Compostable vs biodegradable vs bioplastic: what the labels mean at home

Walk through any supermarket and you will see bags, cutlery and cups labelled biodegradable, compostable or plant-based. They sound similar. They are not, and choosing the wrong one, or putting it in the wrong bin, can cancel out any benefit.

Bioplastic

Bioplastic is a broad term. It can mean plastic made from plants (bio-based), plastic that biodegrades, or both. A bio-based plastic like plant-based PET is chemically identical to ordinary PET: it is made from sugarcane rather than oil, but it does not break down any faster. Other bioplastics, such as PLA made from corn or sugarcane starch, are designed to compost under specific conditions.

Biodegradable

Biodegradable simply means that micro-organisms can eventually break a material down. The word says nothing about how long that takes or under what conditions. Almost anything biodegrades eventually, so on its own the word is close to meaningless. Some products labelled biodegradable are ordinary plastics with additives that make them fragment into microplastics.

Compostable

Compostable is the most useful label, because it is tied to standards. A certified compostable product breaks down into compost within a set time under specified conditions. There are two main kinds:

• Industrially compostable: needs the high heat of an industrial composting facility; it will not break down properly in a home compost bin
• Home compostable: breaks down in a well-managed home compost at lower temperatures

In India, compostable plastics must be certified to the relevant BIS standard and carry a certification mark. Look for the certification, not just the word.

Where they should go

• Industrially compostable items: wet waste only if your city sends wet waste to an industrial composting plant; otherwise they usually end up in landfill
• Home compostable items: your home or building compost
• Bio-based but not compostable plastics: dry waste, like ordinary plastic
• 'Biodegradable' with no certification: treat as ordinary plastic

The catch

Compostable plastics can contaminate plastic recycling if put in dry waste, and they may not break down in landfill. They are only an improvement when they reach the right facility.

What to do

Prefer reusable options first. Where single-use is unavoidable, certified compostable products are useful for food-soiled items like plates and cutlery that cannot be recycled anyway. And be wary of the word biodegradable on its own; it promises more than it guarantees.