Case-Study: Cardrona Valley Waste Water Treatment Plant

Solar thermodynamic solution for Cardrona Valley Waste Water Treatment Plant

The new plant, designed and constructed by Apex Water, serves the Cardrona village, the Cardrona Alpine resort and new residential and commercial development in the valley. The plant was commissioned in September 2020.

The alpine environment required some innovation for the plant to operate efficiently. In particular, the temperature of the wastewater had to be maintained at an optimum temperature for the bacteria to perform effectively in the treatment process. Direct electric heating was ruled out as inefficient, gas heating was unacceptable due to increased greenhouse gas emissions and direct solar heating would be ineffective during winter. Solar thermodynamic heating was the solution.

The system consists of 32 solar thermodynamic panels and a Solar Block unit. The solar thermodynamic system can take heat from the environment even in snowy winter conditions and at night.

In his paper to the Water NZ conference Dr Matt Savage from Apex Water Ltd says “The solar thermodynamic heating system was able to maintain the reactor temperature above the critical nitrification temperature under all operating conditions. This included through July 2022 when the panels were covered in snow for a week”. In his conclusion he says “Solar thermodynamic heating represents a viable low carbon emission alternative to fossil fuel heating of wastewater in extreme
cold climate environments”.

Here is a link to the full paper presented by Dr Matt Savage from Apex water Ltd at the 2022 Water NZ Conference and Expo:
Here is a link to an article in Business South magazine about the project:

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