Governments implement waste management systems to prevent trash from flowing into or accumulating in dwelling environments. These systems include incineration, recycling, composting, conversion of waste to energy, and landfills. Improper disposal of waste heightens the adverse environmental impact of landfills and puts our ecosystems at risk of deterioration.
Landfill sites, also known as sanitary landfills, are the areas where we dump waste produced by humans. We divert the vast majority of municipal solid waste to land-based landfills. As the world keeps developing, the waste we produce is also increasing. The constant increment in waste production also increases the effects of landfills on the environment.
This article explores the definitions and basic designs of landfill sites. Here, you will learn about the various landfills, their environmental impacts, and ways to reduce their harmful effects.
A landfill is a designated area for disposing of waste. Waste management officials survey and pick out an enormous expanse of land, typically away from residential areas and water sources. They then dig the site deep enough to dispose of waste in layers. Sometimes pits or trenches that already exist are chosen. Then, they press and compact the waste before covering the landfill9.
Out of waste disposal methods, landfill disposal is one of the oldest forms. Decades before engineered landfills became the norm, people dug a pit and dumped waste inside. Landfill sites' design is based on compressing waste into layers. This helps reduce the volume of garbage while landfill workers monitor the waste for liquid and gasses.
The basic design for a landfill must include a layer of protection at the bottom of the pit. The protection layer is necessary to prevent groundwater contamination around the landfill. Pressing the waste to make it smaller and covering it with soil is also mandatory. Sometimes, they can use wood chips to cover up. It is essential to cover the waste daily to prevent animals from digging it up and spreading it around.
Covering the waste also prevents flies from breeding and the spread of pungent odor, waste, and pathogens. An advanced landfill site contains a liner system at the bottom of the pit collecting leachate, the liquid that forms as water percolates through solid waste. Coupled with a leachate removal system, more advanced landfills can also treat the leachate while monitoring groundwater and gas extraction.
Some landfills have a bioreactor system known as aerobic or anaerobic bioreactor landfills. These systems hasten the process of decomposition in organic materials, promoting conditions necessary for the growth of microorganisms that will decompose waste and produce biogas. However, an advanced engineered landfill needs the availability of a skilled operator to maintain its bioreactor systems.
There are many types of landfills for various kinds of waste materials. Four of the most common include:
MSW landfills mainly receive household trash and other types of waste as long as they are not hazardous. Examples of non-hazardous wastes are commercial solid wastes, non-hazardous sludge, and industrial non-hazardous waste.
An industrial waste landfill differs from one that accepts only municipal solid waste. An industrial waste landfill only accepts industrial and commercial solid wastes and conditionally exempts generator wastes.
An industrial waste landfill can also receive inert materials like soil and rocks from excavation sites, glass, ash, clay, furnace slag, and plastics. They also accept cement kiln dust, non-chemically bound sand, and silicon.
This landfill is for solid hazardous wastes. Liquid hazardous wastes do not belong in a standard landfill because of the high contamination risks. Instead, we dump harmful solid wastes into this specific type of landfill and cover them up to prevent environmental pollution.
The construction of hazardous waste landfills has to meet specific criteria. They are:
A C&D landfill receives waste and debris from construction and excavation sites. The waste includes road work materials, excavated materials, construction and renovation waste, and site clearance waste.
C&D landfill doesn't accept hazardous waste and industrial solid waste. However, they accept trash materials like concrete, building wood, road and roofing asphalt, glass, plastics, metals, bricks, and gypsum.
Dumping municipal solid waste in a landfill releases toxic gases into the environment, putting various life forms at risk.
Theoretically, solid waste landfill sites produce 442 m³ of gas, containing 55% of methane and other natural gases. There are two primary gas elements and others in small quantities in gas emissions in landfills4.
The primary toxic gases are methane and carbon dioxide, while the other gases with low concentrations are ammonia, sulfide, and non-methane volatile compounds (VOCs)
Also, chemical and biochemical reactions in landfills create new organic and inorganic matter. For instance, tri and per-chrorethylene compounds transform into vinyl chloride. Amino acids also transform into methyl-mercaptans, while sulfur compounds change to hydrogen sulfide.
Adding some types of industrial waste to landfill sites also produces other greenhouse gases. For instance, the degradation of large plaster boards in landfill sites produces hydrogen sulfide.
Landfill sites that accept municipal solid and industrial wastes produce toluene, xylenes, propylbenzene, vinyl chloride, carbon dioxide, and methane gas.
Statistics show that methane emissions produced by landfill sites are the third-largest source of methane emissions in the United States. Also, methane gas contributes about 30% to global climate change. In 2020, international landfill sites produced 68 million tons of methane gas.
Methane emissions are more potent than carbon emissions, trapping 20 times more solar radiation than carbon dioxide. This makes the equivalent volume of methane gas emissions a more significant contributor to global warming.
There are three processes involved in the production of landfill gases. They are:
Bacterial decomposition produces a large percentage of potent greenhouse gases released from landfill sites. Bacterial decomposition is the act of bacterial organisms breaking down organic waste. These organisms are usually present in the waste naturally and in the soil used to cover the landfill site.
Another way landfill sites produce greenhouse gases is when organic matter changes from liquid or solid form into a vapor. This process produces some non-methane organic compounds.
Landfills are full of chemicals—producing emissions when some of these chemicals interact with one another. For instance, ammonia and chlorine beach interactions produce numerous toxic substances.
Landfill fires are a threat to human health and the environment because of the toxicity they emit. Firefighters and people who live close to landfill sites are at risk of inhaling dangerous emissions should they catch fire, which puts their health at risk. The level of the fire outbreak and its health risks depend on three factors; the municipal solid waste content in the landfill, the nature of the fire, and the geography of the landfill.
The biological processes of the decomposition of decaying organic material produce high levels of carbon and methane emissions. Landfill sites are the largest sources of methane emissions, especially in the United States.
In 1999, U.S. landfills produced 35% of the total methane emissions. Methane is a powerful gas whose role in landfill fires is huge. Methane is highly flammable, leading to the spontaneous combustion of decaying waste materials. Spontaneous combustion is prevalent in many landfills during dry seasons.
Meanwhile, surface fires in a landfill are fire outbreak that refers to the burning of recently buried waste, incompact waste, and waste within the aerobic decomposition layer close to the landfill's surface. Surface fires spread around the landfill and burn heavily because of high levels of methane gas. You can recognize a surface fire at your local landfill. Low temperature, white smoke, and the products of incomplete combustion characterize a surface fire.
Tire fires are outbreaks at landfill sites with dumped tires. Tire fires burn at a high temperature, and the smoke emitted contains carbon monoxide, sulfur dioxide, and products of butadiene and styrene. Also, it produces oil and thick, black smoke. This often leads to water and air pollution. Extinguishing a tire fire outbreak is a difficult feat to attain. The fire burns long and can flare up again weeks or months after extinguishing it2.
Some landfill fire incidents around the world:
Municipal solid waste landfills often pollute the groundwater present in the areas surrounding the landfill site. So, how does groundwater contamination occur?
Apart from producing toxic gases, landfill sites also produce leachate. Leachate is a liquid that drains through the waste dumped in a landfill site. An example of leachate is the liquid in sewage sludge.
Landfill leachate contains four major compounds: nitrogen, volatile organic compounds, heavy metals, and toxic organic compounds. The concentrations of harmful chemicals and toxic substances in leachate vary according to the type and age of landfill waste. Also, seasonal weather irregularities and total precipitation amounts affect the quality of landfill leachates6. Besides biological decomposition, rainfall and surface runoff also contribute to leachate formation.
The toxic substances in landfill leachate are harmful to human health. Chemicals bioaccumulate in organisms, passing through the food chain until it reaches humans.
Research on the toxicity of landfill leachates lists its toxic chemicals as non-ionized ammonia, tannins, and copper. Ammonia has a harmful and toxic effect on human health and the environment. The research showed that the ammonia content in leachate is critically harmful to aquatic organisms. High concentrations of leachate in groundwater also affect vegetation.
Landfill leachate is an immense problem, especially at poorly constructed sites where liner systems built in to prevent the flow of leachates into the environment are either inadequate or non-existent.
Landfills are one of the most extensive facilities for waste management. The construction and presence of landfill in an area enormously impact various living organisms and species.
Creating a landfill site that spans 100 ha affects local species by destroying their habitats. Landfill sites are usually far away from residential areas and human civilization. So, waste management organizations destroy trees and plants to create room for the construction of landfills. Clearing land space for landfills to dispose of waste materials destroys animal habitats and the ecological corridor3.
Landfills also affect the equilibrium of the species in the area. Hazardous waste materials can attract foreign species not native to the site. The negative impacts of landfill waste disposal also affect the soil fauna and flora. Toxic metals and chemicals interact with the soil fauna, leading to contamination (i.e., groundwater contamination). This contamination lowers the soil quality, thus affecting the growth of vegetation and other life forms.
A landfill is a spot filled with intense pollutants. It generates greenhouse gas emissions, groundwater, and surface water contaminants, foul odors, bioaerosol, and noise pollution. This primarily affects landfill operators and people who live close to the landfill.
Constant inhalation of landfill methane can cause loss of coordination, nausea, and vomiting. High methane concentrations in the human body system can also lead to death.
Furthermore, landfill waste produces sulfur dioxide and nitrogen dioxide. The ingestion or inhalation of these compounds can cause nose and throat irritations, bronchoconstriction, and respiratory infections. It is especially dangerous for asthmatic people.
Also, these acidic gasses can cause acid rain to fall. The acidic gasses enter the atmosphere, acidifying the moisture and leading to acid rainfall. Any human that stays around landfill sites for extended periods can develop health problems like reduced lung functions, asthma, ataxia, paralysis, vomiting, emphysema, and lung cancer, especially should they inhale or ingest heavy metals. Illnesses like high blood pressure and anemia also occur because of increased exposure to toxic metals1.
Hydrogen sulfide is a colorless and highly flammable gas produced at landfills. This flammable gas forms when compounds with high sulfate levels mix with hazardous waste. High levels of hydrogen sulfide exposure could lead to central nervous system malfunction and respiratory paralysis.
Studies also show that landfill operators' constant exposure to low concentrations of endotoxins can lead to an inflammatory response to the upper airways through neutrophil activation and the release of cytokines. Other effects of landfill sites on human health are diarrhea, stomach pain, recurring flu, cholera, malaria, cough, skin irritation, and tuberculosis.
Landfill fire outbreaks are also dangerous to human health and the environment. Inhaling the toxic smoke and gases from the fire can cause headaches, nausea, and fatigue from lack of proper sleep.
A burning landfill produces lots of carbon monoxide. Breathing it in causes displacement of oxygen in the blood. It also can prevent oxygen flow to the heart, brain, and other body parts, leading to death or anoxemia.
There are measures we can put in place to mitigate the environmental impact of landfills worldwide. These measures will save us from water and air pollution and protect us from landfill fires and biodiversity loss.
We examined the leachate and its components earlier. We know it is harmful to our health and that of other organisms. To divert waste leachate away from groundwater, landfill workers should treat it regularly. There are three primary treatment methods for leachate. They are biological processes, leachate transfer methods, and physical & chemical methods.
The biological method removes large amounts of leachate with high concentrations of toxicity. Also, it removes organic and nitrogenous substances from newly aged leachate. The efficiency of biological leachate treatment methods depends on its reduced refractory substances.
Split into two, the anaerobic biological treatment process happens in an airless container closed tightly, while the aerobic biological treatment process oxidizes the organic compounds into water and carbon dioxide. The aerobic process removes the ammonia nitrogen in the leachates8.
Waste management associations and those responsible for building landfills must design them correctly to minimize a landfill’s environmental impacts. There should be a double-liner system to minimize leachate flow into the environment. The system should also allow leachate collection, monitoring, and treatment.
Also, the landfill must have a cover. The covers could be soil, preventing pungent odors, litter, fire, and pathogens from spreading. It stops birds, rodents, and flies from breeding in the dump. Landfill cover also minimizes the downward flow of rainwater, preventing the formation and flow of leachates. The cover must resist water, wind erosion, cold weather, and distribution from other living organisms (plants and animals).
Gas emissions are one of the significant adverse effects of landfill sites on the environment. It leads to global warming and climate change. To prevent these, landfill waste management should include landfill gas energy projects.
Landfills should set up a system to capture methane emissions. They can transform the captured gas into electricity. The methane gas converts into water and less potent CO2 during this process. Also, it destroys most of the non-methane organic compounds. Using it as energy should reduce the high levels of landfills’ contribution to air pollution.
There is no absolute and perfect method for waste management. We can always combine various waste management systems to divert waste from the environment. However, we should be watchful of the environmental impacts of these systems because they can also pollute the environment. We are not diverting waste from the environment to create more ecological pollution problems. It negates the whole point of waste management systems.
The impacts of landfill on the environment lead to global climate change and tremendous environmental damage. We keep increasing the rates at which global warming occurs by producing too much waste. Most ways to prevent impacts like greenhouse gas emissions, landfill fires, air pollution, and health concerns depend on the landfill operators.
However, we can reduce the amount of waste we produce by practicing the 4Rs, refusing, reducing, reusing, and recycling waste items where possible. We can recycle plastic, glass, Tupperware, fabrics, and other old items.
You can compost organic waste and use it for your garden. Avoid purchasing plastic items, as they are part of the reasons for landfill pollution. Living an eco-friendly lifestyle helps rescue our consumption and waste production rates.
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ATSDR - Landfill Gas Primer - Chapter 2: Landfill Gas Basics. (2001, November). ATSDR.
Anqi, Tu & Zhang, Zhiyong & Suhua, Hao & Xia, Li. (2020). Review on landfill leachate treatment methods. IOP Conference Series: Earth and Environmental Science. 565. 012038. 10.1088/1755-1315/565/1/012038.
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Jen’s a passionate environmentalist and sustainability expert. With a science degree from Babcock University Jen loves applying her research skills to craft editorial that connects with our global changemaker and readership audiences centered around topics including zero waste, sustainability, climate change, and biodiversity.
Elsewhere Jen’s interests include the role that future technology and data have in helping us solve some of the planet’s biggest challenges.