Is biodegradable plastic the same as compostable?

Plastic pollution has become a global concern, prompting the search for environmentally-friendly alternatives. Biodegradable plastic and compostable plastic have emerged as potential solutions, but are they the same thing? While these two terms are often used interchangeably, there are important differences between biodegradable and compostable plastics.

Biodegradable plastics are designed to break down naturally over time through the action of microorganisms. When exposed to the right combination of heat, moisture, and oxygen, biodegradable plastics will gradually disintegrate into smaller pieces. However, the process can take a significant amount of time depending on various factors such as the type of plastic and the environment it is exposed to.

On the other hand, compostable plastics are designed to not only break down but also to turn into nutrient-rich compost when properly composted. Composting is a process that involves providing the right conditions for organic materials to decompose into humus, a dark, nutrient-rich substance that can be used to enrich soil. Compostable plastics typically require specific composting conditions that may not be available in all environments.

One key distinction between biodegradable and compostable plastics lies in the specific standards and certifications they must meet. Biodegradable plastics, for example, can be certified under various standards such as ASTM D6400 or EN 13432. These standards test for the rate and extent of biodegradation, as well as the absence of certain toxic substances in the final decomposition product.

Compostable plastics, on the other hand, have a more stringent set of standards to meet. The most widely recognized standard for compostability is the ASTM D6400, which specifies that a material must break down into carbon dioxide, water, inorganic compounds, and biomass at a rate comparable to that of natural materials, under specific composting conditions. Additionally, compostable plastics should not contain any toxic substances that could hinder the composting process or pollute the resulting compost.

It is also important to note that biodegradable plastics can break down into smaller pieces known as microplastics. These microplastics can persist in the environment for long periods and may pose a threat to marine life and ecosystems. Compostable plastics, on the other hand, are designed to completely break down into non-toxic substances, leaving no harmful residues behind.

The disposal methods for biodegradable and compostable plastics also differ. Biodegradable plastics can be disposed of in regular waste systems or through composting, depending on the type of plastic and the available infrastructure. However, simply throwing biodegradable plastics into the environment, such as in natural bodies of water or on land, is not recommended, as it can still contribute to pollution and harm wildlife.

Compostable plastics, on the other hand, require specific composting conditions to break down properly. This means they should be disposed of in a commercial composting facility rather than a typical backyard compost pile. Commercial composting facilities have the necessary equipment and conditions to ensure the proper decomposition of compostable plastics.

In conclusion, biodegradable and compostable plastics are similar in that they have the ability to break down over time. However, compostable plastics go one step further by turning into nutrient-rich compost when properly composted. Compostable plastics also have more stringent standards to meet and require specific composting conditions for proper decomposition. While both options offer potential solutions to plastic pollution, it is important to choose the right disposal method and understand the specific requirements of each type of plastic to ensure their environmental benefits are realized.