Solids & Biosolids

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Our laboratory is accredited to test solids, sludges and biosolids for a range of metals, organisms, and organic chemistry matter. The analyses carried out on soils are often used for land contamination assessment, landfill/clean fill criteria acceptance, environmental monitoring, resource consent compliance, and one-off projects.  

Biosolids are sewage sludges that have been treated and stabilized. Once the appropriate testing has been carried out, these biosolids can be safely applied to land and used as a fertilizer. Biosolids often contain a variety of micro-nutrients such as nitrogen and phosphorus, along with metals, calcium, magnesium, and potassium that are beneficial for plant growth. 

It is important to monitor biosolids as if applied in excessive amounts, some of these elements can cause damage to plant or animal health. There are also potential pathogenic micro-organisms such as viruses, helminths, and protozoa and health risks to be aware of. 

Solids - what do we test for?

Heavy metals

TCLP (Toxicity Characteristic Leaching Procedure)

SPLP (Synthetic Precipitation Leaching Procedure)


Total organic carbon

Organic contaminants (SVOC, VOC)

Pesticides and herbicides

Hydrocarbons (PAH, TPH)

Biosolids - what do we test for?

E. coli


Helminths, adenovirus, enteric virus etc




Nutrients (Nitrogen and Phosphorus)