What is the Difference Between Biodegradable, Compostable and OXO Biodegradable?

Etymologically Speaking

What is Compostability?

The word “compost” first appeared as a French word in the 13th century and means “mixture of leaves, manure, etc., for fertilizing land“.

The word “compost” is etymologically related to the French word “compote” (14th century) and refers to “stewed fruits, fruit preserved in syrup”. The etymological root of the french words “compost” and “compote” goes back to the Latin word “composita” which means “placed together“.

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The term “decomposition” dates back from 1762 and means “act or process of separating the constituent elements of a compound body“. In ‘decomposition’, we recognise 3 words: “de” (the opposite of), “com” (together, with) and “position” (to place).

“Compost” is initially linked to “manure” and “fertilizing land“. The etymological root of “manure” is related to the Latin word “manuoperare” and French word “manovrer ” meaning “to work with the hands, cultivate, carry out, make, produce”.

What is Biodegradability?

The word “bio-degradable” dates back from 1962 and means “susceptible to decomposition by living organisms” (especially bacteria) and consists of 3 words “bio“, “degrade” and “able“.

“Bio” refers to life or biology and its etymological root lies in the Greek word “bios” meaning “one’s life, course or way of living, lifetime“. The opposite of “bios” is “zoe” which means “animal life, organic life“. In other words, the opposite of “biology” is “zoology”. However, since 19th Century modern science “bio” has been extended to mean “organic life, plant life” while “zoo” is restricted in modern use to “animal life”.

Bio may also refer to “biota“. Bacteria and fungi are sometimes referred to as flora, as in the term gut flora. Fauna and Flora are collectively referred to as Biota (life).

“Degrade” is related to the 12th century French word “degrader“, which means to “deprive of office, dignity, or honors; reduce from a higher to a lower rank”. In that sense, we could understand the process that converts a polymer to a monomer as a degradation.

Chemically Speaking

What is Compostability?

Decomposition happens when micro-organisms break down organic matter into compost through a process called composting. Composting requires human management.

The micro-organisms involved in decomposition are: bacteria, actinobacteria, fungi, protozoa and rotifers. These organisms require 4 ingredients: carbon, nitrogen, oxygen and water.

Compost is rich in nutrients and is used in gardening and organic farming. The advantages of compost is that it can be used as a soil conditioner, fertilizer and natural pesticide for soil.

Degradation of materials by microorganisms when oxygen is present is called aerobic digestion, and the degradation of materials when oxygen is not present is called anaerobic digestion. Anaerobic reactions produce methane, while aerobic reactions don’t. Both reactions produce carbon dioxide and water.

We differentiate between home and commercial (industrial) composting. In the case of home composting, aerobic composting usually takes place aboveground while anaerobic composting happens underground.

What is Biodegradability?

Biodegradation happens when organic matter is broken down by microorganisms, such as bacteria, fungi. The process of biodegradation can be divided into three stages:

Biodeterioration is a surface-level degradation that modifies the mechanical, physical, and chemical properties of the material
Biofragmentation of a polymer is the lytic process in which bonds within a polymer are cleaved, generating oligomers and monomers in its place.
The resulting products from biofragmentation are then integrated into microbial cells, this is the assimilation stage

Legally Speaking

The executive branch (Government) usually propose a draft law to the legislative branch (Parliament) who will amend and vote on it. After adoption by parliament, the legislative proposal becomes law. We usually find definitions, rules and requirements in laws. The rules and technical requirements set into the law can be moulded into a standard.

The notion of ‘claim’ is important. A claim is when a producer pretends that his product or packaging has a specific attribute such as compostability or biodegradability. Third parties and independent laboratories will test the product or packaging to see whether it meets the technical requirements set in the law and /or standard and give a ‘certification’ to the producer.

This certification usually enables the producer to make a claim and/or use a label that was conceived by or with consent of that third party lab. Labels enable producers to officialise and publicise their claim and to share info with the consumer to create some kind of trust or added value. Both elements are valuable marketing attributes.

Here is the “Seedling-label” accepted in Belgium, Switzerland, Germany, The Netherlands, Poland and United Kingdom.

Compostability Claims

There are two possible “compostability claims”: commercial and home compostability. Home compostability is made at home while commercial compostability is done by an industrial facility. A certification is needed for each of these claims.

Legally speaking, you need to have a label or certification to claim commercial and/or home compostability.

Practically speaking, you need (1) separate sorting & collection, local commercial compost facilities and a usage for the compost to make commercial composting work; and (2) a compost bin (aboveground composting) and/or garden (underground composting) to make home composting possible. These practical requirements are the fine line in the sand that distinguish between compostability (ability to compost) and the actual composting.

Commercial Compostable Certifications

AS 4736 (Australian Standard – read more)
EN 13432 : this European Norm/Standard for compostability of packaging is linked to the European Directive on Packaging and Packaging Waste 94/62/EC). This certification certifies that the plastic and all other components of the product are commercially compostable (colours, labels, glues and – in case of packaging products – residues of the content).
EN 14995 (European Standard for compostability of plastics linked to the European Directive on Packaging and Packaging Waste 94/62/EC). Please note that EN 13432 applies when the plastic is used for packaging purposes.
ASTM D 6400 or 6868 (American Society for Testing and Materials) Standard Specification for Labeling of Plastics Designed to be Aerobically Composted in Municipal or Industrial Facilities. This specification covers plastics and products made from plastics that are designed to be composted in municipal and industrial aerobic composting facilities).

Home Compostable Certification

There is currently no international or European standard for home composting. However, there are national regulations, standards and certifications.

UNI 11183 (Italy)
AS 5810 (Australian)
NT T 51-800 (France)
OK Compost (Belgium)

Biodegradability Claims

Producer claim that his product or packaging is biodegradable. Here are the following options:

Biodegradable in compost (the claim should be home or commercial compostable (see above))
Biodegradable in soil (EN 17033 or OK Biodegradable Soil Label for Mulch Covers)
Biodegradable in water (No reliable standard exist)
Biodegradable in sea water (No reliable standard exist)
Biodegradable in space (No data and no standard exist)

The Difference between Biodegradation vs Composting

Etymologically speaking

According to Wikipedia, there is no universal definition for “biodegradation” and there are various definitions of “composting”.

The word “composting” is much older than the word “biodegradable”, and has thus more historical weight. On the other hand, people become more scientifically aware over time and new words such as “biodegradable” may have been an upgrade or sophistication compared to the word “compostable”.

Originally, compostability referred to the ability to initiate a process that lead to the creation of compost, while biodegradability referred to the ability to degrade through a biological process.

Chemically Speaking

The difference between the two is that bio-degradation is a naturally-occurring process while composting is human-driven. Composting is an accelerated biodegradation process due to optimized circumstances. Technically speaking, it is probably correct to say that the material/packaging biodegrades during the composting process. Composting includes human management, while biodegradation does not exclude it.

Methane is created during anaerobic composting. It is 26 times more potent than carbon dioxide as a greenhouse gas and is a significant contributor to global greenhouse gas emissions. The aerobic process of composting does not produce methane because methane-producing microbes are not active in the presence of oxygen.

The chances are higher that in the case of bio-degradation without human intervention, we’re dealing with an aerobic process and thus no production of methane.

Legally Speaking

Both words are often used as synonyms but do not mean exactly the same. The term “composting” is often used to describe the biodegradation of packaging materials; and vice versa.

However, legal definitions exist for compostability. Four criteria are offered by the EU in EN 13432 to define “compostability”. In other words, plastic packaging must fulfil following rules to be accepted for industrial composting.

Disintegration (fragmentation) and loss of visibility in the final compost. After 3 months, the mass of residues has to be less than 10% of the original mass.
Biodegradability, the capability of the compostable material to be converted into CO2 under the action of microorganisms (90% biodegradation must be reached within 6 months).
Absence of negative effects on the composting process.
Amount of heavy metals has to be below given maximum values, and the final compost must not be affected negatively.

Basically, the legislation defines under what conditions, at what speed and what the composition of the compost must be.

What is the difference between Oxo-Degradable and Oxo-Biodegradable?

Oxo-degradation” is defined by CEN (the European Standards authority) as “degradation resulting from oxidative cleavage of macromolecules.” This describes ordinary plastics, which abiotically degrade in the open environment and form microplastics, but do not become biodegradable except over a very long period of time.

By contrast, “oxo-biodegradation is defined by CEN as “degradation resulting from oxidative and cell-mediated phenomena, either simultaneously or successively” These plastics convert by oxidation into biodegradable materials over a much shorter timescale.

CONCLUSION

Etymologically speaking, compostability refers to the end use of the residue (compost to fertilise land) and chemically speaking the process should be initiated by humans.
Biodegradability puts the focus on the process of biological degradation, but the residue doesn’t have to be used for compost and the process doesn’t have to be controlled by humans. However, on the last point it is interesting to note that these plastics are designed to be “biodegradable”: biodegradable additives are added to the plastics to attract and allow microorganisms to degrade the polymers. Technically speaking, one may argue that this counts as human involvement.
There’s a difference between the ability to decompose (compostability) or biodegrade (biodegradability); and the actual composting or biodegradation.
There’s a difference between real life conditions and test lab conditions. There was an article published on this recently (The Biodegradable Label Just Received a Huge Blow)

CLOSING REMARKS

Is the current legal environment aligned to the etymological and chemical reality, and to consumer habits?
Are there enough local commercial composting facilities to make it work?
Is separate sorting, collection and composting necessary for compostable plastics / polymers or can it be mixed with other organic waste?
Are mentalities changing? Will future generations look at waste management in a different way ?
To what extend are economic interests playing a role in the legal definitions and legislative decision-making process?
Is it in our interest to have compostable and biodegradable plastics? Are governments and industry doing enough to make it work?
We have gradually created laws and given rights to protect the fauna and flora. Shall we do the same with micro-organisms one day? To what extend are micro-organisms affected by biodegradable additives? Does it impact the PH grade of the local fauna and flora for instance?
The press release of the European Council of 22/05/2018 says that “Member states will ensure that by 31 December 2023, bio-waste is either collected separately or recycled at source (e. g. home composting). This is in addition to the separate collection which already exists for paper and cardboard, glass, metals and plastic.” The Council defines home composting as “recycling at source”. Is this etymologically and chemically correct?

REFS