TL: THE RELATIONSHIP BETWEEN CHLORINE INPUT TO COMBUSTORS AND
DIOXIN OUTPUT: AN ANNOTATED BIBLIOGRAPHY
SO: Pat Costner, GREENPEACE INTERNATIONAL, (GP)
DT: 11 SEPTEMBER 1997

INTRODUCTION

     Chlorine is the limiting element for dioxin 1 formation in
waste combustion systems.  This circumstance suggests that the
total dioxin output 2 from these systems can be reduced and/or
eliminated by curbing chlorine input, i.e., the implementation
of materials policies for chlorine-containing materials.  Such
materials policies were acknowledged almost a decade ago by the
U.S. Environmental Protection Agency.  For example, the Agency
outlined two approaches for reducing dioxin output from hospital
waste incinerators:  

1) replacement of  polyvinyl chloride (PVC) by other low-
chlorine plastics; and 

2) segregating PVC from incinerator inputs:i "Plastics and
metal-containing components of the waste, such as sharps, could
be segregated:  this could result in lower HCl, polychlorinated
dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans, and
trace meal emission rates. ... Another approach to possibly
lowering HCl and PCDD/PCDF emission rates would be to have
hospitals use low chlorine content plastics. This could be
accomplished if the health care industry were to use plastics
such as polyethylene and polystyrene in place of polyvinyl
chloride, which contains over 45 weight percent chlorine."

Similarly, in 1995, an advisory group for the U.K. Department of
the Environment discussed the applicability of such materials
policies for thermal processes in general:ii"One of the more
obvious primary ways of minimising TOMPS [toxic organic
micropollutants, e.g., dioxins]  in incinerators and in other
thermal processes is to try to avoid (or reduce) TOMPS, their
precursors or fundamental species (such as chlorine or bromine)
being included in the feedstock."

     Some of the materials policies that have been formally
incorporated into dioxin abatement efforts as well as others
that are recommended or proposed are as follows: 

     * A 1996 report from the Intergovernmental Forum on
Chemical Safety (IFCS) concluded that it was appropriate and
important to consider materials policies in developing
strategies to minimize and/or eliminate releases of both the
polychlorinated and polybrominated dioxins and furans;iii

     * The Governing Council of the United Nations Environmental
Programme adopted the recommendations of the IFCS report on Feb.
7, 1997, as part of the process of achieving  a global, legally
binding agreement to eliminate or reduce persistent organic
pollutants in the global environment;iv

     * On November 22, 1996, the American Public Health
Association adopted a resolution urging health care facilities
and suppliers to reduce or eliminate their use of PVC and other
chlorinated plastics that are currently disposed of in medical
waste incinerators;v

     * The Central Pollution Control Board of India ruled in
July 1996 that polyvinyl chloride (PVC) can no longer be burned
in medical waste incinerators;viIn 1994, the International Joint
Commission (IJC) between the U.S. and Canada recommended that
"...the Parties ... alter production processes and feedstock
chemicals so that dioxin, furan and hexachlorobenzene no longer
result as byproducts" and "... develop timetables to sunset the
use of chlorine and chlorine-containing compounds as industrial
feedstocks and that the means of reducing or eliminating other
uses be examined." vii  This followed the IJC's 1992 conclusion:
"We know that when chlorine is used as a feedstock in a
manufacturing process, one cannot necessarily predict or control
which chlorinated organics will result and in what quantity. 
Accordingly, the Commission concludes that the use of chlorine
and its compounds should be avoided in the manufacturing
process;"viii 

     * and In 1992, the German Federal Government enacted a
prohibition against using chlorinated and brominated compounds
as petrol additives to reduce dioxin release via car
exhausts.ix    

There is ample scientific support for materials policies that
require 1) replacement of chlorine-containing materials in
products destined for disposal in incinerators or interactions
in other thermal processes or 2) segregation of chlorine-
containing materials from wastes and other inputs to
incinerators and other thermal processes.  This is evidenced  by
the findings and conclusions of a  majority of related studies
published in the peer-reviewed scientific literature.  Listed
below are many of these studies, in addition to some of the more
frequently-cited studies showing negative findings.  

Reports and papers are presented in reverse chronological order.

To present a brief but accurate synopsis of each study,
annotations are composed primarily of direct excerpts, which are
printed in italics, in addition to some general descriptions and
comments, which appear in standard print. 

References
    
1997

1. Thuss, U., Herzschuh, R., Popp, P., Ehrlich, C., Kalkoff,
W.-D.  PCDD/F in flue gas and in bottom ash of lignite domestic
combustion and the role of the salt content of the burned
briquettes.  Chemosphere, 1997, 34 (5-7), 1091-1103.

Lignite briquettes with different salt contents ("normal"-coal,
300 ppm w/w, "salt"-coal, 2000 ppm w/w) were burned in a common
type of a house heating facility.  The content of
polychlorodibenzodioxins and furans (PCDD/F) in the flue gas and
in the bottom ash were determined.  The values calculated from
the homologue sums were significantly higher for the "salt"-coal
briquettes regarding their flue gas concentrations and slightly
increased in respect to the bottom ashes.  Taking into account
a wide variety of additional analytical parameters and
considering mechanistic aspects, our assumption was proved that
the higher chlorine content of the "salt"-coal briquettes is
responsible for the increased values.  

A house-heating facility (tiled stove with air circulation) with
a heating power of 9 kW was chosen to carry out the
investigations.

It is easily understood why chlorine, as an atom, which is
multiple incorporated in the PCDD/F-molecules, is of high
importance for the PCDD/F formation.  

A comparison of both coal sorts shows that the chlorine content
is approximately seven times higher for the "salt" briquettes
and their bottom ash (Table 2).  The bottom ashes amount has
approximately twice as much chlorine than is present in the
briquettes.  These chlorine values are in good accordance to the
PCDD/F-emission concentrations.

Concerning the ITE-concentrations the "salt"-coal flue gas
emissions are approximately seven times higher, regarding to the
homologue sums a four fold increase was determined.  

From the discussion of the single parameters it can be deduced
that the higher PCDD/F-emission of the "salt"-coal combustion is
caused by the higher chlorine content of the "salt"-briquettes. 
All other alternative approaches to explain this difference were
found to be non-relevant _ 

The only plausible explanation for the higher PCDD/F content of
the "salt"-coal bottom ash is the higher chlorine content as
well.

Lastly, our own results show that even a relatively small
surplus of chlorine causes a significantly higher PCDD/F-
emission.  Such a surplus could be realized by admixtures of
chlorine containing waste.

2. Pandompatam, B., Kuman, Y., Guo, I., Liem, A.J.  Comparison
of PCDD and PCDF emissions from hog fuel boilers and hospital
waste incinerators. Chemosphere, 1997, 34 (5-7, 1065-1073

A pilot-scale incinerator with a nominal capacity of 50 kg/h was
successfully used to simulate PCDD and PCDF emissions from hog
fuel boilers processing NaCl contaminated bark.  With 0.76 wt.
% chlorine in the bark, about 50 and 100 ng/m3 of total PCDD,
total PCDF were detected.  The corresponding PCDD and PCDF
values for the uncontaminated control bark were 0.3 and 0.3
ng/m3.  The Toxicity Equivalent (TEQ) for the 0.76 wt. % salt
contaminated bark combustion was 3 ng/m3 as compared to the
control value of 0.02 ng/m3.  

In the pulp and paper industry, "hogged fuel," consisting of saw
dust and bark is usually burnt for energy recovery purposes. 
Recent field studies [2,3,4] showed that PCDD and PCDF are
formed from combustion of sodium chloride (NaCl) contaminated
hog fuel.  The salt contamination occurs during the sea
transportation of logs to the coastal pulp mills. The
concentration of salt in the hog fuel can very up to 1% dry
weight while the typical moisture level is approximately 50%.  

3. Gullett, B., Raghunathan, K.  Observations on the effect of
process parameters on dioxin/furan yield in municipal waste and
coal systems.  Chemosphere 1997, 34 (5-7), 1027-1032.

Effects of fly ash loading; ash-borne, extractable organics;
sulfur dioxide (SO2) and hydrogen chloride (HCl) concentration;
and combustion quality on the formation of polychlorinated
dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD/F) were
evaluated in pilot scale tests simulating municipal waste
combustion and coal/waste co-combustion testing. 

The apparent absence of PCDD/F from coal combustion processes
may be due to a number of factors including lack of appropriate
catalysts, lack of organic products of incomplete combustion,
insufficient chlorine, and the presence of catalyst-poisoning
sulfur as SO2.  _

In this current work, reduction of PCDD/F formation at an S/Cl
of 1/1 shows that, at HCl concentrations used in Tests  G and H
(440 ppm), the presence of an available chlorinating species may
be reaction-limiting.  Because we have also seen an effect of
combustion conditions, it is clear that both available Cl and
organics are limiting PCDD/F formation.

Formation of PCDD/F in these tests was limited by extra-particle
factors, likely the concentration of organic and chlorine
reactants.


1996

1. Manninen, H., Perkio, A., Vartiainen, T., and Ruuskanen, J.
Formation of PCDD/PCDF: Effect of fuel and fly ash composition
on the formation of PCDD/PCDF in the cocombustion of refuse-
derived and packaging-derived fuels. Environ. Sci. & Pollut.
Res. 3 (3): 129-134 (1996)

Manninen et al. (1996) concluded that "...the correlation of the
fuel Cl content and PCDD/Fs was significant...."

"Their study was carried out "... in a normal multi-fuel power
plant by co-combustion of packaging-derived fuel (PCF) or
refuse-derived fuel (RDF) with fossil fuels, such as coal or
peat. This work includes the results of 17 co-combustion tests
and an evaluation of the results by the Principal Component
Analysis (PCA) and the Partial Least Squares Projections to
Latent Structures (PLS)."

"Because a mixture of packaging materials can contain metals
from foils and printing inks, chlorine from PVC, and food
contaminants, a question has emerged:  How do these metals and
chlorine affect PCDD/F formation?  On the other hand, does the
combustion of packaging material with sulphur containing coal
have an inhibiting effect on the formation?  The objective of
this study was to find answers to these questions by evaluating
the full-scale combustion results from 17 test runs carried out
in a multifuel circulating fluidized-bed boiler (CFB).
Multivariate projection methods such as Principal Component
Analysis (PCA) and Partial Least Squares Projections to Latent
Structures (PLS) were used."

"The co-combustion tests were carried out in a 65 MW CFB
multifuel boiler having an ESP for flue gas cleaning. Operation
parameters were kept constant during every 24 hour test run. 
Temperature in the bed was 850-877 C and 133-140 C in the
sampling point after the ESP. Residence time in the hot zone was
>2s and the oxygen content was 4.5-5.5% (wet) in the furnace."

"Total PCDD and PCDF concentrations in the flue gas after the
ESP, including gaseous phase and particles, and in the fly ash
were small in all tests.  They were on the same level as in
normal power plant combustion and much lower than PCDD/F
concentrations in waste incineration." "The results of the PLS
calculations (-> Fig. 2 and regression coefficients) show that
a lower heating value (LHV in dry solids) or the amount of
volatile components in the fuel mixture, or the temperature of
the bed did not correlate significantly with the PCDD/F values. 
Pb, Cu, Cr and Cl contents of the fuel and polychlorinated
phenols (PCPhs) in the flue gas correlated most closely with the
PCDFs in the flue gas and fly ash." "The calcium content of the
fly ash correlated closely with the Cl content.  This shows that
part of the chlorine was bound by Ca into the fly ash, thereby
decreasing HCl emission in the flue gas.  The correlation of
higher chlorinated PCDDs and PCDFs with Ca, Cl and PCBz in the
fly ash is seen from the results."  "The chlorine content of the
fuel correlated with PCDFs and there was an inverse correlation
between the S/Cl ratio and PCDFs." 

2. Wanke, T., and Vehlow, J.  The influence of flame retarded
plastic foams upon the formation of Br containing
dibenzo-p-dioxins and dibenzofurans in a MSWI.  Organohalogen
Compounds 28: 530-535 (1996)

In this study at the TAMARA facility, Wanke and Vehlow (1996)
found that "an additional input of Br [bromine] into the
incinerator does obviously promote the specific formation of
mixed halogenated [dioxin] congeners significantly.  In Fig. 2
the sum of the Br containing dioxins [in raw gas] is plotted as
a function of the Br input into the incinerator for all test
trials except of those with poor combustion conditions.  As a
first approach the graph can be interpreted as a straight
correlation between both parameters.  The data, however, are
very low and suffer from high analytical uncertainties."

"The same relationship for the bromine containing dibenzofurans
is shown in Fig. 3.  This indicates a correlation at low and
approximately constant furan concentrations at high Br input. 
This behaviour could be explained by assuming a similar de novo
synthesis for the Br containing compounds as has been found for
the formation of chlorinated dioxins and furans."

"According to the de novo synthesis mechanism the inventories of
active carbon, halogenides and copper in the fly ashes control
the formation potential.  Hence the relationship of Br
containing species and the bromide concentration in the fly
ashes should be regarded as has been done in Fig. 4 for the
furans.  This graph demonstrates that the furan levels show
about the same dependence upon the bromide concentration in both
test campaigns."

3. Kanters, M., Van Nispen, R., Louw, R., and Mulder, R. 
Chlorine input and chlorophenol emission in the lab-scale
combustion of municipal solid waste.  Environ. Sci. Technol. 30
(7): 2121-2126 (1996) 

Kanters et al. (1996) concluded, "For efficiently operating MSW
incinerators with a minimum of dioxin emissions, it is important
to control the chlorine load ...A variety of precursors,
including chlorophenols, promote the formation of PCDDs via fly
ash-catalyzed reactions at ca. 300 C."

"Upon pyrolysis/combustion, PVC smoothly eliminates most of its
chlorine as HCl. ... PVC acts as a source of HCl, but its
degradation may also lead to the formation of suitable
precursors [of PCDD/Fs]."  

" [When] conditions are in better agreement with those in a real
MWI [municipal waste incinerator] where HCl is present
throughout the continuous combustion process ... [t]he HCl
concentration in the gas flow was varied, and already with 0.1
g of HCl/Nm3 ... led to a doubling of the CP [chlorophenol]
formation. ... [T]he relation between the CP emission .. and the
HCl emission under standard conditions is shown.  Samples with
a higher chlorine content give a higher CP emission but tend to
reach a plateau value. ... [W]ith added HCl .. it appears that
the CP emission increases quite regularly if not linearly with
[HCl]."

4. Huotari, J., and Vesterinen, R.  PCDD/F emissions from co-
combustion of RDF with peat, wood waste, and coal in FBC
boilers.  Haz. Waste & Haz. Materials 13(1): 1-9 (1996) 

In experiments performed with combustors ranging from small to
full-scale, Huotari and Vesterinen (1996) found as follows: "The
chlorine content of fuel rose up to 0.35% as a measured dry base
(db).  The emissions of the toxic PCDD/F compounds were found to
follow fuel-Cl content trendwise, as expected.  However
quantitatively the relative emission levels varied with the
factor of 103 at the same Cl- content in fuel.  ... The PCDD/F-
emissions are related to fuel-Cl content."

5. Vesterinen, R., and Flyktman, M.  Organic emissions from co-
combustion of RDF with wood chips and milled peat in a bubbling
fluidized bed boiler.  Chemosphere 32(4): 681-689, 1996. 

In their study of a full-scale combustor, Vesterinen and
Flyktman (1996) concluded as follows: "In co-combustion of RDF
[refuse derived fuel] with wood chips the clear correlation was
seen between the chlorine content of the fuel mixture and the
PCDD/F concentration in flue gas.   A similar correlation was
also seen between the fuel chlorine and chlorophenol
concentration in flue gas."   

6. Wikstrom, E., Lofvenius, G., Rappe, C., and Marklund, S.
Influence of level and form of chlorine on the formation of
chlorinated dioxins, dibenzofurans, and benzenes during
combustion of an artificial fuel in a laboratory reactor. 
Environ. Sci. Technol. 30(5): 1637-1644 (1996).

Using a lab-scale apparatus, Wikstrom et al. combusted an
artificial waste with varying levels of chlorine contributed by
either PVC or CaCl 2*6H2O.  They concluded, "The results from
this study indicate no correlation between the quantities of
formed PCDDs/PCDFs and PCBzs (chlorobenzenes] in the combustion
process and the level of chlorine in the fuel, when the chlorine
level is below 1%.  However, when the level of chlorine in the
fuel exceeds 1%, an increased formation rate was noted.  No
distinction in the formation rate of the chlorinated
micropollutants was noticed between the two different chlorine
sources."

It is important to note, however, that they also offered
another, somewhat different conclusion: "[N]o correlation is
shown between PCDD/PCDF and PCBz formation and chlorine content
when the total chlorine amount in the fuel is 0.5% or lower."

"To avoid these mechanisms influenced by the uncontrolled
formation of precursors, all experiments were performed with a
high combustion efficiency (CE).  The only variation between the
experiments were the form and content of chlorine in the fuel "

"This study shows that the emission is not influenced by the
form of chlorine in the fuel, either organic or inorganic. ....
... Figure 5 and 6 show that approximately 1% chlorine in these
fuels is a threshold value for the formation of excess PCDD/PCDF
and PCBz during combustion. ... Thus, the chlorine content in a
normal MSW is below the threshold value of 1% for an increase in
PCDD/PCDF and PCBz formation.  ... The results from this study
do not support the opinion that an elimination of only PVC will
contribute to a considerable reduction of PCDD/PCDF emissions if
the combustion process is well controlled, as in this study."

[Note: This study and those studies described by its authors as
supporting their finding of a positive correlation between
chlorine input and dioxin output were reviewed and this finding
was corroborated.  However, neither the data presented by
Wikstrom et al (1966) nor any of the other studies cited support
the contention that this positive correlation ceases to exist
when the chlorine content of the combustor feedstock falls below
1 percent.]

1995

1. Moller, S., Larsen, J., Jelnes, J.E., Faergemann, H.,
Ottosen, L.M., and Knudsen, F.E.  "Environmental Aspects of
PVC." Environmental Project No. 313.  Denmark:  Ministry of the
Environment, Danish Environmental Protection Agency, 1995.

In their review of data from full-scale combustors, Moller et
al. concluded as follows: "The hydrochloric acid content in the
stack fume is dependent on the content of PVC and other chlorine
sources in the waste.  It is calculated that 2/3 of the chlorine
in the Danish incinerator plants originates from PVC in the
waste and thus also the hydrogen chloride formed. Burning PVC
also yields a large amount of soot-containing smoke.  ... The
presence of chlorine in the material gives the potential for
contribution to the formation of polychlorinated dioxins and
furans during the fire.  If formed, it seems that these
substances have the highest tendency to be present in the soot. 
The amount will depend on the fire conditions such as oxygen
available, temperature, catalyst available such as copper and
the amount of chlorinated material, e.g., PVC involved in the
fire.  However, the content of PVC in the waste also contributes
to the emission of dioxins and heavy metals."

"There seems to be a relationship between HCl emissions and the
emissions of a number of chlorinated organic compounds including
dioxins.  However, the relationship is a 2nd or 3rd order
relationship (Tromp et al. 1994, Shepherd, 1993, Miljostyrelsen,
1989A; Boerekamps-Kanters, Louw, 1992; Mark, 1994).  It is most
likely that the reduction of the chlorine content in the waste
can contribute to the reduction of the dioxin formation, even
though the actual mechanism is not fully understood.  The
influence on the reduction is also expected to be a 2nd or 3rd
order relationship."

2. Thomas, V.M., and Spiro, T.G.  An estimation of dioxin
emissions in the United States.  Toxicol. and Environ. Chemistry
50:1-37 (1995)

In their study, Thomas and Spiro (1995) reviewed data from a
broad array of combustion systems, concluding as follows: 
"Nevertheless, the data presented in section 4 will show that
dioxin emission factors from combustion of similar fuels, with
broadly similar combustion systems and pollution control
devices, typically vary by less than an order of magnitude. 
This holds true, for example, for hospital waste incinerators,
sewage sludge incinerators, and industrial wood boilers.  Thus,
for most processes dioxin emissions can be categorized by the
combustion activity.  Exceptions are the incineration of
municipal and hazardous waste, for which different types of
combustion systems can have dioxin emission factors that differ
by more than an order of magnitude."

"While a dependence on chlorine content might seem to be a
foregone conclusion, there has in fact been doubt on this point
since limited data, on test-burns at municipal waste
incinerators, for example, have shown no correlation.  There
are, of course, many variables besides chlorine content,
especially the operating conditions of the combustion system,
and the application of pollution control technology.  Figure 1
shows that favorable operating conditions (open symbols) can
lower emissions by as much as two orders of magnitude.  But
under poorly controlled conditions (closed symbols), there is a
clear dependence on chlorine content.  Moreover, the
relationship is more than proportional since the slope of the
loglog plot is somewhere between one and two.  Since dioxin
molecules contain more than one chlorine atom, a higher order
dependence is not unexpected."

3. Halonen, I., Tarhanen, J., Ruikojarvi, P., Tuppurainen, K.,
and Ruuskanen, J.  Effect of catalysts and chlorine source on
the formation of organic chlorinated compounds.  Chemosphere 30
(7): 1262-1273 (1995)

"Two series of catalyzed incineration tests were performed in a
32 kW laboratory pilot plant to study the effects of metal
catalysts on the formation of chlorobenzenes, chlorophenols and
polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs).
... Sodium chloride, representing inorganic chlorine, and
tetrachloroethylene representing organic chlorine, were used as
chlorine sources in the basic fuel with the different catalysts.

Metals and chlorine accounted for 0.5 weight-% of the total fuel
flow."

"Organic chlorine with the catalyst promoted the formation of
particle-bound PCDD/Fs, whereas inorganic chlorine was observed
to promote the formation of PCDD/Fs more effectively in the gas
phase than in the particle phase."

"The highest concentrations of chlorobenzene were observed with
all the metals when organic chlorine was used as the additive
chemical, the chlorobenzene concentrations in particles being
especially high relative to the situation with inorganic
chlorine. ... The addition of organic chlorine increased the
chlorophenol concentration more than did inorganic chlorine,
this being especially the case in the gas phase (Fig. 6)."  

1994

1. Cains, P.W. and Dyke, P.  Chlorinated dibenzodioxin and
dibenzofuran emissions from waste combustion plants in the UK. 
Chemosphere 28(12): 2101-2119 (1994) 

"Simple global correlations of dioxin and furan levels against
general parameters such as the CO or HCl concentration in the
flue gas, Cu, Cl or S level in the feedstocks, grit ashes or
particulates entrained in the flue gas, combustion or boiler
exit temperatures are not sufficiently robust to characterize
the conditions that promote formation in a general or universal
way.  Specific correlations of PCDD/F levels against the copper
and chlorine contents of entrained particulates tentatively
support results of laboratory studies on the role of Cu and Cl
in fly ash in promoting PCDD/F formation."

2. U.S. Environmental Protection Agency.  Combustion Emissions
Technical Resource Document (CETRED). Draft. EPA 530-R-94-014,
Washington, D.C. May 1994.

"The absence of any apparent trends in the PCDD/PCDF emission
data versus either HCl or THC does not preclude these as
important parameters in characterizing dioxin/furan emissions. 
It does suggest, however, that the scatter in the data set
combined with other potential dominant trends can mask smaller
effects that might be anticipated."

3. Mark, F.  "Energy recovery through co-combustion of mixed
plastics waste and municipal solid waste,"  Association of
Plastics Manufacturers in Europe (APME), June 1994.

"In order to categorise the relative effects of polymers on the
combustion of MSW the project studied three test cases: * 
combustion of MSW containing an average level of polymers - base
case *  combustion of MSW containing an added 7.5 per cent by
weight of mixed plastics waste - medium polymer case *
combustion of MSW containing an added 15 per cent by weight of
mixed plastics waste - high polymer case." The total polymer
content in residual MSW ranged from 8.5 to 12 per cent weight,
depending on collection sites." "Analysis of the mixed waste
plastics used as fuel in the test programme was undertaken by
... Three 230 kilogram bale samples of representative mixed
waste were hand sorted to show the following contents:...' "Use
of identification codes on sample items showed the split by
polymer to be ... polyvinyl chloride 4% wt." "APME estimates the
European average content of PVC in MSW to be approximately 10
per cent weight, so to match this figure the PVC element of
mixed waste polymers used for testing was increased by the
addition of post-use articles such as PVC pipes and flooring
products. This meant that the addition of plastics, with an
average heat of combustion three times higher than standard MSW,
caused the total feed to the combustor to be reduced
accordingly."

"... soot blowing was carried out two hours before, and at the
end of every six hour sampling period.  Change over times from
one condition to another  - ie A to C - were a minimum period of
12 hours to ensure stable boiler conditions."

"Two types of additives - lime, with or without carbon -were
used during the test to confirm the effectiveness of carbon in
removing dioxins and furans."

"HCl concentration in the flue gas rose as expected because of
the addition of PVC to the waste plastics, although this was
subsequently reduced to amounts found in normal clean gas by the
emission control system." [No data were given for uncontrolled
HCl levels.  I.e., HCl measurements were taken following
treatment for acid gas removal.]

"Increased hetero atom content was recorded only for the Cl
concentrations in the raw gas." [No raw gas data were given]. 
"Peaks in raw gas concentrations were only two to three times
the normal value of 1.5 g HCl/m3.  There was no increased
formation of chlorinated dibenzodioxin/furans (PCDD/F) in the
raw gas when adding mixed waste plastics." No correlation
between polymer content and increased occurrence of PCDD/Fs can
be derived from the results of these tests.  This was true even
when the higher concentrations of PVC were present.

[Note: As the above description of this study show, the results
are of limited usefulness in assessing the relationship between
chlorine (or PVC) input and dioxin output: 1) no direct
determinations of either the chlorine or PVC content of the
incinerator feedstock were undertaken; 2) waste feedrates were
apparently decreased as plastics (including PVC) content was
increased; 3) the use of additives, lime with and without
carbon; obscures data interpretation; and 4) the frequency of
soot blowing combined with abbreviated stablization times (as
little as 12 hours) can be expected to have considerable
influence on dioxin formation as well as measured dioxin
values.]

4. Ruuskanen, J., Virtiainen, T., Koja, I., Manninen, H.,
Oksanen, J., and Frankenhaeuser, M.  Formation of
polychlorinated dibenzo-p-dioxins and dibenzofurans in
co-combustion of mixed plastics with coal, exploratory principal
component analysis.  Chemosphere 28: 1989-1999 (1994) 

"The purpose of the tests was to examine the effects of
sulphur-rich coal on the formation of chlorinated hydrocarbons
like PCDD/PCDFs. ...No correlation between HCl and furans and
dioxins [in flue gas] was found.  On the other hand, in fly ash
samples the significant correlation of HCl and furans was
obvious."

5. Wilken, M.; Boske, J.; Jager, J.; Zeschmar-Lahl, B.  PCDD/F,
PCB, chlorobenzene and chlorophenol emissions of a municipal
solid waste incineration plant (MSWI) - variation within a five
day routine performance and influence of Mg(OH)2-addition. 
Chemosphere 29 (9-11): 2039-2050 (1994).

At the Bielefeld-Herford municipal solid waste incinerator in
Germany, reductions in PCDD/F emissions were achieved as
follows: " ... [T]he average of 2.73 ng I-TEQ/m3 and the median
of 2.81 ng I-TEQ/Nm3 of the actual routine performance lie
distinctly below former emission concentrations, which ranged
from 2.9 to 4.2 ng I-TEQ/Nm3.  The same trend can be observed
for PCB, but not for chlorobenzenes and chlorophenols.

Since the measurement in december 1991 effective emission
reduction means like 
*  exclusion of PVC and computer scrap in the input,
*  optimizing combustion operation,
*  installation of a high-performance quasi-dry flue gas
purification system in 1993 have been realized at this plant."

1993

1. Jager, J., Wilken, M., Beyer, A., Rakel, H., Zeschmar-Lahl,
B., Jager E.  Practical concepts to minimize the emission of
halogenated organic compounds from municipal solid waste
incinerators.  Chemosphere 27 (1-3): 141-148 (1993) 

In experiments with full-scale combustors, Jager et al. found as
follows:  "At MWI A, addition of polyvinylchloride resulted in
a slight but not significant increase in PCDD/PCDF in clean gas,
while concentrations of chlorobenzenes, PCB and hydrogen
chloride increased rapidly.  Nevertheless, the chlorine content
in the input must have had an influence on the dioxin emission,
as has been observed at MWI C at the summer and winter campaign.

Lenoir et al. also observed a significant increase in PCDD/PCDF
emission after addition of 3% PVC to the waste input. ...  At
MWIs A and D, the raise of the bromine content in the input
material resulted in a significant rise of mixed-halogenated
dioxins and furans, especially monobromo-polychloro compounds,
and in increase of chlorinated dioxins and furans too (Fig. 5)."

2. Burns, D.B., "Final Report Consolidated Incineration Facility
Metals Partitioning Test (U)," WSRC-TR-93-623,  U.S. Department
of Energy, Savannah River Technology Center, Aiken, SC, August
31, 1993 

"The chloride concentration in the waste with PVC was
approximately 6 wt%, while the waste without PVC contained 1.5
wt% chloride. ... The measured offgas HCl concentrations ranged
from 63% to 1% of the theoretical HCl emissions.  The difference
is most likely due to the chlorinated metal compound formation
in the kiln.  The HCl sampling method is not isokinetic, thus
particles with condensed metal chloride compounds would not have
been collected.  Also, chlorine from volatilized chlorinated
metal compounds in the sample would not be detected unless the
chlorine dissociated from the metal. ...The data in Table 13
shows the most significant variable influencing PCDD/PCDF
emissions is waste chloride concentration." 

[Note:  This study also showed that increased chlorine caused an
increase in submicron particulate concentration, suggesting that
the more PVC burned, the higher the concentrations of submicron
particles in offgases and, consequently, the poorer the capture
efficiency of APCDs.   Higher chlorine also caused higher VOC
emissions.]

3. Jager, J., Wilken, M., Beyer, A., Rakel, H., Zeschmar-Lahl,
B., and Jager, E.  Practical concepts to minimize the emission
of halogenated organic compounds from municipal solid waste
incinerators.  Chemosphere 27 (1-3): 141-148 (1993)

"Recommendations concerning waste input
*  Reduce halogen availability in the combustion chamber by
excluding certain materials from MWI input. 
*  Exclude brominated compounds (e.g., electronic scrap) from
your MWI. 
*  Exclude polyvinylchloride (PVC) from combustion in order to
reduce halogen offer and PCB, chlorobenzene and hydrogen
chloride emissions."

4. Halonen, I., Tarhanen, J., Oksanen, J., Vilokki, H.,
Vartianinen, T., and Ruuskanen, J.  Formation of organic
chlorinated compounds in incineration of pulp and paper mill
biosludges.  Chemosphere 27(7): 1253-1268 (1993).

"Biosludge mixtures were incinerated in a pilot scale
circulating fluidized be incineration plant. ... In fly ash ...
[c]orrelation was present only between the isomers of PCDD/PCDFs
and the concentrations of sulphur and chlorine content in the
fuel." 

[Note: This conclusion  was based on principal component
analysis.]

5. Halonen, I., Tarhanen, J., Kopsa, T., Palonen, J., Vilokki,
and H. Ruuskanen, J.  Formation of polychlorinated dioxins and
dibenzofurans in incineration of refuse derived fuel and
biosludge. Chemosphere 26 (10): 1869-1880 (1993).

"PCDD/PCDF formation at 850 C was observed to depend on chlorine
content in the fuel."

"The results of the three fuel mixture incineration tests (fig.
2) show that increased chlorine content in the fuel produced
higher PCDD/PCDF concentrations formed at 850 C (AHC), but
similar correlation at 200 C (ABH) was not seen in combustion
tests of biosludge. .. It is obvious that variables other than
the chlorine and PCDD/PCDF input contents in the fuel have an
influence on formed PCDD/PCDF levels. ... The chlorine content
of fuel materials had the most effect on PCDD/PCDFs formation at
the high temperature region of the flue gas.  When the flue gas
temperature decreased the correlation of the chlorine content in
fuel with the formation of PCDD/PCDF compounds disappeared."

6. Wagner, J., Green, A.  Correlation of chlorinated organic
compound emissions from incineration with chlorinated organic
input.  Chemosphere 26 (11): 2039-2054 (1993).

"We find several statistically significant relationships between
HCl emissions (a surrogate for PVC in the waste) and the
emissions of a number of chlorinated organic compounds. ...These
results, contrary to the prevailing opinion [1], lead to the
physically reasonable conclusion that decreases in the levels of
organically bound chlorine in the input leads to decreases in
chlorinated organic emissions. ... In final summary the CCTL's
experimental, phenomenological, and theoretical studies of toxic
emissions from incineration all support the physically intuitive
hypothesis that reduction of chlorinated plastics in the input
waste stream results in reduction of aromatic chlorinated
organic emissions [21].  ... While the CCTL's measurements have
been limited to volatiles and light semi-volatiles these result
are expected to apply to other chlorinated aromatic hydrocarbons
emissions such as phenols, dioxins, and furans, which we have
not measured.  A number of other publications support a PVC-PCDD
association [22-26].  Bulley has also found experimentally that
reduction of PVC input leads to reduced chlorinated dioxins and
furans [27].  Thus we are convinced that, when all other factors
are held constant, there is a direct correlation between input
PVC and output PCDD/PCDF and that it is purposeful to reduce
chlorinated plastics inputs to incinerators"

7. Frankenhaeuser, M., Manninen, H., Kojo, I., Ruuskanen, J.,
Vartiainen, T., Vesterinen, T.R., Virkki, J., Organic emissions
from co-combustion of mixed plastics with coal in a bubbling
fluidized bed boiler. Chemosphere 27 (103): 309-316 (1993). 

"The objectives of this study were to examine the extent to
which mixed plastics (4 % Cl) can be burned in a modern boiler
together with coal (0.5% S), and to check the influence of the
sulphur/chlorine ratio in the fuel on emissions.  ... No clear
correlation to increased mixed plastics feed could be seen [in
flue gas emissions of PCDD/F].  PCDD/F in fly ash increased
significantly with increased mixed plastics feed ... It is
probable that the sulphur contained in the primary fuel poisoned
the catalysts responsible for the formation of PCDD/F in all the
plastics/coal blends."

8. Altwicker, E., Konduri, R.K.N.V., Lin, C., Milligan, M.S. 
Formation of Precursors to Chlorinated Dioxins/Furans under
Heterogeneous Conditions.  Combust. Sci. Technol. 1993, 88,
349392.

"As the Cl/C [chlorine/carbon] ratio increases the concentration
of potential chlorinated agents can be expected to increase thus
increasing the concentration of CBs [chlorobenzenes] (cf. table
5)."

9. Fangmark, I., van Bavel, B., Marklund, S., Stromberg, B.,
Berge, N., and  Rappe, C.  Influence of combustion parameters on
the formation of polychlorinated dibenzo-p-dioxins,
dibenzofurans, benzenes, and biphenyls and polyaromatic
hydrocarbons in a pilot incinerator.  Environ. Sci. Technol. 27
(8): 1602-1610 (1993).

"There are also a few other significant main effects, although
just above the 95% confidence level.  For PCDFs, PCBz, and PCBs
the addition of HCl is such an effect and for PCDDs it is the
H20 concentration in the fuel.  Although the variable HCl is
free of confoundings, the effect is too small to make any
further conclusions."

10. Gullett, B., Lemieux, P., Kilgroe, J., and Dunn, J. 
Formation and prevention of polychlorinated dibenzo-p-dioxin and
polychlorinated dibenzofuran during waste combustion:  The role
of combustion and sorbent parameters.  Presented at the 1993
Conference on Municipal Waste Combustion, Williamsburg,
Virginia, March 30-April 3, 1993.

In experiments with a pilot-scale combustor, Gullett et al.
found as follows: "[HCl] is a significant parameter ...
Increases in [HCl] always lead to increases in [PCDD], within
the range of our data and model, which should hold for [Cl2  <
100 ppm.  This should always be the case in field operations. 
[Cl2 ] is a significant predictor for all three models.  ...
Test without addition of Cl as HCl or Cl2  also show large
increases in PCDD and PCDF, indicating that sufficient Cl
precursors are also present on the fly ash to produce PCDD and
PCDF. The effect of additional HCl and Cl2  is, within
statistical limits, always to dramatically increase the levels
of PCDD and PCDF from those of undoped baseline runs.  Thus,
both in situ, on-particle Cl and gaseous Cl lead to increased
yields, although the yield from the latter is generally over
twice that of the former."

1992

1. Thomas, V. Total PCDD and PCDF Emissions from Known
Combustion Sources and the Relationship of Chlorine Content to
PCDD and PCDF Emissions.  PU/CEES Working Paper No. 129,
Princeton University, July 1992.   

"... [C]hlorine is not the only determinant of dioxin emissions. 
However, for larger variations in chlorine content, the data
indicate a relationship between chlorine content and dioxin
emissions.  While there are sources with high chlorine content
and low dioxin emissions, there are no known sources of low
chlorine content and high dioxin emissions."

2. Takeshita, R., Akimoto, Y., and Nito, S.  Relationship
between the formation of polychlorinated dibenzo-p-dioxins and
dibenzofurans and the control of combustion, hydrogen chloride
level in flue gas and gas temperature in a municipal waste
incinerator.  Chemosphere 24(5): 589-598 (1992) 

At a full-scale combustor, Takeshita et al. found as follows: 
"The control of polychlorinated dibenzo-p-dioxins and
dibenzofurans (PCDDs/Fs) formation was investigated in a
municipal waste incinerator equipped with the electrostatic
precipitator (EP).  The simultaneous control of combustion,
hydrogen chloride (HCl) concentration level in the flue gas and
the gas temperature proved very effective in the control of
PCDD/Fs formation, reducing the concentration levels of PCDDs/Fs
in the flue gas at the EP outlet to 0.2 ng/Nm3 as
2,3,7,8-tetrachlorodibenzo-p-dioxin when evaluated by the
international toxicity equivalent factors."      

PCDDs/Fs Concentrations in EP Ash

As shown in Fig. 5, with increasing gas temperature or HCl level
in the gas except for exp. 4, the PCDDs/Fs concentrations tended
to increase, and at any of similar gas temperature, the
concentrations tended to increase at higher HCl levels. 
However, the PCDDs/Fs concentrations in the EP ash samples were
closely related to the amount of injected slaked lime. ... At
any of similar gas temperature, the amounts of PCDDs/Fs formed
at the high HCl level were higher than those measured at the
middle HCl level, and at similar middle and high levels of HCl,
the amounts of PCDDs/Fs formed at higher gas temperatures were
higher than those formed at lower gas temperatures.  At a gas
temperature of 300 C, HCl in the flue gas markedly increased the
formation of PCDDs/Fs."

PCDDs/Fs Concentrations in EP Outlet Gas

... The PCDDs/Fs concentrations in the gas when the
gas temperature was 300 C were at higher levels in proportion to
the HCl concentration levels.  When the gas temperatures were
200 and 240 C, the PCDDs/Fs concentrations at the lowest HCl
level in the gas were remarkably higher than at other HCl
levels.  This phenomenon indicates that the PCDDs/Fs formation
was linked to some other factors increasing the amount of dust
in the gas as shown in Fig. 8."

3. Johnke, B., and Stelzner, E., "Results of the German dioxin
measurement programme at MSW incinerators," Waste Management &
Research 10: 345-355 (1992). 

In their study with full-scale combustors, Johnke and Stelzner
found as follows:  "The addition of PVC (1% wt) to the waste
resulted in a marked increase in HCl levels in the raw gas, but
in no significant change in PCDD/PCDF concentrations.  However,
it cannot be concluded from this that PCDD/PCDFs do not form in
the incineration of PVC. ... Tests involving an increased supply
of bromine in the waste have also been performed; here, a
distinct increase in polyhalogenated dioxin/furan levels and a
slight increase in the concentrations of the chlorinated
PCDD/PCDFs as well as benzenes, was ascertained."

4. Mattila, H., Virtanen, T., Vartianinen, T., Ruuskanen, J. 
Emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans
in flue gas from co-combustion of mixed plastic with coal and
bark.  Chemosphere 25 (11):1599-1609 (1992)

In their study, conducted using a full-scale combustor, Mattila
et al. reported as follows: "Our results prove the evidence for
conversion of chlorinated plastic material to polychlorinated
dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans
(PCDFs). ...   the total amount of PCDD/Fs correlate closely
with the formed HCl concentration in tests 1 to 3, but in test
4 the yield of PCDD/Fs was ten times higher than expected. ...
This full scale study showed that the formation of PCDDs and
PCDFs is connected with the total chlorine content in the fuel
mixtures.  The results give a strong support to the PCDD/F
formation mechanism involving chlorinated plastics as the
identified chlorine source.  The second major implication of the
PCDD/F formation is its relationship to the concentration of HCl
formed during combustion."

5. Hassel, G.R., Rizeq, R.G., Barton, R.G., and McGrath, T.P.,
Emissions assessments from incineration of large volume
parenteral plastic containers.  in Proceedings of the 1992
Incineration Conference: Thermal Treatment of Radioactive,
Hazardous Chemical, Mixed and Medical Wastes, Albuquerque, New
Mexico, May 11-15, 1992, pp. 483-488.   

"Both PE/PP[polyethylene/polypropylene] products produced about
10 grams of HCl per kilogram of plastic.  The EVA produce about
three times more, and  the PVC samples produced roughly thirty
times more HCl than  the PE/PP samples.   ... The significance
of the chlorine content in a waste stream has been reported with
conflicting conclusions.  In a study involving municipal solid
waste incinerators, formation of PCDD/PCDF was not shown to have
any correlation to either the concentration of chlorine in the
waste or the concentration of HCl in the combustion gases (6). 
On the other hand, a broader study indicated that both organic
and inorganic chlorine in a waste have "a statistically
significant influence on the dioxin formation" (7).  The
parenteral plastics data apparently indicate that chlorine is an
important but not overriding factor in PCDD/PCDF formation. 
Comparison of the data from the two PE/PP products points to the
significance of the catalytic effect of copper.  Comparison of
the data from the PE/PP bottle and the two PVC products points
to the significance of chlorine.   Comparison of the EVA data to
all the other products can be construed to signify the
importance of certain products of incomplete combustion."

6. Kopponen, P.; Torronen, R.; Ruuskanen, J.; Tarhanen, J.;
Vartiainen, T.; Karenlampi, S.  Comparison of cytochrome P4501A1
induction with the chemical composition of fly ash from
combustion of chlorine containing material.  Chemosphere 1992,
24 (4), 391-401.  

"PVC-containing material is a source of PCDDs/PCDFs because of
the chlorine it contains.  There is direct evidence of the
conversion of PVC to PCDDs and PCDFs in pyrolysis (Marklund et
al. 1986).  During combustion and pyrolysis of pure PVC and PVC-
containing materials in the atmospheric air, significant amounts
of PCDDs/PCDFs have been reported to be produced in both
laboratory experiments (ppm range) and in fires (ppb range)
(Christmann et al. 1989; Theisen et al. 1989).  Furans were the
predominant compounds detected"

At a 60 megawatts district power plant, Kopponen et al. (1992)
combusted a mixture of coal and bark mixture with the addition
of PVC and non-chlorinated plastics.  The chlorine content and
PCDD/F concentrations in fly ash for each experiment was as
follows:                                                       
Experiment     Added Material Total Chlorine Content   PCDD/F  
                              in Fly Ash, pg/g 
1                   None           0.04 % (w/w)        77.1 
2              Non-chlorinated 
               Plastic             0.04 % (w/w)        109     
3              PVC + non-
               chlorinated 
               Plastic             0.4 % (w/w)         654     
4              PVC                 1.2 % (w/w)         9768

"... the total PCDD/PCDF concentrations were over 100 times
higher in the fly ash from combustion of chlorine containing
material (combustion 4) than those of basic fuel (coal and bark
materials).

1991

1. Fangmark, I., Marklund, S., Rappe, C., Stromberg, B., and
Berge, N.  Use of a synthetic refuse in a pilot combustion
system for optimizing dioxin emission, Part II.  Chemosphere 23
(8-10): 1233-1243 (1991) 

"In contradiction to what was reported earlier (Vikelsoe, 1990) 
our experiments show that when increasing the HCl concentration
in the flue gases from what can be formed from the 1% PVC (8
g/h) to an additional 10 g/h, which is more than doubling, no
measurable effect on the PCDD/PCDF emission could be observed.
...It is also interesting to note that although we are burning
a fuel with a constant amount of PVC we find a large range of
dioxins and dibenzofurans emitted.  The highest value in table
5 is more than 150 times the lowest value, primarily due to
different conditions in the cooling section."

[Note:  An examination of the data in this report show that, for
sample 1, all experiments at the high  HCl value had an overall
average emission of dioxins of 66.1 ng TEQ /Nm3  and, at the low
HCl level, an average of 42.2 ng TEQ/Nm3  For sample 2, the high
HCl values were associated with an average emission of 62 ng
TEQ/Nm3;  for low HCl, 47.3 ng TEQ/Nm3.  This shows an overall
average increase in dioxin emissions of 42 percent when HCl
levels were doubled.]

2. Lenoir, D., Kaune, A., Hutzinger, O., Mutzenich, G., and
Horch, K.  Influence of operating parameters and fuel type on
PCDD/PCDF emissions from fluidized bed incinerator.  Chemosphere
23: 1491-1500 (1991). 

Lenoir et al. studied the formation of dioxin during combustion
with two chlorine sources (NaCl and PVC) in a pilot-scale
combustor, finding as follows: "The investigated fuel types
varied in the chlorine content which, in some experiments, was
increased by adding NaCl or polyvinylchloride (PVC).  Only the
addition of 3 % PVC to polyethylene resulted in an increase in
PCDD/F concentrations. ... [A]ddition of 3 % PVC to PE increased
PCDD/F levels by a factor of 3 compared to the mean value for
pure PE combustion. ... [S]tatements about the influence of
incinerator operating conditions and fuel types on PCDD/F
emission might have to be modified if the total PCDD/F
concentration in the flue gas, rather than the PCDD/F fraction
attributed to coarse and fine fly ash, had been considered."

3. Yasuhara, A., and Ito, H.  Combustion of Poly (vinyl
chloride).  J. Environ. Chem. 1: 525-528 (1991) 

"Main combustion products of poly(vinyl chloride) were
polynuclear aromatic hydrocarbons.  Formation of
chlorine-containing compounds was little. Formation of
polychlorinated dibenzo-p-dioxins and dibenzofurans
was confirmed.  Temperature of maximum PCDDs and PCDFs formation
was 600 C.  Essential profiles of PCDDs and PCDFs formation at
various temperatures were similar.  Formation amounts of PCDFs
were more than those of PCDDs."

Combustion of PVC (from clear PVC gloves) gave the following
yields of PCDD/Fs:               
Temperature,  C          PCDD/Fs, ng/g PVC
300                      3.22                
400                      5.753
500                      12.212 
600                      20.466
700                      17.633
800                      12.267

Pasek, R., Chang, D.  Potential benefits of polyvinyl chloride
and polyvinylidene chloride reductions on incinerator emissions.

Air Waste Manag. Assoc. 1991, 91-33.1.

[Note:  This study is described in Wikstrom et al. (1996) as
showing a positive correlation between chlorine input and dioxin
output.  However, we are, as yet, unable to locate this paper.]

4. Karanen, E., Aittola, J.-P., Lappanen, A.  Combustion of wood
and plastic waste from packaging industry in residential
furnaces.  Energy Environ. D: 517-531 (1991).     

[Note:  This study is described by Wikstrom et al. (1996) as
showing a positive correlation between chlorine input and dioxin
output.  However, we are, as yet, unable to locate this paper.] 

5. Kevin, R., Beach, B., Beach, L.O., Gullett, B.K.  The role of
the gas-phase Cl2 in the formation of PCDD/PCDF during waste
combustion.  Waste Manage. 11, 97-102 (1991).   

[Note:  This study is described by Wikstrom et al. (1996) as
showing a positive correlation between chlorine input and dioxin
output.  However, we are, as yet, unable to locate this paper.] 

1990

1. Manscher, O., Heidam, N., Vikelsoe, J., Nielsen, P.,
Blinksbjerg, P., Madsen, H., Pallesen, L., and Tiernan, T.  The
Danish Incinerator Dioxin Study. Part 1.  Chemosphere 20
(10-12): 1779-1784 (1990) 

From their analysis of data from 10 municipal solid waste
incinerators and two hospital incinerators, Manscher et al.
concluded as follows:  "For models that, in addition to the
block effects, contain the parameters of load and excess air, it
is found that among the rest of the parameters considered, only
the hydrogen chloride becomes significant. ... {They found} ...
a 14 % increase in the dioxin emissions when the HCl emission is
doubled.  This relation is valid in the range of 100 to 1000
mg/m3 of HCl."

2. Vikelsoe, J., Nielsen, P., Blinksbjerg, P., Madsen, H., and
Manscher, O.  Significance of chlorine sources for the
generation of dioxins during incineration of MSW.  Organohalogen
Compounds 3: 193-196 (1990). 

In experiments at a full-scale combustor, Vikelsoe et al. found
as follows:  "The results showed increased dioxin emission at
high levels of PVC and NaCl, and decreased emission at high lime
levels."  

[Note: When the PVC content of municipal solid waste was
doubled, dioxin emissions (only PCDDs were measured) increased
by 32 percent and HCl emissions by 64 percent.  Doubling NaCl
concentrations led to a 17 percent increase in dioxin emissions
(PCDDs only)  and a 9 percent increase in HCl.  When HCl
concentrations were doubled, dioxin emissions (PCDDs only)
increased by 42 percent.]

3. Gullett, B.K.,  Bruce, K., Beach, L.O. Formation of
chlorinated organics during solid waste combustion.  Waste
Manage. Res. 8: 203-214 (1990) 

"The formation mechanisms of the precursors of polychlorinated
dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF)
were examined in a laboratory reactor.  Both homogeneous and
heterogeneous reactions were studied between 200 and 800 C. with
HCl, Cl2, and phenol as reactants in a simulated flue gas
containing oxygen.  Analysis of the reactor effluent showed the
homogeneous phase production of chlorophenols and
non-chlorinated dioxin and dibenzo-p-dioxin and dibenzofuran,
potential precursors to PCDD and PCDF, was related to HCl
concentration, reaching a maximum formation level around 650 C. 
However, Cl2 produced a greater variety of chlorinated aromatics
at levels over three orders of magnitude greater than with HCl,
with product concentrations reaching maximum formation levels
around 350 C.  Heterogeneous tests at 450 C using a CuCl
catalyst increased formation of chlorinated organics and PCDDs
and identified the major chlorinating reactant to be Cl2."

4. Gullett, B.K., Bruce, K., and Beach, L., The effect of metal
catalysts on the formation of polychlorinated dibenzo-p-dioxin
and polychlorinated dibenzofuran precursors.  Chemosphere 20
(10-12): 1945-1952 (1990) 

"Therefore, reducing the amount of Cl2 present in the PCDD/PCDF
formation region should decrease the levels of these highly
toxic compounds found in municipal waste combustors."

5. Oudhuis, A., Tromp, P., Olie, K., and Moulijn, J.  Formation
of PCDDs and PCDFs during low-temperature pyrolysis of PVC in an
inert and oxidative atmosphere.  Organohalogen Compounds 3:
303-305 (1990) 

"The emission levels of flexible PVC are an order of magnitude
higher than those of virgin PVC. ... This result confirms that
the formation of PCDDs and PCDFs is due to secondary reactions
of organics with HCl. These results are in contrast with the
work of Giugliano et al. (3), where no detectable amounts of
PCDDs and PCDFs were found during incineration of waste
containing PVC, but in agreement with the work of Tyksklind et
al. (4) and Theisen et al. (5) in which more or less the same
complex patterns were reported."      

1989

1. National Environmental Protection Agency, Denmark. 
Dioxinemission ved affaldsforbranding (in Danish, English
summary available).  Miljoprojekt nr. 117 (1989).

In their study of full-scale combustors, the Danish EPA noted a
14 percent increase in dioxin emissions from municipal waste
combustors  and a 25 percent increase from medical waste
incinerators when HCl concentration doubled.

2. Christmann, W., Hasiske, D., Kloppel, K.D., Partscht, H.,
Rotard, W.  Combustion of polyvinylchloride - an important
source for the formation of PCDD/PCDF.  Chemosphere 19: 387-392
(1989). 

"During combustion and pyrolysis of pure polyvinylchloride (PVC)
and PVC-cable sheathings in air atmosphere, PCDD/PCDF are formed
in significant amounts up to the ppm range. ... Obviously, in
many incineration and pyrolysis processes as well as fires, PVC
can be considered a main source for the formation of dioxins and
furans. ... In the experiment with the soldering iron, we could
show that even at temperatures around 350 C dioxins and furans
are formed by the charring of cable coatings in amounts that
exceed the German statutory regulation for dangerous substances
considerably.  ... Also, neither in combustion nor in pyrolysis
experiments with chlorine-free polyethylene samples could
dioxins or furans be detected."

3. Takeshita,  R., Akimoto, Y.  Control of PCDD and PCDF
formation in fluidized bed incinerators.  Chemosphere 19 (1-6):
345-352 (1989). 

" ...levels of PCDDs in the EP outlet gases tended to decrease
in proportion to the decrease in levels of hydrogen chloride in
the flue gases. ...  At higher levels of hydrogen chloride in
the gases, PCDFs were increasingly formed.... From the
relationship between hydrogen chloride levels in the gases
at the EP outlet and the total amounts of PCDDs and PCDFs as
shown in Figure 11, it is clear that the control of hydrogen
chloride levels by the supply of Dolomite to the furnace
controlled the formation of PCDDs and PCDFs successfully."   

4. Giugliano, M., Ceernuschi, S., Ghezzi, U.  The emission of
dioxins and related compounds from the incineration of municipal
solid waste with high contents of organic chlorine (PVC). 
Chemosphere 19: 407-411 (1989). 

"The incineration of urban wastes with added PVC, up to 10% by
weight, did not produce the emission of detectable
concentrations of polychlorinated dibenzodioxins and -furans
upstream flue gas cleaning equipment. ... The tests were
conducted in a 1.5 t h-1 industrial rotary kiln/afterburner
combustion chamber, equipped with a fuel oil burner of high heat
output that makes the unit a nonconventional system particularly
interesting for the thermal destruction of organic
micropollutants.  ... Sampling was performed upstream the air
pollution control equipment ... For organic micropollutants, 3.5
to 5 m3 of gas at normal conditions were collected in duct with
an allglass isokinetic probe followed by a glass wool filter for
particulate matter retention, two consecutive water cooled
flasks at 2 C and a final C-18 adsorbent cartridge. ...
Detection limits of the analytical procedure employed are 0.5 ng
for 4- to 7-CDDs and -CDFs, 2.5 ng for 8-CDDs and -CDFs, ..."  

[Note: The failure by Giugliano et al. to detect any dioxins may
well be attributed to reliance on an analytical procedure which,
by today's standards, had unusually high detection limits.]

5. Gullett, B., Bruce, K., Beach, L.  Formation mechanisms of
chlorinated orgnaics and impacts of sorbent injection. 
Presented at the International Conference on Municipal Waste
Combustion, U.S. EPA/Environment Canada, Hollywood, FL, April
1989 

Gullett et al. observed that while the presence of HCl is
not likely to be directly responsible for PCDD/PCDF formation,
at elevated temperatures 650 C (1202 F) it promotes the
formation of chlorobenzenes and dibenzofurans and furans
(PCDD/PCDF precursors).

6. De Fre, R., and Ryman, T.  PCDD and PCDF formation from
hydrocarbon combustion in the presence of hydrogen chloride. 
Chemosphere 19: 331-336 (1989).

De Fre and Rymen (1989) found  as follows when carrying out
experiments with HCl concentrations ranging from 150 ppm to 4.5
percent: "The relationship between the HCl concentration and
the generated PCDD/PCDF concentration under fixed combustion
conditions appears to be exponential ... [with] PCDD and PCDF
formation ... found over a temperature range from 900 C to 240
C. ... Since HCl is the combustion product of all organochlorine
compounds it follows that any of these compounds is a potential
dioxin precursor on combustion.  Furthermore, any industrial
process where HCl is allowed to contact flue gases is a possible
source of PCDDs and PCDFs."

1988

1. Yasuhara, A., and Morita, M.  Formation of chlorinated
aromatic hydrocarbons by thermal decomposition of vinylidene
chloride polymer.  Environ. Sci. Technol. 22 (6): 646-650 (1988)

From the pyrolysis under an airstream of two kinds of vinylidene
chloride polymers used for food wraps, Yasuhara and Morita found
as follows:  "...[M]any chlorinated aromatic compounds were
produced by pyrolysis even at 200 C.  ... Particularly,
chlorinated aromatic compounds were detected in large
quantities.  These compounds were divided into several groups,
that is, chlorinated benzenes, chlorinated styrenes (PCSs),
chlorinated phenols, chlorinated phenylacetylenes, PCNs
[polychlorinated napthalenes], PCBs [polychlorinated biphenyls],
and chlorinated benzofurans (PCBFs)."

2. Gottesman, R., Carroll, W., Fishbein, L.  Vinyl industry
response to environmental concerns about PVC in municipal solid
waste.  Energy Prog. 8: 148-153 (1988).

"... the prime objective of this study was to determine
whether dioxins and furans, PCDDs and PCDFs are generated when
PVC is incinerated. PVC users were concerned about dioxin
because:  incinerators do emit dioxin; chlorine is needed to
make it; PVC is a source of chlorine; and, dioxin found in lake
sediments only postdates commercialization of PVC. ... As
expected, the amount of PVC in the waste being incinerated does
increase the amount of HCl in the combustion gases.   ... In
this, and the Prince Edward Island Study, the data show that the
amount of dioxin that finally came out of the incinerator in
these test runs was approximately the same amount as that that
came in with the MSW.  In other words, there was no net increase
in environmental dioxins as a result of the incineration
process.  ... At the tertiary duct and the boiler outlet, none
of the contrasts associated with the amount of PVC were
significant at the 5% level for either PCDDs and PCDFs." 

[Note:  This study has been cited by some authors as having
found no correlation between chlorine input and dioxin output. 
Since the authors do not present actual input or output data,
their findings cannot be reviewed.  However,  their last
statement shown above leaves open the possibility that a
positive correlation was found between the amount of PVC
combusted and dioxin concentrations at the tertiary duct and
boiler outlet but that this positive correlation was significant
at some level below 95 percent.]

1987

1. Karasek, F., and Dickson, L.  Model studies of
polychlorinated dibenzo-p-dioxin formation during municipal
refuse incineration. Science 237: 754-756 (1987).

"The chromatograms show the similarity in the isomer
distribution of dioxins formed from labeled pentachlorophenol
and from PVC combustion products with that of dioxins extracted
from fly ash collected from the municipal incinerator."

2. Vogg, H., Metzger, M., Stieglitz, L.  Recent findings on the
formation and decomposition of PCDD/PCDF in solid municipal
waste incineration.  Presented at the seminar:  "Emissions of
Trace Organics from Municipal Solid Waste Incinerators," 
Copenhagen, January 1987

Vogg et al. found that the formation of dioxins and furans in
MWC fly ash at low temperatures is enhanced by the presence of
HCl, SO2, and H2O. They also found that high chloride
concentrations in fly ash apparently favor the formation of
PCDD/Fs.

1986

1. Marklund, S., Kjeller, L.-O-., Hansson, M., Tysklind, M.,
Rappe, C., Ryan, C., Collazo, H., and Dougherty, R. 
Determination of PCDDs and PCDFs in incineration samples and
pyrolytic products, in  Rappe, C., Choudhary, G., and Keith, L
(eds), "Chlorinated Dioxins and Dibenzofurans in Perspective;
Lewis Publishers: Chelsea, MI, 1986.

"The laboratory pyrolysis of PVC and Saran clearly shows that
PVC and other organochlorine polymers can be precursors to the
PCDDs and PCDFs found in various incinerators.  This is a very
important observation because the New York  Department of
Sanitation recently claimed "PVC has never been shown to be a
precursor of PCDF/PCDD. ...  A recent German pamphlet arrives at
the same erroneous conclusion. ... From this table it is clear
that the inhalation exposure is marginal compared to the
exposure via food, especially fish and other foodstuffs from the
aquatic food chain."

1983
1. Liberti, A., Goretti, G., and Russo, M.V.  PCDD and PCDF
formation in the combustion of vegetable wastes.  Chemosphere
12(4-5): 661-663 (1983).

"The analysis of various vegetables showed the presence of
polyphenols but no phenols have been identified.  From the
analysis carried out on vapours and particulates obtained from
the combustion of the vegetable materials both phenols and
polyphenols have been identified and measured. 

Nor chlorophenols neither chlorinated species have been however
identified in the emissions.

When the combustion is performed either in the presence of
chlorine mixed to the air stream or PVC added to the material,
noticeable amounts of chlorophenols are found in emissions: 
dichloro-, trichloro-, tetrachloro and pentachloro-phenols have
been identified in the concentration range of microgram par g of
examined material.  As a consequence also appreciable amounts of
PCDD and PCDF have been identified and the relative
concentration reported in table 2.

It is evident that either the lack of chlorine donors or
phenolics in the material to be submitted to incineration
prevents such reaction [PCDD/F formation].  According to this
mechanism it is possible to explain why for long time vegetable
materials have been incinerated without any damage to the
environment in spite of the large amounts of plant phenolics
present.

The separation of material, as PVC, eliminates the precursor
which contributes to the chlorine donation in the pyrolytic
synthesis."

2. Tiernan, T., Taylor, M., Garrett, J., Van Ness, G., Solch,
J., Deis, D., and Wagel, D.  Chlorodibenzodioxins,
chlorodibenzofurans, and related compounds in the effluents from
combustion processes.  Chemosphere 12 (4-5): 595-606 (1983) 

"In a laboratory study intended to assess the importance of the
combustion of conventional fuels as a source of CDDs/CDFs, pine
wood and other fuels were pyrolyzed in air and in air containing
a chlorine source (such as HCl) ...  The experiments in which
pine was combusted In normal air produced no detectable
CDDs/CDFs ...  However, the detection limits achieved in the
analyses for CDDs/CDFs were in the range from 30-500 pg/g of
wood combusted.  It is possible, of course, that still lower
quantities of CDDs/CDFs are formed.  When pine wood was
combusted in the presence of air saturated with HCl vapor,
however, relatively large quantities of the entire series of
CDDs/CDFs were detected [>3000 ng/g of wood burned]."

3. Karasek, F., Viau, A., Guiochon, G., and Gonnord, M.  Gas
chromatographic-mass spectrometric study on the formation of
polychlorinated dibenzo-p-dioxins and polychlorobenzenes from
polyvinyl chloride in a municipal incinerator.  J. Chromatog.
270: 227-234 (1983) 

"Data shown here are the result of addition of 300% the usual
level of PVC to a municipal incinerator. No significant
differences in the concentrations of these substances on the fly
ash were found.... it is evident that in these experiments the
addition of PVC to the feedstock had no observable effect on the
levels of PCDD, and other compounds generated in the
incineration process."

1980

1. Shih, C. et al.  "POM Emissions from Stationary Conventional
Combustion Sources, Exposure, Transport, and Control." 
EPA-600/2-80-156, U.S. Environmental Protection Agency,
Cincinnati, Ohio, June 1980. 

[Note:  When this original study is received, we will provide
appropriate excerpts.  In the interim, the results of this study
were described in  "National Dioxin Study Tier 4 - Combustion
Sources:  Initial Literature Review and Testing Options," 
EPA-450/4-84014b.  Research Triangle Park, NC:  U.S.
Environmental Protection Agency, October 1984, as follows: "Shih
et al  developed a ranked priority list of conventional
combustion  systems emitting polycyclic organic matter including
PCDDs  and PCDFs.  The rationale presented for source ranking 
is based on fuel characteristics and combustion conditions.  
Shih's work places great emphasis on both the chlorine content 
of the feed and the concentration of aromatics in the feed."]

2. Mahle, N. and Whiting, L.  The formation of chlorodibenzo-p-
dioxins by air oxidation and chlorination of bituminous coal. 
Chemosphere 9: 693-699 (1980)

"The current study was undertaken to see whether or not
chlorodioxins could be formed from a naturally occurring organic
starting material such as coal. ... [T]his study does represent
the first attempt to observe the formation of chlorodioxins from
a nonman-made starting material under controlled laboratory
conditions.  ... First, analysis of the  National Bureau of
Standards bituminous coal ... showed no detectable levels of
chlorodioxins ...  Analysis of the coal for total inorganic and
organic chlorine gave 808 +/- 40 ppm ...  [A]nalysis of the
reaction of coal with air at high temperatures ... gave positive
signals barely above the detection limits for H7CDD and OCDD.
... The reaction of coal and sodium chloride with air ... does
not indicate real differences in chlorodioxin levels when
compared to the coal with air experiment.  Substantial amounts
of all analyzed chlorodioxin species were observed in the
chlorination experiment involving coal, air, and hydrogen
chloride ... "  

3. Olie, K., Vermeulen, P., and Hutzinger, O.  Chlorodibenzo-p-
dioxins and chlorodibenzofurans are trace components of fly ash
and flue gas of some municipal incinerators in the Netherlands. 
Chemosphere 8: 455-459 (1977).

"During our investigation of the environmental loading with
organic pollutants by waste products of municipal incinerators
we detected a large number of organochlorine compounds in fly
ash ... [The most abundant chlorinated compounds in all fly ash
samples were highly chlorinated benzenes ... The amount of
chlorodibenzodioxins and chlorodibenzofurans entering the
atmosphere via flue gases is probably quite small.  However, due
to the extreme toxicity of some of the components and the fact
that most incineration plants are located in densely populated
areas extensive monitoring of such facilities might be
advisable."  

[Note:  Table 1 of this report shows all tetra- through octa-
PCDDs and PCDFs were detected in the fly ash of the Arnhem
incinerator, while Table 2 shows that all tetra- through octa-
PCDDs were detected in the flue gas of the Alkmaar incinerator.]


FOOTNOTES

1  In this paper, the terms "dioxin" and "dioxins" include all
of the polychlorinated dibenzo-p-dioxins (PCDDs) and
dibenzofurans (PCDFs). 

2 Dioxin output is the quantity of dioxins released in all
combustor residues - stack emissions, fly ash, bottom ash,
scrubber water, etc. 

i U.S. Environmental Protection Agency, "Hospital Waste
Combustion Study:  Data Gathering Phase," EPA-450/3-88-017,
Washington, D.C., December 1988.

ii Air Pollution Abatement Review Group, "Report on the
Abatement of Toxic Organic Micropollutants (TOMPS) from
Stationary Sources 1995," Prepared at the request of Air Quality
Division, Department of the Environment, AEA Technology,
National Technology Centre, Abingdon, Oxfordshire, UK, 1995. 

iii Intergovernmental Forum on Chemical Safety, "IFCS Ad Hoc
Working Group on Persistent Organic Pollutants Meeting: Final
Report,"  Geneva: IFCS Secretariat, c/o World Health
Organization, 21-22 June 1996.

iv United Nations Environmental Programme, "International Action
to Protect Human Health and the Environment Through Measures 
Which Will Reduce and/or Eliminate Emissions and Discharges of
Persistent Organic Pollutants, Including the Development of an
International, Legally-Binding Instrument," Decision Taken By
Nineteenth Session of  the UNEP Governing Council, Nairobi, 7
February, 1997, Geneva: United National Environmental Programme,
February 1997. 

v  American Public Health Association, Resolution Adopted at the
124th Annual Meeting, New York City, New York, 20 November 1996.

vi Central Pollution Control Board, Ministry of Environment and
Forests, Government of India, "Environmental Standards and
Guidelines for Management of Hazardous Waste,"  New Delhi,
India, 12 July 1996. 

vii International Joint Commission, "Seventh Biennial Report on
Great Lakes Water Quality," ISBN 1-895085-74-8, Washington,
D.C.: International Joint Commission, 1994.

viii  International Joint Commission, "Sixth Biennial Report on
Great Lakes Water Quality," ISBN 1-895085-36-5, Washington,
D.C.:  International Joint Commission, 1992.

ix Schulz,  D., PCDD/PCDF - German policy and measures to
protect man and the environment, Chemosphere 27 (1-3): 501-507
(1993). 3031