Biodegradable vs Compostable Plastics: How They Differ and What to Do with Them

Biodegradable vs compostable plastics: quick overview

The phrase biodegradable vs compostable plastics is common in consumer questions, but the two labels describe different processes and expectations. This guide explains the technical differences, real-world disposal options, standards to watch for, and practical steps to reduce contamination in recycling and composting systems.

Biodegradable vs compostable plastics: definitions and standards

Biodegradable is a general claim that a material can be broken down by microorganisms (bacteria, fungi) into natural substances such as water, carbon dioxide, and biomass. There is no single rate, environment, or residue requirement tied to that label unless a standard is cited.

Compostable means the material meets specific criteria for disintegration, biodegradation, and absence of ecotoxicity in a defined composting process. Industry-recognized standards include ASTM D6400 and EN 13432 for industrial composting, and some jurisdictions reference ISO 17088. These standards require that the material become part of usable compost within a set timeframe and leave no harmful residues.

Key distinctions

• Environment: Biodegradable may break down in soil, marine environments, or landfill—often slowly. Compostable is defined for composting systems (industrial or home).
• Timeframe: Compostable products must meet specified timelines (e.g., disintegration in 12 weeks under industrial conditions). Biodegradable has no universal timeline.
• Residues: Compostable materials must not leave toxic residues; biodegradable items might leave microplastics or additives behind unless certified.

Standards and certifications

Look for labels referencing ASTM D6400, EN 13432, or ISO 17088 for compostability. Some municipal programs accept only certified industrial compostable items because their systems achieve higher temperatures and mixing that home piles usually do not.

How disposal routes differ: recycling, home compost, industrial compost

Choosing the right disposal path prevents contamination and supports proper end-of-life processing. Recycling streams generally do not accept compostable or biodegradable plastics because they can contaminate mechanical recycling processes. Conversely, many industrial composting facilities accept certified compostable plastics but not all home compost setups do.

Home compostable plastic disposal

Home compostable items (labeled as home compostable or meeting specific home-compost standards) are formulated to break down at lower temperatures and with variable moisture. However, rates vary: some items like thin bioplastic films or compostable cutlery may still take months to fully disintegrate in small backyard bins.

Industrial composting vs home composting

Industrial composting facilities reach sustained high temperatures (55–70°C), controlled aeration, and long active phases that accelerate breakdown. Materials certified to industrial standards often will not fully compost in a backyard pile because of lower temperatures and less agitation.

COMPOST checklist: a decision framework

Use the COMPOST checklist to decide how to handle a plastic item:

• Certification — Is there a recognized compostability standard listed? (ASTM D6400, EN 13432, ISO)
• Outcome — Will it become non-toxic compost or likely leave residues?
• Method — Is industrial composting required, or is it home-compostable?
• Processing availability — Does a local municipal/industrial compost facility accept it?
• Open-labeling — Is the labeling specific and not just "biodegradable" without standard references?
• Sortability — Will it contaminate recycling if placed in curbside recycling bins?
• Timeframe — How long will it take in likely local conditions?

Real-world example

A coffee shop switches from conventional polystyrene lids to PLA lids labeled "compostable." The COMPOST checklist flags PLA lids as compostable but only under industrial conditions. Without access to an industrial composting collection program, those lids will likely contaminate recycling if placed in the blue bin and will persist in a backyard compost pile. The practical choice: collect PLA items separately and route them to a covered composting program or choose non-plastic reusable options.

Practical tips for consumers and facilities

• Confirm local acceptance: Check municipal composting rules before tossing items into curbside organics—rules vary by city and facility.
• Read labels for standards: Prefer products that reference ASTM D6400, EN 13432, or ISO 17088 if industrial composting is available.
• Avoid mixing streams: Do not place compostable plastics in curbside recycling, and avoid putting conventional plastics in organics bins.
• Reduce at source: Favor reusable containers and reduced packaging whenever feasible to avoid the disposal dilemma.

Common mistakes and trade-offs

Common mistakes include assuming "biodegradable" equals safe to home-compost or that all compostable items will vanish quickly. Trade-offs involve convenience versus certainty: compostable plastics can reduce landfill persistence when processed correctly, but require compatible collection and processing infrastructure. Choosing compostable options without local industrial compost access can increase contamination and processing costs.

Core cluster questions

1. What does compostable plastic mean compared to biodegradable plastic?
2. Can compostable plastics go in curbside recycling?
3. How does industrial composting differ from backyard composting for plastics?
4. Which standards certify a plastic as compostable?
5. How to identify home compostable products versus industrial-only compostable items?

For local guidance on home composting practices and what materials are suitable for backyard composting, consult municipal resources or authoritative guidance such as the U.S. Environmental Protection Agency's composting overview (EPA: Home Composting).

When to choose biodegradable, compostable, or neither

Choose compostable when the product is certified and a compatible industrial composting program is accessible. Choose biodegradable cautiously and only when the claim cites an environment and timeframe. Often the best choice is to avoid single-use plastic alternatives altogether by opting for reusable or repairable products.

FAQ

What is the difference between biodegradable vs compostable plastics?

Biodegradable indicates that microorganisms can break down the material in some environment over time. Compostable indicates the material meets specific criteria to break down in a composting process within a set timeframe and leave non-toxic residues. Compostable is a stricter, standards-backed claim.

Are compostable plastics recyclable?

Typically not in mechanical recycling streams. Compostable plastics can contaminate recycling unless a facility specifically accepts them for chemical recycling or a dedicated composting program exists. Always follow local guidance.

Can compostable plastics break down in a backyard compost bin?

Some items labeled "home compostable" are designed for lower-temperature backyard systems, but many certified compostable plastics require industrial composting conditions and will not fully break down at home.

How should consumers verify compostability claims?

Look for references to recognized standards (ASTM D6400, EN 13432, ISO 17088) and check whether local collection and industrial composting facilities accept those materials.

What happens if compostable plastics end up in landfill?

Landfills are typically anaerobic and cold, so compostable plastics may not break down quickly and could produce methane if conditions allow. Proper routing to composting systems is important to realize environmental benefits.