Overview and Definition
Composting is a natural process that turns organic materials into a conditioner for soil. As an organic-matter resource, compost has the unique ability to improve the chemical, physical, and biological characteristics of soils.
“Biodegradable” and “Compostable”
You may remember from high school geometry class that while every square is a rectangle, not every rectangle is a square. That’s a lot like the difference between the terms “biodegradable” and “compostable”. While everything that is compostable is biodegradable, not everything that is biodegradable is compostable.
Composting in the United StatesAccording to the EPA’s 2015 data on Municipal Solid Waste (MSW) generation, Americans composted 8.9% of all the waste we generated. Compare that with 52.5% for Landfill, 25.8% for Recycling, and 12.8 % for Combustion with Energy Recovery.
In the EPA data, composted material is broken out into two main categories – yard trimmings (think leaves, cut grass, etc ) and food. In 2015, Americans generated almost 35 million tons of yard trimmings, and composted 61.3% of it. Contrast that with generating over 40 million tons of food scraps and composting only 5.3% of it!
Lack of Infrastructure for Food Scraps
Just as with traditional recycling, composting rates depend greatly on the infrastructure available, meaning how many facilities are in place to accept compostable materials for processing. A 2017 study conducted by BioCycle determined that there were 4,713 total compost facilities in the United States. Of those 4,713 facilities, 57% accept yard trimmings only, which helps explain why we see the number we do for total tons of yard waste composted. 5% accept yard trimmings and food scraps only, and another 13% accept “Multiple Organics”, which includes food scraps.
Another layer to the infrastructure issue is collection. In order for organics to be diverted from landfills, we need collection and transportation infrastructure to get those organics to composting facilities. This is true for commercial collection as well as residential (curbside collection). While access to collection infrastructure is expanding, it still lags well behind where traditional landill and recycling streams are.