Compostable plastics can leave up to 10% residuals after 85 days of the composting process.

In order to be certified compostable in Canada, the product must, among other criteria, disintegrate by at least 90% within 84 days (almost 3 months!) of the composting process, which can imply up to 10% of residuals.

Compostability CertificationThere are several brands of certification of compostable products, especially for plastic bags. Certifications have guarantee limitations however:

  • Plastic can be certified compostable under typical composting conditions reproduced in laboratory, but in practice the composting technologies and conditions may vary (e.g. meteorological conditions).
    • The Marks of Conformity provide compost facility operators a guarantee that the certified products will biologically degrade in accordance with the specified criteria, without negatively impacting the compost produced. However, it does not guarantee that the material is suitable for composting at a specific facility (Canadian Council of Ministers of the Environment (CCME), 2010).
    • Whether compostable products, certified or not, are accepted at a compost facility will mostly depend on the facility’s operating equipment
  • Biodegradation is not identical to both anaerobic (composting) and anaerobic (biomethanation) conditions due to a number of factors (temperature, micro-organisms, humidity, etc.).  However, there is currently no specific certification for the disintegration and biodegradation of compostable plastic products in anaerobic conditions (biomethanation).
    • The European standards (EN 13432 and EN14995) mention some procedures for determining the feasibility of processing compostable plastics in anaerobic conditions, but they are optional.
    • The methods for determining the biodegradability and disintegration of compostable plastics in Canada’s national standard (CAN/BNQ 0017-088) do not include analyses in anaerobic conditions; a product’s compostability is tested solely in aerobic composting conditions.

Compostability certification for paper bags

  • A certification is not a legal obligation. It is a voluntary registration; a product can meet a standard without necessarily obtaining the certification associated with it.
  • The Paper & Paperboard Packaging Environmental Council states that certification for paper materials should remain an option not a requirement (PPEC, 2011. Factsheet 22f).


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