Food waste / Nick Saltmarsh via Flickr

Globally, about a third of all the food produced is wasted. In the US, according to some estimates, the figure is about 40%. About 75% of it winds up in landfills. Only just over 6% gets composted. In 2018, US food waste weighed about 103 million tons and was worth about $161 million. Keeping food waste out of landfills would be a big deal indeed.

Food waste makes up the largest portion of what goes into America’s landfills. It amounts to nearly a quarter of all municipal solid waste. Add to that other organic wastes such as yard trimmings.

Landfills generate methane, a particularly potent greenhouse gas. They generate 15% of methane emissions in the US.

The landfill system is broken

Hickory Ridge Landfill near Conley, Georgia. Opened 1993, closed 2006, capped 2011. Wikimedia Commons

Waste management firms make their money by hauling trash and dumping it. More and more landfills are owned by private companies. Industry owns just less than half of all landfills, but they represent almost 90% of landfill capacity. Private companies often operate government-owned landfills. Current economic models, therefore, practically require haulers to dump at landfills.

The typical load combines both compostable and non-compostable waste. If a landfill wanted to compost organic waste, it would have to build not only a composting facility, but also machinery to separate organic waste from everything else.

Many landfills are reaching their maximum capacity and will close by 2050. Siting new ones is always difficult. No one wants to live near a landfill. In the past, too many have been built in poor neighborhoods, often those with a majority population of people of color.

Available land for new landfills is now mostly in rural areas. Most of the population lives in urban areas. At best, then, we will have sufficient landfill space in the near future. But most of the population will have to transport their trash long distances. And that’s expensive.

To protect current landfill capacity, many states and municipalities have started to ban dumping of organic wastes, including both food waste and yard waste. California has committed to reducing organic waste in its landfills by 75% by 2025.

Four alternatives to keep food waste out of landfills

Industrial composting, turned aerated pile method /

We must both reduce the amount of food we waste and find different ways to dispose of it in the meantime. We have basically four alternatives to keep food waste out of landfills:

• Waste to energy
• Composting
• Anerobic digestion
• Hydrothermal liquefaction

Waste to energy means incineration. While it’s possible simply to burn trash and bury the ash somewhere, in practice, most incinerators capture the heat for power generation or some other purpose. Siting new incinerators has proven as difficult as siting new landfills, and for many of the same reasons. Europeans burn a higher percentage of their trash than Americans do.

Industrial composting works about the same way as home composting, except it requires much more space and heavy equipment. Some of that equipment enables the pile to reach much higher temperatures. In turn, that enables industrial composting facilities to handle meat and other substances not compostable at home.

Composting requires air; anerobic digestion excludes air. Landfills basically operate on anerobic digestion. Anaerobic bacteria emit large quantities of methane. Anaerobic digestion facilities can capture and use the methane.

Hydrothermal liquefaction is an emerging technology still in the pilot phase. It subjects wet biomass to high heat and pressure, which depolymerizes polymers, such as cellulose. The process produces a liquid comparable to crude oil.

Any of these processes can be economically viable. No one of them is superior to all the others. For one thing, the technology that is most feasible in one region of the country may be less feasible elsewhere.

While incinerators require operation at a large scale, industrial composting and anaerobic digestion can operate at medium or large scale. The optimum food waste management system, then, would use different technologies at different scale in different parts of the country.

Composting

A Portland, Oregon resident adds kitchen food scraps to yard debris in a roll cart as part of the community’s source separated organics (SSO) program. Photo by Tim Jewett – City of Portland Bureau of Planning and Sustainability. Public domain from Wikimedia Commons

Of these alternatives, composting is the most familiar. It’s also the only one that works at a small scale. People can compost at home or collaborate with neighbors in a community composting project.

Composting organic waste would dramatically reduce methane emissions. It would also provide superior agricultural fertilizer. But industrial composting facilities serve only 4% of US households.

As practiced now, composting takes a couple of months to complete.  It can create odors. A Malaysian company, MAEKO, is working on a new composting technology. Its single-unit machine controls heat, airflow, and agitation of materials. It also has an embedded crushing unit to speed up the process.

The company, which now operates in four countries, claims that it can reduce the volume of waste by 80% in just 24 hours. Its process also controls odors with a special ventilation and filtration system.

Maximum daily input for one of their machines is one ton. It also makes a “Munchbot” unit for household use.

Operating at such a small scale puts MAEKO’s technology within reach of developing countries and other places that cannot afford the high start-up costs of regular industrial composting. It would probably also benefit small American landfills that want to start composting organic waste.

Technological innovation alone can’t keep food waste out of landfills, though. We need to overhaul the entire waste management structure both in terms of the legal framework and developing new business models.

Sources:

The broken system that sends most food waste and organic matter to landfills / Jim Giles, Green Biz. September 4, 2020
Food waste in America: facts and statistics / Ryan Cooper, Rubicon. August 25, 2020
What to do with food waste? Well, that depends / DOE/National Renewable Energy Laboratory. July 6, 2021 [Link no longer works.]
Zero food waste to landfill by 2030: the technology making this possible / Bea Howarth, AZoCleantech. July 6, 2021