what is the difference between degradable, biodegradable and compostable?

We have been thinking about this post for a while because we consider that it’s very important to  differentiate between biodegradable, compostable and degradable. 

Biodegradable

It is a characteristic of a material that, by biological action changes, thus losing its original properties. At the chemical level, it means that the molecules become simpler and more stable.

In addition, it is a “simplification” of the material through organisms such as plants, animals, microorganisms and fungi as well as under natural environmental conditions. However, this degradation will depend on the complexity of the substance, temperature, medium… Finally, it is important to highlight that the result of this process will vary if is carried out in the presence or absence of oxygen.

Organic waste in landfills will biodegrade to methane

Biodegradation can also carried in an industrial terms, such as the production of biogas. This will require certain conditions of temperature, anaerobiosis and specific microorganisms to produce the methane gas.

Compostable

This means to a material that by biological action allows the conversion and valorization of organic matter in a product rich in humic compounds, always in the presence of oxygen. Compost has an earthy appearance, free of odors and pathogens, which is also used as a basic fertilizer and as a partial or total substitute for chemical fertilizers.

There are different ways to compost depending on the technology:

Domestic composting

It does not usually exceed 40 degrees and depends a lot on humidity and climate. It usually takes more time to produce the compost.

Composting allow us to reduce our footprint

 

Industrial composting

It is a technified process where a controlled medium with high temperatures and humidity is used.

So far, I would like to highlight the following:

Everything compostable is biodegradable but not all biodegradable is compostable.

Biodegradation can be carried out with or without oxygen, meanwhile, compost need oxygen. 

Degradable

Now, this term is misleading. We already wrote about it the other day in bioplastics. If we refer to plastic materials, such as those made of polyethylene PE and chemical additives, then we are meaning degradation as the process that occurs in the presence of oxygen, under the effect of heat and UV. When plastics lose mechanical strength, they fragment and disappear visually, forming microplastics.

Plastic trash in the forest will get degraded to microplastics

So, what does all this mean?

In the case of degradable products, such those made of plastic, they can be degraded and after a while we will stop seeing them but, that doesn’t mean that they have been incorporated into a biological cycle. They simply degraded into microscopic pieces that nature can’t use so far:  microplastics.

But when we refer to composting vs. biodegrade there are many more aspects involved. For example, let’s talk about a piece of fruit that ends up in a landfill. This piece of fruit can biodegrade due to the presence of living beings, but in two different ways:

  1. If it remains on the surface, the fruit is exposed to animals, fungi and microorganisms, being metabolized by them and producing CO2, a process similar to composting.
  2. If it is buried under a large mass of material, the oxygen does not reach that layer, the only thing that can degrade it are anaerobic microorganisms, being metabolized to CH4 (methane), which is much more harmful if it is done without control. However, this process can be carried out industrially to obtain biogas, as we have already mentioned.

Finally, if that same piece of fruit is composted, either domestically or industrially, we know that it will be biodegraded by an aerobic metabolism (with oxygen) in a controlled manner and more quickly, left as a CO2 product and compost which can be used as fertilizer for agriculture.

Conclusions

With all this, we want to emphasize several aspects:

  1. Degraded does not mean that it disappears or that any organism uses it, but that we cannot see the “pieces” anymore.
  2. The fact that something is biodegradable, only means that depending on the conditions certain and specific it will be either transformed to CO2 or methane.
  3. The same material, such as an apple, can have a much higher impact if it ends up in the least indicated place (landfills). Our actions matter and to separate and use the organic waste well can lead to a big difference.

This flower is both biodegradable and compostable, depending on the oxygen, temperature and place to be discarded

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