United States
Environmental Protection
Agency
Research and Development
Industrial Environmental
Research Laboratory
Cincinnati OH 45268
EPA-600/S2-84-150 Nov. 1984
SEPA Project Summary
Environmental Characterization
of Disposal of Waste Oils by
Combustion in Small
Commercial Boilers
Paul F. Fennelly, Mark McCabe, Joanna M. Hall, Mary F Kozik, Marilyn P. Hoyt,
and Gary T. Hunt
In this project, air emission tests
were conducted on seven boilers in the
size range 0.4 to 15 x 10' Btu/hr while
these boilers were firing waste oil. The
main purpose of the project was to
document the extent to which chemical
contaminants in waste oil are de-
stroyed during the combustion pro-
cess. These data are of interest because
one of the more common and wide-
spread practices for disposing of waste
oils is burning as a supplemental fuel.
Chemicals which were spiked into
the waste oil before combustion in-
cluded: chloroform, 1,1,1-trichloroeth-
ane, triehloroethylene, tetrachloroethy-
lene, trichlorobenzene, 1-chloronaph-
thalene, 2,4,5-trichlorophenol, and
chlorotoluene. Destruction efficiencies
ranged from 99.4 to 99.99 percent. Con-
centrations of these chlorinated hydro-
carbons in the flue gas ranged from 40
to 400 M-g/m3. The concentrations of
lead and zinc in the flue gas ranged be-
tween 5,000 and 72,000 M.g/m3 and
3,000 and 34,000 |xg/m3, respectively.
The average emission rate of HCI from
the seven boilers was 2.6 Ib/hr.
This Project Summary was de-
veloped by EPA's Industrial Environ-
mental 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
information at back).
Purpose and Scope of the
Project
In recent years the environmental im-
pact of the disposal of used oils has
been a growing concern. Numerous
studies conducted by state and Federal
agencies have documented the pres-
ence of contaminants such as polynu-
clear aromatics (PNAs), chlorinated hy-
drocarbons and heavy metals in sam-
ples of used motor oils. One of the more
common and widespread practices for
disposing of used oils is burning as a
supplemental fuel. In some cases,
waste oil is burned directly; in others, it
is blended with other fuel feedstocks.
The disposal of waste materials in
boilers is of particular interest because
to date, there has been little documen-
tation of the extent to which chemical
contaminants in waste oil are destroyed
during the combustion process.
In this project, tests were conducted
on boilers in the size range of 0.4 to 25
x 106 Btu/hr. These are commonly clas-
sified as commercial sources, as op-
posed to industrial or electric utility
sources. Commercial boilers are of par-
ticular interest with regard to waste oil
disposal for several reasons. These
units generally would use untreated or
poorly characterized waste fuels. They
could be expected to provide less effi-
cient combustion because of the gener-
ally intermittent mode of operation. In
addition, their widespread distribution
and their low stack heights makes their
emissions more proximate to the gen-
eral population.
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Seven boilers were designated for
testing in the program. The units were
selected so as to provide a representa-
tive cross section of the commercial
boiler population. A 4000-gallon lot of
used automotive oil was obtained in
order to maintain a consistent supply
of waste fuel for the program. Portions
of the base stock oil were spiked with
predetermined amounts of selected or-
ganic compounds which are typically
found in waste oil and in some cases
are considered hazardous waste mate-
rials. The selected compounds were
chloroform, 1,1,1-trichloroethane, tri-
chloroethylene, tetrachloroethylene, tri-
chlorobenzene, 1-chloronaphthalene, 2,
4,5-trichlorophenol, and chlorotoluene.
Table 1 shows data comparing a typi-
cal spiked waste oil feed in this project
with data from a cross section of repre-
sentative waste oils.
Measurements were conducted at
each of the sites to determine the atmo-
spheric emissions of particulate, inor-
ganic compounds (principally lead and
HCI), and volatile organic and semi-
volatile organic material. The destruc-
tion and removal efficiencies (ORE) for
each of the spiked components were
also determined. A listing of the boilers
and a summary of the tests conducted
at each site are presented in Table 2.
Test Results
Destruction and Removal
Efficiencies
In general, the data of the principal
atmospheric emissions indicate that the
emission rates of the principal inor-
ganic components, lead and HCI, were
substantially higher than the organic
emissions from the six boilers tested.
The average paniculate emissions for
the six boilers tested was determined
to be 0.7 Ib/hr (0.3 lb/106 Btu heat input).
Combustion efficiencies, calculated for
each of the boilers, ranged from 99 to
greater than 99.9 percent.
The flue gas emissions of the organic
compounds of interest correspond to
destruction and removal efficiencies of
99.4 to 99.99 percent as indicated in
Table 3. There were no strong correla-
tions between destruction efficiency
and boiler size or firing technique. One
trend that is apparent from the data is
that the destruction efficiencies for the
semivolatile compounds are consis-
tently higher than those of the volatile
compounds. The fact that generally
higher DREs were achieved for the
semivolatile components, trichloroben-
Table 1. Concentrations of Selected Contaminants in 24 Representative Waste Oils—
Compared With a Typical Spiked Oil Used in This Project
Concentration
Representative oils3
Contaminant
Average
Flange
Typical "spiked oil,'
(this project)
Elements
Aluminum
Arsenic
Barium
Cadmium
Chlorine
Chromium
Iron
Lead
Magnesium
Vanadium
Zinc
Volatile Organics
Trichlorotrifluoroethanes
1,1,1-trichloroethane
Trichloroethylene
Tetrachloroethylene
Toluene
Chloroform
Semivolatile Organics
45
12
66
1
2260"
6
240
1100
260
3
800
410
700"
600
400"
3100
1-640
< 1-100
10-160
< 1-2.8
50-27,000
<1-37
60-980
350-2060
5-590
<1-13
90-1550
<20-1900
<20-14,800
<20-4900
<20-13,000
380-12,000
10.2
14.0
59.5
2.2
12,000
7.1
168
1,520
200
2.2
743
3,500
50
3,100
2,800
2,500
Phenol
2,4,6-trichlorophenol
N-nitrosodiphenylamine
Benz(a)anthracene
Benzofajpyrene
4,4'-DDE
PCBs
Trichlorobenzene
1-chloronapthalene
25
<5
<5
20
<5
<5
<5
—
—
<5-70
<5-< 10
<5-< 10
<5-40
<5-30
<5-< JO
<0. 1-65
—
—
10
1,000
<10
16
—
—
<6
1,800
1,500
a Taken from U.S. DOE Report. No. DOE/BC/10375-6, Oct. 1983.
*Average value does not include maximum value shown in range.
—Denotes data not available or not investigated.
zene, 1-chloronaphthalene and trichlo-
rophenol, is consistent with the ranking
of the spike compounds on the EPA
Hierarchy of Waste Incinerability.
Generally the lowest DREs were
found in site A, the only boiler rated at
less than 1 x 106 Btu/hr. This unit nor-
mally fires a No. 2 fuel oil and its adap-
tion to firing waste oil proved difficult.
Eventually dilution of the waste oil on a
1:1 basis with No. 2 oil was required for
acceptable operation. Even with this
modification, the combustion efficiency
and destruction efficiencies were sig-
nificantly lower than the other units.
Concentrations of
Contaminants in Combustion
Gases
The concentration ranges in the stack
gas of the compounds studied within
the program are given in the full report.
In general, concentrations ranged from
40 to 400 |xg/m3 for the volatile com-
pounds and from about 10 to 50 M-g/m3
for the semivolatile compounds. On a
volume/volume (v/v) basis, these are
very low concentrations. As an exam-
ple, a range of 40 to 400 jjig/m3 for a
compound such as trichloroethylene
corresponds to a concentration of 7.4
to 74 parts per billion (ppb) on a vol-
ume/volume basis. Conducting emis-
sion tests at these low concentrations
required extensive refinement of avail-
able emission source testing
techniques.
Lead and Other Metal Emissions
The samples of flue gas particulate
collected at each site were analyzed for
a total of 27 metals by Inductively
Coupled Argon Plasma Emissions
Spectroscopy (ICAP) techniques. Lead
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Table 2. Boiler Descriptions
Rated
Site capacity Method of
description KfBtulhr Boiler type atomization
A 0.5 Cast iron Mechanical
B° 1.0 Scotch firetube 2 pass Rotary cup
C 2.4 Horizontal return tube Rotary cup
D 2.7 Scotch firetube 3 pass Air
E 3.4 Scotch firetube 4 pass Rotary cup
F 4.2 Scotch firetube 3 pass Air
G 12.5 Scotch firetube 4 pass Air
'Boiler not available for testing in the program due to problems with the burner
Table 3. Calculated Destruction and Removal Efficiencies (%)
A C D
Volatile Compounds
Chloroform 99.65 99.91 99.96
Trichloroethane 99.78 99.95 99.97
Trichloroethylene 99.45 99.92 99.89
Perchloroethylene 99.74 99.91 99.86
Semivolatile Compounds
Trichlorobenzene 99.84 99.98 99.96
1-chloronaphthalene 99.95 99.95 99.95
2,4,5-Trichlorophenol >99.97 >99.99 —
and zinc were present at concentrations Other metals that receive
substantially higher than any other tention were arsenic, ca
trace metals. The lead concentrations in chromium. These were gen
the flue gas samples ranged from 5,380 enough concentrations in t
jxg/m3 to 72,400 |o,g/m3 corresponding to so that when diluted in the
Site
description
Office building
Dairy complex
Greenhouse
Office building
Greenhouse
Greenhouse
Greenhouse
assembly and fuel feed system.
E F
99.90 99.94
99.37 99.80
99.85 99.92
99.73 99.85
99.90 » 99.96
> 99.94 99.98
^99.92 »99.98
Spike level
of each Total
component number of
(ppm) test runs
1,500, 3
3,000 3
3,000 3
3,000, 3
1 0,000 3
3,000, 3
5,000 3
3,000 3
5,000 3
3,000 3
10,000 1
Average by
G compound
99.95 99.88
99.93 99.80
99.87 99.82
99.96 99.84
99.89 >99.92
99.92 >99.95
— >99.97
d special at- sistent with the much higher ash con-
dmium and tent of waste oil, which can range from
erallyatlow 0.15 to 1.5 percent. Particulate sizing
ie stack gas measurements conducted at four test
atmosphere sites indicated that 80 to 90 percent of
an average emission rate of 0.12 Ib/hr.
Calculations based on simplified mod-
els have shown in some cases, lead
emissions at these levels could cause
violations of ambient air quality stan-
dards for lead. The concentrations of
zinc in the flue gas ranged from 3,100
to 34,000 fJLg/m3, corresponding to an
average emission rate of 0.06 Ib/hr. The
ratio between lead and zinc emissions
was generally 2:1, consistent with their
concentration in base stock oil, which
was 1,550 ppm and 760 ppm by weight,
respectively. Lead and zinc compounds
are commonly found in waste automo-
tive oil and result from both gasoline
and oil additives.
they should not cause major problems,
but the situation is still of some concern
as the concentration of these metals
could be substantially higher in other
waste oil base stocks (e.g., see Table 1).
The results of metal emissions are
summarized in Table 4.
Particulate and Chloride
Emission
Particulate emission rates at the six
sites ranged from 0.07 to 1.2 Ib/hr with
an average value of 0.73 Ib/hr (0.34 Ib/
106 Btu heat input). This is significantly
higher than the literature value of 0.09
lb/106 Btu for commercial boilers firing
residual oil, but the higher value is con-
the particulates containing lead are sub-
micron in nature and would be readily
inhalable.
The flue gas emissions of HCI from
the six boilers averaged 2.6 Ib/hr. This
is a relatively high emission rate for
such small units, but it is below the 4.0
Ib/hr air emission standard established
for hazardous waste incinerators, which
would typically burn large quantities of
chlorinated compounds similar to those
used in this program.
Mass flow calculations indicate that
50 to 60 percent of the lead and chloride
introduced into the boilers exists from
the system in the flue gas streams. The
analysis of samples of firetube ash col-
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lected at a single site indicates concen-
tration levels of lead and chloride in the
ash on the order of 1 to 2 percent. Data
from the stack gas emissions coupled
with the chemical analysis of the fire-
tube fly ash and the waste oil provide
for material balance closures at about
65 percent for the total system. This
was considered a reasonable closure
for the purpose of this project and
further investigative work on the re-
maining 35 percent was not performed.
Products of Incomplete
Combustion
The flue gas samples from each site
were screened by gas chromatography/
mass spectrometry (GC/MS) for addi-
tional organic components considered
to be potential products of incomplete
combustion. The types of compounds
which were identified are given in the
full report. In general, the components
were nonchlorinated in nature and were
representative of the types of com-
pounds that result from the combustion
of traditional fossil fuels. These com-
pounds were also very typical of con-
taminants sometimes found on the
blank sample adsorbing medium, XAD-
2 resin. The extent to which these com-
pounds, when detected, resulted from
combustion byproducts or from resin
contaminants could not be determined;
hence, the concentrations could be
viewed as upper limits for many of the
nonchlorinated products of incomplete
combustion. During the course of this
program, there were some baseline
runs done on conventional No. 4 fuel
oil. As expected, no chlorinated hydro-
carbons were detected in the stack gas,
with detection limits being 8 jjig/m3.
With conventional No. 4 oil, combus-
tion products such as naphthalene and
similar PAH compounds were 100 n-g/
m3 or less.
Chlorinated dibenzofuran (PCDF) or
chlorinated dioxin (PCDD) species were
detected in 15 of the 25 samples anal-
yzed as shown in Table 5. The concen-
tration of these compounds ranged
from 0.07 to 17 (ig/m3. On a volume/vol-
ume basis, this corresponds to a range
of 7 to 470 parts per trillion (ppt).
Bulk samples of firetube ash collected
at one of the sites contained parts per
billion levels of 11 PCDF and PCDD
isomers on a weight by weight basis.
Because chlorinated dioxins and chlori-
nated dibenzofurans were found in the
flue gas, tests were also conducted on
the waste oil base stock, both spiked
Table 4. Concentrations of Metals in Flue Gas (\>.g/m3)
Site A C D E
Arsenic
Cadmium
Chromium
Lead
Zinc
11.2
31.2
62 2
9,680
5.150
655
102
166
72,400
33,700
26.1
8.3
112
5.390
3.134
106
182
230
20,300
12.100
251
350
205
49.800
26,800
286
81
263
51,000
27,000
Table 5. Average Concentrations in Stack Gas of Dibenzofuran and Dioxin Species from
Tests Exhibiting Detectable Levels fog/m3)
Dibenzofuran
Chlorodibenzofuran
Dich/orodibenzofuran
Trich/orodibenzofuran
Tetrachlorodibenzofuran
Dibenzodioxm
Chlorodibenzodioxin
Dichlorodibenzodioxin
Tetrachlorodibenzodioxin
Octach/orodibenzodioxin
62(5)
0.8(3)
1.9(2)
1.3(3)
5.4(2) 3.4(5)
0.52(1)" 0.7(3)
0.07(1)
0.43(2)
0.27(1)
0. 18(1)
4.5(1)"
8.0(5) 16(3)
0.4(2) 2. 1(1)"
0.24(1)
0. 17(1)
0.73(1)
1.6(1) 2.4/1)
17(1)"
2.7(3)
1.4(1)
'Samples from 5 tests analyzed.
''Samples from 2 tests analyzed.
'Samples from 3 tests analyzed.
"Quality assurance samples indicate potential loss.
() number of tests in which component was detected.
and unspiked to determine the extent
to which these types of compounds
might be present in the oil. No chlori-
nated dioxins or chlorinated dibenzofu-
rans were found in either the spiked or
unspiked oil.
Test Methods
Waste Oil Analysis
Waste feed samples were analyzed
for chloride, metals and the organic
spike components. The chloride content
of the fuel was determined by Parr Oxy-
gen Bomb Combustion followed by Ion
Chromatography (1C) analyses. Metals
concentrations were determined by
means of ICAP. The samples were pre-
pared for ICAP analysis by a controlled
dry ashing procedure utilizing IR lamps.
The volatile organic analysis of the
waste fuel was accomplished by extrac-
tion followed by purge and trap GC/MS
techniques in accordance with EPA
Method 624 procedures. Sample prepa-
ration followed procedures as given in
Method A101B5, with the substitution
of tetraglyme (tetraethylene glycol di-
methylether) for the polyethylene
glycol normally specified. Tetraglyme is
similar in nature to polyethylene glycol,
but was found to contain fewer poten-
tially interfering contaminants.
The analysis of the waste oil for the
semivolatile components of interest
was performed using a gas chromato-
graph equipped with an electron cap-
ture detector (GC/ECD). Initial analysis
of the waste oil employing silica gel
chromatographic cleanup and GC/MS
techniques was determined to be inap-
propriate due to the unacceptable sam-
ple recoveries for trichlorobenzene and
trichlorophenol.
Combustion Gas Sampling and
Analysis
The determination of volatile organic
concentrations in the flue gas was car-
ried out using a gas chromatograph
equipped with an electron capture de-
tector (GC/ECD). Duplicate, integrated
samples of flue gas were collected in
nonreactive Tedlar bags and injected
into the instrument using a heated gas
sampling loop. Each of the samples,
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were analyzed in duplicate, with replica-
tion sample values to within ±10 per-
cent as the criterion for acceptance. The
accuracy of the calibration standards
developed for the analysis were verified
by comparison of NBS traceable stan-
dards.
A modified Method 5 train equipped
with an XAD-2 resin trap was used to
collect particulate, semivolatile organic
compounds, metals and HCI compo-
nents from the flue gas of the boilers.
The particulate, XAD-2 resin and flue
gas condensate samples from the train
were combined and solvent extracted;
analysis of solvent extracts was con-
ducted using capillary GC/MS. Aliquots
of these sample aliquots were further
concentrated for subsequent analysis
for polychlorinated dibenzofuran and
polychlorinated dibenzodioxin species.
The analysis was conducted using a
quadrupole Hewlett Packard 5985 GC/
MS system fitted with a fused silica
capillary column.
A single set of Method 5 samples
from each site was subjected to inor-
ganic analysis for chloride and particu-
late metal determinations. Samples of
the collected gas condensate were
analyzed for chloride by direct injection
on an Ion Chromatograph. Particulate
samples from the train were prepared
for metal determinations by a hot nitric
acid leach followed by ICAP analysis.
Additional samples of particulate
were collected at four sites using an An-
dersen High Capacity Sampling System
(HCSS) for particle size determinations.
The size fractionated particulate (10 (xm,
10-3 fxm, 3-1 (Jim and 1 n-rn) were ex-
tracted using 3M nitric acid and ana-
lyzed for lead using atomic absorption
spectrophotometry.
Samples of firetube ash were col-
lected for chloride, metals and semi-
volatile organic analysis. The methods
for the trace metal and organic determi-
nations are as described above. Ali-
quots of the samples were subjected to
a hot aqueous leach to extract soluble
chloride species followed by 1C analy-
sis. Additional samples were analyzed
by EP Toxicity in accordance with the
procedures outlined in §260.20 and
§260.21
Quality Assurance Procedures
Quality control checks were per-
formed to ensure the collection of rep-
resentative samples and the generation
of valid analytical results. Blank sam-
ples including field biased blanks and
method blanks, were used to assess the
possible contamination of the samples.
Duplicate and spiked samples were
routinely employed during the program
to verify the precision and accuracy of
the analysis.
EPA quality control concentrates and
NBS Standard Reference Materials
were used where appropriate to assess
the analytical work. A comprehensive
systems audit was conducted during
the program to ensure that the project
goals and requirements set forth in the
Quality Assurance Plan were met.
Conclusions
Although a sample population of six
boilers is very limited, several general
conclusions can be reached regarding
the combustion of waste automotive
fuels in boilers in this size range.
1. It is possible to achieve combus-
tion efficiencies greater than 99.9
percent for small commercial boil-
ers firing waste oils.
2. Destruction and removal efficien-
cies of greater than 99.9 percent
can be obtained for chlorinated or-
ganic contaminants typically pres-
ent in waste oils. For the volatile
compounds studied (chloroform,
trichloroethylene, trichloroethane
and perchloroethylene), destruc-
tion and removal efficiencies were
on the order of 99.9 percent. For
the semivolatile compounds, (tri-
cnlorobenzene, 1-chloronaphtha-
lene, and trichlorophenol), de-
struction and removal efficiencies
were on the order of 99.95 percent.
3. For boilers above 1 x 106 Btu/hr
input, there were no apparent cor-
relations between boiler size or fir-
ing method and destruction effi-
ciency of organic contaminants.
4. Inorganic components, as op-
posed to organic components of
waste oil, have substantially
greater mass emission rates to the
atmosphere as a result of the com-
bustion of automotive waste oils.
The principal inorganic compo-
nents of concern are lead, hydro-
chloric acid and total particulate.
Also of potential concern are arse-
nic, cadmium and chromium. The
particulate lead emissions from a
source may, during the peak heat-
ing season, affect the compliance
with the primary ambient air stan-
dard for lead. A significant percen-
tage of the particulate lead emis-
sions is submicron in nature and
would be readily inhalable.
5. Detectable levels of emissions of
polychlorinated dibenzofurans
and polychlorinated dibenzo-
dioxins compounds were found in
some of the boilers tested. These
compounds, when present, were
usually at levels less than 5 (xg/m3,
which is less than 0.5 part per bil-
lion by volume in the stack gas.
The extent to which these com-
pounds pose a hazard at these low
levels is undetermined.
Tests were done on the base stock
waste oil, with and without the
spiked contaminants, to determine
the extent to which the oil may
have contained trace levels of
dioxin. No dioxin or dibenzofuran
compounds were detected in any
of the oil samples; detection limits
were 200 ppb by weight for TCDD
and TCDF. If dioxin compounds
were present at or below their de-
tection limits, such a quantity
would not be large enough to ac-
count for the observed levels in
the stack gas even with zero per-
cent destruction. Therefore, dioxin
and dibenzofuran found in the
stack gas most probably was
formed during the combustion
process.
6. The fly ash deposited in the fire-
tubes of the boilers may contain
percent levels of lead and parts per
billion levels of chlorinated diben-
zofuran and dioxin compounds.
The ash has the potential for being
classified as hazardous on this
basis, and may be subject to
hazardous waste regulations for
disposal.
'•USGPO: 1984 — 559-111/10724
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Paul F. Fennelly, Mark McCabe, Joanna M Hall, Mary F. Kozik, Marilyn P Hoyt,
and Gary T Hunt are with GCA Corporation, Bedford, MA 01730
Harry Freeman and Michael Petruska are the EPA Project Officers (see below)
The complete report, ent/tted "Environmental Characterization of Disposal of
Waste Oils by Combustion in Small Commercial Boilers, "(Order No PB85-105
880, Cost: $17.50, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone. 703-487-4650
Harry Freeman can be contacted at-
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
Michael Petruska can be contacted at:
Office of Solid Waste
U.S Environmental Protection Agency
Washington, DC 20460
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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