Landfill facts for kids
A landfill is a special place where we put our waste materials, like the trash from our homes. It is the most common way to get rid of waste. People used to just leave trash in piles or throw it into holes. But since the 1940s, we started burying waste in a more organized way. This includes covering it with soil every day.
Landfills need a lot of land. They can also create environmental problems. Some landfills are used for temporary storage or to sort waste for recycling. If a landfill is not built strongly, it can shake or even turn into liquid during an earthquake. Once a landfill is full, the land can be used again for other things.
Both active and closed landfills can affect the environment for many years. They release landfill gases that contribute to climate change. They also release dirty liquid called landfill leachate. This liquid contains many harmful substances.
Contents
- Understanding Landfills: Where Our Trash Goes
- How Landfills Work
- The Life of a Landfill: What Happens to Waste
- Environmental Concerns: Protecting Our Planet
- After a Landfill is Full
- Smart Ways to Manage Waste
- Rules Around the World
- Different Kinds of Landfills
- Tiny Helpers: Microbes in Landfills
- Other Ways to Handle Waste
- Countries with Strict Rules
- See also
- Images for kids
Understanding Landfills: Where Our Trash Goes
How Landfills Work
Operators of modern landfills follow specific rules for non-hazardous waste. They use special methods to:
- Keep waste in the smallest possible area.
- Press the waste down to reduce its size.
They also cover the waste daily with layers of soil or other materials. These materials can include wood chips.
When trash trucks arrive, they are often weighed. Workers might check the loads to make sure only allowed waste is brought in. Then, the trucks drive to the "tipping face." This is where they unload their trash. Large machines like compactors or bulldozers spread and press the waste. Before leaving, trucks might get their wheels cleaned. This helps keep local roads clean. Weighing trucks helps keep track of how much waste comes in each day.
At the tipping face, the pressed waste is covered daily. This cover can be soil, wood chips, or special foam. This daily cover helps control smells and pests. The space filled each day with waste and cover is called a daily cell. Pressing the waste tightly helps the landfill last longer.
The Life of a Landfill: What Happens to Waste
The term landfill often means a municipal or sanitary landfill. These facilities became common in the 1960s and 1970s. They helped stop the use of open dumps. A sanitary landfill is carefully built to hold and separate waste. These landfills are like giant bioreactors. Tiny living things called microbes break down the waste over time. This turns complex waste into simpler, less harmful substances. Environmental engineers design and manage these facilities.
Waste breaks down in stages. First, microbes use oxygen to break down some materials. Then, as oxygen runs out, different microbes take over. They work without oxygen. Solid organic waste breaks down quickly. Larger pieces turn into smaller ones. These smaller pieces dissolve in water. Then, they change into gases like carbon dioxide (CO2) and methane (CH4). The rest of the waste stays as solids and liquids.
The breakdown process happens in five main stages:
Starting Out (Phase I)
When waste first enters the landfill, there is a lot of oxygen in the empty spaces. As more waste is added and pressed down, the oxygen slowly decreases. Microbes that use oxygen grow and become more numerous. They start breaking down the waste.
Changing Conditions (Phase II)
The oxygen is quickly used up by the microbes. The landfill layers become less oxygen-rich and more oxygen-free. Microbes then start using other chemicals, like nitrates and sulfates, instead of oxygen.
Acid Forming (Phase III)
In this stage, the waste starts to break down into acids. This makes the liquid inside the landfill more acidic. Many intermediate compounds are formed. These acids are then changed into CO2 and hydrogen gas. This phase helps break down a lot of the waste. Metals might become more easily dissolved in the acidic liquid.
Methane Production (Phase IV)
The acids from the previous stage are turned into methane (CH4) and CO2. This is done by special microbes called methanogens. As these acids are used up, the liquid in the landfill becomes less acidic. The amount of methane and CO2 gas produced increases a lot. This is usually the longest stage of decomposition.
Final Stage (Phase V)
In the last stage, the microbes slow down. There are fewer nutrients left for them to use. Methane production almost stops. Oxygen slowly starts to enter the landfill again from the air. The remaining organic materials continue to break down. They turn into substances similar to humus in soil.
Environmental Concerns: Protecting Our Planet
Landfills can cause several problems. Heavy trucks can damage local roads. Dirt from truck wheels can pollute roads and waterways. The surrounding natural environment can also be harmed. This includes groundwater or aquifers and the soil itself.
Dirty Water (Leachate)
When rain falls on open landfills, water soaks through the trash. This water becomes dirty with dissolved materials. It forms a liquid called landfill leachate. This leachate is full of organic matter, heavy metals, and other harmful substances. If this liquid is not contained, it can pollute groundwater. Modern landfills use thick, waterproof liners and collection systems. These systems catch the leachate. The collected leachate can then be treated or evaporated. Once a landfill is full, it is sealed to stop rain from entering. This prevents new leachate from forming. However, liners do not last forever. So, the ground around landfills must be checked regularly for leaks.
One big problem with leachate is nitrogen, especially in the form of ammonium. When waste breaks down, it releases carbon substances and ammonium. Inside landfills, there is no oxygen for the usual nitrogen removal process. This can cause a lot of ammonium to build up in the leachate.
Landfill Gases
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When organic waste breaks down without oxygen, it creates landfill gases. These gases are mainly CO2 and CH4. The amount of each gas depends on the landfill's age, waste type, and moisture. On average, about half of landfill gas is methane, and a bit less than half is CO2. Landfill gas also contains small amounts of other gases.
Landfill gases can leak into the air and soil around the landfill. This makes landfills a major source of greenhouse gases. Methane is especially powerful for global warming. It is much stronger than CO2 over short periods. Well-managed landfills collect and use these gases. They can be burned off (flared) or used to generate electricity. Monitoring these gases helps keep workers safe. In the United States, over 850 landfills use systems to recover landfill gas.
Other Problems
Landfills can also disturb wildlife. Animals might lose their homes or get sick from eating trash. Dust, bad smells, and noise pollution are other issues. Landfills can also lower property values nearby. Poorly managed landfills can attract pests like rats and flies. These animals can spread diseases. Covering the waste daily helps prevent these problems.
After a Landfill is Full
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Once a landfill is full, a top cover or cap is placed over it. This stops more rain from getting in. The landfill then enters an "aftercare" stage. During this time, environmental problems are reduced. This includes maintaining liners, capturing greenhouse gases, and treating dirty liquids. This aftercare can last for many decades, or even longer. It can also be very expensive.
Smart Ways to Manage Waste
Making Landfills Better
Modern landfills aim to be more sustainable. One idea is a bioreactor landfill. This type of landfill speeds up the breakdown of waste. It does this by adding air or by recycling the dirty liquid through the waste. Bioreactor landfills help remove pollutants faster. This means less long-term care is needed. It also reduces costs and future environmental impact. An added benefit is more gas production during the active period. This allows for more efficient energy generation.
Finding Useful Materials
Landfills can be seen as a source of useful materials and energy. In some parts of the world, people search landfills for items that can still be used. Companies also find ways to recover materials and energy. Gas-recovery systems are common examples. Some waste incinerators also recover materials. They use special filters to do this.
Turning Old Landfills into New Spaces
After a landfill is closed and capped, the land is often reused. Popular ideas include creating parks or bike paths. Some old landfills are used for solar arrays to generate electricity. They can even become living areas.
Rules Around the World
Canada
In Canada, provincial environmental agencies regulate landfills. They have laws to protect the environment. Older landfills are monitored to prevent leaks. Some old landfill sites have been turned into parks.
European Union
Countries in the European Union must follow the European Landfill Directive. Most EU countries have laws that ban or greatly limit putting household trash in landfills.
United States
In the U.S., each state's environmental agency regulates landfills. These state rules must meet or exceed the standards set by the United States Environmental Protection Agency (EPA). Getting permission to build a landfill can take many years. It costs millions of dollars. It also requires detailed studies to ensure safety and environmental protection.
Different Kinds of Landfills
- Municipal solid waste: These landfills take in household trash and other non-hazardous materials. A Bioreactor landfill is a type that specifically breaks down organic material.
- Industrial waste: These are for commercial and industrial waste. This group also includes landfills for construction debris and coal ash.
- Hazardous waste or PCB waste: These landfills handle dangerous waste. In the U.S., they are monitored under the Toxic Substances Control Act of 1976 (TSCA).
Tiny Helpers: Microbes in Landfills
The tiny living things, or microbes, in a landfill are very important. They help break down the waste. Scientists have even found bacteria in landfills that can digest plastic!
Other Ways to Handle Waste
Besides reducing and recycling waste, there are other options instead of landfills. These include turning waste into energy through incineration. Other methods are anaerobic digestion, composting, and mechanical biological treatment. Depending on local costs and benefits, these can sometimes be better than landfills.
The idea of zero waste aims to send as little trash as possible to landfills.
Countries with Strict Rules
Some countries have banned putting untreated waste in landfills. These include Germany, Austria, Sweden, Denmark, Belgium, the Netherlands, and Switzerland.
See also
In Spanish: Vertedero (basura) para niños
Images for kids
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A landfill in Poland
