AWMA 98th Annual Meeting; Minneapolis, MN; June 21-24, 2005

Pilot-Scale Combustion of Building Decontamination Residue

Paul M. Lemieux
U.S. EPA
Office of Research and Development
Research Triangle Park, NC 27711

ABSTRACT

Building decontamination and cleanup efforts from a biological warfare (BW) or
chemical warfare (CW) agent terrorist attack typically result in a significant quantity of
building decontamination residue (BDR). This BDR consists mainly of porous materials,
such as carpeting or ceiling tiles, which were removed from the building either before or,
after decontamination efforts. The BDR is likely to have been decontaminated but due to
its porous nature and the limitations of sampling methodologies, the possibility exists of
the presence of trace quantities of agents, as well as the likelihood of the presence of
varying quantities of decontamination chemicals (e.g., bleach solutions). One likely
disposal technique for the BDR is high temperature thermal incineration. This paper
describes preliminary experiments that were performed in a pilot-scale rotary kiln
incinerator simulator to evaluate the combustion characteristics of BDR in an effort to aid
in the selection of appropriate disposal facilities and to aid facilities in maintaining permit
compliance while processing potentially contaminated BDR.

INTRODUCTION

After a building has gone through decontamination activities following a terrorist attack
with chemical warfare (CW) agents, biological warfare (BW) agents, or toxic industrial
chemicals (TICs), there will be a significant amount of residual material and waste to be
disposed. This material is termed "building decontamination residue" (BDR). Although
it is likely that the BDR to be disposed of will have already been decontaminated, the
possibility exists for trace levels of the toxic contaminants to be present in absorbent
and/or porous material such as carpet, fabric, ceiling tiles, office partitions, furniture, and
personal protective equipment (PPE) and other materials used during cleanup activities. It
is likely that much of this material will be disposed of in high-temperature thermal
incineration facilities, such as medical/pathological waste incinerators, municipal waste
combustors, and hazardous waste combustors.

Although pathogens such as Bacillus anthracis (anthrax) present in BDR are killed at
typical incineration temperatures (> 800 °C), gas-phase residence times (> 2 s), and solid-
phase residence times (> 30 min), it is possible for some of the pathogens to escape the
incinerator due to bypassing the flame zones, cold spots, and incomplete penetration of
heat through the bed. Wood et al., (2004) reported on EPA testing of commercial
hospital waste incinerators by doping large quantities of Geobacillus stearothermophilus
(an anthrax surrogate) spores into the combustors and measuring the number leaving in
the stack emissions and in the incinerator bottom ash, in terms of Log reduction in spore
concentration. It was found that, in certain cases, only a 3-Log reduction in spore

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AWMA 98th Annual Meeting; Minneapolis, MN; June 21-24, 2005

destruction was found, in spite of acceptably high operating temperatures and sufficiently
long residence times.

The EPA instituted a pilot-scale test program to investigate issues related to the thermal
destruction of contaminated BDR (Lemieux, 2004) including carpeting, ceiling tile, and
wallboard. Contaminants to be tested will include BW simulants (Geobacillus
stearothermophilus) and CW simulants (dimethyl methylphosphonate). These tests
would examine time/temperature requirements for spore destruction, issues related to
facility compliance with relevant permits (e.g., emissions of nitrogen oxides), and
understanding which facilities may or may not be appropriate to handle certain types of
BDR.

EXPERIMENTAL

Testing was performed at the EPA's Rotary Kiln Incinerator Simulator (RKIS) facility
located in Research Triangle Park, NC. The RKIS has been used in the past to test a wide
variety of solid and liquid wastes (Stewart and Lemieux, 2003; Lemieux and Stewart,
2004; Lemieux et al., 2004). The RKIS (shown in Figure 1) consists of a 73 kW
(250,000 Btu/hr) natural gas-fired rotary kiln section and a 73 kW (250,000 Btu/hr)
natural gas-fired secondary combustion chamber (SCC). Following the SCC is a long
duct that leads into a dedicated flue gas cleaning system (FGCS) consisting of another
afterburner, baghouse, and wet scrubber. The RKIS is equipped with continuous emission
monitors (CEMs) for oxygen (O2), carbon dioxide (CO2), carbon monoxide (CO),
nitrogen oxides (NOx), and total hydrocarbons (THCs). A series of Type-K
thermocouples monitor the temperature throughout the system. For the initial tests, the
rotary kiln combustion air was flowing at a rate of 85.0 sm3/hr (3000 scfh) and the burner
natural gas fuel was flowing at a rate of 5.66 sm3/hr (200 scfh). The static pressure in the
rotary kiln section was maintained at -0.05 in. w.c..

Secondary Combustion Chamber

Afterburner

Ram
Feed

—ar;

0

Main
Burner

Figure 1. Rotary Kiln Incinerator Simulator.

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AWMA 98th Annual Meeting; Minneapolis, MN; June 21-24, 2005

The initial set of testing was performed with bundles of nylon 6 carpeting cut into 7.6 cm
(3 in.) squares, enclosed in a titanium cage equipped with a wire loop. Embedded into
the bundle was a small sealed metal tube containing a biological indicator spore strip
containing lxlO6 spores of Geobacillus stearothermophilns and a Type-K thermocouple.
The biological indicator carrier tube was autoclaved for 40 minutes at 121 °C prior to
insertion of the spore strip. A diagram of the biological indicator tube is shown in Figure
2. A diagram of the carpet bundle with the biological indicator tube and thermocouple is
shown in Figure 3.

A series of shakedown tests were performed where several different biological indicator
carrier tube designs were tested. The criteria for a successful design was that it was 1)
small, so as not to impose a large heat transfer resistance; 2) not leak when removed from
the hot kiln and quenched in a bucket of water. The non4eaking provision was critical so
that quantification of spore destruction could be performed and to prevent cross
contamination of subsequent runs.

Threaded 3/8" NPT Fitting
Wrapped with TF£ Tape

A

1 25 cm ID

3/8" NPT Black Steel Pipe

Biological Indicator Strip ~7r

Welded cap

Type-K Thermocouple



n

Braided SS
Thermocouple Wire

Figure 2. Biological Indicator Carrier Tube

Wire Loop

el Squares

7.6 cm

Thermocouple Wire
To DAS

Figure 3. Carpet Bundle Illustration

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AWMA 98th Annual Meeting; Minneapolis, MN; June 21-24, 2005

The preliminary spore destruction experiments that are described in this paper are listed
in Table 1. For each experiment, the carpet bundle was wetted in deionized water to
simulate the decontamination process, drained until no more water dripped from the
bundle, and then manually charged into the rotary kiln at a rate of 1 bundle every 10
minutes. The thermocouple in the bundle was connected to the RKIS data acquisition
system (DAS) through a stainless steel braided umbilical that passed through the charging
gate.

At predetermined intervals, a pole with a hook was inserted into the kiln, and the titanium
cage containing the burning mass of carpet was removed from the kiln and quenched in a
bucket of deionized water. The biological indicator carrier tube was removed and sent to
the biocontaminant laboratory for analysis. For the analysis, the spore strip is aseptically
transferred to 10 mL of sterile Nutrient Broth in sterile yellow cap tubes and incubated at
55 °C for seven days. No growth means that all spores were destroyed. Growth means
that heat was not enough to completely kill the spores.

Table 1. Experimental Conditions

Run

Carpet
Mass (g)

Water Mass
added to
Carpet
Prior to
Feeding (g)

Time in
Kiln Prior
to Quench
(min)

1 (12/30/04)

390.5

605.8

2.0

2 (12/30/04)

390.6

640.5

3.0

3 (1/5/05)

405.4

578.3

4.0

4 (1/5/05)

402.6

666.2

5.0

RESULTS

At the time of the writing of this paper, only a limited number of tests have been
performed. Only the presence or absence of spores has been determined, although future
testing will quantify the Log reduction in spores due to the thermal treatment. Figure 4
shows the temperature of the thermocouple embedded in the bundle of carpet as the
carpet was fed into the kiln and burnt. Of note when observing the temperature profiles
are the time at which the bundle reaches approximately 100 °C, at which point the
measured temperature holds steady; the time when the water is all evaporated and the
temperature starts to rapidly climb; and the time at which the burning bundle was
removed from the kiln and quenched in water. As more testing is performed, these
parameters will be used to statistically analyze the data.

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AWMA 98th Annual Meeting; Minneapolis, MN; June 21-24, 2005

300

250

200

150

100

50







— Run 1 (2 min)
	Run 2 (3 min)

j\

1





	Run 4 (5 min)

J

1





1

j





ij i.



hJ



Time (min)

Figure 4. Temperature profiles

Table 2 shows the quantified spore destruction results from the initial tests, and the peak
temperature measured in the carpet bundle. The samples removed at 2 and 3 min had not
reached the point at which the water had boiled off The samples removed at 4 and 5
minutes were removed from the kiln during the time period exhibiting rapid temperature
rise. The variability in the amount of water that was absorbed onto the carpet bundles
accounts for the slight offset between the 4 and 5 min traces. For these preliminary tests,
only a presence/absence of viable spores was determined. Future experiments will
quantify the number of remaining viable spores.

Table 2. Spore Destruction Results

Run

Time

Carpet

Viable



Quenched

Bundle Peak

Spores



(min)

Temperature

Remaining





(°C)



1

2.0

85.9

Y

2

3.0

101.8

Y

3

4.0

268.6

Y

4

5.0

275.4

N

CONCLUSIONS

Preliminary experiments have been performed on the EPA's Rotary Kiln Incinerator
Simulator to investigate destruction of Geobacillus stearothermophilus spores embedded
in a bundle of carpeting. The investigators have been able to successfully recover the

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AWMA 98th Annual Meeting; Minneapolis, MN; June 21-24, 2005

biological indicator strips from inside the burning mass of carpet in order to examine the
effects of time and temperature on spore destruction.

Initial tests show that the spores are apparently killed in the burning mass of carpet prior
to the complete combustion of the carpet bundle. These tests suggest that if contaminated
carpet were burned in such a way that sufficient oxygen is present to allow combustion of
the carpet, then spores are destroyed in a few minutes, which is significantly less than the
average solid-phase incinerator residence time.

ACKNOWLEDGMENTS

The author would like to thank Richie Perry, Nicole Griffin, Chris Winterrowd, and Jeff
Quinto of ARCADIS; and Marc Calvi, Timothy Dean, and Doris Betancourt of
EPA/NRMRL for their invaluable help.

REFERENCES

Lemieux, P. (2004), "EPA Safe Buildings Program: Update on Building Decontamination
Waste Disposal Area," EM, Vol. 29-33.

Lemieux, P.M.; Stewart, E.S. (2004), "A Pilot-Scale Study of the Precursors Leading to
the Formation of Mixed Bromo-Chloro Dioxins and Furans," Environmental Engineering
Science, Vol. 21, pp. 3-9.

Lemieux, P.; Stewart, E.; Realff, M.; Mulholland, J.A. (2004), "Emissions Study of Co-
firing Waste Carpet in a Rotary Kiln," Journal of Environmental Management, Vol. 70,
pp. 27-33.

Stewart, E.S.; Lemieux, P.M., "Emissions from the Incineration of Electronics Industry
Waste," IEEE International Symposium on Electronics and the Environment & the IAER
Electronics Recycling Summit Electronics Goes Green 2003 International Congress and
Exhibition: Life-Cycle Environmental Stewardship for Electronic Products, Boston, MA,
May 19-22, 2003.

Wood, J.P.; Lemieux, P.M.; Lee, C.W., "Destruction Efficiency of Microbiological
Organisms in Medical Waste Incinerators: A Review of Available Data," International
Conference on Incineration and Thermal Treatment Technologies, Phoenix, AZ, May 10-
14, 2004.

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