SOLID WASTE MANAGEMENT - MUNICIPAL LANDFILLS
Fifty years ago
Public Health and Planning controls associated
with sanitary landfills were virtually
non-existent. Household and industrial waste was
either burned or dumped into an open pit and
liquids were discharged into the sewage system or
a convenient watercourse.
dumps became "Sanitary Landfills"
operating under license and waste became big
When household products
i.e. solvents, paint, oils, cleaning
compounds, degreasing compounds, caustic compounds, pesticides,
herbicides, etc. are deposited in sanitary landfills, they
degrade and produce by-products which can be more toxic than the products from which they
solid waste is deposited into a landfill a number
of physical, chemical and biochemical reactions
occur that result in the production of leachate.
Leachate is a liquid and is a direct result of
rain sinking into the wastes, picking up
chemicals as it seeps downward. Leachate
characteristics are significantly affected by the
presence of both aerobic and anaerobic bacteria.
the initial stages of landfilling, the
decomposition process is initiated by aerobic
bacteria which readily metabolize the
biodegradable component in organic waste. The
resulting by-product consists of carbon dioxide,
small quantities of water, low molecule fatty
acids and heat. During these early stages
leachate strength is relatively low and odor is
landfilling progresses the landfill goes through
a transition. During this transition period the
aerobic microbes are depleted and the anaerobic
microbes become dominant resulting in a period of
facilitative microbial activity. Typically, the
transition is characterized by a sharp reduction
in pH accompanied by an increase in BOD and COD.
This sharp reduction in pH results in the
solubilization and mobilization of metals and
their accompanying anions. Typical observations
of leachate at this juncture reveal increased
levels of hardness and dissolved solids as well
as metals. Generally, iron concentrations are
characteristically high during this period. This
imbalance results in the emission of foul odor
and a leachate flow that, aside from being thick
and dark in color, emits strong foul odor.
Generally, fly, insect and pest infestations
increase during this period.
odor, accelerate the decomposition of the
biodegradable component in organic waste, reduce
fly and insect infestations and increase the
useful life of a landfill by a substantial
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