What is the difference between ‘biodegradable’ and ‘compostable’?

Category: Innovation and trends in bioplastics

Today there is a wide range of biodegradable and/or compostable products. These terms, so often used nowadays, can lead to confusion, so it is necessary to look at each definition in more detail.

What is a biodegradable product?

Biodegradable products can be degraded by the action of microorganisms existing naturally in the environment such as bacteria, fungi, and algae. To determine if a product is biodegradable, it is first necessary to define the environment of this biodegradation. It is understood that any product is biodegradable in compost under aerobic conditions when it can be broken down by the action of microorganisms in the presence of oxygen to turn into carbon dioxide, water, mineral salts, and new biomass. In addition, 90 % of biodegradation must be achieved within 180 days or less at a temperature of 58°C ± 2°C.

Given that, some standards determine that a product is biodegradable, such as ISO, EN, or ASTM. In Spain, the most common is the UNE-EN ISO 14855 standard on biodegradation under composting conditions and the UNE-EN ISO 17556 standard on biodegradability in the soil at 25ºC and up to two years, and the UNE-EN ISO 14852 standard on the laboratory conditions for biodegradability in an aqueous medium at 20-25ºC with a duration of six months, which can be extended.

To affirm that a product is biodegradable, it must pass the laboratory study of biodegradation in the corresponding medium under the standards mentioned above.

What is a compostable product?

Compostable products can break down biologically forming compost, producing carbon dioxide, water, inorganic compounds, and biomass in its decomposition. It does not generate toxic waste and cannot be visually distinguished, in other words, we obtain a compost of good quality.

To claim that a product is compostable, it must pass all the laboratory studies included in the UNE-EN ISO 13432 standard, which defined the general scheme of tests for packaging:

So, with these definitions, we can claim that compostable products are biodegradable, but not all biodegradable products are necessarily compostable, as long as this process takes place in the appropriate means provided by the standards mentioned above.

Compostability certifications

Also, it is important to mention that biodegradable and/or compostable products are not designed to be abandoned or dumped on the ground in the city, in the countryside, in the environment, in watercourses such as rivers and lakes or even in the sea. Under these conditions, it is not possible to ensure biodegradation since it is only guaranteed under controlled compost conditions and, therefore, in a different environment the performance of these materials is lost.

AIMPLAS has been recognized by TÜV AUSTRIA, the certification body, to carry out the tests required by the standard and thus provides your company with the necessary tools to certify your product as compostable. In addition, pilot disintegration and ecotoxicity tests in higher plants have been accredited through ENAC, thus extending the scope of their accreditation to include more compostability schemes according to UNE-EN 13432, UNE-EN 14995, ISO 18606, ISO 17088 and ASTM D6400.

Biodegradability certifications

Regarding biodegradable products, there are biodegradability certificates in other environments such as biodegradability in soil, especially for products to be used in agriculture, and biodegradability in freshwater and marine environments. However, this does not mean that these products should consciously end up in these mediums. We must collaborate responsibly for the system to work and be effective.

At AIMPLAS, we provide your company with the necessary tools to certify your product. Contact us.

Josep García Severí · Biodegradation & Compostability Laboratory. AIMPLAS

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