TM 5-814-5
(e) Ambient temperature.
nicipal STP avoids the cost of onsite facilities, the
(f) Available moisture from the surrounding
need for personnel to operate them, and future
environment.
operational problems which can result when lea-
(g) Molecular oxygen levels in the refuse. The
chate characteristics change as the landfill ages, or
three primary reasons for assessing leachate quality
leachate volume decreases below the design
before determining the type of treatment required
capacity of an onsite treatment system.
(3) Onsite Treatment.
are to:
(a) Onsite treatment is generally used only at
(1) Identify whether the waste is hazardous.
(2) Design or gain access to a suitable waste-
large, remote landfills. Biological treatment
water treatment plant.
processes are most often used for leachate from
(3) Develop a list of chemicals for use in a
landfills less than five years old, and physical/chem-
ground-water monitoring program. See table 3-1
ical treatment processes for landfills more than ten
for leachate characteristics and common constitu-
years old. Combinations of the two are necessary
ents found in landfill leachate. Leachate quantity is
for landfills between five and ten years old.
(b) Biological treatment removes most dis-
greatly dependent on the landfill design. A quantity
estimate of leachate should be provided before
solved organics, heavy metals, nutrients such as
deciding which treatment/disposal methods will be
nitrogen and phosphorus, and colloidal solids. Typ-
used.
ical biological processes include: activated sludge,
(2) Offsite Treatment. The most common and
stabilization ponds, rotating biological contactors,
often the most economical method for treatment of
and trickling filters.
(c) Physical/Chemical processes include: am-
leachate is to discharge to a municipal sewage
treatment plant (STP) offsite. While there is little
monia stripping to reduce ammonia to nontoxic
data available, some plants have accepted high
levels, carbon absorption to remove a variety of
strength leachate in quantities of 2 to 5 percent of
organic compounds, chemical oxidation (chlorina-
the total daily flow to the plant, and have reported
tion) for disinfection, ion exchange to remove
no adverse impact. However, moderate increases in
soluble metallic elements and certain anions and
oxygen uptake, foaming and odors may occur, in
acids, precipitation, flocculation and sedimentation
addition to increased sludge production and metals
to remove particulates and soluble heavy metals,
concentrations in the sludge. Treatment at a mu-
reverse osmosis to separate out dissolved salts and
3-9
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