United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-84-172 Jan. 1985
X,
&ER& Project Summary
Evaluation of Processed
Municipal Wastes in
Landfill Cells
James M. Kemper, Ned J. Kleinhenz, and Joseph T. Swartzbaugh
This project demonstrated the decom-
position effect of preprocessing land-
filled wastes as relates to leachate and
gas production and the concentrations
of the waste constituents in those
leachates and gases. The study was
performed in Franklin, Ohio, where five
landfill test cells (buried concrete landfill
simulators) were monitored. These five
concrete test cells contained municipal
refuse which was processed as follows:
(1) shredded and baled; (2) baled; (3)
baled and saturated with water; (4)
shredded; and (5) unprocessed. These
processing methods were evaluated by
collecting leachate and gas samples to
determine moisture balances, leachate
pollutant concentrations, and gas com-
positions.
Compared with unprocessed wastes,
the baled wastes produced large quanti-
ties of dilute leachate, and the shredded
wastes produced smaller quantities of
more concentrated leachate. Gas com-
position data from the wastes were
inconclusive because of numerous gas
leaks and the small volume of gas
produced in the system.
This Project Summary was developed
by EPA's Hazardous Waste Engineering
Research Laboratory, Cincinnati, OH,
to announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
Municipal solid waste (MSW) that is
placed in a landfill initially decomposes
under aerobic conditions. This process
slows down as the available oxygen is
exhausted, and anaerobic decomposition
commences. With the onset of anaerobic
digestion, gas is liberated in the form of
methane, carbon dioxide and trace gases
such as hydrogen sulf ide. The generation
of these gases presents potential prob-
lems in the physical area of the landfill
site, mainly because of the methane
content. Methane forms an explosive
combination with the oxygen in air when
present in concentrations of 5 to 15
percent. Thus it is important to determine
the amount and rate at which methane is
produced in a landfill situation. To calcu-
late these data, quantitative and qualita-
tive information is needed on both the
methane produced and the other gaseous
components involved.
Landfills will produce leachate when
subjected to precipitation. This leachate
is formed by the dissolution of both
organic and inorganic materials as the
water infiltrates the waste layers of the
landfill area. The leachate will continue
its filtration through the landfill, ultimate-
ly moving out of the fill area and into the
surrounding soil. Sincethe leachate could
contain large amounts of heavy metals,
pesticides, or herbicides, contamination
of both surface and subsurface water is a
distinct possibility.
Methods and Materials
Three preprocessing steps for MSW
were evaluated i.e., shredding, shredding
and baling, and baling alone. Also studied
was the effect of a saturated landfill
environment on gas and leachate produc-
tion. All data were compared with those
obtained from untreated wastes as a
control.
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The facility designed to accomplish this
goal consisted of five identical, concrete,
in-ground test cells large enough to
contain approximately 10,000 kg of mu-
nicipal solid waste in a simulated landfill
configuration. See Figures 1 and 2 for
facility layout and design, respectively.
A larger instrumentation cell of similar
design was also constructed to collect
data, gas samples, and leachate.
The following type of pretreated solid
waste was placed in each of the five test
cells.
Cell Type of Pretreatment
1 Shredding and Baling
2 Baling
3 Baling (saturated conditions)
4 Shredding
5 No pretreatment
To help ensure waste uniformity, the
initial concept was to obtain all the solid
waste from the City of Oakwood, Ohio.
During the early phase of the project, the
local baling facility was damaged by fire.
New facilities were found in Georgia: a
baling facility in Cobb County and a
shredder facility in DeKalb County. The
MSW was first shredded and then trans-
ported to the test site in Franklin, Ohio.
Because of the extremely complex logis-
tics (including material, equipment, and
personnel requirements) as well as the
financial requirements, it became imprac-
ticable to obtain nonbaled MSW from this
same source. Instead, the nonbaled MSW
was obtained from the original source,
Oakwood, Ohio.
An additional requirement of the con-
tract called for the characterization of the
solid waste at the different facilities.
Therefore, provisions were made for
handsortmg the solid waste at each facil-
ity from which waste was obtained. Three
of these sorts were performed for each
facility in order to better categorize the
solid waste used in this study. A compari-
son of the results of the waste categoriza-
tion procedures is illustrated in Figure 3.
Once the cells were filled and instru-
mented, they were sealed and the test
monitoring was initiated. During the test
period, all cells but No. 3 were subjected
to moisture additions and drainage that
approximated the net infiltration pattern
of landfills in the midwestern United
States.
Results
Nearly 6 years of monitoring the effects
of preprocessing MSW resulted in data
that may affect both future landfill simu-
lation studies and landfill technology in
general.
Test Cells
o
©
Instrumentation
Room
Figure 1. Test cell arrangement.
Gas Meter
Temperature Probe
Leachate
Sump
Figure 2. Stylized diagram of test cell.
This study concluded that temperature
differences among wastes in landfill
simulators need not be taken into account
when evaluating waste processing meth-
ods. The temperature data collected in
this study indicated that the baled cells
had higher initial temperatures than the
nonbaled test cells because of aerobic
decomposition. After this initial stabiliza-
tion period, no major temperature differ-
ences existed between the cells at any
one time. Of course, seasonal changes
occurred in the internal temperatures of
the cells, but each cell matched its
neighbor very closely.
When compared with unprocessed
wastes, the baled wastes produced large
quantities of dilute leachate and the
shredded wastes produced smaller quan-
tities of more concentrated leachate.
Leachate from waste that was both baled
and saturated with water was similar to
the unprocessed waste in leachate
volume and concentration. Gas composi-
tion data from the wastes were incon-
clusive because of numerous gas leaks
and the small volume of gas produced in
the system. Recommendations are includ-
ed to alleviate this problem for future
landfill situations.
Conclusions
In summary, the data indicate that
baling alone and shredding alone are the
processes to consider when designing
sanitary landfills. A locality should choose
a preprocessing method based on the rate
of leaching desired in that area.
Although collection of volume data was
plagued by a constant battle to maintain
gas-sealed test cells over nearly 6 years
of monitoring, this study yielded valuable
information for future researchers who
must construct test facilities to study gas
generation in a landfill environment. The
following recommendations are made for
the construction of future gas-tight test
cells and for collecting accurate gas
measurements:
1. Landfill test cells should be con-
structed of steel rather than con-
crete to eliminate the possibility of
cracks developing as a result of
ground settling.
2. All gas collection lines should con-
sist of metal tubing with high-quality
tube fittings.
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Figure 3.
Food Garden Paper Plastics, Textiles Wood Metal Glass Ash, Fines Sample
Rubber & Rocks Moisture
Leather * Dirt Content
Refuse Categories
Refuse composition comparison.
3. All gas should be collected with
aluminized plastic or Tedlar* gas
bags rather than direct connections
to gas meters.
4. Continuous welding should be used
in any areas that require sealing,
such as the test cell lids.
5. In any case where welding is not
feasible, the surfaces to be sealed
should be smooth and unnotched to
ensure positive placement of any
gasket material. Such gasketed
surfaces should incorporate a seal-
ant and be drawn together with a
bolt-and-nut arrangement.
The full report was submitted in fulfill-
ment of Contract No. 68-03-2598 by
Systech Corporation, Xenia, OH, under
the sponsorship of the U.S. Environmental
Protection Agency.
James M. Kemper, Ned J. Kleinhenz, and Joseph T. Swartzbaugh are with
Systech Corporation, Xenia, OH 45385.
Dirk Brunner and Norms Lewis were the EPA Project Officers fsee below}.
The complete report, entitled "Evaluation of Processed Municipal Wastes in
Landfill Cells,"(Order No. PB 85-117109; Cost: $11.50. subject to change) will
be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield. VA 22161
Telephone: 703-487-4650
For further information, contact Norbert B. Shomaker at:
Hazardous Waste Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
* U S GOVERNMENT PRINTING OFFICE, 1985 - 559-01 6 7892
'Mention of trade names or commercial products
does not constitute endorsement or recommenda-
tion for use.
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Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
EPA
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