Sludge Management

Many industrial and municipal processes produce high water content sludges that are much more difficult to handle when compared to solid wastes. Particular expertise is required for the management and disposal of such wastes which include:

  • Wastewater biosolids
  • Water treatment residuals (e.g. alum sludge)
  • Industrial sludges.

Depending on the sludge, disposal options could include:

  • Co-disposal with municipal solid waste
  • Disposal to a dedicated landfill (monofill)
  • Disposal to land
  • Further treatment and destruction of the sludge

Each management option has advantages and disadvantages.  Choosing one requires consideration of regulatory requirements, sustainability, cost and practicality.


Our civil and environmental teams offer:

  • Sludge/biosolids generation assessments
  • Sludge management options assessment
  • Disposal options assessment
  • Environmental effects assessments and consenting
  • Disposal facility design and management


We have experience in various aspects of sludge management and disposal including:

  • Dewatering and stabilisation
  • Monofill landfill design and operation
  • Co-disposal with municipal solid waste and its effect on:

Landfill gas production
- Leachate quality and quantity
- Waste degradation rates
- Landfill geotechnical stability
- Landfill operations

  • Assessment of effects of disposal

We have been involved in a variety of projects including:

  • Design of major monofill for industrial scrubber waste and clay slimes in Auckland
  • Design of monofill for water treatment residuals in Auckland
  • Major containment facility for industrial biological sludges in Central North Island
  • Lime scrubber waste disposal in Central North Island
  • Bio solids landfill in Auckland
  • Bio solids co-composting in Wellington
  • Bio solids co-disposal in Hong Kong, Wellington and Canterbury
Key Contacts

Tony Bryce Tony Bryce

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