United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-91/007 July 1991
EPA Project Summary
Emissions of Metals and
Organics from Municipal
Wastewater Sludge Incinerators
Michael A. Vancil, Charles R. Parrish, and
Michael A. Palazzolo
In order to provide data for a sludge
regulations development effort, emis-
sions of metals and organics from a
series of four wastewater sludge Incin-
erators were measured. Three multiple
hearth units and one fluldlzed bed
combustor were tested. Emissions were
controlled with a combination of venturl
and/or tray Impingement scrubbers. One
site Incorporated an afterburner as well.
Flue gas testing was conducted at the
Inlet and outlet to the air pollution con-
trol devices at two of the plants. Feed
sludge was also extensively tested for
moisture, metals, and organlcs, as well
as overall feed rate and heating value.
Testing operating conditions were cat-
egorized as short-term versus normal
or long-term conditions, which include
transients, start-up, feed interruptions,
etc.
All test results are fully documented
In individual site reports. Emission test
results for particulate matter/metals
sampling are separated into short-term
versus long-term tests. Gas concentra-
tions, mass emissions rates, metals-to-
particulate ratios, and emission factors
are presented. Results are given for
chromium VI sampling efforts. Metals
concentrations in the various process
streams (sludge feed, scrubber water,
and bottom ash) are also given.
Volatile and semivolatlle test results
ara also presented for flue gas samples
as well as sludge feed samples. Certain
compounds were detected at higher
mass rates in the flue gas than in the
sludge, designating them as products
of incomplete combustion (PICs).
All other test results including CEM
data, PSD data, CDD/CDF data, and op-
erating data are all presented In the
report volumes.
This Project Summary was devel-
oped by the principal Investigators and
EPA's Risk Reduction Engineering
Laboratory, Cincinnati, OH, to announce
key findings of the research project that
Is fully documented In the reports listed
at the end of this summary. (See Project
Report ordering Information at back.)
Introduction
The U.S. Environmental Protection
Agency (EPA) has drafted regulations for
air emissions from municipal wastewater
sludge incinerators that are based on can-
cer risk by inhalation of various metals and
organics. The regulations were authorized
under Section 405d of the Clean Water
Act. A proposal soliciting public comments
was published in the Federal Register on
February 6, 1989. Final regulations are
scheduled for publication in the Federal
Register in January 1992.
To provide data for these regulations,
Radian Corporation performed emissions
stack testing. These tests were performed
at four operating municipal wastewater
sludge incinerators from April to October
1987. The project was jointly funded by
EPA's Risk Reduction Engineering Labo-
ratory (RREL) and its Office of Water
Regulations and Standards (OWRS).
During the project, metals and organics
data were collected to determine:
• Long-term stack emissions over a
range of operating conditions;
Printed on Recycled Paper
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• Long-term and short-term stack emis-
sion rates as related to sludge com-
position;
• tf short-term stack emissions data
taken during periods of best operation
can approximate long-term stack
emissions;
The efficiency of wet scrubbers in
removing metal and organic stack
emissions; and
• Cause and effect relationships be-
tween incinerator operation and
emissions (including the use of an
afterburner).
Test Methods
At Sites 1 and 3, emissions testing was
performed only at the control device outlet
(exhaust stack). At Sites 2 and 4, emis-
sions were measured at both the control
device inlet and outlet. Also, at all four
sites, samples of the sludge feed, scrub-
ber water, and bottom ash were collected.
Analyses of particle size distribution (PSD)
were performed for Sites 2 and 4 and
analyses of chlorinated dibenzo-p-dioxins
and dibenzofurans (CDD/CDF) were per-
formed for Site 4.
Particulate matter (PM) and metals sam-
pling was conducted at the scrubber inlet/
outlet according to EPA Reference Method
12 (Alternate). After gravimetric analysis of
the filters, the particulate was digested in
nitric acid and combined with the impinger
solutions for analysis. Atomic adsorption
(AA) analysis was used for the determina-
tion of arsenic and lead. The determination
of beryllium, cadmium, chromium, and
ntekel was performed using the inductively
coupled argon plasma (ICAP) technique.
Flue gas sampling for volatile organics
was performed using the most recently
developed method by EPA. This method,
using the volatile organic sampling train
(VOST) (SW-846, Method 0030 for sam-
pling and Method 5040 for analysis), is
designed to collect volatile organic com-
pounds with boiling points between 30'C
and 100"C. The organics are collected on
two resin traps in series containing Tenax
resin and charcoal. The sample is col-
lected at 1 L/min for 20 min for each pair of
traps. Four pairs of traps are collected per
test run. The resin traps are analyzed by
the purge and trap techniques followed by
gas chromatography/mass spectrometry
(GC/MS).
Semivolatile samples of the flue gas
were collected according to the semi-VOST
method developed by EPA. The method is
basically a modification of EPA Reference
Method 5 with a condenser and adsorbent
module added after the filter and before
the impinger train to collect semivolatile
organics. The particulate filter, resin trap
and impinger solutions are extracted with-
organic solvent, concentrated, and ana-
lyzed by GC/MS.
Grab samples of the process samples,
which included feed sludge, bottom ash,
and scrubber influent and effluent water,
were collected at regular intervals during
flue gas sampling. The sludge feed was
sampled from the feed conveyor after de-
watering. Bottom ash was collected from
an intermediate point on the conveyor
system prior to combination with other
ashes. Scrubber water was collected from
taps in the pipes. Hourly or 30 min grab
samples were combined at the end of a
test run and analyzed following similar
analytical schemes used for the flue gas
samples.
Continuous emissions monitoring was
also conducted at all four test sites. Gases
such as O2, CO2, CO, SO2, NOX and total
hydrocarbons (THC) were continuously
monitored daily. All results are tabulated
and graphically presented in the individual
site reports.
The key operating parameters that were
monitored include incinerator operating pa-
rameters, sludge feed characteristics, and
wet scrubber system operating data.
Results
The metals found in greatest concen-
trations in the sludge were lead, chro-
mium, and nickel. The highest metal
emission rates (Table 1) were of lead and
cadmium. Chromium, arsenic, and nickel
were the metals most effectively removed
by the scrubbers (Table 2). Lead emis-
sion:! appeared to increase with increasing
maximum hearth temperature.
Testing for organics, in terms of volatile
species (B.P. 30°C - 100°C) (Table 3) and
semivolatile species (Table 4), took place.
For the volatile species, toluene had the
highest concentration in the sludge and
acrylonitrilo, benzene, toluene, chloroform,
and vinyl chloride had, the highest emis-
sion rates. Certain compounds were de-
tected in higher amounts at the stack when
compared to the sludge indicating that they
were PICs (Table 5). Certain species also
appeared to be stripped from the primary
and secondary treatment effluent used in
the scrubbers.
Few of the target semivolatile com-
pounds were detected in either the sludge
feed or at the stack. Bis(2-ethylhexyl)
phthalate had the highest concentration in
the sludge whereas phenol, naphthalene,
and dichlorobenzene had the highest
emission rates at the stack.
The full reports were submitted in fulfill-
ment of Contract No. 68-02-4288 by Ra-
dian Corporation under the sponsorship of
the U.S. Environmental Protection Agency.
A paper containing data summaries has
also been published in Process Safety and
Environmental Protection, Transactions of
the Institution of Chemical Engineers (En-
gland), Part B, Volume 69, Number B1, pp
20-28, February 1991.
Tabla 1. Particulate and Metals Stack Emission Factors for Steady State and Normal Operation
Emission factors (g metal emitted/g metal fed)
Site 1
Site 2
Site3
Site 4 (all steady state)
Pollutant
PM (g/kg dry sludge feed)
Arsenic
Beryllium
Cadmium
Chromium
Lead
Nickel
Steady
state
3.18
<0.01ff>
ND°
0.10
0.002
0.12
0.010
Normal
2.63
<0.02Sf
ND
0.15
0.001
0.21
0.006
Steady
state
0.41
0.031
ND
0.21
0.0065
0.030
0.013
Normal
0.38
0.075
0.002
0.22
0.0038
0.047
0.0097
Steady
state
0.396
0.0011
ND
0.041
0.0025
0.0013
0.0049
Cool
ABoff
1.2
0.0026
ND
0.20
NA
0.10
0.0013
Hot
ABorf
0.55
0.0017
ND
0.23
NA
0.19
0.0007
Hot
ABoff
1.3
0.0013
ND
0.18
NA
0.14
0.0013
Cool, AB off* Cool furnace, afterburner off.
Hot, AB on " Hot furnace, afterburner on.
Hot, ABoff*= Hot furnace, afterburner off.
6 Arsenic not detected in sludge. Detection limit used to calculate emission factor.
ND = Not detected.
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Tables. Metals and Paniculate Removal Efficier
Site 2
Element
Arsenic
Beryllium
Cadmium
Chromium
Lead
Nickel
PM
Steady state
77.2
>74.&
62.8
79.1
76.5
53.1
95.1
Normal
77.7
87.9
68.1
90.6
78.1
80.3
95.4
icy across Scrubber (%)
Site 4
(Steady state
Cool AB off)
97.2
NA"
47.1
98.0
36.6
95.4
97.1
Not detected at outlet Detection limit used to calculate removal efficiency.
* NA = Not available. Beryllium not detected at inlet but detected at outlet
.Jaftfe 3... yOQ.Steck Emission Rates under Steady State, (gram/hr)
Site 4
Compound
Acrylonitrile
Benzene
Carbon tetrachloride
Chlorobenzene
Chloroform
1 ,2-Dichloroethane
trans- 1 ,2-Dichloroethane
Ethylbenzene
Methylene chloride
Tetrachloroethene
Toluene
1 1 1-Trichloroethane
Trichloroethene
Vinyl chloride
Butene
Methylhexene
Xylene
Trimethylbenzene
Thiophene
Pentene
Site 1
6.23
7.87
0.0474
0.490
2.27
0.012
0.0952
0.795
1.04
5.74
2.36
0.134
0.643
2.49
1.14
0.342
2.08
0.092
0.262
0.625
. Site 2
12.6
5.29
0.0026
0.356
0.609
ND
0.009
0.445
0.577
0.882
11.9
0.020
0.157
7.97
0.152
ND
1.00
1.59
1.84
0.123
Site 3
NO"
0.401
0.014
0.0051
3.89
ND
ND
0.024
0.070
0.151
0.067
0.043
0.011
ND
ND
ND
0.405
0.051
ND
ND
Steady
state
21.6
4.40
9.20
0.536
0.251
ND
0.0297
1.06
1.47
0.892
4.15
1.10
1.51
1,10
1.63
0.204
0.287
0.020
0.346
1.54
Hot furnace,
afterburner on
0.317
0.107
0.0055
0.176
0.318
0.0196
ND
0.0125
0.270
0.596
0.429
0.896
0.990
ND
ND
ND
0.038
0.200
ND
ND
'ND = Not detected.
Table 4. Emission Rates for Semivolatiles (gram/hr)
Site 2
Compound
Phenol
Naphthalene
Bis(2-ethylhexyl)phthalate
1,2-Dichlorobenzene
1,3-Dichlorobenzene
1,4-Dichlorobenzene
2-Nitrophenol
S/teV
(controlled)
ND
ND
0.89
1.0
0.83
2.2
ND
(uncontrolled)
49
18
1.1
0.44
ND
0.48
5.5
(controlled)
2.3
2.4
0.85
0.51
0.05
0.62
1.6
Site 3
(controlled)
ND
ND
0.3
ND
ND
ND
ND
Site 4
(uncontrolled)
30.1
13.1
ND
ND
ND
ND
•&U.S. GOVERNMENT PRINTING OFFICE: 1991 - 548-028/40017
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Tablo 5. Summary of VOCs Formed as Products of Incomplete Combustion
SitB 1
Acrylonitrile
Benzene
Mothylene chloride
Tetrachtoroethene
Toluene
Vinyl chloride
Si to 2
Acrylonitrile
Benzene
Vinyl chloride
Site 3
Chloroform
Site 4
Cool furnace, afterburner off
Acrylonitrile
Benzene
Chlorobenzene
Ethylbenzene
Toluene
Vinyl chloride
Hot furnace, afterburner on
Acrylonitrile
Michael A. Vancil, Charles R. Parrish, and Michael A. Palazzolo are with Radian Corporation, Research Triangle Park, NC 27709.
Harry Bostlan is the EPA Project Manager (see below).
The complete report, entitled "Emissions of Metals and Organics from Municipal Wastewater Sludge Incinerators," consisting of
eight volumes, will be sold as a set (Order No. PB91-151472; Cost $160.00, subject to change) or singly.
"Volume I: Summary Report," (Order No. PB91-151480; Cost: $15.00, subject to change) presents a summary of all the emission
test data.
"Volume H:Site 1 Final Emission Test Report," (Order No. PB91-151498; Cost: $31.00, subject to change),
"Volume III: Site 2 Final Emission Test Report" (Order No. PB91-151506; Cost: $31.00, subject to change),
"Volume IV: She 2 Final Emission Test Report—Appendices," (Order No. PB91-151514; Cost: $11.00, subject to change),
"Volume V: Site 3 Final Emission Test Report," (Order No. PB91-151522; Cost: $23.00, subject to change),
"Volume VI: Site 4 Final Emission Test Report,"(Order No. PB91-151530; Cost: $31.00, subject to change),
"Volume VII: Site 4 Final Emission Test Report—Appendices," (Order No. PB91-151548; Cost: $23.00, subject to change), present
the detailed test results from each individual incinerator test program.
"Volume VIII: GC/MS Tapes Review Report," (Order No. PB91-151555; Cost: $23.00, subject to changd) presents the findings
from the review of the original GC/MS organics data. The GC/MS chromatograms were reviewed and additional volatile and
semivolatile organics data were retrieved.
AH volumes of this report will be available from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer 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
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Penalty for Private Use $300
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