Compostable bags are often marketed as an environmentally conscious choice, leading many to believe they will naturally degrade in any waste disposal setting. However, these bags do not effectively break down when placed in a typical landfill. Compostable bags are specifically engineered to decompose under the controlled, high-heat conditions found in industrial composting facilities, requiring a particular environment to return to natural elements.
Compostable Versus Biodegradable
The terms “compostable” and “biodegradable” are frequently used interchangeably, though they have distinct meanings. “Biodegradable” refers to a material capable of being broken down by living organisms, such as bacteria or fungi, and reabsorbed by the natural environment. While all materials will eventually biodegrade given enough time, this term does not specify a timeframe or the end products of decomposition. Biodegradable products may take years or even decades to break down and can sometimes leave behind microplastic waste or other harmful residues.
“Compostable” materials, conversely, are designed to disintegrate into non-toxic, natural elements within a specific timeframe, typically around 90 to 180 days, under controlled conditions. This process requires specific environmental factors like microorganisms, humidity, and heat to yield a finished compost product free from plastics or harmful chemicals. All compostable products are considered biodegradable, but not all biodegradable items are compostable, as the latter demands a regulated environment and a specific outcome. Certified compostable products adhere to strict standards, ensuring they break down completely without releasing harmful substances into the environment.
The Landfill Environment
Compostable bags do not readily break down in landfills due to the specific conditions inherent to these waste disposal sites. Landfills are primarily anaerobic environments, meaning they are deprived of oxygen. Waste is highly compacted and covered, which quickly depletes available oxygen and prevents air from circulating. This lack of oxygen significantly alters the decomposition process compared to natural settings.
Decomposition in landfills largely occurs without oxygen, a process known as anaerobic decomposition. This anaerobic activity by microorganisms leads to the production of methane gas, a potent greenhouse gas that contributes to climate change. Landfills also lack the consistent moisture levels and elevated temperatures conducive to rapid decomposition. The microbial communities necessary for efficient breakdown of organic materials are not active in the oxygen-limited, cooler, and drier conditions of a landfill. Consequently, compostable bags, along with other organic matter, often mummify or persist for decades, rather than breaking down as intended.
The Composting Process
For compostable bags to effectively break down, they require the specific conditions provided by industrial composting facilities. These facilities are engineered to optimize the decomposition process through careful management of several factors. They maintain high temperatures, often ranging from 120 to 170 degrees Fahrenheit (49-77 degrees Celsius), which accelerates microbial activity. Consistent aeration is also maintained.
Industrial composting facilities also control moisture levels, typically keeping them between 40% and 60%, which is essential for microbial growth and activity. A diverse community of microorganisms thrives under these conditions, efficiently breaking down organic materials into nutrient-rich compost. While home composting is viable for some organic waste, most certified compostable bags require the more intense and controlled environment of an industrial facility to fully decompose.
Environmental Considerations and Proper Disposal
The disposal of compostable bags in landfills presents a challenge. When these bags, along with other organic waste, end up in the oxygen-deprived environment of a landfill, they decompose anaerobically, generating methane gas. Methane is a greenhouse gas that contributes to climate change. Diverting organic materials, including compostable bags, from landfills is important for reducing these emissions.
Proper disposal of compostable bags is crucial for them to deliver their intended environmental benefits. This means sending them to industrial composting facilities where the necessary conditions for their breakdown exist. Consumers should check with their local waste management services to determine if industrial composting programs are available in their area and if they accept certified compostable bags. In regions without access to industrial composting, reusable alternatives for bags and packaging offer a more effective way to reduce environmental impact.