Driven by developments in the industries that make and use composts and in the ‘End of Waste’ criteria for compost ‘products’ derived from controlled biowastes, the 2005 edition of PAS 100 has been updated. Replacing it, the 2011 edition has been developed by WRAP with AfOR and the British Standards Institution. It is downloadable from WRAP’s website via this link.
A review group comprising representatives from industry and regulatory bodies contributed to PAS100’s development and the finalised edition takes account of feedback from consultation with the UK’s biowaste management industry and other stakeholders. The review process also took into account recommendations from WRAP sponsored reviews of compost stability testing, plant growth and weeds testing as well as evaluations of test results data on the PAS 100 obligatory parameters.
PAS 100 applies to the centralised, on-farm and community composting of biodegradable wastes and materials that have been kept separate from those that are not biodegradable. It does not apply to composts made by householders for use in their own gardens.
The latest edition incorporates references to current legislation, guidelines and recent scientific reports. It continues to require the composter to supply composts that are fit for purpose, supported by Hazard Analysis and Critical Control Point planning, operation of a Quality Management System (QMS), and the supply of clear information to the customer.
Key changes brought in by the 2011 edition
The composting of sewage sludge or its derivatives is no longer allowed.
Addition of digestates from anaerobic and aerobic digestions processes is allowed, subject to restrictions set out in its scope and section on input materials.
The composting process is allowed to utilise thermophilic aerobic digestion rather than aerobic composting for the sanitisation phase.
Vermi-composting is within the scope of this PAS where it follows a sanitization step of thermophilic aerobic composting or thermophilic aerobic digestion.
A different method for laboratories to use when testing compost samples for E. coli as well as a clarified, separately published method for testing plant response to a compost sample and assessing its weed content.
All PAS 100 obligatory tests and corresponding limits apply to each compost grade for which PAS conformance is claimed, except in the case of the plant response and weeds test and minimum performance requirements which are allowed to be carried out on the principal compost grade only. (In the 2005 edition, additional compost grades only had to pass potentially toxic elements, physical contaminants, stones and stability tests if claimed to conform to PAS 100.)
Upper limits on physical contaminants, including plastic, have been made more stringent as too has the upper limit on stones in a mulch grade. Restrictions on sharps and the composter’s responsibilities have been made clearer.
After validation, PAS 100:2011 recommends that graded compost batches that are sampled and tested are kept on-site until their test results have been received and evaluated, instead of requiring such keeping on-site. However, if compost sample test results are reported by the laboratory and evaluated by the composter after the sampled batch has been dispatched as PAS 100 compost and the test results show failure(s) to comply with any of the quality criteria, the composter is required to notify the customer and regulator of the nature of the batch’s failure.
The composter is required to investigate the cause of any test result that shows failure to comply with any of the quality criteria. The composter must review whether the Quality Management System needs to be changed and, after implementing such change or taking other corrective action, the composter must sample further batches of the same compost grade and obtain laboratory test results for those samples. The composter must then use those results to evaluate whether the change to the QMS or the other corrective action taken was effective, i.e. resulted in compost that complies with the quality criteria. PAS 100:2011 also specifies options for the management of any failed batch (that is on-site when compost test results are received and evaluated).
Status of PAS 100: 2005
The 2005 edition of PAS 100 was superseded from the date the 2011 edition was published, January 2011.
Arrangements for transition of certification
Click here to read more about AfOR’s arrangements for transferring from PAS 100:2005 certification to PAS 100:2011 certification.
Webpage published: 28 February 2011
Become a Member!
Join the Organics Recycling Group at the Renewable Energy Association by clicking below.