What's The Difference Between Biodegradable And Compostable?

We see a lot of products with the label “biodegradable”, but what does that really mean? Biodegradable is a broad term that refers to how a substance will break down at the end of its use. Some biodegradable materials can break down completely into compost while others will break down slowly and can leave pieces of the original substance behind. It can be confusing to understand what materials and products you can compost, versus what materials are going to biodegrade in a landfill. It’s important to know how your products will break down so you can dispose of them properly. We’ll explain the difference.

What Does Biodegradable Mean?

Biodegradable means that a substance will breakdown naturally. Materials can biodegrade with or without oxygen depending on the product and its specific biodegradation requirements. Things biodegrade with the help of microorganisms, fungi and bacteria that help the biodegradable waste break down into carbon dioxide, water, biomass and in some cases, methane gas. The tricky part about biodegradable materials is that there is no time limit. A product can be considered biodegradable if it will break down in two weeks, two months, two years or twenty years. So, when you buy a product that is biodegradable, it is important to know what conditions are best for the product to biodegrade sustainably.

What Is The Difference Between Aerobic And Anaerobic Degredation?

There are also two ways for a material to biodegrade: aerobically or anaerobically. When something biodegrades aerobically, it degrades in the presence of oxygen and other nutrients. The microbes that are present during aerobic degradation consume biodegradable waste completely and release water and some carbon dioxide. Materials that have been aerobically biodegraded usually go back into the earth and soil.

When a material biodegrades anaerobically it does so without oxygen. This process releases gasses like methane and carbon dioxide. When biodegradable materials break down in a landfill environment, they break down through anaerobic biodegradation. This process is much slower than aerobic biodegradation. Without oxygen and optimal conditions for decomposition, like moisture and other nutrients, items in a landfill will sit for years without breaking down. When they do eventually start to biodegrade, methane gas and carbon dioxide is released. Methane and carbon dioxide are greenhouse gasses that contribute significantly to climate change, especially methane.

What Does Compostable Mean?

Compostable materials will break down completely into organic material and become compost. Compost is broken down materials, typically in the form of food scraps, yard waste, paper, or cardboard that can be repurposed and used as a soil fertilizer. When something is composted, it does not leave anything behind. Composting is typically done through aerobic biodegradation, meaning oxygen is present. When your items break down aerobically, they will not release methane. Instead, composted material can go back into the earth as natural soil fertilizer.

There are items that are at-home compostable and items that need to be commercially composted. Make sure you read the labels to know the difference. If something is at-home compostable you can put it in your normal compost pile or drop it off to a local composting facility. That is not the case for all consumer items. There are many consumer products that need to be commercially composted because of the conditions necessary for the item to completely break down. For example, some items need to be heated more than your normal compost pile would be in order to break down completely.

What’s The Difference Between Compostable and Biodegradable?

The differences between biodegradable products and compostable materials is difficult to parse out. All compostable materials are biodegradable, but not all biodegradable materials are compostable. For something to be compostable it has to break down completely, and it typically does so within 60—90 days. Composting needs to have enough water and nutrients for the microorganisms to break down waste properly.

Some biodegradable materials can be composted and break down with aerobic biodegradation. For example, if you dispose of food waste like fruit or vegetable peels in a compost environment, they will break down completely into nutrients that can return directly to soil. But some materials cannot be composted or fail to be composted, and will instead end up in a landfill. For example, biodegradable plastics will break down eventually, but most will turn into compost in a typical compost environment. At home compost cannot heat the plastic enough for it to become compost. If a compostable item like food waste or paper fails to be composted, it will also go to a landfill where it will be forced to biodegrade without oxygen. Materials that end up in a landfill will take a very long time to degrade and can release methane and carbon dioxide gas when they do finally break down.

So, when you buy something that says, “biodegradable”, make sure you really understand what that means. Can your item be composted to turn back to soil, or will it end up in a landfill eventually producing greenhouse gasses? We recommend asking the brands you purchase products from to ensure you know how to best dispose of your products.