What is biodegradable and what is compostable? Differences? Degradation time? We tell you.

Products labeled biodegradable, products labeled compostable, and confused consumers with both labels. By the way, aren’t biodegradable and compostable the same thing? why are these terms confused?

Every day users have a greater tendency to look for more sustainable and environmentally friendly products, so it is not strange to find on the shelves of shops they are filled with products labeled << Two concepts that mislead since they have been used erroneously over time as synonyms. Have you ever wondered how they are different? Is a biodegradable product and/or material the same as a compostable one? We see it as essential to be able to differentiate both concepts, so as you can imagine, no, they are not two equal terms. correlated? Yes, but they do not mean the same thing. We anticipate that compostable products are always biodegradable while a product is biodegradable it does not have to be compostable. Read on to find out.

There are several definitions of the biodegradability or biodegradation concept, so we must be clear about what we mean in each case. In general, the biodegradation process can be defined as the transformation of one or more substances into new simpler compounds through biochemical reactions thanks to the action of microorganisms.

In our case we will focus on the biodegradation or biodegradability of plastics. The European Bioplastics Commission defines that: “Biodegradability or biodegradation is a chemical process in which materials are metabolized into carbon dioxide, water and biomass with the help of microorganisms. The biodegradation process is influenced by environmental conditions and by the material itself”.

Thus, biodegradation is just one of many chemical processes that are part of the natural cycle of life on earth.

In nature, each organic waste has its biodegradation time: straw and wood take longer than cellulose and starch, likewise, in cold and dry environments the process is slower than in warm and humid environments.

One of the questions most sought after by users in relation to this topic is based on the biodegradation time, since after all this is the most important question to take into account, especially when we think about the plastics commonly used.

Each material, product or element has a unique composition, so the degradation time of each one is different, to this we must add the necessary conditions for this biological process to develop. It is evident that there are currently methods to estimate this biodegradation time in the environment, but it should be noted that they will always be estimated data.

These results are obtained through tests carried out in laboratories where the conditions to which a product, material or compound can be subjected for a number of days are simulated. With these tests, relative information is obtained on biodegradation times, and estimates of behavior under simulated conditions and not 100% real, since in nature the variables always end up being more random.

To get an idea of ​​the times it can take for some of the most common elements to biodegrade, the following illustration shows some approximations of the biodegradability time of various elements in a terrestrial environment.

Compostability is a characteristic of a material, product, packaging or component that allows biodegradation under specific controlled composting conditions.

The composting process allows the return of organic matter to the soil and its reintegration into natural cycles by imitating the transformation of organic matter in nature (under aerobic and controlled conditions), allowing materials to be homogenized, sanitized and reduced mass and volume.

Specifically, this process can be defined as a successive action of various aerobic microorganisms on the starting organic matter, resulting in high temperatures, a reduction in the volume and weight of the organic matter or residue, as well as its humification and darkening.

To ensure a correct proliferation of microorganisms, the process conditions must be well controlled and fixed, to achieve adequate mineralization of organic matter.

In composting systems there are two variables that affect the process, we can classify them into two types of parameters:

Monitoring parameters: temperature, humidity, pH, aeration and free air space.
Parameters related to the nature of the substrate: molecular weight of the material, grain or particle size, C/N and C/P ratio, nutrients, organic matter and electrical conductivity.3

To achieve compostability, there are a set of variables that must be given in certain ways in order to ensure that the composting process is carried out successfully.

1. Temperature

Temperature is one of the key factors during the organic matter composting process.

It conditions the microbial activity and the type of microorganism that acts on the organic matter. Therefore, to guarantee that this process generates CO2, water, compost and nutrients for microorganisms and does not generate pathogens, an exhaustive temperature control is necessary during the decomposition of the material.

2. Humidity

Humidity is fundamental for the physiological needs of the microorganisms that participate in the biological process of organic matter decomposition. A humidity below 30% decreases the biological activity, determining that the optimum is between 50-70%.

3.PH

The pH acts on the dynamics of microbial processes. It is a factor that varies throughout the process: a drop in pH levels during the first stages until reaching stability or neutrality in the final stage.

4. Aeration

The amount of oxygen affects the efficiency of composting since the microorganisms involved in it are aerobic. Industrial composting plants have variable percentages of oxygen. A lack of oxygen can cause a delay in decomposition.

5. Free air space

It is necessary that there is a space between particles that allows water and oxygen to circulate, two key elements for the decomposition of organic matter to take place.

The degradation of materials can occur through two types of composting, one that the user himself can carry out in his own home (it is not feasible for all materials) and another type based on industrial composting.

Industrial composting consists of the aerobic biological decomposition and stabilization of organic substrates, under controlled conditions, resulting in the generation of CO2, biomass/compost water and energy (Figure 1).

This decomposition takes place mainly in two phases:

1st Phase: The polymeric chains are shortened, thus producing increasingly simpler compounds with lower molecular weight.
2nd Phase: the waste continues to decompose, but through mostly biological processes (macroorganisms).
The action of the microorganisms in the second phase is essential because they are responsible for completing the degradation of the materials, transforming the organic carbon into CO2, water, biomass, energy and organic matter that is later used by the microorganisms to promote their tissues. or as nutrients.

Both concepts entail a degradation process, however, through composting the process is accelerated due to the creation of controlled conditions that underlie an acceleration of material decomposition.

For what a product is compostable tells us that (under controlled conditions) it is easier to be processed to re-introduce these materials into the environment in the form of organic matter.