Anaerobic digestion is the simple, natural breakdown of organic matter into carbon dioxide, methane and water, by two groups of microorganisms, bacteria and archaea. (adbioresources.org)
Anaerobic digestion is the simple, natural breakdown of organic matter into biogas (carbon dioxide and methane) and organic fertiliser called digestate. (adbioresources.org)
For example, when we work out with weights, there's a natural breakdown of our muscles — a limitation to what we can lift. (relevantmagazine.com)