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  • Writer's pictureSarah Worp

Aerobic vs. Anaerobic Composting Systems

One cold, rainy day, I received a call from a curious member asking what we do with the methane produced in the composting process.

At that time, I was a brand new CompostNow employee and had juuust begun to learn the ropes. This call led me to a number of questions: “What DO we do with the methane? Is methane even a byproduct of our composting method? What IS our chosen composting method?”

Thus began my research into aerobic composting and the benefits of it versus other popular methods of composting, such as anaerobic composting.

What is aerobic (with oxygen) composting?

Aerobic composting is the decomposition of organic materials using microorganisms that require oxygen. It is the chosen composting method of CompostNow and our commercial composting partners. More specifically, we use an aerated or turned windrow pile system, which is an example of aerobic composting because they require oxygen to flow freely in order to breakdown the materials.

When the decomposition process occurs without oxygen, methane is released as a by-product. Aerobic composting requires the introduction of oxygen to compost piles to allow microbes and living organisms to thrive. The only by-products of aerobic composting are heat, water, and a small amount of carbon dioxide. The carbon dioxide produced in aerobic composting systems is easily absorbed by surrounding vegetation – a similar process to how we release carbon dioxide during the respiration process.

While carbon dioxide is classified as a greenhouse gas, it is only 1/20th as harmful as methane, which is released when an anaerobic (without oxygen) method is used.

What is anaerobic (without oxygen) composting?

Anaerobic composting is the method of composting without oxygen, which means the breakdown of the organic materials takes much longer and produces little heat. This lack of heat often results in the survival of many pathogens, weeds, and seeds, and causes a significant amount of methane to be released into the atmosphere.

There are several ways anaerobic decomposition is implemented at scale. Anaerobic digesters are chambers that store food and organic waste. They rely on the lack of oxygen because they capture and use the methane as a by-product for fuel or energy.

Anaerobic conditions can also often be found in landfilling, but not all landfills capture and use the methane as a by-product, instead they allow the harmful greenhouse gas to emit into the air.




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