Diverting Organic Waste From Landfills
As Earth Day approached in April, consumers considered ways to “green” up their lifestyles. One opportunity was how to handle food waste.
Each year in the U.S., nearly 34 million tons of food waste is trucked to landfills. According to the U.S. Environmental Protection Agency, food waste is the single largest component of municipal solid waste sent to landfills. Once there, it quickly decomposes and produces methane, an environmentally harmful greenhouse gas at least 21 times more potent than carbon dioxide. Landfills are considered the third largest sources of methane.
While composting has received a lot of attention as of late, it’s not for everyone. One alternative that might be overlooked is a fairly common household appliance: the food waste disposer. Approximately 50 percent of all U.S. homes have an installed disposer.
Food waste disposers (or “garbage disposals” as they’re commonly known) convert food scraps, which consist of 70 percent water on average, into a liquid slurry that can safely flow into the sewage system or a septic tank. Sending food waste to a wastewater treatment plant rather than sending it to a landfill also reduces the potential contamination of groundwater. For a community of 30,000 households, using wastewater treatment options to dispose of food waste, instead of landfilling, on average, would reduce the carbon footprint by 1.9 million kg, the equivalent of not driving 4.6 million miles.
In an effort to create a more environmentally-friendly waste management policy, Massachusetts this year prohibited hospitals, universities, hotels, large restaurants and other big businesses and institutions producing more than one ton per week from throwing food scraps in the garbage. Rather than thinking of food waste as trash, state environmental officials now view it as a resource. Through a process called anaerobic digestion, organic waste can be converted into energy.
This process provides multiple benefits:
• It creates a biogas that delivers electricity and heat.
• It lowers waste disposal costs.
• It reduces greenhouse gas emissions.
• It conserves landfill space.
At capable wastewater treatment plants, the final product, known as biosolids, can be used as fertilizer.
A pilot program in Philadelphia studied how food waste disposers in residential settings could divert waste from landfills. In partnership with InSinkErator, a manufacturer of food waste disposers, the city installed 200 food waste disposers in two garbage truck routes to determine how much food they could keep out of the trucks and landfills. The study found that usage of disposers reduced food waste by more than 30 percent. The goal is to turn the food waste that is put in a disposer into renewable energy and fertilizer after being processed by wastewater treatment plants.
The New York City Department of Sanitation also recognizes the potential of disposers to make a positive impact on residential waste management. Benefits include reduced odors and fewer pests. Once banned in New York City due to concerns about water bodies surrounding the city and the city’s sewer system, food waste disposers got a second look in the mid ‘90s. Then-Mayor Guiliani – at the urging of the plumbing industry and others - signed a law authorizing the Department of Environmental Protection to study the potential effects of permitting the use of food waste disposers. A comprehensive analysis was conducted by the plumbing industry, representatives of food waste disposer manufacturers and their consultants, and the Department of Sanitation. The study found no significant impacts on the city’s sewer system or water supply system if food waste disposers were permitted.
While running a food waste disposer does involve running water and electricity, the environmental impact is minimal. Disposers use only about 1 percent or less of a household’s total water consumption (about as much water per day as one flush of a toilet) and cost on average less than 50 cents a year in electric usage.
So, will usage of food waste disposers increase as landfill space decreases? Perhaps, with the help of influencers like those in the plumbing industry usage of the disposers will increase. One area of opportunity is those households on a septic system where the use of food waste disposers is below average. A common myth is that households on septic can’t use a disposer. When, in fact, a septic system is designed to safely treat and dispose of household waste from the kitchen and bathroom(s). If the system is sized to handle a dishwasher or clothes washer in addition to sinks and toilets, it can handle a disposer as well.
Another myth that holds people back from grinding food waste is that certain items can’t go down a disposer. The truth is that most food can down a disposer; certain models can even handle more troublesome waste like bones and fibrous materials like celery.
As long as consumers follow these best practices for using a disposer, they should have nothing to fear:
1. Run a moderate flow of cold water.
2. Turn on the disposer.
3. Gradually feed food waste in while disposer and water are both running.
4. Continue to run cold water for a few seconds after grinding is complete.
5. Never pour grease or fat into your disposer or drain.
With better education and outreach to consumers, additional use of food waste disposers can be a win for both plumbers and the environment.
Michael Keleman has more than 20 years of experience in the wastewater field. Keleman is a Registered Environmental Health Specialist with the National Environmental Health Association. He currently serves as manager of Environmental Engineering for InSinkErator (www.insinkerator.com), a business unit of Emerson, a leading manufacturer of food waste disposers. He can be reached at Michael.Keleman@emerson.com.