Large Scale Co-combustion of Plastics from the End-of

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					GPEC 2006 Paper Abstract #E4
Title: Large Scale Co-combustion of Plastics from the End-of-Life Electrical and
       Electronic Equipment at the Wuerzburg Municipal Solid Waste Energy)
       Recovery Plant (MHKW
Authors:
     Britta Bergfeldt                       Hans Dresch                               Bogdan Dima
Institute fuer Technische         Zweckverband Wuerzburg (ZvAWS)                         MHKW
      Chemie (ITC)                      Wuerzburg, Germany                          Wuerzburg, Germany
  Karlsruhe, Germany
  Michael M. Fisher                       Werner Gruettner                              Kai Kramer
American Plastics Council         Zweckverband Wuerzburg (ZvAWS)                   Electrocycling GmbH
  Arlington, Virginia                   Wuerzburg, Germany                           Goslar, Germany
     Theo Lehner                              Frank E. Mark                            Juergen Vehlow
        Boliden                        PlasticsEurope/Dow Europe                  Institute fuer Technische
   Skelleftea, Sweden                      Horgen, Switzerland                          Chemie (ITC)
                                                                                    Karlsruhe, Germany
                                                   ABSTRACT
In a controlled test campaign, a broad consortium of international stakeholders has demonstrated the effects of end-
of-life electrical and electronic equipment shredder residue (ESR) on the performance of a large scale municipal
solid waste energy recovery combustor MHKW in Wuerzburg, Germany. The ESR was highly concentrated with
electrical and electronic plastics. Three test conditions were investigated: 1) base case without additional electrical
and electronic shredder residue, 2) addition of 11 weight percent ESR containing E&E plastics, 3) addition of 26
weight percent ESR with E&E plastics. The fact that some waste electrical and electronic equipment is already in
the mixed MSW feed to many waste-to-energy plants made the testing important for the MHKW operator as well as
for the local regulatory authorities (EPA). The tests investigated the effect of ESR on plant operations, air emissions
(acids, organics, and metals), ash characteristics, and significantly, on the destruction efficiencies for several
chlorinated and brominated substances present in the ESR.
The large scale test used 103 tons of ESR derived from 650 tons of a typical mix of information technology
equipment, consumer electronics, small household appliances, and other products. The ESR was supplied by
Electrocycling in Germany. The tests were successfully completed from an operational standpoint without long
time delays and did not show any mechanical blockage during the test in spite of the high heating value, 23 GJ/t, of
the ESR. The grate was operated at close to 90 percent throughput.
Clean gas concentrations of chlorinated dioxins/furans were all well below the 0.1 ng ITE /m3 regulatory limit. Raw
gas HCl and HBr concentrations were in the expected range of 1000 - 2000 mg/m3 and 50 - 200 mg/m3,
respectively. The conditioned dry lime addition system worked well for a feed concentration of 11 wt % ESR to 26
wt % ESR. The clean gas HCl concentrations could be kept below the limits of the plant’s permit in accordance to
the European Waste Incineration Directive. It has been shown that high levels of ESR can be handled with standard
commercial equipment. The heavy metals raw gas concentration was in line with what can be expected from typical
metal and heavy metal volatility behavior. Most heavy metal raw gas concentrations were lower than observed
during a 1997 test using automotive and appliance shredder residue (ASR). Decomposition of trace organics such as
PCBs and halogenated dioxins and furans as well as flame retardants of the PBDE type during co-combustion was
demonstrated to be sufficiently high to ensure nearly complete destruction of these organic compounds. The heavy
metal leaching of grate ash has been assessed with good results using the European, German, Dutch and USA
procedures. The Wuerzburg test demonstrated the significant potential for modern municipal solid waste energy
recovery plants, in conjunction with other recovery options, to play an important role in the sustainable recovery of
plastics from end-of-life electrical and electronic equipment.
   Large Scale Co-combustion of Plastics from the End-of-Life Electrical
    and Electronic Equipment at the Wuerzburg Municipal Solid Waste
                    Energy Recovery Plant (MHKW)
                             (GPEC 2006)

   Britta Bergfeldt                       Hans Dresch                         Bogdan Dima
Institute fuer Technische      Zweckverband Wuerzburg (ZvAWS)                    MHKW
      Chemie (ITC)                   Wuerzburg, Germany                     Wuerzburg, Germany
  Karlsruhe, Germany

  Michael M. Fisher                    Werner Gruettner                         Kai Kramer
American Plastics Council      Zweckverband Wuerzburg (ZvAWS)               Electrocycling GmbH
  Arlington, Virginia                Wuerzburg, Germany                       Goslar, Germany
     Theo Lehner                        Frank E. Mark                         Juergen Vehlow
        Boliden                   PlasticsEurope/Dow Europe               Institute fuer Technische
   Skelleftea, Sweden                 Horgen, Switzerland                       Chemie (ITC)
                                                                            Karlsruhe, Germany

Abstract

In a controlled test campaign, a broad consortium of international stakeholders has demonstrated
the effects of end-of-life electrical and electronic equipment shredder residue (ESR) on the
performance of a large scale municipal solid waste energy recovery combustor MHKW in
Wuerzburg, Germany. The ESR was highly concentrated with electrical and electronic plastics.
Three test conditions were investigated: 1) base case without additional electrical and electronic
shredder residue, 2) addition of 11 weight percent ESR containing E&E plastics, 3) addition of 26
weight percent ESR with E&E plastics. The fact that some waste electrical and electronic
equipment is already in the mixed MSW feed to many waste-to-energy plants made the testing
important for the MHKW operator as well as for the local regulatory authorities (EPA). The tests
investigated the effect of ESR on plant operations, air emissions (acids, organics, and metals), ash
characteristics, and significantly, on the destruction efficiencies for several chlorinated and
brominated substances present in the ESR.

The large scale test used 103 tons of ESR derived from 650 tons of a typical mix of information
technology equipment, consumer electronics, small household appliances, and other products. The
ESR was supplied by Electrocycling in Germany. The tests were successfully completed from an
operational standpoint without long time delays and did not show any mechanical blockage during
the test in spite of the high heating value, 23 GJ/t, of the ESR. The grate was operated at close to 90
percent throughput.

Clean gas concentrations of chlorinated dioxins/furans were all well below the 0.1 ng ITE /m3
regulatory limit. Raw gas HCl and HBr concentrations were in the expected range of 1000 - 2000
mg/m3 and 50 - 200 mg/m3, respectively. The conditioned dry lime addition system worked well
for a feed concentration of 11 wt % ESR to 26 wt % ESR. The clean gas HCl concentrations could
be kept below the limits of the plant’s permit in accordance to the European Waste Incineration
Directive. It has been shown that high levels of ESR can be handled with standard commercial
equipment. The heavy metals raw gas concentration was in line with what can be expected from
typical metal and heavy metal volatility behavior. Most heavy metal raw gas concentrations were
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                                                                   American Plastics Council, GPEC 2006
                                                                                                 Page 1
lower than observed during a 1997 test using automotive and appliance shredder residue (ASR).
Decomposition of trace organics such as PCBs and halogenated dioxins and furans as well as flame
retardants of the PBDE type during co-combustion was demonstrated to be sufficiently high to
ensure nearly complete destruction of these organic compounds. The heavy metal leaching of grate
ash has been assessed with good results using the European, German, Dutch and USA procedures.
The Wuerzburg test demonstrated the significant potential for modern municipal solid waste
energy recovery plants, in conjunction with other recovery options, to play an important role in the
sustainable recovery of plastics from end-of-life electrical and electronic equipment.

Introduction

The economically and environmentally sound management of end-of-life (EOL) electrical and
electronic equipment (EEE) from both households and businesses is of growing significance
worldwide. The plastics industry represented by the American Plastics Council, PlasticsEurope,
and the Plastics Waste Management Institute of Japan has been actively engaged in evaluating
resource recovery options. Legislation addressing the collection and recovery of EOL EEE exists
in Europe and Japan and will soon to be finalized in China and South Korea. In the United States,
there is no national legislation, but three states, California, Maine, and Maryland have passed
legislation addressing EOL EEE. Many EEE collection programs are underway throughout the
United States and Canada, and some, such as in Hennepin County, Minnesota have been in
existence for over a decade

EOL EEE is a complex resource recovery stream, and how to responsibly manage all of the
materials that make up EEE, some of which contain toxic substances and are potentially hazardous,
is of growing concern. In general, society faces two simultaneous challenges, how to recover and
put back into commerce useful material and energy resources from obsolete EEE rather than have
these products landfilled, and how to responsibly manage a diversity of substances of concern
(from a regulatory perspective) that may be present in these products. There needs to be an on-
going search for sustainable recycling practices that recognize these requirements. Such a search
needs to investigate and analyze integrated resource management solutions that combine the
potential of mechanical recycling of materials (glass, metals, plastics), feedstock recycling of
polymeric materials, and energy recovery of non-recyclable combustibles to work together to
achieve sustainable resource recovery that is environmentally and economically sound (1) – (4).

A missing ingredient is such an analysis has been the lack of detailed information on the use of
material from end-of-life electrical and electrical equipment as a fuel source for modern waste-to-
energy plants and the potential role of waste-to-energy in the responsible management of
substances of concern (SOCs). Some important early research work in this area has been done by
PlasticsEurope and the Institute for Technical Chemistry/Thermal Waste Treatment Division for
the Forschungszentrum Karlsruhe GmbH (ITC) in Germany using the Tamara pilot plant (5,6).

This paper describes a recent international energy recovery demonstration designed to help fill this
gap. Electronic shredder residue (ESR), relatively high in plastics content, and a byproduct of the
EOL EEE dismantling industry after targeted ferrous and non-ferrous metals recovery, was co-fired
with municipal solid waste (MSW) at up to 26% by weight in a modern mass burn waste-to-energy
plant in Wuerzburg, Germany. Similar plants can be found in many regions of Europe, Japan,
Canada, and the United States. During the study, plant operations, raw gas quality, air emissions,
ash characteristics, and destruction of SOCs were monitored. Both industry and government
representatives participated in the project. The results of this first of its kind real-world, large-scale
demonstration project are summarized in this paper.


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                                                                     American Plastics Council, GPEC 2006
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Electrical and Electronic Shredder Residue

When end-of-life mixed electrical and electronic equipment is shredded to facilitate recovery of
metals, the resulting residue stream is called electronic shredder residue (ESR). Today electronic
shredder residue is predominately landfilled. The wide compositional variation of ESR is
described in the literature (7,8) and is due to a number of factors. These include the types and ages
of EOL EEE being processed which reflects the collection system in place (household, commercial,
or industrial), country of origin, extent of dismantling and depollution, types of shredding and other
processing methods, the degree of metals recovery, and the nature and volume of the metals sent
off-site for recovery. In Europe, ESR can be derived in part from white goods (except refrigerators
which are separately processed to remove ozone depleting substances). In the U.S., white goods
are shredded along with automobiles and become part of automotive shredder residue (ASR). The
European Waste Electrical and Electronic Equipment (WEEE) Directive (9) and the Restriction of
Hazardous Substance Directive (RoHS) (10) have led to a far greater mix of EEE being collected
for recovery in Europe than is today being practiced in the North America or Japan.

The ESR for the MHKW energy recovery trial was supplied by Electrocycling in Goslar, Germany.
The Electrocycling plant employs mechanically enhanced manual dismantling lines for many
products to 1. remove components that require special handling such as PCB containing capacitors,
batteries, CRTs, gas discharge lamps, etc.; 2. isolate some plastic housings for shredding and
recycling; and 3. remove reusable parts and components. Shredding of EOL EEE equipment
ranging from telephones to TVs to computers to heavy industrial equipment either before of
following dismantling is the first step in a complex series of material separations that ultimately
lead to marketable ferrous and non-ferrous streams and by-product streams rich in mixed plastics.
All processing is done while materials remain in the dry state, except for the processing of the ESR
fines. Non-ferrous recovery is aided by eddy current separators and air tables depending on
particle size. On average, processed EEE yield 50% ferrous, 30% non-ferrous, and 20% mixed
plastics and filter dust. The plastic rich streams are of two types, course (>2mm) and fines
(<2mm). Both types were used in the combustion trials.

Figure 1 shows a typical mix of end-of-life electronics prior to shredding and Figure 2 shows an
example of course ESR.




        Figure 1: EOL Electronics                         Figure 2: Course fraction of ESR

The total feed to the Electrocycling plant for the trial was 650 tons of EEE consisting of 240 tons of
industrial sourced product and 410 tons of consumer products. Most of the material consisted of
household appliances, information and telecommunications equipment, and consumer electronics.
The amount of ESR in big bags sent to the energy recovery plant from Electrocycling was 50 tons
of course ESR (REST1) and 53 tons of fines ESR (REST2).

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                                                                  American Plastics Council, GPEC 2006
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Characterization of Electronic Shredder Residue for the Combustion Trial

Sampling protocol for ESR is extremely important due to the heterogeneous nature of ESR
reflecting in part the wide range of feedstock types with variable heavy metal content. Starting
with 800 kg of ESR at Electrocycling, two quartering operations resulted in a 50 kg sample of ESR
being shipped to an analytical laboratory for further material separation and analysis. Table 1
shows the results of the basic fuel analysis for REST1 and REST2.

                                Coarse          Fine          Mixture                Typical
                                REST1          REST2         REST1/2
                                 2004           2004           50/50          ESR Range for comparison
Combustion parameters                                        Calculated             Literature (*)
lower Hu            GJ/t           26            20.3           23.1                   9 to 20
LOI         at T,C % wt           82.2           77.6           79.8                   15to 80
Carbon             % wt                                                               20 to 40
Hydrogen           % wt           5.74           5.6            5.67                    2 to 6
Inert content
Ash                % wt           19.4           22.4           21.2                   28-61
Moisture           % wt                                                                 2 to 5


Halogen content
Br                    % wt        2.66            5.5           4.08                   0.5 - 6
Cl                    % wt        1.62            1.6           1.61                   0.5-- 6
F                     % wt        0.05           0.11           0.08                 0.01-0.08


Heavy Metals
Hg                    mg/kg       0.24           1.9            1.07                    1- 49
Cd                    mg/kg       53.8           62              58                     2- 85
Tl                    mg/kg       0.29           0.9             0.6                     n.a.
Sb                    mg/kg       251            87             169                  50 - 10000
As                    mg/kg        4.4           8.3             6.4                   20-50
Pb                    mg/kg       564           1300            932                 1100-11000
Cr                    mg/kg        45            140             93                  1000-1800
Co                    mg/kg        1.9           36             18.9                   13-33
Cu                    mg/kg       547           24000          12274                3700-26300
Mn                    mg/kg        33            260            147                  360-1100
Ni                    mg/kg        53            200            127                  400-1500
V                     mg/kg         1             4              2.6                   20-150
Sn                    mg/kg        22            30              26                   130-400


Sum (Sb to Sn)        mg/kg                     26130          13854                     n.a.


Zn                    mg/kg       529           1400            964                 4600-20000


Table 1: ESR characterization results in comparison with literature data

It is interesting to note that the Hg, Cd, Sb, Pb, and Cu values for ESR are significantly higher than
observed for ASR (11) and the levels of Br and Cl are also higher for ESR than ASR.

Of particular interest in the case of EOL EEE are the concentrations of regulated halogenated
organics and micro-organics such as polychlorinated biphenyls (PCBs), certain brominated flame
retardants, and brominated dioxins and furans. This was of particular interest in this study since
demonstrating the destruction of these regulated substances through the combustion with energy
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                                                                   American Plastics Council, GPEC 2006
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recovery process was an important goal of the study. In support of the combustion trial, the coarse
ESR was subjected to laboratory density separation into three fractions: Lights (density 1.0 – 1.12,
Mediums (density 1.12 – 1.22), and Heavies (density 1.22 – 1.44) and chemical characterization of
the Medium and Heavies was carried out. The Lights plastics fraction was not analyzed for
economic reasons. The analytical results for these ESR fractions are shown in Table 2. The
calculated values for the 50:50 mixture assume that none of the analyzed compounds were present
in the Lights fraction. The regulatory limits refer to German law.


 2004 samples                     REST1               REST2 Mixture         Regulation        Limit value
                                  coarse              fines
                         Lights Medium Heavies              calculated*
                         1.0-1.12 1.12-1.22 1.22-1.44       50/50
 PCB               mg/kg n. a. 12.3           23.8    39,1   22,8           PCB-Directive     50
 PentaBDE          “     n. a.       2,1      30,8     153   79,3           Directive         1000
 OctaBDE                            585      1070      303  299             2003/11/EC        1000
 Penta-Octa-BDE                   1509       2733      971  863
 DecaBDE           “     n .a.      906     1330      1400  901             n.a.
 PBDE (Tri – Deca) „     n. a. 3170         5093       2932 2206            RoHS              n.a.
 PBrDD/F (Sum      “     n. a. 1.78         3.66      2,51  1.74
 Tetra-Octa)
 PBrDD/Fs          µg/kg n. a. 1.29         2.55      4.39  2.54            CVV               1
 4 Congeners 2378
 PBrDD/Fs          µg/kg n. a. 1.58         4.84      5.6   3.36            CVV               5
 8 Congeners 2378

Table 2: Organics and micro organics analysis of ESR test samples

Co-Combustion Testing of ESR and MSW

The project team has had significant experience in the operation of the Wuerzburg municipal solid
waste combustor plant (Figure 3). The plant was previously used by PlasticsEurope in co-
combustion tests on plastics packaging in 1993/94 (12) and by PlasticsEurope and the American
Plastics Council for an ASR test burn in 1997 (11). Over the years, the plant has been
characterized by cost efficient operation, reliable dry scrubbing, long residence time of the furnace
leading to good burn out in the gas phase, proven grate and boiler design leading to excellent
residue characteristics, and well documented emissions.

Mixing of ESR and MSW and General Plant Operations

For these tests, the ESR from big bags and MSW were partially mixed in the feed hopper to the
grate. This strategy did not result in the most efficient mixing but did avoid loss of ESR on the
tipping floor. The feed rate to the grate was automatically controlled to maintain constant steam
rate as the heating value of the feed changed. The feed rate of the MSW ranged from 6.3 to 11 tons
per hour. The basic plant operation and design has been extensively described in earlier reports
(11,12) and is available on the Internet (www.zvaws.de). The plant burns both MSW and various
forms of commercial waste including sewage sludge and is equipped with raw gas conditioning
including a cooler, activated carbon addition along with Ca(OH)2, and catalytic NOx reduction
(SCR).




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                                                                   American Plastics Council, GPEC 2006
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                         Figure 3: Wuerzburg municipal solid waste combustor

ESR and MSW Co-Combustion Protocol

The test protocol consisted of a one week testing period in which the test conditions represented
boiler operation (Line No. 2) at the very end of its cycle before a regular maintenance shut down.
Line 2 was chosen to benefit as much as possible from comparative data of the earlier tests carried
out in 1993/94 and 97. The test conditions were coded as follows:

   A     base case
   B     medium level of 11 wt % ESR addition ,
   C     higher level of ESR addition (> 15 wt% ESR) was intended, but Ca(OH) 2 feed was
         blocked
   D     addition of a high metal containing mixture from various fractions to achieve a grate ash
         which may have some economic value for non-ferrous metal recycling
   E     higher level of 26 wt % ESR addition (repeat of condition C)

The overall operation of the plant was maintained constant as much as possible and conditions kept
close to normal operation.

Solid residue sampling was carried out for grate ash, fly ash, cyclone ash, and fabric filter ash. The
sampling was done by ITC according to the recommendation of the International Ash Working
Group. Magnetic metal removal on grate ash ran continuously.

Extensive gas sampling was carried out by an external contractor including clean gas upstream of
the chimney and raw gas at the end of the emergency cooler. No major time delays affected the
sampling plan.




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                                                                   American Plastics Council, GPEC 2006
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Air Emissions

Clean gas emissions of HCl and HBr were measured following lime treatment. For Condition E
(26% ESR addition) the HCl was 8.6 mg/m3 well below the plant emission limit of 10 mg/m3 and
the HBr emissions was 2.5 mg/m3. These are averages of six half-hour samples. The range of HBr
and HCl concentrations varied +/- 20-30 percent around the mean. Raw gas values were also
recorded. An important aspect of all of the Wuerzburg plastics co-combustion tests is that raw gas
as well clean gas emissions have been extensively studied. This is key to understanding the
combustion process, air pollution control system performance, and solid residue characteristics.

There was no significant effect of ESR on the analyzed clean air emissions. As was the case for
acids, emissions of pollutants such as Hg, NH3, CO, SO2, NOx, and dust were below levels of
regulatory concern. Lime addition rates were 2-3 times the stoichiometric ratio (referenced to the
raw gas concentrations) which is acceptable from a cost standpoint and typical of waste-to-energy
plants. Dioxins and furans were also measured and are discussed later from a mass balance
perspective. Stack emissions of these micro organics were very low and well within regulatory
limits.

The level and range of heavy metals in the clean gas were extremely low and for many elements
were below the detection limits. The raw gas concentrations of heavy metals during the ESR test
burns were lower than observed previously using ASR.

Solid Residues

Grate ashes were analyzed according to official German procedures applicable to ash disposal and
beneficial utilization. Additional measurements were made on boiler ash, cyclone ash, and air
pollution control residues. A full spectrum of heavy metal composition was obtained for these
ashes. Leaching behaviour of the solid residues is of paramount importance relative to disposal
and beneficial utilization. In Europe, fly ash is considered a hazardous waste and must be managed
accordingly. In the United States, grate and fly ash are often combined and tested as such. Thus
the leaching test run during this study used the German and European tests for fresh and aged grate
ash and the TCLP test as practiced in the United States to determine if ashes are hazardous or non-
hazardous wastes for combined grate ash and air pollution control residues. The results of the
leaching test using the German method examining Cr, Ni, Cu, Zn, Cd, Pb, Cl, and SO4
demonstrated that the quality of the grate ashes was not influenced by the co-combustion of ESR.
The same conclusion was drawn from leaching experiments using the European test protocol. In
the case of the TCLP test, an increase in metal leachate concentration was only observed for copper
(not a regulated metal) and for lead under Condition B where a value slightly higher than the
regulatory limit was observed.

Mass Balance Data Emphasizing Dioxin and Furan Destruction Efficiencies

The total mass balance system is shown in Figure 4. Such a system has been employed to
determine destruction efficiencies resulting from the energy recovery process for several regulated
chlorinated and brominated organics that can be found in ESR. The substances of particular
interest in this study were PCBs, PBDEs, PCDD/Fs, PBCDD, PBCDF, and PBDD/Fs. The
concentrations of these compounds were measured at various points during the combustion process
or estimated for MSW based on prior experience and destruction efficiencies were calculated.




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                                                                 American Plastics Council, GPEC 2006
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                                        Ca(OH)2                        Activated
                                                                       carbon


    MSW
                    Furnace                     Emission                                     To
                    Boiler                      control                                      ambient
                                                                                             air

     ESR
                                                                   Filter
                                                                   residue
                   Grate ash
                                              Cyclone
                                              ash

Fig. 4: Schematic diagram for mass flux and destruction efficiency calculations

There were no detectable PBDEs found in the raw gas which confirms very high destruction
efficiencies for this class of brominated flame retardants. The raw gas levels of dioxins and furans
were all within the historic concentration window for the Wuerzburg plant suggesting that ESR did
not significantly increase PXDD/F levels in the raw gas. Measurements on the clean gas and solid
residues indicated that good combustion control and high combustion efficiency were achieved.
The non detectable concentration of PBDEs in the clean gas is understood since there were no
PBDEs in the raw gas confirming the overall high PBDE destruction efficiency that can be
achieved in a well operated MSWC. The level of dioxins and furans in the clean gas emissions
were, as expected, extremely low. The limit of 0.1 ng ITE/m3 specified in Germany and most other
countries was always met. This reflects the use of activated carbon and a final abatement in the
SCR unit used to reduce NOx concentration in the clean gas.

Table 3 summarizes the results of the destruction efficiency calculations for several halogenated
organics.

                                                                      Degree of Destruction, %
 PCBs, incl.                                                                 > 99.5 %
 PBDEs (Penta-Octa) incl.                                                     > 99.99

 PBDD/Fs (Tetra-Octa) excl..                                                   > 99.7
 PBDD/Fs (Tetra-Octa) incl.                                                    > 99.0
 PCDD/Fs for incl.                                                              >90
 PXDD/Fs for incl.                                                              > 94

Table 3: Degree of organic and micro organic destruction during the ESR test burns

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                                                                 American Plastics Council, GPEC 2006
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The results show that the overall destruction coefficient for the sum of the halogenated dioxins and
furans is greater than 94 %. The same is true for the destruction of PBDEs where a very
satisfactory overall destruction coefficient for all penta to octa PBDEs of almost 100 % has been
documented. The relatively low destruction coefficient for the PCBs probably reflects the low PCB
input concentration for the MSW which effects calculation accuracy. The fact that de novo
synthesis of dioxins/furans has been demonstrated to occur in MSW incinerators (12) leads to the
conclusion that the total destruction efficiency is even higher than that presented in Table 3.

Conclusions

The electrical and electronic shredder residue (ESR) co-combusted during this test campaign with
MSW at the MHKW waste-to-energy plant was typical of what can be expected when collection of
EOL EEE is fully underway in Europe and in other regions. The operating conditions during the
test were realistic and simulated the future period in Germany and other countries when MSW
combustors may have to deal with this kind of concentrated feed material (ESR).

The effect of ESR co-combustion on the firing of the waste-to-energy plant was similar to other co-
combustion tests done in 1993/4 with packaging plastics and those carried out in 1997 with ASR.
The combustion efficiency in the gaseous phase has been demonstrated to be similar to what is
found under normal conditions as evidenced by the CO and O2 concentrations remaining the same.
The plastics-rich ESR did not, however, result in measurable greater burn-out on the grate as seen
in pilot scale trials with Tamara.

The effects produced by the addition of 7 to 10 % wt of total shredder residue (SR) derived from
either automobiles and appliances or electrical and electronic equipment are within the operating
range of a modern MSW energy recovery plant. There are no operational difficulties if there is
sufficient mixing of the MSW and SR by the crane operator. This level of ESR co-combustion is
more than adequate to take care of the expected quantities of ESR that will be available in many
regions of Europe and the United States. Heavy metal leaching from grate ash and general
characteristics such as heavy metal content are not negatively affected by SR co-firing and the
beneficial use of ash should not be affected.

The increased raw gas concentrations of heavy metals are directly linked to the amount of ESR
combusted. Concentrations of elements such as Pb, Sn and Zn are increased and to a large degree
are carried in the fly ashes. This is also true for more volatile heavy metals like Cd. The acidic
gases HCl and SOx in the raw gas can be reduced to typical low levels in the clean gas through dry
lime addition.

The PCB content in the ESR fines fraction was high and close to the 50 mg/kg limit value. A
mixture of the coarse and fines fractions gave a value lower than the limit value. The thermal
destruction of PCBs has been demonstrated on a large scale to reach a value greater than 99.5%.
Due to the historical nature of the ESR waste, which may contain penta - and octa – PBDEs, it was
important to show that a high degree of destruction (> 99.99 %) could be demonstrated during a
resource recovery process. Other Br containing flame retardant compounds will go through the
same process conditions, namely, high temperature( > 850 degrees C) and long residence time (> 2
seconds), resulting in a similarly high destruction efficiency. The experience gained from this
concentrated ESR co-incineration test does suggest that similar or even higher destruction
efficiencies would be achieved in the future.

The European WEEE Directive requires a minimum amount of collected WEEE of 4 kg per person
per year. In Germany, as an example, this equates to a minimum amount of collected material of

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                                                                 American Plastics Council, GPEC 2006
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320,000 tons. While it is expected that the collected amount will in fact surpass the legal minimum
amount, the total shredder residue from WEEE treatment in Germany is estimated at minimum of
50,000 t. This quantity could be handled in existing waste-to-energy facilities. Such considerations
demonstrate that municipal solid waste combustors can play an important and ecologically efficient
role in the sustainable management of end-of-life electrical and electronic products in many regions
around the world.

Acknowledgements

This work would have been not possible without the commitment and support of each of the
company stakeholders involved in this cooperative program.

References

(1) M. Fisher, T. Kingsbury, L. Headley, Sustainable Electrical and Electronic Plastics Recycling,
   Proceedings International Symposium on Electronics and the Environment, pp. 292-297,
   Scottsdale, Arizona, 2004
(2) M. M. Fisher, Frank E. Mark, Tony Kingsbury, Juergen Vehlow, and Takashi Yamawaki,
   Energy Recovery in the Sustainable Recycling of Plastics from End-of-Life Electrical and
   Electronic Products, International Symposium on Electronics and the Environment, New
   Orleans, 2005
(3) APME Summary Report, An examination of waste treatment scenarios for plastics form end-
   of-life electrical and electronic equipment using an eco-efficiency model, 2003
(4) APME Summary Report, Recovery options for plastic parts from end-of-life vehicles—an eco-
   efficiency assessment, 2003
(5) Juergen Vehlow and Frank E. Mark Electrical and Electronic plastics waste co-combustion.
   APME TEC Report No 8020
(6) Juergen Vehlow, Frank E. Mark et al. Recycling of Br from plastics containing brominated
   flame retardants in state-of-the-art combustion facilities, APME TEC Report No. 8040
(7) Frank E. Mark, Recovery of Used Plastics from E+E, plast Europe, 9/2002 Sept. Vol. 92, pages
   22-27
(8) Frank E. Mark , Recycling of plastics from electrical and electronic products , Kunststoffe
   2/2004
(9) European Waste Electrical and Electronic Directive, 2002/96/EC, 27 January 2003
(10) European Directive on Restriction of Substances, 2002/95/EC, 27 January 2003
(11) Frank E. Mark, Michael M. Fisher, et al. Energy Recovery from ASR through co-combustion
   with MSW, APME TEC Report No.8026
(12) Frank E. Mark, Energy Recovery through co-combustion of mixed plastic waste and MSW,
   APME TEC Report 8004, June 1994




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