Palmerston North Wastewater Treatment Plant

Palmerston North City Council

Palmerston North, New Zealand

Palmerston North City Council required a review and improvements to the performance of their Anaerobic Digestion Systems at the Palmerston North Wastewater Treatment Plant (WWTP).

Our team’s anecdotal evidence suggested long-term under-performance had been occurring. Our team undertook hydraulic residence time testing on the digesters to reveal that nearly 50% of the reactor volume was poorly mixed and had been for many years despite a number of previous reviews.

Calibre acted as process designers, as well as mechanical and electrical commissioning engineers. First our team undertook hydraulic residence tests and from these recommended a short-term, transitional mixing system, followed by a longer term solution. The short-term solution improved performance sufficiently, allowing a single digester to accept the entire plant’s waste sludge. This allowed the second reactor to be removed and upgraded.

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The modifications made to the system increased the system capacity more than 300%. On our recommendation the council developed the facility into a co-digestion facility for combined source segregated trade sludges and waste, as well as biosolids. As a result the gas production has increased three-fold, resulting in an upgrade payback period of less than three years.

Project highlights

  • Enabled new revenue streams
  • 300% digester capacity increase
  • Green electricity export to grid

Business:

Calibre

Awards:

  • 2015 ACENZ Innovate NZ Awards of Excellence – Silver Award

Contact

Jurgen Thiele

Calibre

+64 3 374 6515
Jurgen.Thiele@@calibregroup.com

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