What components make up landfill gas?
By volume, landfill gas is about 50 percent methane and 50 percent carbon dioxide and water vapor. It also contains small amounts of nitrogen, oxygen, and hydrogen, less than 1 percent NMOC, and trace amounts of inorganic compounds. Some of these compounds have strong, pungent odors (for example, hydrogen sulfide, or H2S). Nonmethane organic compounds consist of certain HAP and VOC, which can react with sunlight to form ground-level ozone (smog) if uncontrolled. Nearly 30 organic HAP have been identified in uncontrolled landfill gas, including benzene, toluene, ethyl benzene, and vinyl chloride. Exposure to these HAP can lead to adverse health effects. Thermal treatment of NMOC (including HAP and VOC) and methane through flaring or combustion in an engine, turbine, boiler, or other device greatly reduces the emission of these compounds.
