Biodegradable, compostable, and degradable are all common terms thrown around in sustainable product marketing. They are easily confused, especially for a newcomer. Knowing the difference can help you navigate around shops and product descriptions without being fooled by confusing terminology.
What is Degradable?
If a product is degradable, it will break down and diminish in quality over time. The best example of a degradable product is anything made of petroleum-based plastic. Plastic is not an organic material; thus it never undergoes the natural process of decomposition1. Decomposition occurs when bacteria, fungi, and other organisms feed off dead organic matter. These decomposer organisms do not eat plastic; therefore plastic never fully reintegrates into the environment. Instead, plastic is broken down over time as it is exposed to heat, sunlight, and water.
If we leave a plastic bottle outside, floating in the ocean, it will slowly degrade in quality. The sun, water, and salt will eat away at the plastic, and slowly the single bottle will break into thousands or even millions of tiny pieces of plastic, known as microplastics1. Microplastics can be so small they are invisible. A swimming fish may inhale the microplastics from our bottle, and it will be embedded into their tissues. If a larger fish comes and eats that fish, it will accumulate some of that plastic as well. Since plastic is not digested by living organisms, it only ever accumulates in living tissue along the food chain1. Additionally, plastic degrades in quality, so even if we can recover the plastic from the ocean, we can never use it to make another plastic bottle.
What is Biodegradable?
Biodegradable refers to products that degrade through biomechanical processes. biodegradable products can be broken down by decomposers, unlike degradable products2. Since biodegradable products can be processed by decomposers, the materials in a biodegradable product can be reused in natural biological processes.
The timeline for a biodegradable product is very slow, but not endless. Some human-made biodegradable products, like a bamboo container, will take much longer to decompose than a bamboo plant would2. However, in order to be labeled biodegradable, the product must be able to decompose naturally.
What is Compostable?
A product is compostable if it can be safely added to a composting system. Compost piles, bins, and boxes are a collection of organic materials, often food waste or yard clippings, that can be added together to create fertile soil3. The perfect compost can create a natural fertilizer that can be used in place of chemical fertilizers. Composts can be created at your home, or on a larger scale. Most home composts are simple, without much work required. Industrial compost machines can speed up the process to create fertilizer out of food scraps in minutes3.
The most important factor of the compostable classification is whether it can safely be added to compost without adding any harmful elements. There should be no metal or plastic in a compost pile. Those materials will not help the composting process, and they can even harm plants or animals who may come in contact with the compost. Therefore most compostable materials are simple, like food scraps, coffee grounds, brown paper bags, and grass clippings. Adding processed items to compost may hinder the quality of the compost.
What's the difference?
The difference between biodegradable, compostable, and degradable is how the item breaks down in a natural environment. Degradable products degrade in quality and size but are never safely reincorporated into the biological cycle1. Biodegradable products can degrade naturally, but it may take years. Compostable products are easily incorporated into the biological environment, with little harm done to natural cycles. A banana rots away in 90 days; a plastic bottle never does.
Biodegradable products may have metals or minerals within them2. Metals are not part of the biological cycle, and they cannot be digested like organic compounds. Biodegradable products can have a mixture of elements, meaning they should not be ingested4. Because of this, not all biodegradable products are compostable. We do not want metals in the soil we grow our food in.
Degradable materials decrease in quality over time, in fact, they become more harmful as they degrade5. Biodegradable and compostable materials exist in a cycle, while degradable materials do not. Biodegradable and compostable materials are valuable even as they degrade. A banana peel is more ecologically valuable after decomposing than before.
Which is more Eco-friendly?
These three terms refer to the disposal process of certain products. Whether something is degradable, compostable, or biodegradable depends on what the product is made from, not how it’s thrown away. There is nothing we can do to make a degradable product into a biodegradable product after it has already been made. Therefore, we should be choosing biodegradable and compostable products over degradable ones to limit the total demand for harmful degradable products4.
Composting is essentially the natural process of decomposition. In nature, bacteria, fungi, and algae eat dead plant and animal matter. In the decomposition process, the decomposers excrete waste that is beneficial to the soil around them3. Worms are often added to compost piles to speed up the decomposition process. This is a natural process that will happen to anything that was once living. Compost systems allow humans to harness the power of decomposition. Composted material is known as “black gold” because of the amazing benefits it has to gardens3.
Composting is arguably the most Eco-friendly because it is the most natural process. Compostable products are all organic, there is no plastics or metal involved which may cause living organisms harm3. Biodegradable products are also eco-friendly, but they are not as easily reincorporated into nature. Degradable products should be avoided because once the product is made, there is no guarantee of safe disposal. By choosing compostable or biodegradable products, we can reduce the presence of harmful materials in our environment.