email
printSanitary Landfills
From CopperWiki
Effective solid waste management is a major concern for cities in most emerging economies. Ineffective management practices create a negative impact on the environment, human health and eventually on foreign investors and tourists and the health of the economy.
Contents |
[edit] Waste Disposal Concerns
- Current disposal practices in cities are by sanitary landfill or open dumping.
- Existing dumpsites in most cities are getting saturated and causing health concerns.
- With land shortages, finding new sites is getting difficult.
- People object to having sanitary landfill sites near them.
- Trash in a landfill doesn’t break down as there is little oxygen or moisture inside. This calls for constant monitoring and maintenance of landfill for at least 30 years
Landfills can be very harmful both for the human health and environment. This is because food waste buried inside landfills decompose easily for lack of contact with sun or air. Food waste in landfills contributes to the creation of lechate, which contains a number of harmful ingredients. Visit this site and try making an experimental landfill – Landfill in a Jar [1]
As organic waste like food and yard waste contains a lot of moisture and, therefore, can’t be put in incinerators also. The only viable alternative is to compost them. Composting is a form of organic recycling and helps to divert material from landfills.
[edit] Electronic Waste in Landfills
Computers and mobile phones can take hundreds of years to degrade in landfill sites. Mobile phone batteries contain mercury and cadmium and once they leak into the soil can pollute the landscape around the landfills. Electronic batteries dumped in landfills cause pollutions which lead to mental health problem like autism, ADHD, and Alzheimer’s disease. Same is the case for iPod batteries and television sets. Instead of sending to the landfill you can trade your old mobile phones at Envirofone [2]
Electronic circuit boards, batteries, and color cathode ray tubes (CRTs) can contain hazardous materials such as lead, mercury and hexavalent chromium. If improperly handled or disposed of, these toxins can get released into the environment through landfill leachate or incinerator ash. (Find out about WEEE directive with Computer Aid International [3])
[edit] Site Selection
Site selection of a sanitary landfill is perhaps the most important phase of planning. A necessary condition in designing a sanitary landfill is the availability of vacant land that is accessible to the community being served, and has the capacity to handle several years of waste material. In addition, cover soil must be available. The following factors have to be taken into consideration while selecting a site:
- Proximity to major roadway
- Load limits of roadway
- Speed limits
- Bridge capacities
- Underpass limitations
- Traffic patterns and congestion
- Detours
- Average haul distance or haul time
- Buffer areas around the site
- Historic buildings, endangered species, wetlands and other environmental factors
- Zoning requirements
- Climate
- Hydrology
- Availability of cover material
- Public opposition
The type of soil available at the site is important and has a great bearing on the design and operation of a landfill. Essential elements of soil evaluation are chemical properties of bed rock, soil type, permeability, workability and vegetation.
The compacted soil cover is important as it is expected to serve many other functions such as controlling rodents, flies and scavenging birds, supporting vegetation and restricting moisture and gas movement.
[edit] Engineering
A lot of care goes in determining the location of new landfills. Sites located on faulted or highly permeable rock are passed over in favor of sites with a less-permeable foundation. Rivers, lakes, floodplains, and groundwater recharge zones are also avoided. It is believed that the care taken in the initial location of a landfill reduces the necessity for future clean-up and site rehabilitation. Locations near airports are avoided because the landfill usually attracts birds that can interfere with aircraft.
Trench and Area methods Trench and area methods, or a combination of both, are used in the operation of landfills. Both methods operate on the principle of a "cell," which in landfills comprises the compacted waste and soil covering for each day. The trench method is good in areas where there is relatively little waste, low groundwater, and the soil is over 6 ft (1.8 m) deep. The area method is usually used to dispose of large amounts of solid waste.
[edit] The Trench Method
In the Trench Method,
- a channel with a typical depth of 15 ft (4.6 m) is dug, and the excavated soil is later used as a cover over the waste.
- Grading in the Trench method must accommodate the drain-off of rainwater.
- Another consideration is the type of subsurface soil that exists under the topsoil. Clay is a good source of soil because it is nonporous. Weather and the amount of time the landfill will be in use are additional considerations.
[edit] The Area Method
In the area method, the solid wastes and cover materials are compacted on top of the ground. This method can be used on flat ground, in abandoned strip mines, gullies, ravines, valleys, or any other suitable land and is useful when it is not possible to create a landfill below ground.
[edit] The Ramp Method
A combination method is called the progressive slope or ramp method, where the depositing, covering, and compacting are performed on a slope. The covering soil is excavated in front of the daily cell. Where there is no cover material at the site, it is then brought in from outside sources.
[edit] Landfill Gas to Generate Electricity
As per the United States Environmental Protection Agency (EPA) directive all new landfills are required to collect a lechate collection system which accelerates the decomposition of solid waste. Electricity is also generated from landfills by capturing the methane gas produced during decomposition. In Yolo County, California, a landfill releases 1.4 million cubic feet of gas a day for electricity generation
The Shuangkou landfill gas project, located in Tianjin, China, will generate electricity from gas recovered from the Shuangkou landfill by 2008. A landfill gas collection system will be installed to produce power. Gas will be collected in pipes from a series of wells that tap into waste disposal sites
[edit] Avoid Landfill - Compost Your Garbage
It is estimated that more than 600lbs of organic yard and kitchen materials can be diverted per home through backyard composting. By composting your organic waste you not only recycle decomposed material into a rich soil, but also save landfill space. By composting food and garden waste you reduce your household garbage by one third to a half.
You can make online purchase of compost bins at the following sites -
- http://www.cboinc.com/select.htm
- http://www.recyclenow.com/compost/
[edit] Why compost?
- Helps divert waste from the landfill, waterways and water treatment facilities.
- Backyard composting is much cheaper than municipal collection and disposal.
- You can reduce use of pesticide because of less pest problems
- Have healthy soil and better plant
- Moisture retention in the soil improves by addition of organic materials
- Feeds beneficial organisms.
- Compost amends both sandy and clay soils.
- Compost helps the soil hold nutrients long enough for plants to use them.
- Saves money–you avoid the cost of buying soil conditioners, bagged manure etc.
- Produce plants with more nutrient value.
[edit] What can I put in my Composter?
You can compost almost anything that is organic, such as:
- fruit and vegetable scraps
- tea bags, coffee grounds
- crushed egg shells
- grass cuttings, prunings and leaves
- small amounts of shredded paper and soft cardboard
- animal hair
- vacuum dust (only if you have woolen carpets)
[edit] You can’t compost
- cat or dog excrement
- meat
- cheeses
- fish
- disposable nappies
- shiny card
- hard objects
[edit] Helpful Tips
- Put some grass cuttings or vegetarian animal manure in the compost bin for best results as they heat up and speed up the composting process. However, they should be mixed with other organic waste to avoid slime formation.
- Place the bin in the sun as it is important to keep the compost bin warm. Turn the material regularly to allow air to get to the center of the bin. This will also speed up the decomposition process.
- The more serious citizens can purchase a 16-minute film (DVD-R version) Compost Truth or Consequences [4]
[edit] Decomposition
A landfill has three stages of decomposition
- Aerobic phase
During this phase solid wastes that are biodegradable react with the oxygen in the landfill and begin to form carbon dioxide and water. Temperature rises about 30°F (16.7°C) higher than the surrounding air. Weak acid forms within the water and some of the minerals are then dissolved.
- Anaerobic phase
Microorganisms that do not need oxygen break down the wastes into hydrogen, ammonia, carbon dioxide, and inorganic acids.
- Methane gas Production
During this stage of decomposition methane gas is produced. Sufficient amounts of water and warm temperatures have to be present in the landfill for the micro-organisms to form the gas. About half of the gas produced during this stage is carbon dioxide, but the other half methane. Systems of controlling the production of methane gas are either passive or active. In a passive system the gas is vented into the atmosphere naturally, and may include venting trenches, cutoff walls, or gas vents to direct the gas. An active system employs a mechanical method to remove the methane gas and can include recovery wells, gas collection lines, a gas burner, or a burner stack. Both active and passive systems have monitoring devices to prevent explosions or fires.
[edit] Common Questions on Landfill Gas Exposure
- How can I be exposed to landfill gas?
The gas produced in the landfills travels through the soil and reaches the atmosphere. The gas at times enters buildings even if they are not located on the landfills.
- How can landfill gas affect my health?
Landfill gas has an odor which causes irritation leading to nausea and headaches. Certain compounds in the gas are hazardous if large amounts are released. Small amounts, however, do not cause any serious health risk. Methane present in landfill gas is highly inflammable, but is a health risk if present in large amounts.
- Why is methane a fire hazard?
Methane is lighter than air and collects at the top of enclosed spaces. Once it enters buildings, it gets trapped in the lower parts of a building, such as the basement, and when its level reaches 5 percent of the air, it can cause a fire or an explosion if a spark or flame is present.
- What can be done at a landfill to stop the gas?
A ventilation system may be used to remove gases.
[edit] References
- http://www.idph.state.il.us/envhealth/factsheets/landfillgas.htm
- http://web.mit.edu/urbanupgrading/urbanenvironment/sectors/solid-waste-landfills.html
- http://books.google.com/books?id=6KrBmuJdoREC&dq=sanitary+landfill&printsec=frontcover&source=web&ots=juygfVilv9&sig=Eui-W9D3mP9QdfM0hP2jd0omkyg#PPA41,M1
- http://science.jrank.org/pages/3805/Landfill-Method-types.html
- http://science.jrank.org/pages/3806/Landfill-Decomposition.html
- http://science.jrank.org/pages/3807/Landfill-Operating-principles.html
- http://www.lib.niu.edu/ipo/1989/ip890920.html
- http://www.tameside.gov.uk/corpgen1/composters.htm
- http://www.china-economy.net/landfill-gas-to-generate-electricity/
