Emisiones e contaminantes atmosféricos

1. Atmospheric Environment 41 (2007) 8527–8536
Dioxins, furans and polycyclic aromatic hydrocarbons emissions
from a hospital and cemetery waste incinerator
Giuseppe Mininnia
, Andrea Sbrillib
, Camilla Maria Bragugliaa
, Ettore Guerrieroc
,
Dario Marania,, Mauro Rotatoric
a
CNR, Istituto di Ricerca sulle Acque, via Reno 1, 00198 Roma, Italy
b
UNIDO (United Nation Industrial Development Organization), Vienna International Center, Wagramerstrasse 5, A-140 Vienna, Austria
c
CNR, Istituto sull’inquinamento atmosferico, Via Salaria Km 29,300, 00016 Monterotondo, Italy
Received 28 March 2007; received in revised form 5 July 2007; accepted 10 July 2007
Abstract
An experimental campaign was carried out on a hospital and cemetery waste incineration plant in order to assess the
emissions of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polycyclic
aromatic hydrocarbons (PAHs). Raw gases were sampled in the afterburning chamber, using a specifically designed device,
after the heat recovery section and at the stack. Samples of slags from the combustion chamber and fly ashes from the bag
filter were also collected and analyzed. PCDD/Fs and PAHs concentrations in exhaust gas after the heat exchanger
(200–350 1C) decreased in comparison with the values detected in the afterburning chamber. Pollutant mass balance
regarding the heat exchanger did not confirm literature findings about the de novo synthesis of PCDD/Fs in the heat
exchange process. In spite of a consistent reduction of PCDD/Fs in the flue gas treatment system (from 77% up to 98%),
the limit of 0.1 ng ITEQ Nm 3
at the stack was not accomplished. PCDD/Fs emission factors for air spanned from 2.3 up
to 44 mg ITEQ t 1
of burned waste, whereas those through solid residues (mainly fly ashes) were in the range
41–3700 mg ITEQ t 1
. Tests run with cemetery wastes generally showed lower PCDD/F emission factors than those with
hospital wastes. PAH total emission factors (91–414 mg kg 1
of burned waste) were in the range of values reported for
incineration of municipal and industrial wastes. In spite of the observed release from the scrubber, carcinogenic PAHs
concentrations at the stack (0.018–0.5 mg Nm 3
) were below the Italian limit of 10 mg Nm 3
.
r 2007 Elsevier Ltd. All rights reserved.
Keywords: Cemetery wastes; Hospital wastes; PCDD/F; PAH; Emission factors; Incineration
1. Introduction
In the past years many emission inventories have
been carried out to evaluate the potential emission
of polychlorinated dibenzo-p-dioxins/polychlori-
nated dibenzofurans (PCDD/Fs) from the main
industrial sources. In 2001, emissions from hospital
waste incinerators in the European Union were
estimated in 200–400 g ITEQ year 1
, accounting for
25% of total PCDD/Fs emissions (Paradiz et al.,
2001). The 5th Action program of the European
Union had the aim to achieve the 90% reduction by
ARTICLE IN PRESS
www.elsevier.com/locate/atmosenv
1352-2310/$ - see front matter r 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.atmosenv.2007.07.015
Corresponding author. Tel.: +39 06 8841451;
fax: +39 06 8417861.
E-mail address: marani@irsa.cnr.it (D. Marani).

2. 2005 for emissions from municipal and hospital
waste incinerators and power plants. However, in
2004 the European Dioxin Emission Inventory
Project showed that there was still a large number
of hospital waste incinerators with a large varia-
bility of emission factors, which could be considered
significant local sources of PCDD/Fs (QuaX et al.,
2004).
Due to the high content of chlorine, hospital
waste incineration can lead to the formation of
PCDD/Fs (EPA, 1990, 1994; Wagner and Green,
1993), which can be released both in air and in the
ashes (Kolenda et al., 1994; Grochowalski, 1998). In
Italy these solid residues cannot be disposed off
in landfill for hazardous wastes, as long as the
PCDD/F ITEQ concentration exceeds the limit of
10 mg ITEQ kg 1
provided by the Legislative Decree
36/03 implementing the European Directive 99/31
(European Commission, 1999).
As far as cemetery wastes are concerned, the
wood used for coffins are typically treated with
preservatives such as polyvinyl chloride, creosote
(a polycyclic aromatic hydrocarbons (PAHs)
mixture) or insecticides in light organic solvents
that may induce the formation of PCDD/Fs
(Salthammer et al., 1995).
In Italy, PCDD/Fs atmospheric emission factors
from hospital waste incineration have been reported
as 0.8 mg ITEQ t 1
of waste (ANPA, 2002), but as
yet very few emission data are available for this
sector.
Incineration is also known as a major source of
PAHs (Mascolo et al., 1999). Non-ideal conditions
such as the cooling of hot gases in the combustion
zone due to the contact with the chamber walls or
insufficient oxygen supply can induce incomplete
combustion and pyrolysis reactions. These factors
lead to the formation of toxic organic compounds
among which PAHs are of major concern for their
relative abundance in the emissions and potential
impact on human health (Ana et al., 1999; Akimoto
et al., 1997; Mininni et al., 2000). It is well known
that the combustion of polymeric materials, such as
polyethylene and polystyrene, which are present in
hospital wastes, produces large amounts of PAH
and soot (Wang et al., 2002). In spite of that, few
studies are reported on PAH emissions from
hospital waste incineration (Liow et al., 1997; Lee
et al., 2002; Walker and Cooper, 1992; Wheatley
et al., 1993). In Italy specific emission factors for
PAHs from hospital waste incineration are not
available, but for municipal and industrial waste an
emission factor in the range 50–500 mg kg 1
of waste
is provided (ANPA, 2002).
With the aim to increase the database for
PCDD/Fs and PAHs emission inventory, an experi-
mental campaign was carried out on a full-scale
incineration plant where hospital and cemetery
wastes were combusted. A second objective of this
campaign was to check on a full-scale plant the
hypothesis of de novo synthesis reactions that may
occur in the heat exchanger. This hypothesis was
checked by performing the pollutant mass balance
in the heat exchanger unit.
2. Experimental
The main units of the full-scale plant are a rotary
kiln furnace, an afterburning chamber, a heat
recovery system and a flue-gas cleaning system,
which consists of a dry reactor with injection of
about 10–11 kg h 1
of dry lime, a bag filter with pre-
injection of cooling air and a wet scrubber. Plant
capacity is about 600 kg h 1
of waste. The flow sheet
of Fig. 1 shows the schematic of the plant. The
figure also reports the three gas sampling points
located in the afterburning chamber, after the heat
exchanger, and at the chimney.
Table 1 reports the operating conditions of the
eight tests performed. In the tests 1–3 and 5–7
hospital wastes were burned, whereas in the tests 4
and 8 cemetery wastes, mainly consisting of coffins
with relevant materials, were used. The temperature
of the exhaust gases was measured in the after-
burning chamber (910–1200 1C), after the heat
recovery section (190–351 1C) and at the stack
(70–99 1C). Oxygen varied in the range 1.5–8.9%
by volume in the afterburning chamber and in the
range 1.2–7.8% in the heat recovery section.
Table 2 reports the production rates of slags,
boiler ashes and fly ashes for each test.
Samplings of PCDD/Fs and PAHs were carried
out in the afterburning chamber using a sampling
device specifically designed to resist at high tempe-
ratures in very aggressive conditions. The widely
used alloys or hastelloy and titanium cannot be
employed for this purpose, because they can crash
in the presence of acids and at high temperature
(41100 1C). Ceramic materials are known to be
resistant at high temperature and corrosive condi-
tions but they may present problems due to
their fragility, adsorption of micropollutants and
deposition of particulate matter onto surface of
porous material. For this reason a ceramic probe
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G. Mininni et al. / Atmospheric Environment 41 (2007) 8527–8536
8528

3. made of alumina with zero porosity was adopted,
because, among other refractory materials, it exer-
ted the best properties with negligible adsorption
and good resistance to corrosive environment at
high temperature.
The PCDD/Fs sampling must be carried out in a
range of temperature such that water condensation
and PCDD/F de novo synthesis, which is known to
occur in the range 250–400 1C (Gullett et al., 1990;
Stieglitz et al., 1990; Stanmore and Clunies-Ross,
2000), are prevented. Therefore, raw gases sampled
at the afterburning chamber were quickly cooled to
110–140 1C in a concentric tube exchanger using
diathermic oil. The inner tube, where gas passes
through, is made of titanium, since such material is
more acid resistant than stainless-steel. The section
for micropollutants entrapment is formed by a
ceramic thimble filter, placed in a thermostatic
chamber set at 110 1C, followed by an adsorbent
ARTICLE IN PRESS
Table 1
Main operating conditions of the full-scale incineration plant
Test Feed
(kg h 1
)
Sampling point
1 2 3 1 2 3 1 2 3
Temperature (1C) Oxygen (%) Flow rate (Nm3
h 1
)
1 630 1200 320 96 5.0 4.0 16.5 1765 1662 6277
2 595 – 260 95 – 3.6 16.2 – 1957 7093
3 540 – 280 88 – 3.6 16.5 – 2190 8468
4 525 910 351 70 8.9 7.8 16.5 2966 2719 7975
5 557 1110 190 86 1.5 1.2 16.3 2196 2162 9110
6 684 1170 217 86 8.0 6.9 16.2 2962 2731 8022
7 530 1200 227 88 8.0 7.7 16.9 2611 2552 8279
8 640 1150 231 81 6.7 6.3 16.5 2393 2327 7603
1: afterburning chamber; 2: heat exchanger; 3: stack.
Rotary kiln
furnace
Afterburning
chamber
Air-exhaust gas
heat exchanger
Water-exhaust gas
heat exchanger
Dry
reactor
Air
Bag filter
Lime
Scrubber
Chimney
Slags Fly ashes
1
2
3
Boiler ashes
Hospital and
cemetery wastes
Fig. 1. Flow sheet of the hospital and cemetery waste incineration plant with exhaust gas sampling points 1, 2 and 3.
Table 2
Production rates of solid residues from different equipment
(kg h 1
)
Test Slags Boiler ashes Fly ashes
1 113.4 2.2 15.7
2 107.1 2.0 15.0
3 97.2 1.7 13.8
4 94.5 1.5 12.5
5 100.3 1.8 13.3
6 123.1 2.1 18.3
7 95.4 1.5 12.6
8 115.2 2.1 16.5
G. Mininni et al. / Atmospheric Environment 41 (2007) 8527–8536 8529

4. resin (about 30 g of XAD-2), placed in a cold
thermostatic section. Volatile and semi-volatile
compounds were collected in the XAD-2 resin.
Water was eventually condensed in the water
collection system maintained at about 5 1C by a
cryostat. The accuracy of measures was tested by
experimental samplings with standard PCDD/Fs
carried out at laboratory scale. The results sug-
gested that in the condensation water the PCDD/Fs
concentration was negligible. Furthermore, the
probe was tested against any gas and particles
leakage in the sampling train. On the other hand,
comparative samplings in the incineration plant
were not carried out, since conventional sampling
devices made of other materials cannot stand the
high temperature of the afterburning chamber.
Sampling after the heat exchanger and at the
stack was performed following the EN1948-1 filter/
condensation method (CEN, 1996) for PCDD/Fs
detection and the Italian Unichim 825 method
for PAHs detection (Unichim, 1988). In this case,
conventional titanium probes were used for both
sampling procedures.
In each sampling point two samples were also
collected for measuring particulate matter, SO2,
NOx, CO and VOC concentration, following the
relevant Italian Unichim methods.
Samples in the tests 2 and 3 were not collected
in the afterburning chamber due to operating
problems.
Extraction of PCDD/F from liquid samples
(condensed water) and from solid samples (filters,
fly ashes and slags) was carried out following the
EN1948-2 method. An aliquot of the extracts was
eluted with hexane on a silica gel column (to collect
aliphatic hydrocarbons) and with toluene to collect
PAHs.
Slags sample for PCDD/Fs analysis, collected in
the test 7, was lost during the analytical phase.
The separate extracts were finally analyzed by
HRGC/LRMS. A gas chromatograph Fisons 8000
coupled with a selective mass detector Fisons MD
800 was used. Two chromatographic columns with
different polarity (DB5 MS and DB dioxin) were used
for PCDD/Fs separation. The mass spectrometer was
used after testing the absence of interferences.
Results of the measurements were standardized
at the 0 1C, 101.3 kPa and at oxygen concentration
of 11%.
3. Results and discussion
3.1. Macropollutants
Table 3 reports the macropollutant values mea-
sured at the exit of the heat exchanger and at the
stack. As expected, concentration decreased signifi-
cantly in the gas treatment section. If a comparison
with the half-hourly emission limits at the stack
provided by the Directive 2000/76 on Waste
Incineration (European Commission, 2000) is car-
ried out, the results of Table 3 show a general
compliance of the incineration plant with the
legislative requirements. The only exception regards
CO, whose high concentrations suggest that the
combustion conditions were not properly opti-
mized, especially for tests using hospital wastes.
3.2. Dioxins and furans
Tables 4 and 5 show the PCDD/Fs concentra-
tions found in the gas and solid residues samples,
respectively. In spite of the operating temperature of
the afterburning chamber higher than 1100 1C,
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Table 3
Macro-pollutants (mg Nm 3
) at the exit of heat exchanger (HE) and at the stack
Test SO2 NOx CO Organic carbon Particulate matter HCl
HE Stack HE Stack HE Stack HE Stack HE Stack HE Stack
1 1224.0 44.5 131.9 50.1 839.8 961.6 8.80 1.0 2736.8 19.9 72.3 33.7
2 442.5 35.4 66.1 12.9 560 262.2 8.95 1.3 – 36.3 63 9.1
3 663.6 57.1 78.5 34.5 637.3 343.2 6.55 0.5 – 2.7 31.9 10.6
4 351.0 25.0 102.2 50.2 460.2 110.1 14.60 2.21 1066.7 0.1 14.9 12.4
5 439.2 50.3 96.3 13.6 610.0 112.7 10.80 6.40 1510.2 0.6 31.4 11.2
6 410.6 48.8 137 84.3 798.6 209.9 11.90 1.70 2319.1 0.1 63.9 28.6
7 585.3 39.2 86.2 29.7 880.1 202.7 3.50 0.10 1140.5 9.8 245.1 66.2
8 745.0 29.4 115 37.8 790.4 72.3 42.32 9.91 2212.9 0.3 80.2 21.7
G. Mininni et al. / Atmospheric Environment 41 (2007) 8527–8536
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5. which should be suitable for destruction of
PCDD/Fs (Lindner et al., 1990), very high concen-
trations were always detected in this section.
Though a sharp decrease of the above concentra-
tions was observed in the down flow sampling
points, the limit of 0.1 ng ITEQ Nm 3
at the stack
was never met (0.19–2.69 ng ITEQ Nm 3
).
As far as solid residues are concerned, both fly
ashes and slags show concentrations comparable
with those provided by the Dioxin Toolkit (UNEP,
2005) for advanced incineration plants. In spite of
this, in five out of eight fly ash samples PCDD/Fs
concentrations were higher than the limit of
10 mg ITEQ kg 1
for disposal in hazardous waste
landfill sites provided by the European Directive
99/31 (European Commission, 1999). A peak value
of 147 mg ITEQ kg 1
was reached in test 2. Fly
ashes from hospital wastes showed higher concen-
trations than fly ashes produced from cemetery
waste. In the slags much lower (3–4 order of
magnitude) PCDD/Fs concentrations were detected
(0.004–0.12 mg ITEQ kg 1
) with respect to those
found in fly ash. Anyway, in both kinds of samples
PCDFs congeners were predominant with respect to
PCDDs, according to literature findings (Pohlandt
and Marutzky, 1994).
In the afterburning chamber, PCDD/Fs concen-
trations were not significantly correlated either with
temperature or with oxygen concentration.
PCDD/Fs concentrations after the heat exchan-
ger were always lower than the corresponding
values in the afterburning chamber. These results
are somewhat unexpected, as the conditions inside
the heat exchanger may induce PCDD/F de novo
synthesis (temperatures varying in the range
250–400 1C and the presence of particles acting as
active sites where formation reactions might take
place) (Lindner et al., 1990; Mariani et al., 1990;
Benfenati et al., 1991). However, to better assess
PCDD/F formation or removal inside the heat
exchanger, a complete mass balance must be
performed around this unit, considering all the
gaseous and solid contributions. The mass balance
can be determined considering gas flow rates in
ARTICLE IN PRESS
Table 4
PCDD/Fs concentrations in exhaust gases (ng ITEQ Nm 3
)
Test 1 2 3 4 5 6 7 8
Afterburning chamber
PCDD 143.0 – – 64.8 16.2 20.1 15.5 66.3
PCDF 179.7 – – 96.4 68.5 40.4 50.2 102.9
PCDD+PCDF 322.7 – – 161.2 84.7 60.4 65.7 169.2
Heat exchanger
PCDD 5.93 2.25 6.88 5.87 3.86 0.55 1.12 0.30
PCDF 23.16 5.55 16.35 25.66 7.38 2.16 5.68 0.85
PCDD+PCDF 29.08 7.81 23.22 31.53 11.24 2.71 6.81 1.16
Stack
PCDD 0.07 0.15 0.08 0.07 0.58 0.15 0.29 0.04
PCDF 0.21 0.30 0.25 0.47 2.11 0.51 1.29 0.15
PCDD+PCDF 0.29 0.46 0.33 0.54 2.69 0.66 1.58 0.19
Table 5
PCDD/Fs concentrations in the solid residues (mg ITEQ kg 1
)
Test 1 2 3 4 5 6 7 8
Fly ashes
PCDD 9.5 46.4 41.0 0.4 4.4 1.0 1.1 1.5
PCDF 22.0 100.7 104.7 1.3 16.1 7.0 9.6 4.2
PCDD+PCDF 31.5 147.1 145.8 1.7 20.6 8.0 10.7 5.7
Slags
PCDD 0.016 0.037 0.019 0.002 0.002 0.002 – 0.035
PCDF 0.040 0.084 0.041 0.002 0.004 0.002 – 0.066
PCDD+PCDF 0.056 0.120 0.059 0.004 0.007 0.004 – 0.101
G. Mininni et al. / Atmospheric Environment 41 (2007) 8527–8536 8531

6. sampling points 1 and 2, boiler ash production rate
and the relevant total (not only ITEQ) PCDD/F
concentrations. For this purpose PCDD/Fs con-
centration in boiler ashes were estimated as 10%
of those of filter ashes, according to European
Commission BREF document on Waste Incinera-
tion (European Commission, 2005; Giugliano et al.,
2001, 2002). Total concentrations and mass balance
results are reported in Table 6. Positive numbers
suggest that a reduction of PCDD/Fs occurs in the
device. Since the temperature range in the heat
exchanger is not suitable for their destruction,
removal of such compounds may likely be explained
by their adsorption on the walls of the device
or on particles entrapped on surfaces (boiler
cleaning was not performed in the full-scale plant
during this study). In conclusion, in contrast with
previous literature findings, the mass balance
evaluation seems to exclude the de novo synthesis
in the operating conditions of this experimental
campaign.
Table 4 shows that the PCDD/Fs removal
efficiency of the pollution control devices of the
incineration plant (bag filter and wet scrubber) was
in the range 77–98%. As expected, at the stack the
low chlorinated and more volatile PCDFs homo-
logues, such as T4CDF, P5CDF and H6CDF, were
found as the predominant forms.
3.3. Polycyclic aromatic hydrocarbons
Tables 7 and 8 report total and carcinogenic
PAHs concentrations in the flue gas and in the solid
residues, respectively. According to the Italian
Legislative Decree 133/05 implementing Directive
2000/76 on Waste Incineration, carcinogenic PAHs
include: benzo(a)antracene, benzo(b)fluoranthene,
benzo(j)fluoranthene, benzo(k)fluoranthene, benzo(a)-
pyrene, indeno(123,cd)pyrene, dibenzo(a,h)antracene,
dibenzo(a,l)pyrene, dibenzo(a,e)pyrene, dibenzo(a,i)-
pyrene and dibenzo(a,h)pyrene. Total PAH also
included: acenaftylene, acenaftene, fluorene, fenan-
threne, anthracene, fluoranthene, pyrene, crysene
and benzo(ghi)perylene.
PAHs concentrations in the afterburning chamber
were not significantly correlated with temperature,
ARTICLE IN PRESS
Table 6
Total PCDD/Fs concentrations in the gaseous and solid samples, and mass balance in the heat exchanger
Test Afterburning
(ng Nm 3
)
Heat exchanger
(ng Nm 3
)
Fly ashes
(mg kg 1
)
Mass balance in the heat exchanger
(inlet–outlet) (mg h 1
)
1 8618 893.7 1039.4 13.50
2 – 377.0 4915.3 –
3 – 847.0 4897.3 –
4 3087 811.1 69.0 6.94
5 2415 270.6 584.3 4.61
6 1416 105.2 309.7 3.84
7 1670 201.1 416.4 3.78
8 4657 76.8 240.4 10.91
Table 7
Total and carcinogenic PAHs in the raw and flue gases (ng Nm 3
)
Test Afterburning chamber Heat exchanger Stack
Total Carcinogenic Total Carcinogenic Total Carcinogenic
1 8866.8 137.4 437.5 54.4 1103.7 18.0
2 – – 240.9 3.2 3479.3 45.9
3 – – 173.4 16.6 997.4 139.8
4 5825.0 1022.1 1668.7 11.4. 2288.2 270.2
5 11389.9 594.5 314.9 13.9 3448.4 498.2
6 4712.8 185.9 516.3 32.0 762.3 59.9
7 3377.0 51.2 407.6 65.5 2460.4 166.3
8 7670.6 24.5 710.1 17.1 4646.1 31.7
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7. whereas, as expected, a negative correlation was
found with oxygen concentration in the afterburn-
ing mixture (Fig. 2).
As in the case of PCDD/Fs, also PAHs concen-
trations show a sharp decrease after the heat
exchanger, but in this case a significant increase is
again shown at the stack. This behavior can be
explained by a possible stripping of material
previously captured in the scrubber, as reported in
literature (Benfenati et al., 1991). Concentrations at
the stack were anyway well below (100–1000 folds)
the current Italian standard (10 mg Nm 3
) on carcino-
genic PAHs.
As far as solid residues are concerned (Table 8),
comparable concentrations were found in the
slags and in the fly ashes. Abundance of heavier
compounds (Benzo(a)anthracene, Chrysene and
Benzo(b)fluoranthene) was, as expected, higher in
the slags (7–20%) than in the fly ashes (3–10%).
In order to compare PAHs behavior with that of
PCDD/Fs, a similar mass balance between input
and output of the heat exchanger was evaluated. In
this case, PAH concentrations of boiler ashes were
assumed equal to those of fly ashes, considering that
slags and fly ashes concentrations were very close
(Table 8). In Table 9, the results of the mass balance
are reported both for total and for carcinogenic
PAHs. Like in the case of PCDD/Fs, mass balance
for total PAHs shows always positive numbers,
which suggest a probable adsorption on the wall of
the heat exchanger.
Finally, it must be pointed out that Phenanthrene
and Pyrene were the most abundant congeners for
the cemetery wastes tests. Samples from hospital
wastes generally showed higher percentages of the
carcinogenic compounds with respect to those
relevant to cemetery wastes.
3.4. Emission factors
Emission factors of PCDD/F and PAHs are
shown in Tables 10 and 11, respectively. In addition
to total emission, the tables also show the contribu-
tion of the different emission routes (gaseous and
solid).
The main contribution of PCDD/F ITEQ emis-
sion comes from the fly ashes, which represent
91–98% of total emission in the tests carried out
with hospital wastes and 81–87% in those where
cemetery wastes were fed. Stack contribution to
PCDD/Fs emission is typically below 10%, with
exception of test 4 (cemetery waste) where stack
contributes for 16% of total emission.
In terms of total PCDD/F emission, the tests run
with cemetery wastes generally show lower emission
factors than those run with hospital wastes. Any-
way, even within the same kind of feed, emission
factors may vary of about one-order of magnitude.
ARTICLE IN PRESS
0
2
4
6
6
8
10
12
0 2 4 8 10
Oxygen %
PAHs
(µg
Nm
-3
)
R2 = 0.82
Fig. 2. Correlation between PAHs and oxygen concentration in
the afterburning chamber.
Table 8
Total and carcinogenic PAHs in the solid residues (mg kg 1
)
Test Slags Fly ashes
Total Carcinogenic Total Carcinogenic
1 1165.9 190.5 1398.4 52.4
2 720.7 52.6 466.5 30.9
3 406.5 27.6 2346.5 78.9
4 294.3 58.5 1686.4 128.6
5 1824.1 292.3 1097.9 78.3
6 403.2 73.0 326.0 22.8
7 226.5 33.1 852.9 87.7
8 244.3 21.6 342.7 33.2
Table 9
Mass balance of total and carcinogenic PAHs in the heat
exchanger
Test Inlet–outlet (mg h 1
)
Total PAHs Carcinogenic PAHs
1 11.82 0.04
2 – –
3 – –
4 10.28 2.81
5 22.40 1.14
6 11.85 0.41
7 6.47 0.17
8 15.99 0.05
G. Mininni et al. / Atmospheric Environment 41 (2007) 8527–8536 8533

8. This may reflect the large variability of composition
in the feed.
For hospital wastes the Dioxin Toolkit provides
four classes of PCDD/F emission factors through
air and through solid residues, according to the
degree of sophistication of the incinerator techno-
logy. The four classes span from the uncontrolled,
batch type combustion, without an air pollution
control system (APCS), up to the high technology,
continuous, controlled combustion, with a sophis-
ticated APCS in place. If the emission factors
reported in Table 10 are compared with those
provided by the Dioxin Toolkit, it may be seen that,
whereas factors for air emissions are comparable
with those of incineration plants of class 4
(continuous combustion with sophisticated APCS),
the emission factors for solid residues are of the
same order of magnitude of values given for class 3
(controlled, batch type combustion, with good
APCS in place).
Regarding the PCDD/Fs emissions through the
stack, comparison with the data provided by the
Italian Agency for the Environmental Protection
(ANPA, 2002) shows a difference of at least one-
order of magnitude (0.8 mg ITEQ t 1
against a range
2.3–44 mg ITEQ t 1
measured in this study). To this
purpose, it must be pointed out that data provided
by ANPA were mostly based on European and
international inventories, due to the lack of a large
database on the Italian situation. In addition, the
high emission factors found in this work may be
partially ascribed to the not fully optimized condi-
tions of the incinerator, as suggested by CO data in
Table 3.
As far as the carcinogenic PAH emission is
concerned, Table 11 shows that emission factors
vary in a smaller range with respect to PCDD/Fs
emission factors and that there is no significant
difference between the two kinds of feed. Major
contributions come from stack and fly ashes, with
shares spanning from 11% up to 79% for stack and
from 18% up to 77% for fly ashes.
A comparison of PAH emission data with litera-
ture findings lead to contrasting results. A strong
difference is evidenced with the work of Lee et al.
(2002) which in the study on the emission of PAHs
from mechanical grate and fixed bed incinerators
report concentrations and emission factors for stack
flue gases much higher than those reported in this
study, up to 2–3-order of magnitude, even excluding
the high concentration of Naphthalene (not con-
sidered in this study). On the other hand, slightly
higher (one-order of magnitude) or comparable
concentrations were found in the fly ashes and
bottom ashes, respectively.
In the study of Wheatley and Sadhra (2004), the
same PAHs congeners evaluated in this work
(excluding some heavier compounds) were analyzed
in the bottom ashes produced by a modern, pulsed
hearth hospital waste incinerator. In this case,
ARTICLE IN PRESS
Table 10
PCDD/Fs emission factors in the main output streams
(mg ITEQ t 1
of burned waste)
Test Slags Boiler ash Fly ashes Stack Total
1 10.1 11.1 786.0 2.9 804
2 21.6 49.1 3707.2 5.5 3783
3 10.6 45.3 3733.4 5.2 3795
4 0.8 0.5 41.0 8.2 51
5 1.2 6.5 492.8 44.0 544
6 0.7 2.5 214.7 7.7 226
7 – 3.1 254.6 24.7 281
8 18.1 1.8 146.6 2.3 169
Table 11
Total and carcinogenic PAHs emission factors in the main output streams (mg kg 1
of burned waste)
Test Slags Boiler ash Fly ashes Stack Total
Total Carc. Total Carc. Total Carc. Total Carc. Total Carc.
1 209.9 0.03 4.93 0.18 34.92 1.31 11.00 0.18 260.7 1.71
2 129.7 0.01 1.56 0.10 11.76 0.78 41.48 0.55 184.5 1.44
3 73.2 0.00 7.30 0.25 60.10 2.02 15.64 2.19 156.2 4.46
4 53.0 0.01 4.68 0.36 40.15 3.06 34.76 4.10 132.6 7.53
5 328.3 0.05 3.47 0.25 26.31 1.88 56.40 8.15 414.5 10.32
6 72.6 0.01 1.02 0.07 8.74 0.61 8.94 0.70 91.3 1.40
7 40.8 0.01 2.46 0.25 20.25 2.08 38.43 2.60 101.9 4.94
8 44.0 0.01 1.11 0.11 8.83 0.86 55.19 0.38 109.1 1.34
G. Mininni et al. / Atmospheric Environment 41 (2007) 8527–8536
8534

9. comparable concentrations and emission factors
were found.
Finally it must be pointed that, in spite of
incomplete optimization of the combustion process,
cumulative (air and solid residues) emission factors
of total PAHs (91–414 mg kg 1
of waste) fall in the
range of values reported by the Italian ANPA
(50–500 mg kg 1
) for incineration of municipal and
industrial wastes (ANPA, 2002).
4. Conclusions
The experimental campaign on hospital and
cemetery wastes incineration provided useful data
on PCDD/Fs and PAHs emission, which may
increase the reliability of emission databases on
the incineration of this class of waste materials.
PCDD/Fs emission factors for air (2.3–44mg
ITEQ t 1
of burned waste) were comparable with
those provided by the Dioxin Toolkit for incineration
plants of class 4 (continuous combustion with
sophisticated APCS). On the other hand, the emission
factors through solid residues (mainly fly ashes)
spanned from 41 up to 3700mg ITEQ t 1
of waste
and can be broadly considered of the same order of
magnitude of values given for class 3 (controlled,
batch type combustion, with good APCS in place).
In spite of the fact that the APCS included a
bag filter and a scrubber, PCDD/Fs concentration
at the stack was always higher than the limit of
0.1 ng ITEQ Nm 3
set by the European Directive
2000/76. Similarly, PCDD/Fs concentrations in
the fly ashes were generally higher than the limit
of 10 mg ITEQ kg 1
for disposal in hazardous
waste landfill sites provided by the European
Directive 99/31.
The PCDD/Fs mass balance regarding the heat
exchanger did not confirm the hypothesis of the de
novo formation of PCDD/F occurring during the
heat exchange process.
PAH concentration, after a sharp decrease from
the afterburning chamber to the heat exchanger,
showed an increase at the stack probably due to
releases of such compounds from the scrubber compo-
nents. PAH total emission factors (91–414 mgkg 1
of
burned waste) were in the range of values reported
by the Italian Agency for Environmental Protection
for incineration of municipal and industrial wastes.
In spite of the observed increase after the heat
exchanger, carcinogenic PAHs concentrations at the
stack (0.018–0.5 mg Nm 3
) were below the Italian
limit of 10 mg Nm 3
.
Acknowledgements
The research project was funded by Structural
Funds managed by the Italian Ministry of the
Research and Science. The authors would like to
thank the kind assistance of Rocco Antonacci in the
experimental tests on the full-scale plant and of
Massimo Bianchini during laboratory activities in
micropollutants determination.
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