United States
Environmental Protection
Agency
Water Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-86/039 June 1986
c/EPA Project Summary
Determining the Effectiveness
of an Afterburner to Reduce
Dioxins and Furans
Salo E. Miller, Fred L. DeRoos, James E. Howes, Jr., and Ben W. Lykins, Jr.
During reactivation of granular acti-
vated carbon (GAC) used in the treat-
ment of municipal water supplies, a po-
tential exists for the release of
adsorbed organic compounds or their
reaction products into the environ-
ment. Combustion is normally em-
ployed to reduce or eliminate trace or-
ganics from these types of effluent
streams. The purpose of this study was
to evaluate the effectiveness of an
afterburner in reducing or eliminating
the occurrence of dioxins and furans in
the reactivator effluent streams. Quan-
titative measurements were made of
tetrachlorodibenzo-p-dioxins (TCDDs)
and tetrachlorodibenzofurans (TCDFs)
in all effluent streams from the Cincin-
nati (Ohio) Waterworks reactivator unit
and penta-, hexa-, hepta-, and octa-
chlorinated dioxins (CDDs) and furans
(CDFs) in a preselected number of sam-
ples.
Seven tests were performed to deter-
mine TCDD and TCDF emissions from
the Cincinnati Waterworks carbon reac-
tivation unit. The test sequence and
sampling matrix is shown in Table 1.
The tests were conducted during reacti-
vation of a batch of carbon that had
been used to adsorb trace organics
from Cincinnati municipal drinking
water. During Tests No. 1 and 7, the
natural gas and fuel oil supplies used to
fire the fluidized-bed reactivation sys-
tem were sampled to determine if poly-
chlorinated biphyenyls (PCBs) were
present. The effluent streams along
with reactivated and spent carbon feed
samples were analyzed to determine
(1) 2,3,7,8-TCDD and 2,3,7,8-TCDF con-
centrations; (2) total TCDD and TCDF
concentrations; and (3) the TCDD and
TCDF isomeric composition, i.e., the
number and, when possible, the iden-
tity of isomers in the sample. A selected
number of samples were analyzed for
the higher homologues of dioxins and
furans.
This Project Summary was devel-
oped by EPA's Water Engineering Re-
search 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
Activated carbon has been used for
many years to remove taste and odor
components from drinking water. More
recently, studies have focused on acti-
vated carbon treatment to remove po-
tentially hazardous trace organics from
municipal water supplies. In this regard,
the Cincinnati Waterworks (CWW), in
conjunction with the U.S. Environmen-
tal Protection Agency (EPA), has been
conducting a study on the effectiveness
of granular activated carbon (GAC) for
removing these compounds from drink-
ing water. Carbon used for water treat-
ment can be thermally reactivated in a
fluidized-bed furnace and reused in the
water treatment process. During carbon
reactivation, organic compounds could
be released into effluent streams that
will enter the environment. A part of the
total evaluation of the net gains
achieved by removing trace organics
from water must include an examina-
tion of the potential for causing expo-
sure to the public via alternative path-
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Table 1. Test Sequence and Sampling Matrix for Cincinnati Waterworks Carbon Reactivator Tests
Process Streams to be Sampled
7 NG
2 NG
3 NG
4 NG
5 NG
6 NG
7 FO
No. Samples
To be Analyzed
Afterburner
Off/On
Off
Off
On
On
On
Off
Off
GAC
Feed
No
Yes
Yes
Yes
Yes
Yes
No
Spent
GAC
X
X
X
TP
X
1
Regen.
GAC
X
X
X
TP
X
7
Scrubber
Water
X
X
T
X
TP
X
X
2
Carbon
Fines
r
X
X
X
TP
2
ABtc>
1 sec
T
2
AB
2 sec
T
TP
4
Recup.
Inlet
TP
T
TP
T
8
Stack
T
TP
4
Fuel
Supply
P
X
X
X
P
2
a) NG - Natural Gas, FO - Fuel oil.
b) X - Sample collected and archived.
T - Sample collected and analyzed for TCDD/TCDF only.
TP - Sample collected and analyzed for TCDD/TCDF and PCDD/PCDF.
P - Sample collected and analyzed for PCB.
c) Modified Method 5 train with a sorbent (XAD-2) used for each test.
ways. Substances removed from the
water must be properly handled regard-
less of the treatment methodology
used.
During August and September 1982,
a study was performed by Battelle's
Columbus Laboratories (BCD to mea-
sure TCDDs and TCDFs in the effluent
streams of the CWW carbon reactiva-
tor.1 Since this work, the reactivation
system has been modified by incorpo-
rating an afterburner in the off-gas
streams from the fluidized-bed reactiva-
tion unit. The purpose of the afterburner
is to destroy organic compounds in the
off-gas stream by thermal decomposi-
tion and, thus, minimize their release
into the environment.
The purpose of this second study was
to evaluate the effectiveness of the af-
terburner unit in reducing or eliminat-
ing the occurrence of dioxins and furans
in the reactivator effluent streams and
to determine quantitatively TCDDs and
TCDFs in all effluent streams from the
Cincinnati Waterworks reactivator unit
during a carbon reactivation cycle. The
possible presence of TCDDs and TCDFs
in the spent carbon feedstock and PCBs
in the fuel gas supply used to fire the
reactivator were also evaluated.
Seven tests were performed to mea-
sure TCDD and TCDF levels in the efflu-
ent streams and the spent carbon feed-
stock of the Cincinnati Waterworks
carbon reactivation system (shown
schematically in Figure 1). The tests
were conducted during reactivation of
an approximately 40,000-lb batch of
GAC, which had been used in a contac-
tor for approximately 200 days to treat
Cincinnati municipal water.
During each test, samples were ac-
quired from the process streams identi-
fied in Figure 1. The stack, afterburner,
and recuperator effluent streams were
sampled with an EPA Method 5 train
that had been modified by adding
a water-cooled condenser and 22-g
XAD-2* trap between the filter and first
impinger to collect TCDDs and TCDFs in
the vapor phase of the sample stream.
Gas temperature at the exit of the
XAD-2 trap was maintained at <20°C
(<68°F). Grab and composite proce-
dures were used to collect samples of
the dryer off-gas cyclone catch, scrub-
ber water, reactivated carbon, and
spent carbon feed. During two of the
tests, the natural gas and fuel oil were
sampled (XAD-2 trap for the natural gas
and grab sample for the fuel oil) to de-
termine if PCBs were present in the fuel
supply used to fire the carbon reactiva-
tion system.
TCDD and TCDF analyses of the efflu-
ent and spent carbon feed samples
were performed by (1) either Soxhlet or
liquid-liquid extraction to remove the
analytes from the sample matrix and
(2) removal of co-extracted interfer-
ences with silica liquid chromato-
graphic columns, TCDD and TCDD iso-
mers were identified and quantitated by
combined high resolution gas chro-
1 Howes, J. E., Jr., DeRoos, F. L, Aichele, D., Kohler,
D. F., and Larson, M. E. "Determination of Dioxin
Levels in Carbon Reactivation Process Effluent
Streams." Final Report on EPA Contract No. 68-02-
3487, Work Assignment No. 16, May 1983.
'Mention of trade names or commercial products
does not constitute endorsement or recommenda-
tion for use.
matography/high resolution mass spec-
trometry (HRGC/HRMS). PCB analyses
were performed by (1) Soxhlet extrac-
tion of the XAD-2 and (2) concentration
of the extract. PCBs were determined by
combined HRGC/MS.
Results
No 2,3,7,8-TCDD was detected in any
emission or process streams. TCDD was
not detected in any stack particulate
samples; however, small concentra-
tions were detected in the vapor phase
(XAD-2) of the afterburner and recuper-
ator. Low concentrations were also
found in one cyclone catch sample.
Octa-CDD was detected in all emission
and process streams, ranging from
3.123 ng/dry standard cubic meter
(dscm) (0.153 ppt) in recuperator partic-
ulates to 0.15 ng/g (0.007 ppt) in the
spent GAC. Hepta-CDD was detected in
all emission streams, ranging from
0.27 ng/dscm (0.014 ppt) in the after-
burner particulates to 0.024 ng/dscm
(0.001 ppt) in the vapor phase of the
afterburner. Trace amounts of the
hepta-CDD were also detected in one
spent GAC sample. Penta- and hexa-
CDD were detected in the vapor phase
of the recuperator. The values were
0.128 ng/dscm (0.008 ppt) and 0.372 ng/
dcsm (0.021 ppt), respectively. Trace
amounts of hexa-CDD were also de-
tected in the cyclone catch.
No 2,3,7,8-TCDF was detected in the
particulate phase of any emission
stream; however, trace amounts were
found in the gas phase of all emission
streams. Low concentrations were also
observed in one cyclone catch sample.
TCDF was found in recuperator emis-
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Spent Carbon
Storage Tank
Exhaust
Stack
"LJ
Venturi
Scrubber
Tray
Scrubber
Heat
Exchanger
Reactivated
Carbon
Storage Tank
Scrubber
Water
Discharge
v£)
Process Streams
To be Sampled:
Reactivated Carbon
Slurry
(A) Stack Effluent
(fi) Cyclone Fines
(c\ Venturi/Tray Scrubber Water
CD) Reactivated Carbon
Spent Carbon Feed
Afterburner Effluent (1 sec residence!
Afterburner Effluent (2 sec residence)
) Heat Recuperator Inlet
Figure 1. Cincinnati Waterworks carbon reactivation system.
slons (participate and gaseous) and in
the gaseous phase of the afterburner
and stack. The range was from 0.01 ng/
dscm (0.0007 ppt) in recuperator partic-
ulate to 1.357 ng/dscm (0.10 ppt) in the
vapor phase of the recuperator. TCDF
was also observed in the cyclone catch
and in the spent GAC. Penta-CDF was
detected in emissions (gaseous and
particulates) from the afterburner and
recuperator. None were detected in
stack emissions. The range was 1.067
ng/dscm (0.071 ppt) in the gaseous
phase of the recuperator, to 0.015 ng/
dscm (0.001 ppt) in the particulate
phase of the afterburner. No penta-CDF
was found in any of the process sam-
ples. Hexa-COF was detected in the
vapor phase of the recuperator and
afterburner and in the particulate phase
of the afterburner and stack. The range
was 0.756 ng/dscm (0.046 ppt) in the
vapor phase of the recuperator to
0.007 ng/dscm (0.0004 ppt) in the vapor
phase of the afterburner.
Trace amounts of the hexa-CDF were
also found in the cyclone catch. Hepta-
CDF was detected in the vapor phase of
the recuperator and afterburner and in
the particulate phase of the afterburner
and stack. The range was 0.756 ng/dscm
(0.046 ppt) in the vapor phase of the re-
cuperator to 0.018 ng/dscm (0.001 ppt)
in the vapor phase of the afterburner.
Trace amounts of the hepta-CDF were
found in the spent GAC. Octa-CDF was
detected in the vapor phase of the recu-
perator and afterburner and in the par-
ticulate phase of all emission streams.
The range was 0.368 ng/dscm (0.018
ppt) in the particulate phase of the recu-
perator to 0.012 ng/dscm (0.0006 ppt) in
the vapor phase of the afterburner. No
octa-CDF was detected in any process
samples.
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Only one PCB isomer was detected in
the natural gas supply and none in the
fuel oil. The monochlorobiphenyl (C\-\)
detected in the natural gas was 0.71 ng/
sample (0.056 ppb by volume). The de-
tection limit of the monochlorobiphenyl
is 0.18 (jig/sample.
Reactivated carbon and spent carbon
samples obtained during the test pro-
gram and a sample of virgin carbon of
the type being reactivated were ana-
lyzed for total organic halogens (TOX).
The TOX levels found in the samples
were: virgin carbon, <50 mg/Kg; reacti-
vated carbon, <50 mg/Kg; and spent
carbon, 416.3 mg/Kg.
The full report was submitted in fulfill-
ment of Contract No. 68-01-6702 by
Battelle-Columbus Laboratories under
sponsorship of the U.S. Environmental
Protection Agency.
Salo E. Miller. Fred L DeRoos, and James E. Howes, Jr. are with Battelle-
Columbus Laboratories, Columbus. OH 43201.
Ben W. Lykins. Jr. is the EPA Project Officer (see below).
The complete report, entitled "Determining the Effectiveness of an Afterburner to
Reduce Dioxins and Furans," (Order No. PB 86-175 718/AS; Cost: $16.95,
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 Officer can be contacted at:
Water 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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60604
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