It is common for individuals to encounter confusion regarding the terms “compostable” and “biodegradable” when considering product disposal. These terms are frequently used interchangeably, yet they describe distinct processes and material characteristics. Understanding their differences is important for making informed decisions about environmental impact.
Understanding Biodegradable
A material is considered biodegradable if it can naturally decompose through the action of microorganisms such as bacteria, fungi, and algae. This breakdown process transforms the material into simpler, natural elements like water, carbon dioxide, and biomass.
Biodegradability implies a natural return to the environment, but it does not specify a timeframe for decomposition. Common items like food scraps and paper products biodegrade quickly. However, materials like wood or certain plastics can take hundreds of years to biodegrade, depending on environmental conditions.
Understanding Compostable
Compostable materials are a specific subset of biodegradable materials that break down under particular conditions to create a nutrient-rich soil amendment known as compost. This decomposition requires a controlled environment with specific parameters: high temperatures, adequate moisture, and specialized microorganisms. The process occurs within a defined timeframe, resulting in material indistinguishable from the surrounding compost.
Industrial composting facilities provide optimal conditions for many compostable products, maintaining temperatures of 130-160°F (55-70°C). These facilities ensure rapid breakdown and transformation into stable compost.
While some materials may be suitable for home composting, which operates at lower temperatures and is a slower process, not all items labeled “compostable” will break down effectively in a typical backyard compost pile. Certified compostable items, like bioplastics or food service ware, often carry labels from organizations such as the Biodegradable Products Institute (BPI) or meet standards like ASTM D6400, indicating they meet industrial composting criteria.
Key Distinctions Between Them
The primary difference between biodegradable and compostable materials lies in the specific conditions and timeframes required for their breakdown. While all compostable items are inherently biodegradable, not all biodegradable items qualify as compostable. Biodegradable simply means a material will eventually break down into natural elements, but it does not specify how quickly or under what conditions this occurs.
Compostable materials, conversely, are designed to decompose within a shorter, defined period under specific, controlled composting conditions. The end product of a compostable material’s breakdown is usable compost, which enriches soil. In contrast, a biodegradable material might break down into its constituent elements without necessarily forming a beneficial end product, and its decomposition time can be indefinite.
Why These Differences Matter to You
Understanding the distinction between compostable and biodegradable is important for proper waste management and environmental protection. Misinterpreting these terms can lead to “wishcycling,” where items are placed in the wrong disposal streams, causing contamination.
For example, placing a “compostable” plastic item into a recycling bin can contaminate the plastic recycling stream, making the entire batch unusable. Similarly, if a compostable item is sent to a landfill, it may not break down as intended due to the lack of oxygen and specific microbial activity in landfills. This can result in the item persisting for a long time or producing methane, a potent greenhouse gas.
To ensure correct disposal, consumers should look for specific composting certifications on products and and verify if local composting facilities accept such materials. Opting for compostable products is most impactful when there is an accessible and appropriate composting infrastructure available to process them.