The increasing focus on sustainable living has brought terms like “biodegradable” and “compostable” into common discussions, particularly concerning packaging. While often used interchangeably, these terms carry distinct meanings, especially regarding how products break down and where they should be disposed. Understanding these differences is important for making informed choices about eco-friendly bags and ensuring their proper end-of-life management.
Understanding “Biodegradable”
“Biodegradable” refers to a material’s capacity to break down naturally through the action of microorganisms, such as bacteria and fungi, returning to the environment. This process converts complex organic compounds into simpler substances like water, carbon dioxide, and biomass. However, the term does not specify the time frame or environmental conditions required for this breakdown. Practically anything will biodegrade given enough time, which can confuse consumers. Some biodegradable plastics may take months to years to decompose even optimally, and significantly longer in environments like landfills where oxygen and moisture are limited.
Defining “Compostable”
“Compostable” signifies a material’s ability to break down completely into natural elements like humus, carbon dioxide, and water, within a specific timeframe and under controlled composting conditions. This process requires sufficient heat, moisture, and microbial activity, typically found in commercial composting facilities or well-managed home compost piles. The resulting compost must be free of toxic residues and support plant growth. For a product to be certified compostable, it must meet rigorous standards established by organizations like ASTM International (e.g., ASTM D6400) and CEN in Europe (e.g., EN 13432). These standards dictate the required rate of disintegration and biodegradation, ensuring the material breaks down into small fragments within weeks and fully biodegrades within a few months, typically 90 to 180 days.
The Crucial Distinction
The primary difference between “biodegradable” and “compostable” lies in the specificity of their breakdown requirements and outcomes: all compostable materials are inherently biodegradable, but not all biodegradable materials are compostable. “Biodegradable” lacks precise standards for breakdown time, environmental conditions, or resulting byproducts, meaning a “biodegradable” bag could take decades to degrade in a landfill, potentially leaving microplastic fragments. In contrast, “compostable” implies adherence to strict, certified standards that guarantee complete breakdown into non-toxic components within a defined period under specific composting conditions. For example, ASTM D6400 requires 90% of the material to biodegrade within 180 days in a commercial composting facility without leaving harmful residues. This distinction is important because a product labeled merely “biodegradable” may not be suitable for composting facilities and could contaminate compost streams or persist in the environment.
Identifying Truly Compostable Bags
Consumers can identify genuinely compostable bags by looking for specific certification logos from recognized third-party organizations. In North America, the Biodegradable Products Institute (BPI) certification mark, often with a swirl design, indicates a product meets ASTM D6400 or D6868 standards for industrial compostability. This certification ensures the product has been tested to break down in industrial composting facilities without leaving toxic residues. In Europe, the Seedling logo, owned by European Bioplastics, serves a similar purpose, certifying products that comply with the EN 13432 standard for industrial compostability and is typically accompanied by a registration number. It is advisable to check with local composting facilities, as not all facilities accept all certified compostable products due to variations in their processing capabilities and accepted materials.