Biodegradation is the breakdown or decomposition of materials by microorganisms. It refers to the processes that transform materials into less complex compounds that can be used and reused by living systems. Biodegradation is used for waste management and environmental remediation, also known as bioremediation. It is an important process that helps to maintain the global carbon cycle and revitalize the environment.1

Bacteria and fungi, like yeast and mold, are the microorganisms most commonly used in the biodegradation process. These organisms transform substances through metabolic or enzymatic processes, which can be either aerobic, if oxygen is present, or anaerobic, if oxygen is not present.2 Although biodegradation processes vary significantly, aerobic decomposition typically produces carbon dioxide, water, and minerals, as well as other gases like hydrogen sulfide and dinitrogen.3 Anaerobic decomposition also yields carbon dioxide, as well as gases like methane.

Biodegradable substances are generally organic, such as plant and animal matter, or materials that come from living organisms, but some inorganic materials with similar properties are also biodegradable. Some microorganisms can even decompose or transform toxic, inorganic pollutants like hydrocarbons such as oil, polychlorinated biphenyls (PCBs), hydrocarbons, radionuclides, pesticides, and metals. However, in most cases this has been shown to be effective in a controlled setting, but not necessarily in nature, where factors like competing microorganisms and unfavorable conditions—including aeration, moisture, pH, and temperature—can inhibit biodegradation.4 Biodegradation can be used to treat water and soil, and to preserve wood and agricultural products, but a substance’s propensity to biodegrade does not necessarily correspond with low toxicity—many carcinogens, mutagens, and reproductive toxicants are biodegradable.5

Naturally occurring biodegradation can be used as a remedial action to restore sites of contamination, although it is a long-term process that can take years or decades. It is effective in certain kinds of contamination sites: as a primary remedial action in low- and medium-priority sites in which pollution is contained to unsaturated soil and groundwater is not corrupted; as a secondary action after contamination levels have been reduced by other measures; or as part of a comprehensive remediation plan.6

Biodegradation should not be confused with composting; although both are processes of decomposition, not all materials that biodegrade are compostable. Composting is a kind of aerobic biodegradation that turns organic materials into substances that condition soil. It is a relatively short-term process—while it is not standardized, most composters expect decomposition to occur within around 80 days. By contrast, biodegradation is not time-sensitive, so any material that eventually will be decomposed can be considered biodegradable.7

There are many criteria and tests used to determine biodegradability. These include testing methods defined by the Organization for Economic Co-operation and Development (OECD). Companies that make biodegradability claims should use these testing methods.8 Testing methods for composting include the EN 14046—or ISO 14855, biodegradability under controlled composting standards—which evaluates whether microorganisms can decompose 90 percent of a given material in less than six months.9 Products that contain carcinogens, mutagens, or reproductive toxicants are not eligible to make biodegradability claims because of their risk to human health and the environment.10

  1. Sidi Mohammed Ben Abdellah University
  2. Parsons School of Design’s Healthier Materials & Sustainable Building Certificate Program
  3. SCS Global Services
  4. Sidi Mohammed Ben Abdellah University
  5. Environmental Protection Agency
  6. Wisconson Department of Natural Resources
  7. The European Commission
  8. Parsons School of Design’s Healthier Materials & Sustainable Building Certificate Program
  9. The European Commission
  10. Environmental Protection Agency

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