Aerobic vs. Anaerobic Digestion: Benefits & Comparison

aerobic digestionEach year, nearly 35 million tons of food scraps are tossed out in America alone. This represents roughly 1/2 of everything we are burying within landfills.

However, with eco-awareness on the rise, a growing percentage of this waste is being processed into high-quality compost via both aerobic and anaerobic processes.

This is reducing the strain on landfills while creating viable compost that can be used for everything from residential gardens to commercial landscaping projects.

While there are benefits to both anaerobic and aerobic digestion, comparing the two shows that aerobic digestion is a better option for our environment, your operations, and your bottom line.

Anaerobic Digestion

Anaerobic compositing is an expensive process to complete. It requires continual introduction of large quantities of feedstock in order for the process to work efficiently. This is one of the reasons that it generates large quantities of methane gas as the food waste decomposes. That methane gas is not only highly combustible, methane gas is one of the most potent greenhouse gasses on the planet. Further, as this gas builds up within the system, the pressures within make it highly explosive and a safety hazard that must be monitored closely.

Additionally, as the compost is broken down by anaerobic digestion, it creates a sludge-like material that is even more difficult to break down. This requires time and considerable amounts of energy to accomplish. As a matter of fact, it can take up to a year before an anaerobic composter can fully break down the raw material into a viable compost.

Aerobic Digestion

The process of aerobic digestion that takes place within in-vessel aerobic composters is very similar to the process that occurs without any human assistance in nature. However, instead of taking place on the forest floor beneath the pitter patter of hooves and the like, the process takes place in a container that is easily monitored and maintained.

As aerobic digestion within the in-vessel composter takes place, the byproducts are simply heat, water, and carbon dioxide (CO2). While CO2 is a greenhouse gas, it is at least 1/20th as potent as methane. To minimize the impact on the environment, the CO2 gas can be safely collected via a gas collection system that will prevent the gas from seeping out into the environment.

Naturally, one of the most important benefits of aerobic compositing is that the heat which is produced during the decomposition process is great enough that it kills harmful bacteria and pathogens within the pile. This is not the heat of Hades or Phoenix in July, but rather it ranges between 55F and 140F, and it usually lasts for just a few days or so. While this heat is killing the harmful bacteria, it is also facilitating the growth of beneficial bacteria species including psychrophilic, mesophilic, and thermophilic bacteria which thrive at the higher temperature levels. These bacteria facilitate a healthy biomass that plants feed on and thrive in.

Which is Better for Your Needs?

From start to finish, the process of aerobic digestion takes about 5 days in an in-vessel rotary drum composter system. This makes it far more efficient than anaerobic composting systems. Plus, the byproducts of aerobic digestion are far safer for both personnel and the environment. Coupled with the amount of space, time, and effort required to transform everything from food scraps to yard waste, aerobic digestion simply comes out on top of the pile.