What’s the best way to dispose of leftovers this Thanksgiving?

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During the 20th century, Philadelphia residents had an unusual and environmentally friendly method of tossing out their leftovers. Every week before dawn, pig farmers from New Jersey collected buckets of food waste from curbsides and fed the scraps to their pigs.

However, that tradition is long gone. Today, 206 million pounds of food waste is sent to landfills or incinerators in Philadelphia each year, according to the Philadelphia Water Department.

“The history of Philadelphia is that we don’t throw away our food,” said Paul Kohl, a civil engineer for the city’s water department. “But we’ve become food throw-away-ers.”

In 2019, residents, retail and the service industry combined generated 66 million tons of food waste nationwide, according to the U.S. Environmental Protection Agency. Almost 60% was sent to landfills. Food waste in landfills contributes to more climate-warming methane emissions than any other landfilled materials, according to the EPA.

Between Thanksgiving and New Year’s, there is about a 25% increase in food waste, according to the non-profit organization the Ecology Center.

As the holiday season approaches, WHYY News asked food waste experts about alternatives to the trash can.

Is it better to use the garbage disposal?

The Philadelphia Water Department touts the food waste disposer, better known as the garbage disposal, as an environmentally friendly way to discard leftover food. Once food waste makes its way to the city’s sewage treatment plant, methane is captured and reused as energy for on-site electricity through a process called anaerobic digestion.

“The city has come to the conclusion that it’s a sustainability device,” Kohl said of the garbage disposal. “It makes a lot of sense to keep food out of landfills.”

However, not everyone agrees.

The EPA says along with incinerating food waste or sending it to a landfill, disposing of leftovers down the drain is among the least preferred ways of throwing out food. When food waste is sent down garbage disposals, it takes some time before making its way to the sewage plant. That means methane can still be released well before reaching the anaerobic digester.

Even when a treatment plant generates energy through anaerobic digestion, “the recovered energy does not offset the methane emissions from wasted food in sewers and extra energy demand for wastewater treatment,” the EPA states on its website.

Some food waste experts say using an anaerobic digester at a sewage treatment plant to capture some methane is still better than nothing.

However, only a few sewage treatment plants nationwide use anaerobic digestion as a renewable energy source. Even more methane can be released into the atmosphere when these facilities do not use a digester, said Charles Haas, an environmental engineering professor at Drexel University.

“Or, it will result in the production of more sewage sludge that ultimately will likely have to be landfilled anyway,” he said.

Though the EPA encourages people to avoid sending food waste down the drain, there are more disconcerting impacts associated with the trash can. Sending food waste to a landfill involves the use of gas-guzzling trucks, for instance. There are other problems too, Haas said.

“You need mechanical equipment at the landfill to place the solid waste in the landfill and to cover it up periodically,” he said. “And then even from landfills, you get water pollution associated with rain and precipitation that drains through the landfill that forms leachate that may need to be collected and treated.”

Using the garbage disposal also requires water and electricity. Kohl advises residents use cold water while emptying food waste down the sink, because hot water requires more energy use.

Kohl said residents can put fruits, small bones, vegetables, vegetable peels, celery and leftovers down the garbage disposal. However, residents should not pour fats, oils or grease down the disposal because it can clog the sewer system.

Upcycling and reusing food

Experts say composting, which breaks down organic materials into nutrient-rich soil, is one of the more preferred ways of handling food waste. Compost is often used on farms or in gardens to reuse some of the nutrients that would have gone to waste if leftovers were thrown out or sent down the garbage disposal.

The city of Philadelphia is working to expand its composting efforts, and city officials and the EPA say compositing is one of the better ways of disposing of food waste.

Residents can also take advantage of community composting facilities, which collect compost from residents for a fee. However, that too, involves vehicle emissions.

“Unless you just chop it up and put it into your dog’s dinner bowl, there will always be some cost in terms of human energy, and mechanical energy,” said Howard Neukrug, director of the Water Resources Center at the University of Pennsylvania.

The EPA states the most preferred options are to redistribute leftovers to animals or people —- or to not waste food in the first place.

There are several resources people can use to find their local food pantry to donate any excess fresh food, said Sara Elnakib, a registered dietician and professor at Rutgers University. She also recommends sharing food with family and friends.

“It’s an excellent way to ensure that not only the nutrients, but also the calories that are in the food, are actually being redistributed,” Elnakib said.

While 30 to 40% of food is wasted each year, 18 million households in the U.S. were food insecure last year, according to the U.S. Department of Agriculture.

Elnakib said the rules around food donation vary by state.

However, the best option is to prevent food waste in the first place, Elnakib said. She recommends shopping with a list and meal planning to prevent impulse buying, storing bulks of food in a freezer, and keeping track of items that need to be eaten right away. Elnakib added that if a food item is past its sell-by date, it doesn’t mean it’s not safe to eat.

“Oftentimes people think about date labels as expiration dates, but oftentimes they’re quality assurance dates and they actually have nothing to do with expiration,” she said. “Most date labels are safe for human consumption after the date.”