The terms "biodegradable" and "compostable" are often used everywhere, but they are often used interchangeably, incorrectly, or misleadingly, which adds to those who are trying to shop in a sustainable way their uncertainty.
1. Definition of biodegradable
Biodegradable refers to any substance that can be decomposed by microorganisms (such as bacteria and fungi) and absorbed into the natural environment. Biodegradation is a naturally occurring process.
When an object decomposes, its original components are broken down into simple components, such as biomass, carbon dioxide, and water. This process can be carried out in the presence or absence of oxygen, but it takes less time when there is oxygen, just as a pile of leaves in your yard decomposes in a season.
The time for biodegradation ranges from a few days (e.g. vegetable waste) to 500 years or more (e.g. plastic bags).
Biodegradation time of household items
Vegetables: 5 days to 1 month
Paper: 2 ~ 5 months
Cotton T-shirt: 6 months
Leaves: 1 year
Nylon fabric: 30-40 years
Aluminum cans: 80~100 years
Polystyrene foam cup: more than 500 years
Plastic bag: more than 500 years
How long the biodegradation takes depends on the chemical composition and storage method of the object. Variables such as temperature, water, light and oxygen affect the degradation rate. Most landfills lack sunlight, air, and moisture, so the biodegradation process is significantly slowed down.
Vegetable skins, egg shells, paper and garden waste can all be directly biodegraded. When these items are discarded, they decompose in a relatively short time, so they can be absorbed into the natural environment.
In contrast, materials such as foam, plastic, and aluminum are generally considered non-biodegradable because they take a long time to decompose.
Figuring out whether an object is actually biodegradable can be a challenge, especially when you are evaluating objects that are not normally made of biodegradable materials, such as mobile phone cases or handbags. So, if you want to determine whether something is biodegradable, check the packaging and don’t hesitate to contact the manufacturer for inquiries.
In other words, most "biodegradable" consumer products will not actually be absorbed into the ground through natural biodegradation. In order to biodegrade, they need to create a specific set of conditions through the composting process.
2. Definition of compostable
The term "compostable" refers to a product or material that can be biodegraded in a specific, human-driven environment. Unlike the completely natural biodegradation process, composting requires human intervention.
In the composting process, microorganisms decompose organic matter with the help of humans, and humans provide the water, oxygen and organic matter needed to optimize the conditions. The composting process usually takes several months or 1-3 years. Time is affected by variables such as oxygen, water, light, and the type of composting environment. There are two main types of compost:
(1) Residential composting: Residential composting involves collecting food residues in trash bins or piles, mixing them with garden waste, and regularly decomposing them into more basic organic matter. For this reason, you cannot break down things like meat, cheese, and fish in a residential trash can because it does not generate enough heat at all.
(2) Commercial composting: Commercial composting includes screening and sorting organic and inorganic substances, using chippers and grinders to decompose them, and creating optimal humidity, temperature and oxygen conditions. Therefore, commercial composting machines can decompose products that are more complex than household composting machines.
You will want to know if the product can be composted in the trash can in the backyard or if it needs to be commercially composted. Not all cities offer commercial compost, and you don’t want to choose a compostable product, only to find that you can’t compost it.
1. Biodegradable and compostable plastics
If you recently purchased a mobile phone case, travel mug, or reusable shopping bag, you may have encountered biodegradable and compostable plastics, also known as bioplastics.
Many restaurants have even begun to use bioplastics to make take-out containers, tableware and cups. These things are usually made of materials such as corn starch, cellulose, and soybeans. After proper composting, they will decompose into non-toxic carbon dioxide, biomass and water.
However, just because plastic is biodegradable or compostable does not mean that it will decompose under any circumstances or that it is truly eco-friendly. Before your next purchase, consider the pros and cons of biodegradable plastics.
Advantages of biodegradable and compostable plastics
1. Unlike traditional petrochemical plastics, bioplastics are plant-based.
2. Bioplastics manufacturing may have a lower carbon footprint than traditional plastics, but there are many variables and uncertainties.
Disadvantages of biodegradable and compostable plastics
1. Decomposing bioplastics requires high temperatures that can only be obtained in industrial composting facilities. In household compost piles or landfills, they take a long time to decompose.
2. Bioplastics cannot solve the problem of marine plastics because they cannot rapidly biodegrade under ocean conditions.
3. Bioplastics cannot be mixed with recyclable plastics, they must be recycled in different substreams.
Choose biodegradable or compostable products
If you want to reduce the impact on the environment, compostable items are a good choice. Composting an item means that it will not end up in a landfill. If you compost at home, you can use these organics to help the plants in your garden grow. In addition, the labeling of compostable products is usually more straightforward, so you can be sure that you are choosing a more environmentally friendly product.
In other words, compostable products require certain conditions to decompose, so it is important to commit to truly composting these products instead of sending them to landfills.
If an item is determined to be commercially compostable, make sure you have a facility that can dispose of garbage. Bioplastics are better than traditional plastics in some respects, but if they are not handled properly, they can still have a negative impact on the environment.
As always, the best option is to reduce your consumption, reuse what you already have, and avoid disposable products as much as possible.
