When reducing plastic consumption, eliminating high-volume single-use items (i.e., those things that we use daily or weekly) has the greatest impact. Trash bags are one of those high-volume items. When Nicole and I started our low-waste journey, my parents asked us how to reduce their use of plastic trash bags. At first the solution seemed obvious: buy biodegradable trash bags. My parents found numerous options, including UNNI bags from Amazon, and eventually ordered these from Green Paper Products. After some research, however, we found that their purchase was not as beneficial as we initially thought. Specifically, biodegradable/compostable trash bags do not “biodegrade” (in the colloquial sense) in landfills.

Bottom Line Up Front

Unless you buy 100% compostable bags and send them to a composting facility, I do not recommend that you buy biodegradable, degradable, or compostable trash bags. Landfills do not allow biodegradable or compostable bags to break down as intended, and it takes 2.7 times more energy to produce compostable bags than traditional plastic bags.

Instead, you should support the plastic recycling industry by purchasing trash bags made from recycled plastic. We buy the trash bags pictured below. Where possible, you should also re-purpose other plastic bags. For instance, we reuse the plastic bags in which our tortillas are packaged to pick up our cat’s waste.

The Technical Bit

The term biodegradable is interchangeable in colloquial speech with “compostable” and “degradable”, but the exact definitions of these three terms contain important distinctions.

Biodegradation is a natural process in which bacteria break organic material down into gas, water, and biomass. Often, other natural factors such as sunlight and temperature assist degradation by weakening the structure of the organic materials. Bacteria can process organic material with oxygen (aerobic digestion) or without oxygen (anaerobic digestion). Aerobic digestion breaks organic material down more quickly than anaerobic digestion. Both processes release gas. Aerobic digestion releases CO2, which is a greenhouse gas, but anaerobic digestion releases methane, which is a greenhouse gas that is ~20x more potent than CO2.

Now here’s the shocker: landfills do not to allow organic materials to break down aerobically. Landfills pack waste so densely that light and oxygen are not present, and organic materials break down very slowly, releasing methane in the process. Therefore, sending biodegradable or compostable trash bags to a landfill is arguably no better than sending your trash in a plastic bag.

Trash bags labeled as biodegradable and degradable are often plastic bags with additives that break the plastic into tiny pieces. These pieces can be harmful to the environment and difficult to clean up. These types of bags should go to a landfill, and are again, generally no better than a regular plastic bag.

Compost is King

Only 100% compostable trash bags are environmentally friendly if you have access to an industrial composting facility. Look for products that are certified by the Biodegradable Products Institute and have the Compostable Logo. Trash bags that are compostable, filled only with compostable materials (FYI, your dog/cat’s poop may not be compostable, so check with your composting facility), and sent to an industrial composting facility, break down into CO2, water, biomass, and inorganic compounds. This process generates soil that creates a healthy environment for plants to grow. Composting is a carbon sink because the plants and mircoorganisms that grow in the soil trap carbon from CO2 in the air and return it to the soil.

Good, Better, Best,

Mike