality programme.
Discharging into Whakarewarewa Forest is no longer viable as a sustainable option for several reasons including cultural concerns. It is also resulting in ground over-saturation that's detrimental to trees, making it an unreliable filtering system and adding to pollutants entering the Puarenga Bay.
The proposed upgrade would treat wastewater to an extremely high standard, removing pollutants like nitrogen and phosphorus and disinfect bacteria like E. Coli. The recovered water would be clean and would not pollute the lake.
How is wastewater in the city is currently treated?
Current Wastewater Treatment Service
Rotorua's wastewater (sewage) is treated daily at a central Wastewater Treatment Plant on Te Ngae Rd, using a 5-stage Bardenpho process. This was the first full biological nitrogen and phosphorus process used for municipal wastewater in New Zealand, and in terms of nitrogen, the discharge water is already one of the best in the country. The sludge produced (biosolids) is blended with wood pulp and vermi-composted, then cultivated into land that is used to grow a fodder crop.
To protect the quality of the water in Lake Rotorua, the treated water from the plant is currently irrigated to pass through the land in Whakarewarewa Forest before the groundwater discharges to Lake Rotorua.
The Rotorua Wastewater Treatment Plant currently serves a population of approximately 60 000 people residing in the city.
- We treat an average of about 20 000 m3 (20 000 000 litres) of wastewater each day. We have the capacity to treat and discharge up to 44 000 m3
- Most of Rotorua's wastewater is generated by domestic use. A small percentage is from industrial use
What are we proposing to do?
With leadership from the community-led group, the Rotorua Project Steering Committee and other key rōpū (groups) including cultural expertise, Council endorsed the committee's preferred option to upgrade the Wastewater Treatment Plant.
The proposed upgrade would include:
- Increasing its flow capacity
- Stormflow storage
- Additional phosphorus removal
- UV treatment
- Land contact bed