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How Does Composting Work?

While not as catchy as the three R’s (reduce, reuse, and recycle), there’s another great way we can decrease the amount of waste we produce: composting.

While we can (and should) start by turning our discarded fruits and vegetables into nutrient-rich material that can support healthy soils, composting doesn’t necessarily end there. The process can help us curb food waste, but we can compost much more than that as this article will demonstrate.

The Problem of Food Waste in America

The problem of food waste is staggering. According to the Food and Agriculture Organization (FAO), if global annual food waste was a country, it would equal the world’s third-largest greenhouse gas emitter.  

In the U.S. alone, around 133 billion pounds of edible food ends up wasted every single year. This means we throw away around 30 to 40% of our food supply. This costs Americans an astonishing $161 billion according to the USDA.

Food waste makes up roughly 24% of the waste stream that enters our landfills, higher than any other single material. Fortunately, composting can help us save money, save resources, and save our planet and food waste is just one thing that can be transformed into a valuable resource. 

What is Composting? How Can it Help?

How exactly does composting work? Let’s start with a definition of the final product, courtesy of the U.S. Composting Council:

“Compost is the product manufactured through the controlled, aerobic, biological decomposition of biodegradable materials.”

Finished compost or "humus" is a dark, nutrient-dense earthy material that can be used to grow plants or improve soil health. How do we get there? Let’s take a look at the process of turning organic waste into finished compost.  

The process of composting

There are a few elements required for the process of composting: 

  • Organic Waste including kitchen waste, grass clippings, raked leaves, etc
  • Soil or another source of microorganisms
  • Water 
  • Air/Oxygen

In a well-managed compost system, microorganisms in the soil consume organic materials. This breaks them down into humus that is rich in soil-boosting, inorganic nutrients like potassium, nitrogen, and phosphorus.

Home vs. Commercial Composting

It’s important to realize that natural materials will eventually decompose on their own. We're just speeding up the decomposition process by creating an environment with microorganisms and adequate water and temperature conditions. The faster and more efficiently we recycle organic waste in controlled environments, the faster we can access the finished compost. 

Depending on the type and volume of organic material available, the compost process can occur in either home or commercial environments. 

Home Composting:

Using a backyard compost tumbler, bin, or heap, home composting transforms organic waste like food scraps and yard waste into nutrient-rich humus. 

A home composting system requires three basic ingredients: browns (carbon rich dead twigs, leaves, and branches); greens (nitrogen rich food waste, coffee grounds, and grass clippings); and water.

Given the temperature limitations of home composting systems, certain items might not fully biodegrade. This makes commercial composting is a better option for additional compostable materials.

Commercial Composting:

Using a multi-step process, ideal conditions are created regarding particle size, water, air, and carbon to nitrogen ratios. In an industrial composting facility, the conditions are right for the rapid biodegradation of many types of organic material. 

Commercial composting is the best way to transform a wide range of organic matter into finished compost. This includes compostable food packaging, meat, dairy, food oils, or anything harmful bacteria might be present in.

Prevalence of Composting

When it comes to required composting materials, one of the most essential is oxygen. Without free-flowing oxygen, a byproduct is created. Biogas or greenhouse gases, which is roughly 50% carbon dioxide and 50% methane

Methane is the more potent greenhouse gas, trapping atmospheric heat at rates roughly 28 to 36 times higher than carbon dioxide

This brings us to a big problem, the prevalence of composting. In the U.S., our abysmal composting rates hover between roughly 6% and 8.9%.

When green materials like food waste and compostable packaging are sent to landfills, they’re directly contributing to our warming climate. 

Common (and Uncommon) Items that Can Be Composted

As the number of items that can be composted increases, we see an increase in composting efforts. These are happening at the federal, state, local and individual levels.

Traditionally, the following items could be composted (in a home compost bin):

  • Fruit and vegetable waste
  • Coffee grounds
  • Teabags
  • Grass clippings & dead leaves
  • Newspaper
  • Paper napkins
  • Printer paper
  • Cardboard (free from plastic & tape)
  • Sawdust or wood shavings
  • Eggshells*
  • Cooked grains (rice, pasta, bread, tortillas)*
  • Spoiled food (excluding animal products)*

* May lead to pest problems

With the help of commercial composting systems, however, traditionally difficult items can also be effectively transformed to nutrient-rich humus:

How Does Composting Work to Support a Healthy Planet?

The number of compostable items in our lives is on the rise. Since more people are sipping coffees out of compostable cups and dining from compostable bento boxes, we’re also seeing an increase in composting programs and facilities. 

In 1996, San Francisco became the first U.S. city to establish a citywide food scrap composting program. Currently they recycle and composts roughly 80% of their waste

Since then, other cities like Portland, Oregon, Boulder, Colorado, and Seattle, Washington have followed suit. Many others have begun trialing curbside compost pickups or have established drop-off composting locations. 

By composting nationally, we can potentially reduce the amount of trash that ends up in American landfills by at least 30%. By using compostable materials and sending them to appropriate facilities, we can all support our planet by recycling valuable organic materials.