United States
Environmental Protection
Agency
Hazardous Waste Engineering ~* &
Research Laboratory / | \
Cincinnati OH 45268
Research and Development
EPA/600/S2-85/091 Dec. 1 985
c/EPA Project Summary
Study of Codisposed
Municipal and
Treated/Untreated Industrial
Wastes
Larry W. Jones, Tommy E. Meyers, and Robert J. Larson
54
A study was undertaken to deter-
mine the long-term effects of codis-
posal of industrial waste (IW) and mu-
nicipal solid wastes (MSW) under
controlled, simulated landfill condi-
tions. Three IW's (treated or untreated
by solidification) were disposed with
MSW in nine specially designed test
cells at an approximate volume ratio of
1:4. The sealed test cells were leached
with distilled water at a rate of 1.27 cm
per week. Leachate was collected
anaerobically and analyzed for 28
parameters monthly or quarterly over a
4-year period. The three IW's were an
electroplating waste (EPW), a chlorine
production brine (CPB), and a glass-
electronics etching sludge (GES). Two
processes were used for solidification
of the wastes: one added cement plus
a patented ingredient to waste, and
the other mixed waste with lime and
flyash.
In all cases, the codisposal of treated
or untreated IW and MSW had signifi-
cant effects on the nature of the
leachate produced. All IW's increased
the pH of the leachates from about 5.3
to 6.3, which alone could affect compo-
nent solubilities and biological activi-
ties of the MSW. The GES inhibited bio-
logical activity in the MSW to the
greatest extent, and the EPW inhibited
it less. The CPB had little or no effect on
the MSW biological activity. Both pre-
treatment systems greatly decreased
the apparent effects of IW on the bio-
logical activity in the MSW.
Heavy metals in the untreated and
treated IW's generally did not appear in
the MSW leachates in appreciable
amounts. However, heavy metal con-
centrations were generally increasing
in the leachates during the last year of
the study.
IW's containing soluble salts (CPB,
for example) are not good candidates
for disposal with MSW, even after pre-
treatment. Levels of salts from CPB test
cells were high and consistent over the
entire study period, even when the CPB
was pretreated.
Interaction of leachates with a 31-cm
layer of soil at the bottom of the test
cells produced only minor modifica-
tions in leachate quality. However, in-
teraction of soil and leachate can in-
crease rather than reduce the pollution
potential of the leachate.
This Project Summary was devel-
oped by EPA's Hazardous Waste Engi-
neering Research Laboratory, Cincin-
nati, OH, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
Disposal of industrial wastes (IW's)
has become increasingly expensive and
difficult because of heightened public
awareness and regulatory restrictions.
In the past, nearly all types of wastes
were indiscrimirtantly disposed of at lo-
cal dump sites. Increasing interest and
progress in landfilling technology
quickly followed U.S. Environmental
Protection Agency (EPA) bans on burn-
ing at dumpsites. Landfilling is now the
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recommended and nearly universal
method of disposal for municipal solid
wastes (MSW), and IW's have been
delegated to secure landfills or
incineration.
Though disposing of hazardous IW
along with MSW in dumps and landfills
was a common U.S. practice until a few
years ago, little information is available
in this country on the environmental ef-
fects of this practice. Codisposal with
MSW is the recommended practice for
many hazardous wastes in Great
Britain, where researchers claim that
the scientifically determined disposal of
hazardous wastes with MSW can be an
acceptable and even preferred manage-
ment alternative for many toxic
substances.
This study addresses the effects of IW
and MSW codisposal in a simulated
MSW landfill environment. Eleven large
(181-cm-diameter) test cells were f'lled
with MSW only or with MSW plus one
of three IW's—an electroplating waste
(EPW), a chlorine production brine
(CPB), and a glass-electronics etching
sludge (GES). Two additional smaller
cells were also filled with MSW only. All
wastes were collected from actual in-
dustrial waste streams.
A secondary goal of the study was to
investigate the possible use of chemical
solidification/stabilization of the IW to
reduce contaminant loss in the codis-
posed wastes. Two commercially avail-
able methods were used for this
process.
This report describes the overall re-
sults of the leaching data from all three
IW's, treated and untreated, for leachate
samples collected above and below a
31-cm soil layer over the complete four-
year (1510-day) study period.
Materials and Methods
The three IW's, treated or untreated,
were codisposed with MSW in nine
large (9.65 m3 total volume), especially
designed test cells. MSW and treated or
untreated IW were loaded m the test cells
in a ratio of approximately 4.1 by volume.
The sealed test cells were leached with
distilled water at a rate of 1.27 cm per
week. The leachate was collected anaer-
obically and analyzed for 28 parameters
monthly or quarterly over the four-year
study period.
Four test cells loaded with MSW only
were also included in the study as con-
trols. Of these cells, two were smaller
and had half the height and diameter
(i.e., 1/8th the volume) of the large cells.
Selected Wastes
The three IW's included in this study
(EPW, CPB, and GES) are largely inor-
ganic, have high levels of toxic heavy
metals and/or soluble inorganic salts,
and are produced in large quantities in
the United States. They are considered
to be some of the most difficult to con-
tain and are at the root of many environ-
mental problems.
The MSW used in this study was pro-
vided by the Sanitation Department of
the City of Vicksburg, Mississippi, and
by two private haulers operating in War-
ren County, Mississippi. Residential col-
lection routes were selected to exclude
any commercial, industrial, or hospital
wastes.
Test Cell Design
The test cells were designed to simu-
late a 1.83-m-diameter core through a
typical landfill in which IW and MSW
might be codisposed. The cells were de-
signed so that deionzied leaching water
of known composition and pH could be
added in premeasured amounts
through the top of the otherwise sealed
cells and the resulting leachates could
be sampled above and below a 31-cm
soil layer. The test cells were free-
standing, rolled steel cylinders housed
in a large-scale facility that maintained a
temperature of 25 ± 3°C year-around.
All interior cell surfaces were coated
with an acid-base resistant coal tar
epoxy to protect the walls from corro-
sion or leaching. As mentioned, 11 of
the units were large (1.83 m internal di-
ameter by 3.66 m high), and two were
small (0.91 m inside diameter by 1.93 m
high). The small cells were filled with
MSW only and were used to evaluate
the effects of test cell size on leachate
quality. All cells contained polyethylene
beads in the leachate storage space on
the bottom to provide support of the
soil layer and pore space storage for
leachate.
Test Cell Loading
Two large and two small cells were
loaded with MSW only. The remaining
nine cells were loaded with two layers
of treated or untreated IW interspersed
between three layers of MSW. The
MSW was placed in 30.5-cm lifts that
were compacted to 400 to 415 kg/m3 wet
density with a 2315-kg lead weight.
Each layer of chemically treated IW was
made up of four cylindrical, 61-cm-
diameter cores of solidified/stabilized
waste product. MSW was also packed
around the treated IW cores and com-
pacted to approximately the same wet
density by use of a hand-held tamper.
This loading yields an MSW-to-IW vol-
ume ratio of approximately 4 to 1, which
is in the range recommended for
codisposal.
Leachate Collection and Pro-
cessing
Leachate samples were handled with
care to preserve their anaerobic nature
during sampling and before preserva-
tion. Quarterly leachate samples were
drawn by suction from the test cells
through Tygon* tubing into a 500-ml
stoppered glass aspirator bottle
mounted on the glovebox. Leachate
was then forced inside the glovebox
with He pressure. The glovebox had
previously been purged with He for at
least 5 minutes. The smaller monthly
samples were prepared within the
glovebox without contacting atmo-
spheric air. They could be subsampled
and preserved quickly enough to make
the He atmosphere unnecessary.
Parameters measured included the fol-
lowing:*
Specific conductance B
Alkalinity Be
Cl Cd
TKN Cr
TP
TOC
Ca
Fe
K
Mg
Mn
Na
Al
As
Cu
Hg
Ni
PB
Se
Zn
BOD5
COD
TVA
pH
F
*TKN = Total Kjeldahl Nitrogen; TP
= Total Phosphate; TOC = Total
Organic Compound; BOD5 = Bio-
chemical Oxygen Demand; COD =
Chemical Oxygen Demand; TVA =
Total Volatile Acids.
Conclusions
Leachates from Cells Contain-
ing MSW Only
Leachates from the test cells contain-
ing only MSW were typical of those re-
"Mention of tradenames or commercial products
does not imply endorsement or recommendation
for use.
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ported in the literature. Initial leachates
have very high organic loadings,
slightly acidic pH (around 5.3), and sig-
nificant ionic loadings. Early samples
exceeded drinking water standards for
all constituents with an established
standard except Cu. Throughout the
study, Fe and Mn concentrations aver-
aged 1000 and 100 times the drinking
water standard, respectively. As, Cr, Se,
Zn, and Cl also exceeded these stan-
dards in their average concentrations in
the leachate.
Levels of constituents varied greatly
in the leachates from the four cells con-
taining MSW only. This variability set
the lower limit for detecting the effects
of adding IW's to the MSW.
Levels of constituents varied greatly
in the leachates from the four test cells
containing MSW only. This variability
set the lower limit for detecting the ef-
fects of adding IW's to the MSW.
The two small control cells, contain-
ing only 1/8 the volume of the larger
ones, received twice the volume of
leachate per kg of dry MSW. Compari-
son of these results with those of the
larger control cells indicated that the
loss of many metals and the oxygen de-
mand were proportional to the amount
of leachate produced and largely inde-
pendent of the amount of waste or its
configuration. However, losses of the
highly soluble constituents such as Na
and Cl were more nearly proportional to
the amount of MSW loaded into the test
cell than to the volume of the leachate
produced.
Leachates from Cells Contain-
ing Codisposed IW and MSW
In all cases, the codisposal of treated
or untreated IW with MSW had signifi-
cant effects on the character of the
leachates produced.
Organic Parameters
Untreated IW's Disposed with
MSW
Inclusion of any of the untreated IW's
increased leachate pH from about 5.3 to
about 6.3, which alone would be ex-
pected to affect component solubilities
and biological activities. The GES ap-
peared to inhibit MSW biological activ-
ity to the greatest extent. Cells contain-
ing untreated GES had leachates with
lower COD and BOD (both averaged
only 28% of the values for MSW-only
leachates), lower TOC (29% of MSW-
only values), and lower TVA (34% of
MSW-only values). The untreated EPW
had a smaller inhibitory effect, on these
parameters, averaging 50% to 75% of
their values in the MSW-only leachates.
The untreated CPB had little or no effect
on these parameters; however, it did
produce a small pH change. The inhibi-
tion appears to be the result of minor
components such as toxic metals rather
than high soluble salt levels or high pH.
Treated IW's Disposed with
MSW
Test cells containing solidified IW's
and MSW produced leachates with pH
values and organic parameters similar
to the MSW-only leachates. Thus, both
processes appeared to overcome the in-
hibitory effects of the IW's on the micro-
biological processes in the MSW.
Heavy Metals
Heavy metals in the IW's were not
readily leached out of the test cells. The
EPW, for example, contained the
highest levels of the heavy metals—6%
Cr, 10% Cu, and 0.3% Ni. This untreated
waste produced leachates with signifi-
cantly increased levels of these metals,
but the increases were very small com-
pared with the total metals added to the
cells. Test cells with MSW and treated
EPW did produce significantly higher
leachate levels of Ni but not of Cr or Cu.
Test cells with MSW plus treated or un-
treated CPB or GES produced leachates
without significantly higher or lower
metal levels, since neither waste con-
tained appreciable amounts of heavy
metals.
The codisposal of MSW and IW's con-
taining high levels of heavy metals in
hydroxide sludges may be an environ-
mentally acceptable option since the
added metals were not found in large
quantities in the MSW-IW leachates.
Note, however, that the metal levels in
these leachates were slowly increasing
in the last year of the study, and their
levels could increase appreciably over
time. Also, the added IW appears to in-
hibit or modify the microbial activity in
the MSW mass; thus long-term results
cannot be predicted without knowledge
of how metal ions affect MSW microbial
stabilization.
Soluble Salts
Soluble salts in the IW's were imme-
diately apparent in the leachates from
those test cells. The cell containing
MSW plus untreated CPB produced
leachates with extremely high Na and Cl
concentrations, even after four years.
Solidification of the CPB did reduce the
initial concentrations, but their losses
were still high and consistent through-
out the study. Na and Cl were also
found at consistently higher levels in
leachates from test cells containing
both treated and untreated EPW and
GES, but these concentrations were
only two to three times those of MSW-
only leachates. The codisposal of MSW
and IW's with high levels of soluble
salts, therefore, appears to be environ-
mentally unsafe because of the rapid
and large losses of salts to leaching
waters even after pretreatment with
solidification.
Calcium and Magnesium
The divalent cations Ca and Mg were
prevalent in all leachates, including the
controls. The presence of treated or
untreated IW increased their concentra-
tions by 100% to 200%. Ca was a major
component in all the IW's and was
found near its solubility limit in all IW
leachates.
Iron
Fe levels in the leachates are probably
indicators of the overall microbial activ-
ity in the waste mass. Addition of any of
the untreated IW's to MSW consistently
lowered the Fe concentration in the
leachates produced, most likely be-
cause of inhibition of the microbial
activity in the test cells.
Interaction of Leachates with
the Soil Layer
Interaction of leachates from test cells
with a 31 -cm layer of a clayey-sandy soil
produced only minor modifications in
leachate quality. Most constituents
were not affected by passage through
this layer, but As and TP were signifi-
cantly removed. Al, Cd, and Hg were
added to the leachates from the soil in
significant amounts. The interaction of
MSW leachates with underlying soils
requires more study. Apparently, the
soil cannot simply be considered as an
absorber of materials from the passing
leachate. Leachates can interact with
the soil and remove selected soil con-
stituents, thereby increasing rather than
reducing the overall pollution potential
of the leachate.
The full report was submitted in fulfill-
ment of Interagency Agreement No. D4-
0569 by the U.S. Army Waterways Ex-
periment Station under the sponsorship
of the U.S. Environmental Protection
Agency.
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Larry W. Jones, Tommy E. Myers, and Robert J Larson are with U.S. Army
Engineer Waterways Experiment Station, Vicksburg, MS 39180.
Robert E. Landreth is the EPA Project Officer (see below).
The complete report, entitled "Study of Codisposed Municipal and Treated/
Untreated Industrial Wastes," (Order No. PB 85-235 588/AS; Cost: $20.50,
subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, V'A 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Hazardous Waste Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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