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Compostable vs Biodegradable: What Is the Difference?

The main difference between compostable and biodegradable materials is how, where, and how quickly they break down. Biodegradable materials can be decomposed by microorganisms under suitable conditions, but the term may not specify a timeframe or disposal method. Compostable materials must biodegrade under defined composting conditions without leaving harmful residues. Therefore, all compostable materials are biodegradable, but not all biodegradable materials are compostable.

Biodegradable materials

Biodegradable materials can be broken down by microorganisms into water, gases, minerals, and biomass. The process depends on temperature, moisture, oxygen, material thickness, and the surrounding environment. A credible claim should specify where and how quickly the product is expected to break down.

Compostable materials

Compostable materials biodegrade under controlled composting conditions without leaving harmful residues. They require suitable moisture, oxygen, heat, microorganisms, and processing time. Certified products must meet defined requirements for biodegradation, disintegration, and finished compost quality.

Compostable vs Biodegradable: Key Differences

Although both materials can break down naturally, their required conditions, timeframes, and disposal methods are different. The main differences include:

Meaning:

Biodegradable materials can be broken down by microorganisms, while compostable materials must decompose under defined composting conditions.

Breakdown time:

Biodegradable claims may not specify a timeframe, while compostable materials must meet recognised time requirements.

Residues:

Certified compostable materials should not leave harmful residues or reduce compost quality.

Disposal:

Compostable products require an accepted composting stream, while biodegradable products should follow their specific disposal instructions.

Environmental impact of compostable and biodegradable materials

Their environmental impact depends on production, use, collection, and disposal methods.

Waste reduction: Proper processing may reduce long-term plastic waste.
Organic recovery: Compostable products can support suitable composting systems.
Incorrect disposal: Landfills may not provide the conditions needed for decomposition.
Waste contamination: Incorrect sorting can disrupt recycling or composting streams.
Overall impact: Benefits depend on materials, production, transport, and local infrastructure.

Common Compostable and Biodegradable Materials

Manufacturers can choose from several material families depending on performance, processing, and end-of-life requirements.

Polylactic acid

Polylactic acid, or PLA, is commonly made from renewable resources such as corn starch or sugarcane. Its clarity and rigidity suit cups, food containers, trays, cutlery, and 3D-printing filament. Many PLA products require industrial composting conditions.

Polyhydroxyalkanoates

Polyhydroxyalkanoates, known as PHAs, are produced through microbial fermentation. Different formulations can provide varying flexibility, strength, and biodegradation behaviour. Suitability for compost, soil, or aquatic environments must be confirmed for the specific material.

PBAT

Polybutylene adipate terephthalate, or PBAT, is a flexible biodegradable polymer. It is commonly blended with PLA or starch to improve the toughness of compostable films, bags, and packaging. Although PBAT is generally fossil-derived, suitable formulations can meet compostability requirements.

PBS and BioPBS

Polybutylene succinate, or PBS, provides mechanical strength, flexibility, and heat resistance. BioPBS uses renewable feedstock for part of its production. These materials can be used in packaging, tableware, and agricultural applications.

Starch-based compounds

Starch-based compounds are commonly used for bags, films, loose-fill packaging, and disposable products. However, the presence of starch alone does not confirm compostability. The complete formulation and finished product should be tested.

Compostability Standards and Certifications

Recognised standards help businesses verify whether materials meet specific compostability requirements.

ISO 17088:2021 covers the identification and labelling of plastics suitable for recovery through aerobic composting. ASTM D6400 applies to plastics designed for municipal or industrial composting facilities. EN 13432 is another recognised standard for compostable packaging.

Testing commonly examines:

Biodegradation under controlled conditions
Physical disintegration during composting
Limits for regulated substances
Effects on finished compost quality

Businesses should request certification or test documentation instead of relying on descriptions such as “green” or “environmentally friendly.” Certification should ideally cover the finished product because inks, adhesives, coatings, and additives may affect compostability.

Choosing a Material That Matches Its End of Life

The compostable vs biodegradable distinction is mainly about evidence and disposal conditions. Biodegradable materials can be broken down by microorganisms, while compostable materials must satisfy more specific requirements for timing, disintegration, residues, and compost quality.

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Whether a business requires dependable materials, advanced manufacturing solutions, or long-term sourcing assistance, Okaya can help identify options suited to specific operational goals. Discover more about Okaya and explore how its global capabilities can support sustainable business growth.

Frequently Asked Questions

1. Is compostable the same as biodegradable?

No, as compostable materials are biodegradable, but they must break down under defined composting conditions and meet requirements for timing, disintegration, and compost quality. Biodegradable is a broader term that may not specify these conditions.

2. Can biodegradable plastic go into a compost bin?

Biodegradable plastic does not necessarily go into a compost bin. Only place it in a compost bin when the product is specifically certified for the relevant home or industrial composting environment.

3. Can compostable packaging go into a recycling bin?

Generally, compostable plastic packaging should not be mixed with conventional plastic recycling unless the local waste provider specifically accepts it. It may contaminate established recycling streams.

4. How can businesses verify a compostable material?

Check for certification against a recognised standard, review supporting test documentation, identify whether it is home or industrially compostable, and confirm that the intended waste facility accepts it.

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