The report below presents a state of the art summary of the composting of commercial and non-green waste materials within the UK and the methodology to do it.

This report illustrates that in the UK open turned aerobic windrows are the favoured option even for non-green municipal solid waste and commercial wastes.  A number of in vessel systems were seen to be operating on a small scale.  The report also highlighted that whilst aerobic seems predominant there is interest is using anaerobic systems for processing and stabilising the waste streams.  The main difference between aerobic and anaerobic systems can be summarised as:

?       Aerobic systems break down the organic materials in the presence of oxygen with the microbes using nitrogen and carbon as the primary food sources.  Water vapour and carbon dioxide (CO₂) are the primary bi-products from this process.

?        Anaerobic systems break down and stabilise the material with a lack of oxygen with the microbes using sugars as their primary food source.  Methananagenic compounds and CO₂ are the main bi-product from this process.

Within this identification of aerobic and anaerobic systems four main methods were identified, these were:

?       Turned/static aerobic windrow composting ? aerobic and biological.

?       In vessel aerobic windrow composting ? aerobic and biological.

?       Mechanical breakdown ? non-biological.

?       Anaerobic digestion ? anaerobic and biological.

There is a need for longer term, strategic research covering key areas of:

?       Process and quality control, including leachate and mal-odours.

?        Market information.

The Composting Association has set up a strategic research working group to bring together interested organisations both commercial and academic to try and develop a more co-ordinated research strategy for the UK composting industry.