What Happens to Trash in Landfills?
Like plants and animals, all products have a life cycle. Some products can be reused or recycled, minimizing their environmental impact. But eventually, a lot of what we humans consume gets tossed into the garbage. Out of sight, out of mind, right?
Not exactly. If you’ve ever wondered about what happens to your trash once it leaves your home, you’re not alone. That said, the subject of trash is taboo in the modern world; we don’t like to be reminded of all of the waste we generate on a daily basis. The truth is, while some waste can be diverted, a lot of trash (especially plastic) eventually makes its way to the landfill, or worse: the ocean.
But what exactly happens to trash at the landfill, and how is it managed? In this article, we’ll take a closer look at what happens to trash from collection all the way to the landfill, and beyond.
Photo by Alina Grubnyak
Where does our trash go?
We’re all part of a system that generates waste. Even individuals aiming for a zero waste lifestyle are part of this system; clothes wear down eventually, and even products bought in bulk were likely packaged and transported with non-renewable resources at some point. Whether you produce just a small amount of waste or the national average of 4.9 pounds of trash per person per day, the odds are that at least some of it has ended up in the landfill.
While efforts to divert waste away from the landfill are increasing (such as through recycling and composting), household garbage, also known as municipal solid waste, or MSW, is often bound for the landfill. But if you think that a landfill is just a dump site, think again: landfills are carefully engineered facilities that are designed to hold, bury, and manage waste materials.
But what happens to waste beyond this point?
Garbage collection
Before trash can even make it to the landfill to be buried, it first has to be collected. In the US, most household garbage gets collected locally by waste management companies.
If you’re like most people, chances are you toss your waste in a garbage bin lined with a plastic bag. Common items might include single use plastics, wrappers, paper, and food waste. Occasionally you might throw out larger items such as old furniture or torn clothing.
When the bag is full, you tie it shut and toss it in a garbage collection bin. On collection day, you roll the bin out to the street, and the garbage truck picks up its contents when it passes your house along the route. Sound familiar?
After your trash leaves your house, it still has a long way to go before it arrives at its final resting place. The garbage truck continues along its route until it has reached capacity. Then, it drives to a waste holding facility or transfer station and dumps out its contents, which are reloaded into large semi-trucks to be taken to the nearest landfill.
At the landfill, semi-trucks are weighed upon arrival. They dump their contents in an open cell, and are weighed again upon leaving. Only now has your trash finally reached the landfill, where it’s ready to be buried.
Note: in some cases, waste goes to an incinerator, where energy can be recovered from the combustion of waste, a process you can learn more about here.
Waste diversion
Not all garbage collection looks quite the same, however. While landfills are federally regulated, waste management happens on a local scale. How waste gets sorted – and to what degree – depends largely on the systems in place locally.
In areas with recycling and/or composting programs, for instance, residents are responsible for sorting their waste at home into separate categories. While imperfect, recycling greatly reduces the amount of waste that ends up in landfills, also known as waste diversion. This is important for several reasons:
Extends the lifespan of landfills
Conserves natural resources
Reduces greenhouse gasses
Some municipalities collect mixed waste (also known as single stream waste or “all in one” waste). In these instances, waste gets sorted at a “dirty” Materials Recovery Facility (MRF). Using a mix of manpower and technology, viable recyclables can be recovered at this point.
Unfortunately, recovery rates are often much lower with mixed waste systems due to rates of contamination. Plus, some mixed waste collection programs skip the dirty MRF and head straight for the landfill, further limiting waste diversion.
On a national scale, however, all is not lost. Rates of recycling and composting are increasing, though there is still a lot of room for improvement!
Hazardous waste management
Ideally, anything that is considered hazardous waste (including paints, stains, poisons, etc.) would be properly disposed of or recycled locally. The EPA has numerous guidelines and regulations to help waste facilities as well as individuals understand hazardous waste and its disposal.
Usually, individuals can take household hazardous waste to local collection facilities for free, where the waste can then either be recycled or properly disposed of at an incinerator or hazardous waste landfill. Businesses or other generators of hazardous waste (such as hospitals) are likewise responsible for making sure their hazardous waste is properly recycled, disposed of, or treated.
You can learn more about hazardous waste management here.
What happens to trash at the landfill?
Whatever doesn’t get recycled, composted, incinerated, or polluted into the environment eventually makes its way to a landfill. But a landfill isn’t just a dump; it’s a carefully engineered facility that manages waste in order to minimize its environmental impact.
How landfill cells work
When trash, or MSW, arrives at a landfill, it is taken to a cell. A landfill usually has only one or two cells open at any one time in order to reduce impacts such as smell.
Once the trash has been dumped into the landfill, a trash compactor works to evenly spread the waste and compact it. This step not only reduces the volume of the trash, but also stabilizes the landfill. At the end of the day, all of the new trash gets covered by soil, debris, or some other approved cover in order to minimize smell, emissions, and animal activity.
Before a cell has filled up, excavation of the next cell begins so that there is no break in trash collection.
Methane gas collection
In the landfill, compacted trash slowly decomposes, releasing methane, a potent greenhouse gas. Food waste is the biggest driver of these emissions, not only because it decomposes rapidly but also because it is the single largest category of material that ends up in municipal landfills.
Modern landfills are designed to maximize the collection of methane gas, rather than allowing it all to escape into the atmosphere. Despite these efforts, landfills are responsible for 14.1% of human-related methane emissions.
Turning methane into electricity
Increasingly, landfills are collecting methane gas and turning it into electricity. The methane is “vacuumed” through a series of pipes, then filtered, processed, compressed, and finally combusted to generate usable energy for nearby cities.
But combustion is not the only process through which methane, otherwise known as biogas or landfill gas, can be repurposed. According to the US Department of Energy (DOE), with some additional conditioning, biogas can even be turned into a biofuel to power vehicles.
Burning off excess methane
Whether a landfill has a methane collection system and energy plant in place or not, excess methane is usually burned off to mitigate the amount of methane gas escaping into the atmosphere. While this method is imperfect, it converts most of the methane to CO2, which is a less potent greenhouse gas.
Leachate collection
In addition to methane gas, your trash also results in a byproduct known as leachate, a liquid that forms as water (i.e. rainwater) filters through the layers of waste in the landfill. Leachate contains hazardous chemicals as well as other kinds of suspended solids that can pose a serious risk to the environment as well as human health if not properly managed.
To prevent groundwater contamination, leachate is collected, contained, and/or treated, a process you can learn more about here.
Landfill closure and reclamation
When all of the cells in a landfill have been filled, the entire landfill has to be closed up. Landfill capping usually consists of adding layers of clay and soil to create a more or less impermeable layer above all of the compacted trash. Pipes are installed to collect methane gas, which is then either burned off or converted into electricity.
Because landfills are considered a “temporary” use of land, a closed landfill is usually reclaimed in one way or another. For example, closed landfills can be replanted with native species and turned into habitat for plants and wildlife. There are also examples of closed landfills being turned into soccer fields and parks.
Due to the possibility of landfills shifting over time, large-scale construction on top of landfills is typically avoided. However, there’s huge potential for other kinds of reclamation projects, including solar farms as well as agricultural fields for growing crops for biofuel or animal feed.
Regardless of how a closed landfill is reclaimed, it has to be closely monitored for 30 years to make sure waste and pollutants are not escaping into the surrounding environment.
Extending the lifespan of landfills
Despite the efforts to mitigate environmental impact, landfills remain a significant source of pollution, waste, and greenhouse gas emissions. Reducing the amount of waste sent to landfills not only reduces the environmental impact of waste, but also conserves natural resources and increases the lifespan of landfills. Given that landfill space is limited, this should not be overlooked.
Waste diversion practices include recycling, composting, and waste-to-energy technologies (such as combustion). Composting is something you can easily do at home or on a local scale, while recycling depends heavily on local infrastructure.
Luckily, national incentives and increased awareness are leading to more and more waste diversion, and many landfills have already been able to remain open long after closure was initially estimated. That said, we have a long way to go considering how much waste is sent to landfills every day.
To reduce the amount of trash you send to the landfill, consider the 7 R’s of waste management: Rethink, Refuse, Reduce, Reuse, Repair, Recycle, Rot.
How do you reduce your trash? Share your tips in the comments below!
