How to know if a product is biodegradable? The biodegradability test

Currently, large quantities of plastics are generated. One of the solutions that industry has found is that they are biodegradable. The ‘usual’ plastic can take between 300 and 400 years to degrade, while biodegradable plastics take less than 6 years, which is a very relevant improvement. Today we explain all the secrets of these materials and how the biodegradability test is carried out.

What are biodegradable materials?

The term “biodegradable” is trendy, but is necessary that its meaning is well defined to be able to address eco-friendly strategies in industrial activity. A biodegradable material is one whose chemical composition allows its autonomous degradation through biological media, that is, through intrinsic processes of bacteria and other biological microorganisms. This implies that in the removal of these materials, an external contribution of chemical reagents or aggressive degradation conditions are not needed. In these materials, the metabolic processes of the microorganism are the ones that carry out the decomposition of the materials in a reasonably short period and under standard environmental conditions of light, temperature and humidity.

As we have indicated in the definition of biodegradable materials, the degree of biodegradability of a material is related to its chemical composition and its structure, which must allow that, over time, its compounds will be reduced to the elements that make it up and can come back to incorporate to natural processes present in the environment. Therefore, the grade of biodegradability will depend basically on the time that will take the biodegradable material to return to nature without causing any danger.

Types of biodegradability

How we have mentioned in the previous section, biodegradable materials decompose through biological processes of microorganisms under normal environmental conditions. However, there can be two types of biodegradability, depending on the conditions under which decomposition occurs:

• Aerobic biodegradability. This type of biodegradability is characterized mainly because microorganisms degrade biodegradable materials in the presence of oxygen. As a consequence, deterioration and breakage of the links of the internal structure of these materials occurs, mainly resulting in water and carbon dioxide, in addition to mineral products and biomass derived from elements of its chemical composition.
• Anaerobic biodegradability. Unlike aerobic biodegradation, this type of degradation differs because microorganisms decompose biodegradable materials in the absence of oxygen. Also, worth highlighting, that pH and temperature conditions from the residue have a great influence on the effectiveness and performance of the process. As sub-products of this process, mainly carbon dioxide and combustible gases are obtained, mostly methane. This type of biodegradation has become in a line of investigation with a lot of potential since it could lead to a future fuel source respectful of the environment.

Advantages of biodegradable materials

The main advantages of biodegradable materials are:

• Low environmental impact. Intrinsic characteristics of the incorporation of biodegradable materials into nature after their useful life is that they offer a sustainable solution to reduce the carbon footprint from an industrial process.
• Absence of waste generation. As the same name indicates, the main advantage of a biodegradable material is that does not accumulate any residue after use.
• Re-use. In addition, to be able to be reincorporated into nature and disappear, biodegradable materials can be re-manufactured with other compounds or serve as energy sources, introducing themselves as an environmental strategy with great potential for next future.

How can we evaluate if a product is biodegradable? Biodegradability test

The fact that a material can degrade through its biological processes of microorganisms, depends on the presence of these in the places where they are cast aside and stored. This means we will not find the same biodegradability conditions in a landfill as in the sea.

Due to the importance of this environmental problem, large international organizations have defined regulations that allow materials to be classified in terms of their biodegradability capacity through standardized biodegradability tests.

There are different norms related to biodegradable materials. As an initial point, it is important to highlight the european normative EN 16575, which defines that, a material is biodegradable when it can decompose through the action of microorganisms in the environment, giving rise to by-products that are not harmful to nature.

One of the most important defined legislation is the one done by the American Society for Testing and Materials (ASTM), specifically, the normative ASTM D-6954 establishes the patterns to define biodegradability tests of materials. This norm allows categorising materials according to their biodegradability when the residue of that material experiments the degradation process, and analysis of the compounds that can liberate to the environment, which is defined as its ecotoxicity. Ecotoxicity currently is legislated by the normative EN 13432, which is defined as the capacity of a material to liberate toxic substances and heavy metals to the environment in their degradation process.

Last but not least, some norms allow evaluation if a residue can be reused in processes such as composting, among which stand the norms ASTM, D6400, ISO 17088, EN 14995 and EN 13432. Among them, special attention is paid to the composition of residues to avoid the liberation of harmful substances for the environment such as heavy metals, the behaviour of the residue about the biological process of degradation and the quality of the final composting obtained.

ATRIA can help you to perform your compostability / biodegradability tests of your products and materials. Write to us to know more about these tests!