is the ability of substances and materials to be transformed, through the action of microorganisms present in the environment, in humus, water and carbon dioxide.
is the capacity of an organic material to be transformed into compost through the composting process. This process exploits the biodegradability of the initial organic materials to transform them into a finished product called compost. Compost is therefore the result of disintegration and aerobic biodegradation of organic material, such as the wet portion of domestic waste.
is an accelerated process of biological treatment of organic waste (kitchen waste, food scraps, grass clippings, twigs, etc.) that occurs in composting systems, where natural biodegradation processes are optimised through the introduction of high temperatures and the optimum ventilation and humidity.
, suitably mixed with grass cuttings and twigs, biodegrades in the presence of air and organic substances, producing carbon dioxide, and transforming into water, compost and heat.
The mature compost is used as fertiliser in agriculture and contributes to the maintenance of soil fertility.
The terms biodegradable/biodegradability
do not define the time nor the place, nor the rate of biodegradation of a material.
The word compostable
, when referring to a product (packaging or a product such as a plastic film), means that this item can be recovered by organic recycling, which includes industrial composting and anaerobic digestion.
The European standard
which defines organic packaging recycling in Italy is UNI EN 13432. UNI EN 14995 defines compostable plastic products, not used as packaging. For both standards, a product is defined as compostable when it meets the following four criteria
a) it must be biodegradable (> 90% compared with cellulose) in a composting process (180 days);
b) it must disintegrate in a treatment cycle (90 days);
c) it should not have toxic effects on the compost produced
d) it must not affect the composting process.
Specific logos exist which identify compostable items, issued by independent bodies, based on parameters set out by the European standards EN 13432 and EN 14995. These logos must be printed on the end product.
Standard EN 13432
, approved unanimously by CEN members was then supported by the European Commission. In fact, EN 13432 is a harmonised standard, which is mentioned in the Official Journal of the European Communities as a reference standard for the European Directive on Packaging and Packaging Waste (94/62/EC). As such, it provides presumption of conformity with the essential requirements for packaging regarding "recoverability in the form of compost" and "biodegradable packaging" according to the European Directive and, at an Italian level, with Legislative Decree no.152 of 3 April 2006, "Environmental Regulations".
- Specifications for Compostable Plastics The ISO (International Organisation for Standardisation), the world's biggest standardisation body, has developed a standard which specifies the procedures and requirements for the identification and marking of plastics and plastic products that are suitable for recovery by aerobic composting.
Similarly to UNI EN 13432, this standard addresses four aspects a) biodegradation; b) disintegration during composting; c) adverse effects on the composting process; d) adverse effects on the quality of the compost produced, including the presence of metals and other restricted or dangerous compounds. It should be noted that the standard explicitly mentions the European Packaging Directive for European applications: “The labelling will, in addition, have to conform to all international, regional, national or local regulations (e.g. European Directive 94/62/EC)”.
- Standard Specification for Compostable Plastics ASTM International is a well-known standardisation body, especially in America. The ASTM D 6400 standard is important historically because it was the first standard to specify the requirements for plastics and plastic-made products to be composted in aerobic composting facilities at municipal and industrial level. The standard determines whether the plastics concerned compost satisfactorily and if they biodegrade at a rate comparable with that of known compostable materials. The test approach of ASTM D6400 is similar to that of EN 13432. The only significant differences are the following: The biodegradation limit, which is otherwise fixed at 90%, is reduced to 60% for homopolymers and for copolymers with random monomer distribution. The duration of the biodegradation test, which is set at 180 days, is extended to 365 days if the trial is conducted with radioactive material, measuring the evolution of radioactive CO2.
UNI EN 14995
Plastics - Evaluation of compostability - Test scheme and specifications This standard was published by the UNI in 2007, assimilating the corresponding European standards. It is not an alternative to UNI EN 13432. In fact, UNI EN 13432 specifies the characteristics of packaging that can be recycled through organic recovery (composting and anaerobic digestion). UNI EN 13432 therefore includes both plastic and lignocellulosic material packaging, but excludes non-compostable plastics used as packaging. For example: compostable cutlery, plastics used in agriculture for compost, compostable bags for waste collection. UNI EN 14995 has filled this gap. From a technical point of view, UNI EN 14995 reflects the content of UNI EN 13432. This means that a plastic material that conforms to UNI EN 13432 also complies with UNI EN 14995, and vice versa.