A Mixed Bag
Yard clippings, uneaten food, discarded paper, even manure—organic waste is any refuse that can be traced back to a plant or animal. Each year, Americans discard more than 139 million tons of this type of waste; it makes up 55 percent of all municipal solid waste.
Breaking It Down
Organic waste breaks down through two different biological processes: aerobic decomposition and anaerobic decomposition. Like aerobic exercise, aerobic decomposition burns a lot of oxygen, generating carbon dioxide, a by-product of biological activity that is essential to the existence of all living things. In contrast, anaerobic microbes thrive in the absence of oxygen and give off methane, a particularly harmful greenhouse gas that has global warming power 20 times greater than carbon dioxide. When buried in a landfill—where the absence of oxygen promotes anaerobic decomposition—organic waste releases large amounts of methane. In 2013, landfills were the third-largest human-made source of methane in the United States, accounting for 17.5 percent of total methane emissions.
Diverting Organic Waste
As concerns over methane emissions have grown, municipal solid waste managers have implemented composting and recycling programs to divert organic waste from landfills. Many states have also implemented restrictions on what may be discarded in landfills, banning yard trimmings and encouraging composting by facilities that generate very high volumes of food scraps, such as hospitals, large restaurants, and college dining halls. Since 1990, diversion of organic waste from landfills has increased from just 4 percent to 21 percent. These efforts capture valuable nutrients to generate energy, promote soil quality, and reduce greenhouse gas emissions associated with decomposition.
Waste as Resource
When isolated and specially treated, organic waste can be used to generate energy, using anaerobic digesters. These relatively high-tech systems capture methane and other gases from decomposing municipal solid waste to produce electricity, heat, and fuel in the form of compressed natural gas. More than 621 of these systems—collectively generating 16 billion kilowatt hours of electricity annually, powering more than 1 million homes and heating nearly 750,000 of them—have already been incorporated into municipal solid waste facilities in nearly every state, with plans for more in the works.
Composting, a technique that has been utilized for thousands of years, produces a crumbly, earthy-smelling substance called humus. Known as black gold, compost mixed into soil promotes healthy plant growth, making it a particularly popular soil addition with organic farmers and home gardeners alike. In addition to acting as a natural fertilizer, compost naturally deters weeds and pests, reducing the need for chemical pesticides and fertilizers, which have negative environmental effects.
A single-person household might choose vermicomposting, in which red worms nosh on food scraps in a special container under the kitchen sink, while a municipality might implement a vast outdoor system of compost piles to transform barnyard waste, institutional food scraps, and yard trimmings into a rich soil addition for local landscapers and farmers.
As with all waste management, repeat the mantra “reduce, reuse, recycle.” Minimize food waste by planning your meals, labeling leftovers, and making an effort to utilize a greater portion of your purchases. You can reduce your yard waste by practicing grasscycling, which encourages mowing the lawn whenever it is higher than 3 or 4 inches, cutting no more than one third of the grass blade or one inch total, and using grass clippings to fertilize your lawn.
While paper can be composted, you should recycle any unsoiled paper—there is a good market for recycled paper, and paper recycling is widely available. However, you may need to explore your options for disposing of other organic waste. Resources vary by state and municipality. Some may offer organic waste pickup as part of their collection program, while others may have designated drop-off sites. Contact your local solid waste facility or cooperative extension to learn about composting and other organic waste disposal options available in your area.