Pukete Wastewater Treatment Plant Upgrade

Hamilton City Council

Hamilton, New Zealand

Hamilton City Council wanted to upgrade the Pukete plant sludge digester system to ensure adequate treatment capacity for the increasing treatment plant sludge inflows over the next decade. An additional requirement was to achieve digester tank redundancy to allow safe operation of the plant when one digester was out of service for maintenance or repairs.

Our waste value recovery team advised council on effective solutions for digester mixing and solids handling. By adding “smart” process technology and improving the treatment performance of the existing digesters, our solution saw the capacity of each existing digester improve by more than 100%. This achieved the required digester tank redundancy, without the need to construct new digesters and improved the robustness of the sludge digestion process. With construction of new digesters deferred by up to 10 years, the client was able to obtain $3m construction cost savings. This success is now used to instruct similar ongoing Calibre digester capacity upgrade design projects in Australia.