Physical contaminants (especially plastic) in composts and digestates are of growing concern to operators, environmental regulators and wider stakeholders. 

Through reseach projects spanning more than 10 years we have developed considerable expertise/experience in the analysis of composts, digestates and similar matrices. 

Standard physical contaminant analysis involves the manual separation of physical contaminant fragments in >1 or 2 mm (depending on the matrix) size fractions. We can then report recovered contaminants on the basis of mass, surface area and size. 

Further analysis can include the use of basic screening for the relative abundance of compostable/non-compostable plastic contaminants or more specialised spectroscopy based polymer determination.

Examples of our industry leading research can be found online. Alternatively get in contact to find out more. 

Stability is an important compost quality criterion. Recognised potential issues with unstable composts include risk of self-heating leading to fires, causing nuisance odours and attracting disease vectors. 

Compost stability can be assessed using a variety of tests ranging from biological to chemical and physical. Biological stability tests are currently most used, based on measuring CO2 production and/or O2 consumption, or heat production. 

At Solidsense Ltd, we are specialists in the assessment of compost (and other organic waste materials) stability assessment with experience and setup for a range of biological stability tests including dynamic and static CO2 based tests and self-heating tests. 

• ORG0020 (BSI PAS100 Stability Test)
• Static dynamic respiration test
• Dewar self-heating test

If you have a special project needing expert compost stability advice get in touch.  

Mature compost can be defined as material ready for its intended use having been through the self-heating process and cured. 

Typically compost is used for plant growth and so mature compost in this context means the compost doesn't contain phytotoxic compounds or inhibition seed germination and plant growth. 

Tests to addess compost maturity for plant growth can include seed germination or plant growth assays. The latter typically running for 10 or more days. 'Rapid' compost maturity tests can also be used to assess / optimise compost processes. Alternatively, for other end use applications, different tests can be developed/applied.  

Culture based microbiology expertise including plate count and presence/absence tests supported by microscopy and molecular microbiological techniques for characterisation. 

General sample characterisation to support specialist testing including:

• pH
• Electrical conductivity
• Moisture content
• Laboratory compacted bulk density (LCBD)
• Particle size distribution

Molecular biological techniques can be used to quantify the abundance of specific microbes (bacteria, fungi, viruses) or characterise specific communities. 

We have expertise applying specialist molecular biology techniques for a range of clients testing bioaerosol, compost, digestate and soil samples.