HAZARDOUS WASTE TREATMENT - Environmentally Conscious Materials Handling - page 192

less than 1 percent nonmethane organic compounds, and trace amounts of inor-
ganic compounds. The decomposition process in a landfill that is generating
significant amounts of gas lasts about 15 to 25 years, and the volume of gas
decreases steadily over this period of time. There are two compliance options
under the regulations: install a landfill gas collection system and flaring, or install
a landfill gas collection system and an energy recovery system. A flare system
provides the opportunity to combust the landfill gas in the event that the gas is not
needed. However, landfills increasingly capture and use of landfill methane as fuel
for electricity generation through the development of well fields and collection
systems.
There are several treatment options for landfill leachate after collection. For
example, sedimentation, air stripping, adsorption, and membrane filtration are
the major physical methods used for leachate pretreatment. Coagulation with
flocculation and chemical precipitation are the primary chemical methods used
for treating leachate. Some physiochemical processes—including nano filtration,
air stripping, and ozonation—are also utilized for COD and ammonium removal,
as well as toxicity reduction (Kargi et al. 2003). Anaerobic treatment methods are
suitable to concentrated waste streams such as leachate, particularly when used
in an SBR (Kennedy 2000). However, leachate can also have a high variability in
both strength and flows. Anaerobic treatment methods also generate significant
amounts of methane, a potentially valuable product. In the SBRs, slower fill
times than when treating domestic sewage are required, as they result in less
stress on the biological population in the tank especially with the highest organic
loading rates. Leachate from traditional municipal landfills can additionally be
characterized as hazardous, especially to most wastewater systems unable to treat
the high toxicity of the leachate.
REFERENCES
Chambers et al. 1991. In situ treatment of hazardous waste-contaminated soils . Park Ridge,
NJ: Noyes Data Corporation.
Chapell, F. H. 1995. Bioremediation: Nature's way to a cleaner environment. From U.S.
Department of the Interior, U.S. Geological Survey, Fact Sheet FS-054-95 . http://water.
usgs.gov/wid/html/biorem.html.
DePaoli, D., J. Wilson, and C. Thomas. 1996. Conceptual design of soil venting systems.
Journal of Environmental Engineering 122 (5).
Eckenfelder, W. W., Jr. 2000. Industrial water pollution control . McGraw-Hill Series in water
Resources and Environmental Engineering, New York: McGraw-Hill.
Eckenfelder, W. W., Jr., and J. L. Musterman. 1995. Activated sludge treatment of industrial
wastewater . Lancaster, PA: Technomic Publishing Company.