Biosolids Production and End Use in New Zealand

In 2010 the Australian and New Zealand Biosolids partnership commissioned this national survey to identify the main features of biosolids management. This survey catalogued the following primary parameters:

• Biosolids production;
• Biosolids end use;
• Biosolids stabilisation grade;
• Biosolids primary stabilisation process;
• Biosolids dewatering process.

The results of this survey are presented below on a national and state basis.

METHOD

The approach used to determine the biosolids production in Australia was to survey all plants over 25,000 people or 5 ML/day. The ANZBP identified that this criteria would capture around about 80% of New Zealand’s population.

All classifications are made on the basis of tonnes of production.

Production

The total biosolids production of New Zealand identified in the survey is about 58,000 tonnes per year of dry solids. The average solids content of biosolids is 20-25% and this equates to around 0.25-0.3 million tonnes of biosolids in dewatered form (also called wet).

A breakdown of biosolids use is given in the chart below

End use

The following classifications were used for end use:

• Agriculture: for biosolids which is applied to land for its fertiliser value without value added processing
• Composting: for biosolids which processed through a composting facility and used for landscaping or other horticultural use;
• Forestry: for biosolids which is applied to plantation forests to aid tree growth;
• Landfill: for biosolids which is disposed to landfill;
• Sea: for biosolids which is discharged to the ocean;
• Stockpile: for biosolids which is stored, pending future planning, processing or use;
• Unspecified: for plants which did not respond or for which the end use could not be identified.

Important note

The Australian & New Zealand Biosolids Partnership is a division of the Australian Water Association Limited. This information is intended as a first point of reference and should not be relied on as a substitute for professional advice. Specialist advice should always be sought in relation to any particular circumstances and no liability will be accepted for any losses incurred by those relying solely on this information.