How is landfill gas extracted?
LFG is extracted from landfills using a series of wells and a blower/flare (or vacuum) system. This system directs the collected gas to a central point where it can be processed and treated depending upon the ultimate use for the gas. From this point, the gas can be flared or beneficially used in an LFG energy project.
Why is sand used in landfills?
A layer of sand or gravel or a thick plastic mesh called a geonet drains excess precipi- tation from the protective cover soil to enhance stability and help prevent infiltra- tion of water through the landfill cap system. This prevents clogging of the drainage layer.
What are wells that are drilled next to landfills for?
Landfill gas collection wells are individually installed in the waste, connected to a piping network, and ultimately feeds a control device to safely destroy landfill gas. Each individual well is “installed” via two phases: drilling and well installation.
Which of the following system is used for landfill gas collection?
Landfill gas collection is typically accomplished through the installation of wells installed vertically and/or horizontally in the waste mass. Design heuristics for vertical wells call for about one well per acre of landfill surface, whereas horizontal wells are normally spaced about 50–200 ft apart on center.
What is landfill gas called?
Biogas
Biogas is produced naturally by anaerobic bacteria in municipal solid waste landfills and is called landfill gas.
How are landfill gases generated name two types of landfill gases?
Three processes—bacterial decomposition, volatilization, and chemical reactions—form landfill gas. Bacterial decomposition. Most landfill gas is produced by bacterial decomposition, which occurs when organic waste is broken down by bacteria naturally present in the waste and in the soil used to cover the landfill.
Whats at the bottom of a landfill?
Leachate is water that gets badly contaminated by contacting wastes. It seeps to the bottom of a landfill and is collected by a system of pipes. The bottom of the landfill is sloped; pipes laid along the bottom capture contaminated water and other fluid (leachate) as they accumulate.
What do injection wells do?
An injection well is used to place fluid underground into porous geologic formations. These underground formations may range from deep sandstone or limestone, to a shallow soil layer. Injected fluids may include water, wastewater, brine (salt water), or water mixed with chemicals.
What is landfill gas recovery?
Landfill gas (LFG) recovery is the process by which methane gas is collected from solid waste deposited in a landfill. LFG is a natural byproduct of the decomposition of organic material in landfills. The composition of LFG is about 50% methane, 50% carbon dioxide, and a small amount of non-methane organic compounds.
What happens to municipal solid waste in landfills?
It is well known that decomposition of Municipal Solid Waste (MSW) in landfills produces methane gas and other trace toxic gases (e.g., polyvinyl chloride, PCP, etc.). It is necessary to prevent this gas from escaping into the atmosphere to stay in compliance with current Federal and State air pollution prevention regulations.
What are the best practices for landfill gas collection system operation and maintenance?
LFG Energy Project Development Handbook 8-2 Best Practices for Landfill Gas Collection System Operation and Maintenance a high gas collection efficiency to avoid odors and surface emissions, while also avoiding excessive vacuum that can lead to air infiltration. Control System Types
How are gas extraction wells installed?
Once it is determined that a gas extraction well or collector is to be placed, it is installed using several drilling methods such as hollow stem auger, bucket auger or air rotary, or by the horizontal trench method. For vertical wells, the well casing may vary in diameter from 4 inch to 24 inch and the depth will also vary.
What percentage of methane is in a landfill?
In a typical landfill, tuning for 48 to 52 percent methane content in the LFG will result in some infiltration of atmospheric air. Balance gas (nitrogen) may constitute 10 to 15 percent of the LFG with 0to 2 percent oxygen.