How South Korean Food Waste Is Turned Into Feed, Fuel or Fertilizer

Around the world, most of the 1.4 billion tons of food thrown away each year goes to landfills. As it rots, it pollutes water and soil and releases huge amounts of methane, one of the most potent greenhouse gases.

But not in South Korea, which banned food scraps from its landfills almost 20 years ago. Here, the vast majority of it gets turned into animal feed, fertilizer and fuel for heating homes.

Food waste is one of the biggest contributors to climate change, not only because of the methane but also because the energy and resources that went into its production and transport have been wasted, too.

The system in South Korea, which keeps about 90 percent of discarded food out of landfills and incinerators, has been studied by governments around the world. Officials from China, Denmark and elsewhere have toured South Korea’s facilities. New York City, which will require all residents to separate their food waste from other trash by next fall, has been observing the Korean system for years, a spokesman for the city’s sanitation department said.

While a number of cities have comparable programs, few if any other countries do what South Korea does on a national scale. That is because of the cost, said Paul West, a senior scientist with Project Drawdown, a research group that studies ways to reduce carbon emissions. Although individuals and businesses pay a small fee to discard food waste, the program costs South Korea about $600 million a year, according to the country’s Ministry of Environment.

Nonetheless, Mr. West and other experts say it should be emulated. “The South Korea example makes it possible to reduce emissions at a larger scale,” he said.

South Korea’s culinary tradition tends to result in uneaten food. Small side dishes — sometimes a few, sometimes more than a dozen — accompany most meals. For years, practically all of those leftovers went into the ground.

But the country’s mountainous terrain limits how many landfills can be built, and how far from residential areas they can be. In 1995, the government introduced mandatory recycling of paper and plastic, but food scraps continued to be buried along with other trash.

Political support for changing that was driven by people living near landfills, who complained about the smells, said Kee-Young Yoo, a researcher at the government-run Seoul Institute who has advised cities on handling food waste. Because stews are a staple of Korean cuisine, discarded food here tends to have a high water content, which means greater volume and worse odors.

“When all of that went to waste, it emitted a terrible stench,” Mr. Yoo said.

Since 2005, it’s been illegal to send food waste to landfills. Local governments have built hundreds of facilities for processing it. Consumers, restaurant owners, truck drivers and others are part of the network that gets it collected and turned into something useful.

At Jongno Stew Village, a popular lunch spot in the Dobong district of northern Seoul, pollock stew and kimchi jjigae are the best sellers. But no matter the order, Lee Hae-yeon, the owner, serves small side dishes of kimchi, tofu, boiled bean sprouts and marinated perilla leaves.

Customers can help themselves to more, and “people are going to take more than they’re going to eat,” Mr. Lee said. “Koreans like to err on the side of abundance when it comes to food.”

Mr. Lee pays a price for that: about 2,800 won, a little over $2, for every 20 liters of food he throws out. All day, leftovers go into a bucket in the kitchen, and at closing time Mr. Lee empties it into a designated bin outside. On the lid, he attaches a sticker purchased from the district — evidence that he’s paid for the disposal.

In the morning, companies hired by the district empty those bins. Park Myung-joo and his team start rolling through the streets at 5 a.m., tearing the stickers off the bins and dumping the contents into their truck’s tank.

They work every day except Sundays. “Even waiting a day would cause huge amounts of waste to pile up,” Mr. Park said.

Around 11 a.m., they get to Dobong’s processing facility, where they unload the sludgy mess.

Debris — bones, seeds, shells — is picked out by hand. (Dobong’s plant is one of the last in the nation where this step isn’t automated.) A conveyor belt carries the waste into a grinder, which reduces it to small pieces. Anything that isn’t easily shredded, like plastic bags, is filtered out and incinerated.

Then the waste is baked and dehydrated. The moisture goes into pipes leading to a water treatment plant, where some of it is used to produce biogas. The rest is purified and discharged into a nearby stream.

What’s left of the waste at the processing plant, four hours after Mr. Park’s team dropped it off, is ground into the final product: a dry, brown powder that smells like dirt. It’s a feed supplement for chickens and ducks, rich in protein and fiber, said Sim Yoon-sik, the facility’s manager, and given away to any farm that wants it.

Inside the plant, the strong odors cling to fabric and hair. But outside, they are barely noticeable. Pipes run through the building, purifying the air via a chemical process before the exhaust system expels it.

Other plants work differently. At the biogas facility in Goyang, a Seoul suburb, the food waste — nearly 70,000 tons annually — undergoes anaerobic digestion. It sits in large tanks for up to 35 days while bacteria does its work, breaking the organic matter down and creating biogas, consisting mainly of methane and carbon dioxide.

The biogas is sold to a local utility, which says it’s used to heat 3,000 homes in Goyang. What solid matter remains is mixed with wood chips to create fertilizer, which is given away.

Every ton of food waste that rots in a landfill emits greenhouse gases equivalent to 800 pounds of carbon dioxide, researchers have found. Turning it into biogas cuts that in half, said Lee Chang-gee, an engineer at the Goyang plant.

Critics note that for all its benefits, South Korea’s program hasn’t attained one of its goals: getting people to throw away less food. The amount of discarded food nationwide has stayed more or less steady over the years, according to data from the Ministry of Environment.

The system has had other flaws. There have been scattered complaints: In Deogyang, a district of Goyang, residents of one village said the odor from a processing facility was once so bad that they couldn’t leave their windows open. That plant has been inactive since 2018 because of neighbors’ protests.

“When the plant shut down, all the problems disappeared,” said a Deogyang resident, Mo Sung Yun, 68.

But most of the plants nationwide — unlike the landfills they are essentially replacing — have drawn few if any serious complaints from neighbors. Government officials say steadily improving technology has led to cleaner and more efficient operations.

It’s also made disposal easier for many. At apartment complexes around the country, residents are issued cards to scan every time they drop food waste into a designated bin. The bin weighs what they’ve dropped in; at the end of the month they get a bill.

“The bins have gotten cleaner and less smelly,” said Eom Jung-suk, 60, who lives in one such complex.

Ms. Eom has never been charged more than a dollar for the service. In April, she paid 26 cents. But the monthly bill makes her more aware of how much she throws away.

“Just today, at breakfast, I told my daughters to take just enough to eat,” she said.