Anaerobic Lagoon

Client: Wallace Corporation Ltd
Date: July 2012

We have worked closely with Wallace Corporation Limited (WCL) – Waitoa, since 2006 in various environmental, civil works, consents and BNR process management at the Waitoa plant.

The construction of a new covered anaerobic lagoon and prefermenter, at Waitoa, to increase the capacity of the anaerobic treatment system was an exciting development for Wallace Corporation Limited.  It has allowed for the increase in production and is generating significant biogas that will in the future be utilised for onsite uses.

One of the key constraints in the design of the lagoon was the restriction on the outlet flow into the existing aerated lagoon.  The anaerobic lagoon was therefore designed with some flow balancing characteristics.  Another key constraint was finding a suitable site for the new 15,000m3 lagoon without compromising the already tight brownfield site and keeping any rising main lengths to a minimum.

The construction of this new covered anaerobic lagoon has included a new control room and MCC unit to run the process and provide key integration into the existing BNR Plant. Associated pump stations, mixing unit and carbon dosing systems were all designed and constructed to allow flexibility within the wastewater treatment operation.

As part of the design, we provided for a biogas collection system and flare unit which minimises present environmental effects and allows for WCL to harness the biogas energy in the future to fire their gas boilers.  We undertook all the process design, developed the detailed design, assisted with major equipment procurement, earthworks construction supervision and undertook to commission the Works.  We worked closely with WCL and maintained a good level of communications so that the Client received a service that delivered an appropriate solution and met the Client’s needs.

Key Aspects:

  • Engineer
  • Procure and commission

Client: Wallace Corporation Ltd
Date: July 2012

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