Updated standard to improve quality of compost

Following the recent revision process, BSI and REAL have published the revised version of PAS100.

  • The quality of certified compost is set to improve
  • The quality standard for compost ‘PAS 100’ has been updated and more quality controls have been introduced
  • The standard was reviewed and revised over two years by a large number of stakeholders, including market and regulator representatives
  • Key changes include the introduction of requirements for setting up a Safety and Quality Control System to control hazards affecting both the quality and safety of compost
  • The Compost Certification Scheme has set up a Research Hub to fund research to provide robust evidence for future updates 

The quality of independently certified compost is set to improve. The quality standard Ã¢Â€Â˜PAS 100’ has been revised in order to introduce more quality controls to the composting process and an improved composting management system. Farmers, food producers, growing media manufacturers, retailers, and consumers of certified compost can now have even more confidence in the quality of the compost that they use.


The PAS 100 revision process

Over a period of two years, the standard, officially known as a specification, has been reviewed and revised to incorporate new requirements intended to make it more robust. The updated standard is the result of an extensive stakeholder consultation and consensus-building process.

A wide range of industry stakeholders engaged in discussions on how to make PAS 100 fully up-to-date and fit-for-purpose. The revision process was sponsored and led by Renewable Energy Assurance Limited (REAL).

The key decision-makers comprised representatives of producers, certification bodies, environmental regulators, and market representatives. As a result, BSI PAS 100:2018 Specification for composted materials, as it is known, is now a robust quality standard that consumers, markets, and regulators can have confidence in, against which consistently safe, good quality compost can be produced.  


Key changes to the PAS 100 include:

  • A new ‘compost quality’ clause making clearer the existing requirements to produce compost that is fit-for-purpose (suitable for intended use) by checking and agreeing with customers in writing any quality requirements that are more stringent or wider ranging than the minimum baseline quality requirements specified in the PAS.
  • Requirements for a team approach to developing a Safety and Quality Control System (SQCS).
  • The previous Hazard Analysis and Critical Control Point (HACCP) section of PAS 100:2011 has been re-written to extend the requirements. PAS 100:2018 requires producers to set up a SQCS to consider hazards affecting quality as well as safety, relevant to the intended use of the compost. This also relates to the new ‘compost quality’ clause.
  • A requirement for compost to be re-assessed for compliance with the requirements of the ‘compost quality’ clause when stored for a period of six months or longer.
  • A requirement that restricts the dispatch of sampled batches of compost for use until after the test results have been checked for conformance to PAS 100.

How to get a copy of PAS100:2018

You can purchase and download a pdf copy of BSI PAS 100:2018 from BSI's website here and hard copies will be available soon. You can also purchase discounted soft or hard copies directly from REAL, although, they have a limited number so they will be available on a first come first serve basis. Please send an email to to request a discounted copy.

Implementation timescale

There is a three-month transition period in which you are required to implement the new changes to your process. There is a deadline of 31st December 2018 to implement these changes, after which all operators will be audited against BSI PAS 100:2018 from January 1st 2019.

Within this transition period, you will be audited against the previous version (PAS 100:2011), however, when it is possible for the certification bodies to carry out the audits, you can choose to be audited against the new version (PAS 100:2018) within the transition period.

Future updates to the standard

The recent revision has highlighted that the standard is robust and market confidence in both this quality standard and quality compost can be maintained. However, there were limits to what could be revised during this process and what can be revised in the future without relevant evidence. There was not enough scientific evidence available to support some of the proposals put forward during this revision process. 

It was recognised that there is a lack of financial support for the necessary research to be undertaken. For this reason, REAL has devised a mechanism to source funding from the composting and AD industries, in the form of a Research Hub. 

The REAL Compost and Biofertiliser Certification Schemes’ Research Hub has been set up so that the industry will be prepared with the evidence base to support future updates to PAS 100, and other certification scheme protocols.

Virginia Graham, Chief Executive of Renewable Energy Assurance Limited said:

"After two years of working closely with industry and the British Standards Institution (BSI), we are delighted to welcome today the new specification for composted materials. 

The collaborative process of revising PAS 100 was a valuable exercise in furthering understanding of what is considered a robust quality standard by producers, markets, and regulators. 

We are proud to run a reputable certification scheme for assessing conformance with PAS 100 and the Compost Quality Protocol.

Furthermore, we are committed to evidence-based continuous improvement and we are therefore also proud to present our Research Hub this year, a tool that can be used to ensure PAS 100 remains fit for purpose.”

Jeremy Jacobs, Technical Director of Renewable Energy Association said:

"It is essential that any standards are relevant to current market conditions, and the PAS 100 Standard is no exception. The ORG is delighted that this revision took place in order that it assists in building confidence in the market for this valuable resource. We are particularly encouraged by the development of the Research Hub to further build evidence in the future for further improvements to the Standard and ensuring it is fit for purpose in the 21st Century.”

Gregor Keenan, Compost Certification Scheme Producers’ Representative said:

"The revision process has been very robust with significant input from stakeholders including compost producers. We have made some important changes which should increase market confidence and drive continual improvement within the industry. The composting industry has evolved over the last few years to meet the increasing demand for organics recycling and compost products. Markets for quality compost continue to grow so it was vital that this revision process reflected the current landscape as well as looking to the future and I believe that this has been achieved.  

The Producer’s Forum has also welcomed the development of the Research Hub which will provide evidence to inform and support change in future revisions. There will now be a mechanism in place to fund research and the Industry will be able to direct activities to the most relevant areas.  

It has been a long road to get to this point but the process has been transparent and inclusive throughout with multiple workshops and opportunities for all interested parties to contribute. Although the PAS 100 Specification will continue to evolve in years to come I believe that this revision, and the manner in which it was conducted, has developed down a successful blueprint for future progress.”


Safety and Quality Control System

This new section in PAS 100 is based on Hazard Analysis and Critical Control Point (HACCP) principles, which are applied to a composting process. The Safety and Quality Control System (SQCS) introduces a number of checks and controls, throughout the entire composting process, to ensure that compost is fit-for-purpose. This will ensure that hazards relevant for compost quality are identified and controlled.

Producers are required to bring together a team of individuals to develop a SQCS. This team will be trained and experienced to be able to describe the final product in detail and the intended use of the product. 

The team will identify all the operational steps in the production of their product and conduct a HACCP study to identify which hazards and associated risks should be reduced to acceptable levels. They are required to assess both safety and quality hazards relevant for the intended use of the product. The team will identify the production steps, where these hazards will be controlled,and the steps to be monitored. 

The HACCP plan will be kept up-to-date by the SQCS team to take into account the introduction of any new quality requirements or any new potential hazards.

Benefits of using quality compost

Compost, as a material, can improve soil structure and soil health by increasing organic matter and the soil’s ability to retain moisture and nutrients. 

Various technologies can be employed on an industrial scale to treat organic waste materials, such as garden waste and animal by-product materials, to produce compost. This recycling route through composting diverts waste from disposal routes and permits this material to be recycled into agricultural and horticulture.

Consumers who use compost independently certified to PAS 100 through the Compost Certification Scheme, also known as quality compost, can be confident that this compost is consistently safe and reliable. 

The additional PAS 100 requirements (and independent certification against this updated standard) will ensure that the composting processes and composted materials, produced in accordance, is consistently safe and the quality is consistently relevant to the intended use of the compost as a product by the individual customer.

Posted 19/09/18

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