What is composting and how does it work?
Composting is the managed degradation of plant and animal matter under aerobic (with air) conditions. The process mimics natural decay in a controlled environment to speed up the breakdown of these organics. Composting results in a safe and easy-to-use soil amendment — compost.
Insects and bacteria are examples of the types of creatures that feed on discards like food waste and leaves during composting. The larger animals tend to use mechanical methods, while the microscopic rely on chemicals to degrade these materials.
This feeding activity reduces complex compounds into simple molecules that are benign and odor free. Compost is used to build and replenish soils, closing the recycling loop for organic matter.
The only byproducts of composting are CO2 and water; the process produces no waste requiring disposal. The CO2 is considered “carbon neutral” since its release during composting is the same as if decomposed by nature.
Most municipal, commercial, and non-profit composting facilities rely on microbes to do the bulk of the organic decomposition. There are many composting methods in use, although outdoor windrows are among the most common. Earthworms are the primary agents of decomposition in the controlled process known as vermicomposting.
However, some other processes that have the word “composting” attached to their name in the vernacular may not be true composting processes.
Bokashi composting, for example, is an anaerobic (without air) fermentation process. Anaerobic composting is another misnomer. Because neither is aerobic, neither is true composting. Both can biodegrade organics, however. Unfortunately, anaerobic decomposition may generate unpleasant odors since anaerobes produce mercaptan during biodegradation. (Mercaptan is added to odorless natural gas to give the gas its distinctive rotten egg smell.)
Composting digestate, the by-product of energy extraction using anaerobic digestion, increases both the market value and uses for this waste material if managed for quality compost production.
While neglected composting piles have been known to “go anaerobic,” too, a well-managed composting process — one that keeps the piles aerated — will not generate unpleasant odors. Any odors present in the incoming feedstocks will be quickly neutralized, too.