United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-92/240 March 1993
EPA Project Summary
Pilot-Scale Incineration of
Contaminated Sludges from the
Bofors-Nobel Superfund Site
C. King and L.R. Waterland
A detailed test program was performed
at the U.S. Environmental Protection
Agency's (EPA's) Incineration Research
Facility (IRF) to help determine the effec-
tiveness of Incineration in treating two
contaminated lagoon sludges from the Bo-
fors-Nobel Superfund site In Muskegon,
ML The sludges tested were contaminated
with various organic constituents and trace
metals. Three incineration tests were con-
ducted for each sludge, for a total of six
tests, in the IRFs pilot-scale rotary kiln
Incineration system (RKS). Target incin-
eration conditions were held constant for
all six tests, with a kiln temperature of
982°C (1,8000F); kiln exit flue gas O2 at 8%
to 10%; afterburner temperature of 1,204°C
(2,200°F); and afterburner exit flue gas O,
at 6%.
The test results suggest that Incinera-
tion under the conditions tested repre-
sents an effective treatment option for the
lagoon 8 sludge. Substantial decontami-
nation of organics from the sludge was
achieved; the principal organic hazardous
constituent (POHC) was not detected In
the flue gas; partlculate and HCI emis-
sions were low and In compliance with
the incinerator performance standards;
and Incineration residuals (kiln ash and
scrubber liquor) would not be toxicfty char-
acteristic (TC) hazardous wastes based
on teachable trace metal content
Incineration also appears to be an ef-
fective treatment option for the lagoon 3
sludge: substantial organic decontamina-
tion was achieved; the performance stan-
dard of 99.99% destruction and removal
efficiency (ORE) for POHCs was met; and
the resulting kiln ash toxicfty characteris-
tic leaching procedure (TCLP) leachate had
trace metal concentrations below regula-
tory limits. A wet scrubber air pollution
control system (APCS) of the type tested
may not, however, be an appropriate
choice for air pollution control. While HCI
emissions were acceptable, partlculate
emissions at the primary APCS exit were
greater than those allowed by the Incin-
erator performance standards. Low cad-
mium and lead collection efficiencies re-
sulted in cadmium emission levels in the
153 to 206 ng/dscm range and lead emis-
sion levels In the 4,420 to 6,180jig/dscm
range. In addition, the unfittered scrubber
liquor discharge exceeded the TCLP lim-
its for lead and approached the limit for
cadmium (scrubber liquor filtrate concen-
trations may be below these limits). If a
wet scrubber APCS is used, incineration
at a kiln temperature lower than the 982°C
(1,800°F) temperature tested might be war-
ranted. A lower kiln temperature would
likely reduce the amount of cadmium and
lead volatilized and carried out of the kiln
in the combustion gas.
This Project Summary was developed
by EPA's Risk Reduction Engineering
Laboratory, Cincinnati, OH, to announce
key findings of the research project that Is
folly documented In a separate report of
the same title (see Project Report order-
Ing Information at back).
Introduction
One of the primary missions of the IRF,
located in Jefferson, AR, is to support EPA's
Regional Offices in evaluating incineration as
a treatment option for contaminated soils and
sludges at Superfund sites. One priority site
Printed on Recycled Paper
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In Region V is the Bofors-Nobel s'rte in
Muskegon. The U.S. Army Corps of Engi-
neers requested that the IRF conduct test
bums to support evaluations of incineration
as a treatment technology for the contami-
nated sludges at the site.
The Bofors s'rte was included as a Super-
fund site on the National Priority List in
March 1989. Several former lagoons at the
site contain sludges contaminated with sev-
eral volatile and semivolatile organic contami-
nants, chiefly methylene chloride, chloroform,
benzene, toluene, azobenzene, benztiine, and
3,3'-dichtorobonzkiin9. The sludges are also
contaminated with several trace metal con-
taminants, chiefly barium, cadmium, chro-
mium, and lead. The purpose of the test
program was to evaluate the incinerability of
selected site sludges in terms of the destruc-
tion of organic contaminants and the fate of
contaminant trace metals. The specific test
objectives addressed the following questions:
* Can Incineration effectively destroy the
sludges' POHCs to the required ORE of
99.99%?
• Are treated sludges (kiln ash) free of
organic contamination?
• What are the nature and concentrations
of any organic contaminants in the
discharge from a wet scrubber ARCS?
• What is the distrfoutfon of the contaminant
trace metals among the incineration
system discharge streams?
• What is the effectiveness of the IRF
ARCS in collecting partfculate and trace
metals?
This test program investigated the treat-
ability of sludges from two of the five lagoons.
Three incineration tests, under similar incin-
erator operating conditions, were performed
for each of the two sludges. All of the tests
were conducted In the IRFs pilot-scale RKS,
which was equipped with a venturi scrubber/
packed-column scrubber ARCS.
Results of the test program are discussed
in the subsections that folbw.
Test Program
TestFartllty
A process schematic of the RKS is shown
fn Figure 1. The IRF RKS consists of a pri-
mary combustion chamber, a transition sec-
tion, and a fired afterburner chamber. After
exiting the afterburner, flue gas fbws through
a quench section followed by a primary ARCS.
The primary ARCS for these tests consisted
of a venlun scrubber followed by a packed-
column scrubber. Downstream of the primary
ARCS, a backup secondary ARCS, consist-
Ing of a demister, an activatedorbon ad-
sorber, and a high-efficiency partfculate air
(HERA) fiher, is in place.
Test Waste Description
The record of decision (ROD) document
for the Bofors site identifies five lagoon slud-
ges as candidates for incineration treatment.
The sludges in these five lagoons are con-
taminated to varying degrees by several vola-
tile and semivolatile organic compounds. From
the baseline risk assessment, the ROD iden-
tified six principal organic contaminants of
concern: methylene chloride, benzene, 3,3'-
dichlorobenzidine, aniline, azobenzene, and
benzidine. Hazardous metal contaminants
were also present. Among these, cadmium
and lead were present at maximum concen-
trations of 22 and 887 mg/kg, respectively, in
some lagoon sludge samples.
Two of the five incineration candidate slud-
ges, the lagoon 3 and lagoon 8 sludges, were
selected for testing at the IRF based on the
results of the bench-scale thermal treatability
studies and on other considerations.
Test Conditions
Three tests were performed at similar in-
cinerator operating conditions for each la-
goon sludge selected (six tests total). For
each test, sludges were fed to the kiln via the
fiberpack-drum ram feeder system. This sys-
tem batch feeds 1.5-gal fiberpack drums to
the kiln. Each fiberpack drum was packaged
to contain nominally 4.6kg (10 Ib) of sludge.
During each test, one fiberpack was charged
into the kiln every 5 min, resulting in target
sludge feedrates of nominally 55 kg/hr (120 Ib/
hr). The kiln rotation rate was set to result in
solids residences times in the kiln of 45 to
60 min.
Table 1 compares the target and actual
test operating conditions for each test. As
shown, average kiln temperatures were within
25°C (44°F) of target temperatures for all
tests. Kiln exit flue gas O, levels were within
2% of target levels. Afterburner temperature
was within 4°C (7°F) of target for all tests.
Sampling and Analysis
In addition to obtaining sludge feed, kiln
ash, and scrubber liquor samples, the sam-
pling protocol for all tests included sampling
the flue gas at the afterburner exit and at the
scrubber system exit: EPA Method 0010 for
semivolatile organic constituents; EPA Method
0030 for volatile organic constituents; and an
Anderson cascade impactor train for particu-
late size distribution. In addition, the EPA
multiple metals sampling train sampled the
flue gas downstream of the scrubber system
for trace metals. Finally, EPA Method 5 was
used to sample the flue gas at the afterburner
exit, the scrubber system exit, and the stack
downstream of the secondary APCS for par-
tfculate and HCI.
In addition to analyzing flue gas sampling
trans for their sampled analyte set, the sludge
feed sample for each test and each of the kiln
ash and scrubber liquor samples were ana-
lyzed for semivolatile and volatile organic haz-
ardous constituents and trace metals. Also,
the sludge feed and the kiln ash for each test
were subjected to TCLP extraction, and the
resulting leachates were analyzed for trace
metals.
Test Results
Volatile Organic Constituents
Table 2 summarizes the volatile organic
constituent concentrations measured in each
lagoon 3 test sample. A compound is noted
in Table 2 if it was found in any test program
sample in Tests 1 through 3. The major vola-
tile organic contaminants in the lagoon 3
sludge samples were benzene, toluene, me-
thylene chloride, and chloroform. These com-
pounds were generally not found in the incin-
eration residuals streams (kiln ash and scrub-
ber liquor) or in the incinerator flue gas at the
two locations sampled.
Incineration effectively decontaminated the
lagoon 3 sludge of its major volatile organic
constituents. Using the sludge feed and ash
collected weights from each test, and the
composition data in Table 2, the following
decontamination efficiencies were calculated:
at least 99.995% for methylene chloride;
greater than 99.9991% for chloroform; and at
least 99.99994% for benzene and toluene.
Tables summarizes the volatile organic
constituent concentrations measured in each
lagoon 8 sludge incineration test sample.
Again, a compound is noted in Table 3 if it
was found in any test sample from Tests 4
through 6. As shown in Table 3, toluene was
the only volatile organic contaminant found in
the lagoon 8 sludge; it was present at only
3 mg/kg. Toluene was found in all three kiln
ash samples at levels of 36 to 38 (jg/kg. The
amount of toluene discharged in the kiln ash
was about 0.5% of the amount fed. Thus,
incineration achieved a decontamination effi-
ciency for toluene of about 99.5%.
Benzene, ethyl benzene, and xylenes were
found in all kiln ash samples at about 40,10,
and 10 ug/kg, respectively. No toluene, ben-
zene, ethyl benzene, or xylenes were found
in the scrubber liquor or the flue gas at either
location sampled.
Semivolatile Organic Constituents
Of the list of analytes sought in the
semivolatile organic analyseis, only
azobenzene and 3,3'-dichlorobenzidine
were found in the lagoon 3 sludge and
only 3,3'-dichlorobenzidine was found in
the lagoon 8 sludge. The lagoon 3 sludge
contained an average of 5,110 mg/kg of
azobenzene and 4,390 mg/kg of 3,3'-
dichlorobenzidine. The lagoon 8 sludge
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Single -Stage Ionizing
Wet Scrubber
Quench
Afterburner
Air
Natural
Gas,
Liquid
Feed
Transfer Duct
Rotary
Kiln
Natural Gas;
Liquid Feed
Scrubber Uquor
Recirculation
Atmosphere
Demister
t
Stack
Carbon Bed HEPA
Adsorber Filter
Rotary Kiln
Incinerator
Modular Primary Air
Pollution Control
System Devices
Redundant Air
Pollution Control
System
F/gore r. Schematic of the IRF rotary kiln incineration system.
contained 710 mg/kg of 3,3'-
dichlorobenzidine.
No semivolatile organic constituents were
found at concentrations above the method
practical quantitation limit (PQL) in any test
program incineration residuals (kiln ash and
scrubber liquor) or flue gas (measured at
both the afterburner and scrubber exits)
samples. Using the sludge feed and ash col-
lected weights from each test, the sludge
feed organic contaminant concentrations noted
above, and the ash contaminant PQLs, the
following decontamination efficiencies were
calculated: greater than 99.990% to 99.993%
for azobenzene from the lagoon 3 sludge;
greater than 99.989% to 99.992% for 3,3'-
dichlorobenzidine from the lagoon 3 sludge;
and greater than 99.89% for 3,3'-
dtehlorobenzidine from the lagoon 8 sludge.
POHCDREs
Based on POHC selection criteria speci-
fied in the hazardous waste incinerator regu-
lations, the POHCs in the lagoon 3 sludge
would be benzene, toluene, and 3,3'-
dichlorobenzidine; in lagoon 8 sludge the
POHC would be 3,3'-dichlorobenzidine.
Table 4 summarizes the DREs measured for
these POHCs in the tests performed.
As discussed above, no POHCs were de-
tected in any flue gas sample analyzed, with
the exception of benzene in the lagoon 3
sludge Test 1 afterburner exit flue gas. There-
fore, except for this one instance, only a
minimum POHC ORE, based on the flue gas
analysis method PQL, can be established.
Table 1. Target Versus Actual Operating Conditions
Kiln
Afterburner
Exit temperature, °C fF)
Test
1
2
3
4
5
6
Target
982
982
982
982
982
982
(1,800)
(1,800)
(1,800)
(1,800)
(1,800)
(1,800)
Actual average
1,007
986
996
988
976
979
(1,844)
(1,806)
(1,825)
(1,811)
(1,788)
(1,794)
Flue gas Oy %
Target
10
10
10
10
10
10
Exit temperature, °C fF)
Actual average Target
10.3
9.4
8.1
8.1
9.5
9.3
1,204
1,204
1,204
1,204
1,204
1,204
(2,200)
(2,200)
(2,200)
(2,200)
(2,200)
(2,200)
Actual average
1,208
1,208
1,208
1,208
1,208
1,208
(2,207)
(2,207)
(2,207)
(2,207)
(2,207)
(2,207)
Flue gas O? %
Target
7
7
7
7
7
7
Actual average
4.7
11.2'
5.7
5.9
6.0
6.1
Afterburner Oz sampling probe clogged.
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Tsbto 2. Concentrations of Volatile Organic Constituents for the Lagoon 3 Sludge Tests
Sample
Trichloro- 1,1,1-Tri
Bromo fluoro- Methylene Chloro- chloro- Chloro- Ethyl Total All
methane methane Acetone chloride form ethane Benzene Toluene benzene benzene xylenes others
Tostl
Sludgo food, mg/kg
Kin ash, mg/kg
Allot burner exit flue gas, \ig/dscm
Scrubber liquor, pgA.
Scrubber exit Hue gas, pg/dscm
Tost 2
Sludgo food, mg/kg
KUn ash, mg/kg
Afterburner exit flue gas, pg/dscm
Scrubber Kquor, pg/L
Scrubbor exil flue gas, pg/dscm
Tost 3
SkJdgo food, mg/kg
K*7 ash, mg/kg
Afterburner oxit flue gas, pg/dscm
ScrubbarKquor, pg/L
Scrubbor exit flue gas, pg/dscm
4.3
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Table 4. Destruction and Removal Efficiencies (Percent) for the Principal Organic Hazardous Constituents
POHC
Test 1
Measured at the afterburner exit
Test 2
Test 3
Measured at the scrubber exit
Testt
Test 2
Tests
Lagoon 3 sludge
Benzene
Toluene
3,3-Dichlorobenzidine
Lagoon 8 sludge
3,3-Dichlorobenzidine
99.961
>99.9917
>99.9958
Test 4
>99.971
>99.989
>99.984
>99.9950
TestS
>99.972
>99.9922
>99.9959
>99.9942
Test6
>99.971
>99.974
>99.9953
>99.9959
Test 4
>99.975
>99.9930
>99.9913
>99.9949
Tests
>99.975
>99.9914
>99.9970
>99.9946
Test6
>99.974
not found in any lagoon 3 sludge sample are
.listed in the last five columns. The data in
Table 5 show that the metals absent in la-
goon 3 sludge samples were not found in any
other test program sample. Metals found in
the lagoon 3 sludge samples were distributed
among all other incineration residuals and
flue gas samples, with the exception of ar-
' senic, which was not found in the scrubber
exit flue gas in Tests 2 and 3.
The data in Table 5 show that the concen-
trations of the five metals detected in the
lagoon 3 sludge were comparable from test
to test in the incinerator discharge streams
with the exception of arsenic, barium, cad-
mium, and chromium in the scrubber liquor.
Scrubber liquor concentrations for these four
metals were unexplainably lower for Test 3
than for Tests 1 and 2. The data in Table 5
show that arsenic, barium, and chromium
levels in the flue gas were generally less than
50ug/dscm. Cadmium and lead levels, how-
ever, were significantly higher at 153 to 206 ug/
dscm for cadmium, and 4,420 to 6,180ug/
dscm for lead.
All test kiln ash samples were subjected to
the TCLP, and resulting leachates were ana-
lyzed. These results are shown in Tables.
The TCLP regulatory level used to establish
the toxic'rty characteristic (TC) is also noted in
the table. As shown, neither the lagoon 3
sludge nor the kiln ash resulting from its
incineration had leachate metal concentra-
tions that would make them TC hazardous
wastes.
The lead concentrations in the bulk, unfil-
tered, scrubber liquor samples from all three
tests exceeded the TCLP regulatory level;
however, the three-test composite scrubber
liquor TCLP leachate had a lead concentra-
tion below the TCLP regulatory level, as shown
in Table 5.
Table 6 summarizes the trace metal analy-
sis results for all lagoon 8 sludge incineration
test samples. As was the case for the la-
goon 3 sludge tests, no lagoon 8 sludge
sample contained detectable antimony, beryl-
lium, mercury, selenium, or silver. Levels of
arsenic, barium, and chromium in the lagoon 8
sludge were in the same range as in the
lagoon 3 sludge. No cadmium was found in
the lagoon 8 sludge. Also, lagoon 8 sludge
lead levels were much lower than those in
the lagoon 3 sludge.
The data in Table 6 show that the metals
absent in the lagoon 8 sludge were not found
in any other test program sample, with the
exception of cadmium, which was found at
bw levels in the scrubber exit flue gases of all
three tests and in the scrubber liquors of two
of the three tests. Metals found in the la-
goon 8 sludge were distributed among all
other incineration residuals and flue gas
samples, with the possible exception of lead,
which was found in the Tests 5 and 6 kiln ash
samples at just greater than the method de-
tection limit (MDL), and not found above the
MDL in the Test 4 kiln ash samples. Incinera-
tor discharge stream concentrations of the
four metals detected in the lagoon 8 sludge
were comparable from test to test with the
exception of the scrubber liquor arsenic and
lead concentrations and the scrubber exit flue
gas lead concentrations, all of which steadily
decreased from Test 4 through Test 6. The
much higher lead concentration in the Test 4
scrubber exit flue gas, compared with the
Tests 5 and 6 flue gases, is suspected to be
the result of some residual lagoon 3 sludge
material from Test 3 left in the afterburner.
The data in Table 6 further show that nei-
ther the lagoon 8 sludge feed sample nor any
of the test kiln ash samples would be TC
hazardous wastes based on the trace metal
concentrations in their TCLP leachates. In
addition, the trace metal concentrations mea-
sured in scrubber liquor samples were suffi-
ciently low that no test's scrubber liquor dis-
charge would be a TC hazardous waste, with
the possible exception of the Test 4 unfiltered
scrubber liquor.
Table 7 summarizes the test trace metal
distributions among the three incineration sys-
tem discharges: kiln ash, scrubber liquor, and
scrubber exit flue gas. The distribution frac-
tions in Table 7 have been normalized to the
total amount of each metal measured in all
the discharge streams analyzed. Thus, these
normalized values represent fractions that
would have resulted had mass balance clo-
sure in each case been 100%. Use of the
distribution fractions normalized in this man-
ner allow clearer data interpretation, because
they remove variable mass balance closure
as a source of test-to-test data variability. In
other words, because variable and less than
perfect mass balance closure is typically ex-
perienced, the use of normalized distributions
represents a best attempt to quantify metal
partitioning phenomena. Achieved mass bal-
ance closure levels ranged from 42% to 107%
if the lead mass balance closure for Test 4 is
excluded. As noted above, the high Test 4
scrubber exit flue gas lead concentration mea-
sured is suspected to have been affected by
some residual lagoon 3 sludge material, from
Test 3, left in the afterburner.
The distribution data in Table 7 show that
barium and chromium exhibited relatively non-
volatile behavior in all of the tests. Between
84%, and 96% of the barium discharged was
accounted for by the kiln ash in the lagoon 3
sludge tests; even more, 96% to 99%, was
accounted for in the lagoon 8 sludge tests.
Similarly, between 86% and 97% of the chro-
mium discharged was accounted for by the
kiln ash discharges in all of the tests. The
scrubber exit flue gas accounted for 1% to
5% of the chromium measured; the remain-
ing 1% to 10% was found in the scrubber
liquor.
In contrast, cadmium and lead were quite
volatile in the lagoon 3 sludge tests. Only 6%
of the cadmium discharged and 2% to 3% of
the lead discharged were found in the kiln
ash. Further, the major fraction of the cad-
mium and lead that escaped the kiln exited
the scrubber system. About 60% of the cad-
mium discharged in Tests 1 and 2 and 92%
in Test 3 were measured in the scrubber exit
flue gas. Similarly, between 49% and 82% of
the lead discharged in the lagoon 3 sludge
tests was measured in the scrubber exit flue
gas.
Lead was much less volatile in the la-
goon 8 sludge tests. For Tests 5 and 6, as
much as 40% to 69% of the lead discharged
was measured in the kiln ash. Interestingly,
the lagoon 8 sludge contained no measur-
able chlorine (<0.1 %, dry basis). The lagoon 3
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Table 5. Concentrations of Trace Metals for the Lagoon 3 Sludge Tests
Sample As Ba Cd
Cr
Pb
Sb
Be
Se
Average sludga food, mg/kg 1.4 17 11 28
Average sludge feed TCLP leachate, mg/L <0.05 0.092 <0.005
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Table 6. Concentrations of Trace Metals for the Lagoon 8 Sludge Tests
Sample As Ba Cd
Sludge feed, mg/kg
Sludge feed TCLP leachate, mg/L
Test 4 (11/5/91)
Kiln ash, mg/kg
Kiln ash TCLP leachate, mg/L
Scrubber exit flue gas, pg/dscm
Scrubber liquor, mg/L
Test 5 (11/6/91)
Kiln ash, mg/kg
Kiln ash TCLP leachate, mg/L
Scrubber exit flue gas, ng/dscm
Scrubber liquor, mg/L
Test 6 (11/7/91)
Kiln ash, mg/kg
Kiln ash TCLP leachate, mg/L
Scrubber exit flue gas, \s.g/dscm
Scrubber liquor, mg/L
TCLP regulatory level, mg/L
0.82
<0.001
9.1
<0.001
8-9
0.17
4.2
<0.001
6
0.086
3.8
<0.001
3-4
0.022
5.0
38
0.085
65
0.38
3-9
0.18
74
0.41
8-15
0.15
69
0.38
7-14
0.27
100
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exit cadmium emission levels were in the 153
to 206ugAiscm range, and lead emission
lavots wore In the 4,420 to 6,180ug/dscm
range. Furthermore, the unfittered scrubber
liquor discharge exceeded the TCLP limit for
toad; however, scrubber liquor filtrate concen-
trations may be below these limits. If a wet
scrubber ARCS is used, incineration at a kiln
temperature tower than the 982°C (1,800°F)
temperature tested might be warranted. A
lower kiln temperature would likely reduce the
amount of cadmium and lead volatilized and
carried out of the kiln in the combustion gas.
The full report was submitted in fulfillment
of Contract No. 68-C9-0038 by Acurex Envi-
ronmental Corporation under the sponsorship
of the U.S. Environmental Protection Agency.
C. King and LR. Water/and are with Acurex Environmental Corporation,
Jefferson, AH 72079.
R.C. Thumau fs the EPA Project Officer; G.J. Carroll was the EPA Technical
Project Monitor (see below).
The complete report, entitled 'Pilot-Scale Incineration of Contaminated Sludges
from the Bofors-Nobel Superfund Site," (Order No. PB93-141034; Cost:
$44.50, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Off her and Technical Project Monitor can be contacted at:
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-92/240
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