Compost specifications

There are a number of specifications which can be applied to compost. These specifications help to ensure the quality and safety of the compost and composters have to follow strict procedures to ensure specifications are met.

Quality Protocol

In April 2007 the Compost Quality Protocol came into force. The Quality Protocol was developed by the Waste Action & Resources Programme (WRAP), the Association for Organics Recycling (AFOR – previously the Composting Association) and the Environment Agency and applies to compost for use as a product in England and Wales, derived from source-separated, bio-degradable waste.

Everyone that complies with Quality Protocol regulations see their compost deregulated from a waste to a product.

If composters do not comply with the Protocol the compost they produce will be considered to be a waste and waste regulatory controls will apply to its handling, transport and application.

The aim of the Protocol, which composters sign up to on a voluntary basis, is to instil confidence about compost as a product amongst buyers. Compost can be used in Scotland as a 'product' if it has been certified compliant with PAS 100 (see below), has certainty of market and can be put to use without further recovery. According to AFOR's latest figures, published in December 2008, 158 of its members are now compliant with the Quality Protocol.

The Protocol also received the approval of the European Commission's Technical Standards Committee in 2008. This means it is inline with European regulations and Protocol members to trade their product with other members of the EC.

To find out more visit the Environment Agency website.

PAS100

The British Standards Institution has developed a Publicly Available specification for Composted Materials (PAS100: 2005) which sets out a minimum quality level for compost. The PAS100 requires composters to develop a management system and quality policy to ensure compost is fit for purpose.

The composter must also undertake hazard analysis and critical control point planning and ensure that inputs are restricted to source-separated biodegradable material. All materials being treated and all resulting composts must also be traceable. The AFOR Certification Scheme provides the certification for the PAS100:2005. Inspection and accreditation is carried out by two independent certification bodies, Check Mate International and Organic Farmers and Growers.

The PAS100 was originally developed in 2002 and last updated in 2005. It is currently being reviewed again by WRAP, the British Standards Institution, AFOR with support from the Environment Agency.

To find out more, please visit the WRAP website.

Limit levels of defined parameters for PAS100:2005

Parameter	Upper limit
Human pathogens
Salmonella s.p.p.	absent in 25g sample
E. coli	1,000 CFU/g
Potentially toxic elements (mg/kg dry matter)
Cadmium	1.5
Chromium	100
Copper	200
Lead	200
Mercury	1
Nickel	50
Zinc	400
Physical contaminants
Glass, metal and plastic larger than 2mm	0.5% of total air-dried sample by mass (of which less than 0.25% of total air-dried sample is plastic)
Stones and other consolidated mineral contaminants larger than 2mm	8.0% of total air-dried sample by mass
Weed contaminants
Weed propagules	5 viable propagules per litre
Phytotoxins
Plant tolerance	20% below control

PAS 110

There is also a standard for digestate produced from anaerobic digestion, referred to as PAS 110. Please see our AD page for more on this.

Apex Compost

In summer 2002, a commercial partnership of three of the UK's biggest waste management firms - along with a horticulture firm - launched their own quality mark to coincide with the launch of their new compost brand. The APEX standard is a minimum quality specification for green compost only.

SITA, Cleanaway and Onyx (the latter two are now part of Veolia Environmental Services), as well as Freeland Horticulture, launched Apex compost to reassure the garden centre's buying the compost that wherever it had come from in the UK, and whichever company had produced it, it would meet the same high standard. The Apex partnership hoped that their logo would therefore come to be seen as a mark of quality in its own right.

A spokesman for SITA explained that a quality standard benefits both local authorities, by proving green waste is being properly recycled as a saleable material, and bolsters the market for compost itself.

The following analysis should be undertaken on the finished compost on a monthly basis for elements and once a quarter for other parameters and impurities in order to meet the Apex specification:

Parameter	Unit	Frequency	Lower limit	Upper limit
Chemical
pH		Monthly	7.5	8.5
Electrical conductivity	μS/cm	Monthly	750	1200
Organic matter	%	Monthly	25	35
C:N ratio	N/A	Monthly	15	20
Total nitrogen	%	Monthly	0.5	1
Ammonia-N	mg/l	Monthly	1	5
Nitrate-N	mg/l	Monthly	15	120
Total phosphorus	%	Monthly	0.1	0.3
Water soluble Phosphorus	mg/l	Monthly	4	30
Total potassium	%	Monthly	0.5	0.9
Water soluble Potassium	mg/l	Monthly	650	1200
Water soluble Magnesium	mg/l	Monthly	10	30
Free carbonate	%	Monthly	1	5
Moisture content	%	Monthly	35	45
Bulk density	g/l	Monthly	450	550
Heavy metals
Lead	mg/kg	Monthly		<200
Nickel	mg/kg	Monthly		<50
Zinc	mg/kg	Monthly		<300
Copper	mg/kg	Monthly		<130
Arsenic	mg/kg	Monthly		<10
Cadmium	mg/kg	Monthly		<2
Mercury	mg/kg	Monthly		<2
Chromium	mg/kg	Monthly		<100
Water soluble Boron	mg/l	Monthly		<3
Water soluble Chloride	mg/l	Monthly		<850
Water soluble Sodium	mg/l	Monthly		<200
Other
Weed seeds		Quarterly		Absent
Plant pathogens		Quarterly		Absent
Herbicides		Quarterly		Absent
Fungicides		Quarterly		Absent
Insecticides		Quarterly		Absent
Salmonella spp		Monthly		Absent in 25 g
E. coli		Monthly		<1000 cfu/g
Impurities
Stones >2mm		Quarterly		Absent
Plastic, glass, metal >2mm		Quarterly		Absent

For more information please visit the APEX website.

Some composting is manufactured to be compostable. There is already a standard which compostable packaging must meet. The standard, EN 13432, was developed in the wake of the Packaging and Packaging Waste Directive and is recognised by EC countries. The standard ensures that the material is suitable for organic recovery. Currently AFOR is working in partnership with Din Certco, the German certification body, which is responsible for the assessment and certification of packaging that conforms to EN13432.

Materials that are certified compostable are permitted to carry the Seedling Logo, which was originally developed by and is owned by European Bioplastics. This ensures easy identification of compostable packaging. Products with the Seedling logo can only be composted commercially and not in the home.

AFOR is also working on incorporating the Seedling logo into a symbol which will denote packaging which can be composted at home.. A certification scheme for home compostable packaging is being developed.