UES FROM INCINERATION - European...

PÔLE ENVIRONNEMENT

ET GENIE DES PROCEDES

Centre de Tarnos

THE INFLUENCE OF PVC ON THE QUANTITY AND HAZARDOUSNESS OFFLUE GAS RESIDUES FROM INCINERATION

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FINAL REPORT

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Authors :

Jacquinot Bernard Bertin Technologies Tarnos (F)Hjelmar Ole VKI-Water Quality Institute (DK)Vehlow Jürgen Forschungszentrum Karlsruhe (D)

April 2000

PVC.P. 007 EPage : 1

Title of the Project : THE INFLUENCE OF PVC ON THE QUANTITY ANDHAZARDOUSNESS OF FLUE GAS RESIDUES FROMINCINERATION

Contract Number : B4-3040/98/000101/MAR/E3

Contractor : BERTIN

Person to be contacted : Bernard JACQUINOT -Tel. (33) 5 59 64 49 72 - Fax (33) 5 59 64 49 64

1. SUMMARY 8

2. OBJECTIVES AND APPROACH OF THE STUDY 102.1 Objectives 102.2 Approach of the study 10

3. WASTE INCINERATION PROCESSES EXPLOITED IN THE EC 133.1 Combustion step 13

3.1.1Function of the combustion step 13

3.1.2Solutions used and corresponding techniques 13

3.1.3Operating conditions and corresponding outlet streams. 14

3.2 Heat recovery step 143.2.1Function of the cooling step : 14

3.2.2Solutions employed / Operating conditions 14

3.2.3Corresponding outlet composition 15

3.3 Gas Treatment Step (GTS : Gas Treatment System) 153.3.1Function of the GTS 15

3.3.2Solutions employed and related techniques 15

3.3.2.1 They all use successive unit operations which are: 15

3.3.2.2 Types of neutralisation agent commonly employed 16

3.3.2.3 Acids which can be neutralised 16

3.3.3Process description 17

3.3.3.1 DRY-PROCESS 17

3.3.3.2 SEMI-DRY PROCESS 18

3.3.3.3 WET PROCESS 19

3.3.3.4 SEMI WET - WET PROCESS 20

3.4 Regulatory limits of emissions from waste combustion 203.4.1Hazardous waste incineration 20

3.4.2Municipal Solid Waste Incineration 21

3.4.3Application to PVC incineration 21

3.4.4Specific Regulation related to solid residues 21

3.5 Incineration capacities in EC and GTS process distribution 213.5.1Data about Waste generation and elimination in EC 21

3.5.2Combustion processes 22

3.5.2.1 Hazardous waste incineration 22

3.5.2.2 Municipal Solid Waste Incineration 24

3.5.3GTS processes 24

3.6 Selected incineration facilities used for experimental data collection 26

4. GENERAL ASPECTS ON PVC : COMPOSITION AND CONTENT IN WASTES 304.1 PVC composition and main applications 304.2 PVC materials in the EC - production and use of PVC 314.3 Service life of PVC products 324.4 PVC in MSW to be incinerated 33

4.4.1Global composition of Municipal Solid Waste 33

4.4.2Elementary composition of MSW 33


4.4.3 Influence of PVC on MSW composition 34

4.4.3.1 PVC influence on Chlorine content in MSW 35

4.4.3.2 PVC Influence on HMs content in MSW 35

4.5 PVC in hazardous industrial waste 364.6 PVC influence on Clinical Waste (CW) composition 36

5. POST-USE PVC INCINERATION PRACTICE IN EC 375.1 Co-incineration in cement kiln 375.2 Incineration of PVC material from categories 1 and 2 375.3 Incineration of PVC material from category 3 (Clinical waste) 385.4 Incineration of PVC material from category 4 (building demolition) 385.5 Conclusions : type of waste where incineration is influenced by PVC 385.6 Basic point for further calculations 38

6. INFLUENCE OF PVC ON RAW-GAS COMPOSITION 396.1 Partitioning of elements between the Bottom Ashes and Raw-Gas 39

6.1.1Definition of Raw-Gas 39

6.1.2Fundamentals of the thermal behaviour of elements 39

6.1.2.1 Partitionning of chlorine 40

6.1.2.2 Partitioning of sulphur 41

6.1.2.3 Partitioning of heavy metals 41

6.2 Element partitioning in full scale plants 436.2.1Overview 43

6.2.2Case Studies 44

6.3 Influence of PVC on the Volatilisation of Heavy Metals and Trace Elements 476.3.1Fundamentals 47

6.3.2Full scale case Studies 48

6.4 Influence of PVC on organic pollutants in the Raw Gas 50

7. EVALUATION OF THE INFLUENCE OF PVC ON THE QUANTITY OF RESIDUES FROM GAS TREATMENT 517.1 The Fly ash : Its effect on Cl balance, and the influence of PVC on its quantity 51

7.1.1Fly ash flow 51

7.1.2The role of fly ash in the chlorine balance 51

7.2 Gas neutralisation 527.2.1Nature of Neutralisation agent / Chemical reactions 52

7.2.2Required quantities of Neutralisation Agents / Stoichiometric Ratio SR 55

7.2.2.1 S.R. required for wet process and semi Wet - Wet process 56

7.2.2.2 Specific SR for HCl and SO2 in dry and semi-dry processes 56

7.2.2.3 Comparison with experimental results collected from the selected incinerators -Appraisal of the validity of HClstoichiometric ratio 58

7.3 Contribution of PVC to the production of residues and to the neutralisation agent consumption 64

8. EVALUATION OF THE INFLUENCE OF PVC ON THE HAZARDOUSNESS OF THE RESIDUES 658.1 PVC influence on the composition of the residues 65

8.1.1PVC influence on fly ash composition 65

8.1.2PVC influence on the composition of Neutralisation Products 66

8.2 PVC influence on the hazardousness of the residues 678.2.1Approach 67

8.2.2Discussion of the concept of hazardousness applied to APC residues 67

8.2.3Management options and practices for APC residues 68

8.2.4Composition and leaching data for APC residues 70

8.2.5Scenario definitions and calculations 71

9. INFLUENCE OF PVC ON THE COST OF INCINERATION 769.1 Introduction ; Approach 769.2 PVC influence on the investment costs of the plant 77

9.2.1Equipment sizing 77

9.2.2Material choice for the equipment 77


9.3 PVC influence on the operating costs of the plant 779.3.1Neutralisation Agents consumption and cost 77

9.3.2Maintenance costs/Heat recovery yield 79

9.3.3Other costs 79

9.4 PVC influence on the cost of the management of residues to their final destination 799.4.1Final destination of the residues in Europe 79

9.4.2Costs of storage for the residues 80

9.4.3Cost for the management of residues from gas treatment up to their final destination 80

9.5 Heat recovery profit attributable to PVC 819.6 Total cost related to PVC incineration ( ∈∈∈∈/tonne of PVC) 82

10. CONCLUSIONS 86


LIST OF FIGURES

Figure 2-1 Approach of study diagram ..............................................................................................11

Figure 3-1 Scheme : dry process GTS fed with lime and equipped with a single filtration step .........17

Figure 3-2 Scheme : Semi-wet process for Gas Treatment System which belongs to the semi-drycategory ..............................................................................................................................18

Figure 3-3 Scheme : Wet process GTS (neutral scrubber fed with NaOH and water treatment fedwith lime) .............................................................................................................................19

Figure 4-1 PVC Main applications in the EC [Sva98].........................................................................30

Figure 4-2 Bulk market and production of PVC Materials (Western Europe).....................................32

Figure 6-1 Influence of Inorganic Species on the Partitioning of Chlorine [Hun94] ............................40

Figure 6-2 Partitioning of Chlorine [Veh96a]......................................................................................41

Figure 6-3 Vapour pressure curves of selected metals, metal chlorides and metal oxides................42

Figure 6-4 Partitioning of selected elements in TAMARA at 900°C [Mel98].......................................43

Figure 6-5 Evolution of Chlorine content in Raw Gas with initial Chlorine content in MSW................45

Figure 6-6 Evolution of Chlorine content in Raw Gas with initial Chlorine content in the waste .........45

Figure 7-1 Transformation of Würzburg/Noell Curves in the relation between HCl yield and OverallSR .......................................................................................................................................58


LIST OF TABLES

Table 3-1a - Incineration of Hazardous Waste - French data from 1995 and 1996 ..........................22

Table 3-1b - Incineration of Hazardous Waste - German data from 1990 and 1995 ........................23

Table 3-2 - Estimation of the Clinical Waste Incineration in the EC...................................................24

Table 3-3 - Gas treatment for MSWI plants in Europe : number and capacities for each type. .........25

Table 3-4 - Location and type of incineration plants selected ............................................................26

Table 3-5 - Main characteristics of the incineration plants selected for the study ..............................29

Table 4-1 - Typical Metal Content in PVC Products [Buh98] .............................................................31

Table 4-2 - Distribution of PVC materials with regard to the PVC service life [Buh98].......................32

Table 4-3 - Average composition of MSW in the EC and evolution ...................................................33

Table 4-4 - Main elements distribution in MSW from the EC in 1996 ................................................33

Table 4-5 - Typical data of chlorine, sulphur and heavy metals content in the EC MSW ...................34

Table 4-6 - Literature review on PVC contribution to Chlorine content in MSW .................................35

Table 4-7 - PVC contribution to elementary composition of MSW [Rij93] ..........................................35

Table 4-8 - PVC influence on Chlorine content in Clinical Waste ......................................................36

Table 5-1 - Reference Chlorine in MSW and PVC content................................................................38

Table 6-1 - Literature data for distribution of main components from MSW over bottom ash and raw-gas ......................................................................................................................................44

Table 6-2 - Experimental Data collected from incinerator plants in the EC........................................46

Table 6-3 - Influence of PVC on Heavy Metals distribution between Bottom Ash and Raw Gas........50

Table 7-1 - Specific stoichiometric ratio for HCl and SO2 neutralisation with lime.............................57

Table 7-2 - Overall S.R. and Gas Emissions measured for the different selected incinerators..........59

Table 7-3 - Experimental and Theoretical Results from Full Scale Plants .........................................60

Table 7-4 - Experimental and Theoretical Results from Full Scale Plants ........................................60

Table 7-5 - Experimental and Theoretical Results from Full Scale Plants ........................................61

Table 7-6 - HCl Stoichiometric Ratio for the different Gas Treatment process ..................................63

Table 7-7 - Influence of PVC on the quantity of residues ..................................................................64

Table 7-8 - Influence of PVC on the consumption of neutralisation agent .........................................64

Table 8-1 – The estimated amounts of residues or residue components from various APC processesresulting from incineration of 1 tonne of waste with and without PVC. .................................72

Table 8-2 - The estimated amounts of the various residues produced in terms of kg/tonne of wasteincinerated and tonnes per million tonnes of waste incinerated. ..........................................73

Table 8-3 – The estimated amounts of leachate produced annually and over the period of 50 yearsfrom the landfills containing the APC residues resulting from incineration of 1 million tonnesof waste...............................................................................................................................74

Table 8-4 – Estimated accumulated amounts of selected components leached from the landfilledresidues resulting from the burning of waste with and without PVC at L/S = 1 l/kgcorresponding to a period of 50 years. Unit: g/tonne residue...............................................75

Table 8-5 – Estimated amounts of components leached over a period of 50 years from a landfillcontaining the APC residues resulting from the incineration of 1 million tonnes of waste withand without PVC, respectively. ............................................................................................75

Table 9-1 - Neutralisation Agents (N.A.) prices (∈/tonne) .................................................................78

Table 9-2- Neutralisation Agents costs per tonne of PVC in MSW ....................................................78


Table 9-3 - Solid residues storage costs (∈/tonne) ...........................................................................80

Table 9-4 - Cost of the management of the residues per tonne of PVC ............................................81

Table 9-5a - Cost for the treatment of the gas from the incineration of 1 tonne MSW free of PVC ..82

Table 9-5 b - Cost for the treatment of gas from 1 tonne PVC incineration ...................................... 81

Table 9-5 c - Additional cost related to the substitution of 1 kg MSW by 1 kg of PVC .......................83

Table 9-6 - Effect on the cost of Gas Neutralisation due to the PVC increase in MSW .....................85

Table 10-1 - Influence of PVC on the quantity of residues ................................................................87


Acknowledgements

We want to address our warmest thanks to all the individuals we have questioned in order to obtaindata utilised in this study. This applies to the operators of the incineration plants, the national or localauthorities who are included in the reference list of the report under the heading "personalcommunication".

This study, requested by the European Commission’s DG ENV, is based on experimental resultsbacked up by theoretical considerations supported by literature references. The authors have paidparticular attention to reflect all aspects of the problem, and to establish the appraisal of PVCinfluence upon the quantity and hazardousness of incineration residues they consider as the mostrealistic. For this purpose, the authors have selected the references applied in the study inaccordance to an evaluation of their relevance. The arguments and conclusions published in thereport reflect the authors’ position and the Commission does not necessarily endorse every opinionand conclusion as stated in this report.


1. SUMMARY

The study is aimed at identifying the influence of PVC on the quantity and hazardousness of flue gasresidues from incineration.

This comprises :

• The identification of PVC’s influence regarding quantity and hazardousness of flue gas residuesfrom incineration in practice and in theory

• The distinction between dry, semi-dry and wet gas treatment systems

• The identification of the potential environmental and health effects caused by waste-water, sludgeand solid flue gas residues resulting from incineration of PVC

• Estimation of the costs for PVC incineration, including the environmental costs.

The following conclusions are drawn from the present study :

• End of life PVC, when dealt with by incineration, mainly involves Municipal Waste Incinerators, asHazardous Waste Incinerators and cement kilns do not treat PVC rich wastes. PVC is alsopresent in Hospital Waste which is incinerated

• Because of the wide range of uses of the PVC there is a correspondingly wide range ofperformance properties, and hence formulations, required. The content of pure PVC (resin) withinthe various formulations varies from 44% to 93%.

• PVC influence on MSW composition is mainly related to the Chlorine content of the waste to beincinerated: PVC is responsible for 38 to 66 % of the Chlorine content in MSW (5.3 to 7 kg Cl /tonne MSW). PVC only slightly influences the Heavy Metals (HMs) content in the MSW (it affectsmainly Cadmium, as 10% of Cd in MSW is attributable to PVC). PVC influence on Lead content inMSW is assumed to be less than 1%.

• The presence of PVC in MSW has a direct effect on the quantity of Chlorine in the Raw Gas andtherefore on the corresponding Gas Treatment required. The higher Chlorine content in the gasrequires additional Neutralisation Agent supply and therefore affects the quantity of Residues orEffluents generated by the different Gas Treatment Systems (dry, semi-dry and wet).

The Chlorine attributable to PVC directly influences the consumption of Neutralisation Agent (NA)required for ensuring compliance with gas emission regulations.

The corresponding Stoichiometric Ratios (SR) were identified in the literature as follow :1.1 to 2 for dry process with lime1.05 for dry process with bicarbonate1.05 to 2 for semi-dry (including semi-wet) process with lime1.05 to 1.15 for wet and semi wet-wet process with lime or NaOH

The experimental results collected in the selected incinerators are in agreement with the uppervalues of the S.R. ranges. Nevertheless dry process with standard grade lime with a SR of 2 arenot likely to comply with the most severe emission limit 10 mg/Nm3 for HCl.


Experimental SR for HCl neutralisation :Dry process with standard lime : 2Dry process with bicarbonate : 1.05Semi-dry process with standard lime : 1.7Wet and semi wet-wet process with lime or NaOH : 1.1

• This leads to the corresponding quantities of residues per kg of PVC incinerated (Cl content inPVC : 0.25 to 0.53%) :

- Dry process with lime : 0.8 to 1.65 kg residues per kg of PVC "average" : 1.4 kg- Dry process with bicarbonate :0.5 to 1 kg residues per kg of PVC 0.8 kg- Semi-dry process : 0.7 to 1.5 kg residues per kg of PVC 1.25 kg- Wet process : 0.4 to 0.9 kg salts per kg of PVC

(in the liquid effluent)- Semi wet-wet process : 0.5 to 1.2 kg residues per kg of PVC "average": 1 kg

The "average" values correspond to a chlorine content in PVC of 45 %

• PVC-issued gas treatment residues are mainly composed of chlorine salts and neutralisationagent excess. According to the Gas Treatment System these residues are composed of sodiumsalts (wet process with sodium hydroxide) or calcium compounds (CaCl2, Ca(OH)Cl, Ca(OH)2). Inthe current combustion temperature range used for MSW incineration, the higher chlorine contenthas low effects on the transfer of Heavy Metals from bottom ash to Gas Treatment residues.The major effect of PVC on HMs and trace elements concentration in the residues is related tocadmium as PVC is responsible for a 10% increase of Cd content in MSW.

• The cost of the Gas Treatment attributable to PVC is mainly related to the chlorine content rangein PVC : 0.25 to 0.53%.PVC concentration in the waste (0.65 to 0.74%) is sufficiently low that it does not influence thesizing of the equipment, the construction materials utilised or the manpower requirements. Thecost of Gas Treatment attributable to PVC is evaluated as a marginal cost.PVC influence on the cost of Gas Treatment is therefore related to the Neutralisation Agentconsumption and to the management of the solid residues (mostly landfilling).

For a chlorine content of 0.25 to 0.53% in the PVC sent for incineration, the corresponding costs forthe PVC incineration depend on the process exploited for gas treatment :

Additional cost related to PVC

incineration

Stabilisation of the residues prior to their landfilling

∈/tonne of PVC NO INCLUDED

min – max average min - max average

Dry process with lime 95 – 235 195 155 - 350 290

Dry process with NaHCO3 145 – 330 275 170 - 395 335

Semi-dry process with lime 85 – 205 165 130 - 305 245

Wet process with lime / NaOH 00 – 30 20 00 - 30 20

Semi-wet/wet process with lime 55 – 145 120 95 - 225 185Average values are calculated with an average Cl content in PVC of 45%

• The influence of PVC on the hazardousness of the Gas Treatment System residues is difficult toquantify due to the lack of reliable data. Therefore scenario calculations have been run forevaluating the leachates from APC residues issued by different processes with and without PVCin the waste.


PVC is responsible for an increase of the production of leachates from the APC residues : 19 %for dry process, 18 % for semi-dry process, and 5 % for wet process.

For all residues, the incineration of PVC appears to increase the content of leachable salts(primarily chlorides of Ca, Na and K) by a factor of 2. There is no data showing that the leachingof trace elements/heavy metals will increase as a result of the incineration of PVC. There is atheoretical possibility that the leaching of e.g. Cd may increase due to increased chloridecomplexation caused by PVC incineration but no data is available to substantiate this.

In any case APC residues are classified as hazardous waste whatever the PVC concentration inthe initial waste sent for incineration. The APC residue has therefore to be managed inaccordance to the Hazardous Waste regulation and placed in appropriate storage (landfill ormines).

2. OBJECTIVES AND APPROACH OF THE STUDY

2.1 Objectives

The study is aimed at identifying the influence of PVC on the quantity and hazardousness of flue gasresidues arising from incineration.

This comprises :

• The identification of the PVC influence regarding the quantity and hazardousness of flue gasresidues from incineration in practice and in theory

• The distinction between dry, semi-dry and wet gas treatment systems

• The identification of the potential environmental and health effects caused by waste-water, sludgeand solid flue gas residues resulting from incineration of PVC

• Estimation of the costs for PVC incineration, including the environmental costs.

2.2 Approach of the study

In order to meet the objectives mentioned above, the approach illustrated in the figure 2.1 has beenselected and utilised. It consists of the following parallel or successive steps aimed at tracking theeffects of PVC along the incineration process and at describing how it can influence the quantity andthe composition of the different residues or effluents.

STEP 1 :

The incineration processes and associated Gas Treatment Systems (GTS) utilised in the EC aredescribed in this step:

• The type of GTS has a direct influence on the quantity and composition of the residues and/oreffluents generated during the Gas Treatment in relation to the concentration of the acidcompounds which require neutralisation (mainly HCl and SOx).

• In accordance with the EC's classification, the Gas Treatment Systems have been divided into 3categories : Dry, Semi-Dry (including Semi Wet - Wet) and Wet Processes.

• Each GTS has specific characteristics in terms of performance, investment and operating cost aswell as Neutralisation Agent excess requirements and the corresponding generation of residues.


STEP 2 :

Step 2 describes the variety of PVC products and the way these are incinerated after being mixedwith other types of waste :

• The plastic material commonly called PVC is used for numerous applications. The material’sversatility results from the wide range of physical and mechanical properties that can be achievedby utilising a large variety of compositions or formulations. The range of concentrations of chlorineand additives, including Heavy Metals (HMs), are therefore identified.

• Current methods of incinerating end of life PVC products are considered. This mainly comprisesthe combustion of PVC in MSW Incinerators and therefore the range of chlorine content in MSWand the corresponding contribution of PVC are evaluated. A realistic average Cl content, and PVCderived Cl content, in MSW are calculated.

Figure 2-1 Approach of study – diagrammatic representation

STEP 3 :

Step 3 describes the influence of PVC on the combustion step and therefore on the distribution ofchlorine and other pollutants (Heavy Metals, HMs, and trace elements) among the solid phase(bottom ash) and the gas phase (Raw-Gas) which are supplied to the Gas Treatment System.

PVC composition, con-tent in Wastes, post-use

CHAPTER 4/5

Waste IncinerationProcess Exploited in EC

CHAPTER 3

Estimation of ResiduesHazardousnessCHAPTER 10

PVC influence on thecomposition of the Raw-Gas

CHAPTER 6

PVC influence on the quantitiesand composition of Gas

Treatment ResiduesCHAPTER 7/8

Conclusion

Cost of PVC incinerationCHAPTER 9


In step 3, the influence of chlorine on the vaporisation of Heavy Metals, and therefore on possibleHMs transfer from Bottom Ash to Raw Gas, is evaluated for the operating conditions currently usedin MSW incineration furnaces.

STEP 4 :

Step 4 is devoted to the evaluation of the influence of PVC on the quantity of Gas TreatmentResidues as the presence of PVC in the waste has a direct influence on the chlorine quantity in thegas effluent to be neutralised.

In current MSW Incineration the initial waste contains chlorine but also sulphur which has also to beneutralised. The excess Neutralisation Agents required are evaluated for S and Cl respectively inorder to determine the experimental data for the relationship between Cl, and, therefore, PVC on thequantity of Neutralisation Residues.

Evaluations have been made for the different processes - dry, semi-dry and wet systems - accordingto their efficiency, and therefore to the excess of Neutralisation Agent required to comply with Gasemission limits.

STEP 5 :

Step 5 evaluates the influence of PVC on the composition of the Gas Treatment Residues (Fly Ashand Neutralisation Products) or liquid effluents from the different Gas Treatment Systems in relationto the possible Neutralisation Agents.

As the gas emission limits in the EU are stringent, almost all the inorganic pollutants present in theRaw Gas are recovered in the Gas Treatment Residues. This involves mainly chlorine, Heavy Metalsand trace elements submitted to the regulations in force.

The composition of the Gas Treatment Residues reflects the composition of the Raw Gas in terms ofchlorine, Heavy Metals and trace elements which are recovered with the fly ash and NeutralisationProducts (salts mixed with the excess of neutralisation Agent).

STEP 6 :

Step 6 examines the cost for incinerating PVC.

The possible influence of PVC on the equipment size for the Gas Treatment plant as well as on themanpower requirements are first evaluated.

The necessary neutralisation of HCl arising from the PVC is then considered in relation to theNeutralisation Agent consumption depending on the Gas Treatment System and with themanagement of the residues resulting from this neutralisation.

This management of residues is achieved in different ways according to the regulation and/orpractices in the different EC countries : residues are either landfilled (after possible stabilisation),stored in salt mines or used in road construction. These different routes correspond to widelydifferent prices and make it difficult to evaluate the current European situation which is neverthelessdescribed at the end of chapter 9.

STEP 7 :

The report ends up with the synthesis table which summarises the effect of PVC on the quantity andcomposition of the residues from the gas treatment.

In order to achieve the approach described, both theoretical calculations and experimental datacollection from different Europeans Industrial Incineration Plants have been used to complement toliterature survey.


To fully cover the present situation in the EC for incineration capacities in relation to Gas TreatmentSystems as well as MSW composition and chlorine content, efforts were paid to obtain the mostrecent data by checking and updating published information by direct enquiries with incineratoroperators and authorities. It has been observed that a lot of change has occurred in the last years forincineration facilities including a final shut down of old plants, improvement or full revamping of otherones as well as start-ups of new incinerators. Concerning the identification of MSW composition andflows, it is difficult to obtain recent data as the delay in establishing then publishing thecorresponding statistics is about two or three years.

3. WASTE INCINERATION PROCESSES EXPLOITED IN THE EC

Waste incineration processes are commonly composed of the following main steps :• COMBUSTION• HEAT RECOVERY• GAS AND LIQUID EFFLUENTS TREATMENT

The type of waste commonly treated by each process will be indicated if necessary : this relates toHazardous Waste, Hospital Waste, Non-Hazardous Waste (including MSW and industrial nonhazardous waste).

3.1 Combustion step

3.1.1 Function of the combustion step

The main objectives of waste incineration are:• the reduction of the weight and volume of the waste,• the complete oxidation of the organic fraction.

3.1.2 Solutions used and corresponding techniques

The combustion is achieved in two successive reactors :

• The primary combustion chamber, devoted to the solid oxidation, where the successiveelementary steps take place :

Vaporisation of the water present in the initial waste.Gasification of the organic fraction.Oxidation of the remaining carbon.

• The Post Combustion Chamber (PCC), used mainly for hazardous waste incineration, is aimed atachieving the complete oxidation of the gas compounds (CO, chlorinated compounds, etc....).

Different processes are used for the primary combustion in order to ensure the correct distribution ofthe air in the solid layer as well as the controlled circulation of the solid and therefore of its residencetime.

As mentioned elsewhere, more than 90 % of the MSW incineration facilities are equipped with gratesystems which can be :

• reciprocating grates,• roller grates,• oscillating grates.

The remaining capacity is treated in rotary or oscillating kilns as well as in fluidised beds.

Other technologies are based on a two step combustion including a primary pyrolisis.


Hazardous wastes are commonly incinerated in rotary kilns and hospital waste is incinerated indifferent types of furnaces (kiln or grate systems).

3.1.3 Operating conditions and corresponding outlet streams.

For MSW incineration, the primary combustion is generally achieved at about 700°C to 900°C inpresence of an overall excess of air.

As shown in chapter 7, 25 to 30% of the MSW (by weight) is recovered in the solid (bottom ash orslag) extracted from the primary combustion chamber.

Depending on their pollutant potential, bottom ash is either stored in landfills or used in roadconstruction. The pollutant potential is measured by leaching test results -in accordance with thestate regulations in force which commonly refer to soluble fraction, total carbon, sulphates, HeavyMetals (Hg, Cd, Pb, As, Cr6+,…) in the leachates.

The gas leaving the post-combustion chamber (Raw Gas) has the following approximatecomposition for the main compounds : [Kno95 ]

• N2 : 65 - 70 %• O2 : 8 - 12 %• CO2 : 5 - 10 %• CO : 50 mg/m3

• H2O : 10 - 15 %

As function of the MSW composition, the Raw Gas also contains less concentrated but morepollutant compounds as :

• HF, HCl, HBr.• SOx.• POx.• Unburned organic.• NOx : under the usual temperature range in MSW combustion, NOx mainly comes from

nitrogenated compounds present in the waste (PVC does not contain nitrogen and so does notcontribute to the waste).

• PCDD/F : present in Raw Gas after cooling.• The Raw Gas also contains solid Particles (fly ash) which are either carried over by the gas

flow or condensed in the heat recovery step where temperature decreases.

3.2 Heat recovery step

3.2.1 Function of the cooling step :

This consists of :- heat recovery which will make the whole process profitable- cooling of the gas which is necessary for the gas treatment stage.

3.2.2 Solutions employed / Operating conditions

The heat of the gas effluent is transferred to a Heat Recovery Boiler which usually produces 20 to 30MPa steam. Water and steam circulate in the tubes of the bundle. The raw gas outlet temperature iscommonly 130 to 200°C in accordance with the downstream Gas Treatment.


3.2.3 Corresponding outlet composition

The cooling of the gas does not affect the main component flows. It nevertheless has an influence onthe distribution on the composition of the minor compounds (nature of the chemical forms) anddistribution between solid and gas phases : this principally concerns Heavy Metals (HMs) thecomposition of which is temperature dependent.

In the Heat Recovery Boiler part of the fly ash is separated from the gas flow and creates the boilerash.

3.3 Gas Treatment Step (GTS : Gas Treatment System)

3.3.1 Function of the GTS

The function of the GTS is to ensure that relevant regulations in force for gas emission as well as forliquid effluents are complied with. As shown in annex A1.1, the regulation for gas emission dependson the EC countries and refers either to the 369/89.EC directive for MSW incineration or to the ECdirective for hazardous waste incineration (94/67/EC). The latter is far more severe.

For liquid effluents and solid residues, the policies for the EC countries are different.

3.3.2 Solutions employed and related techniques

Four major routes are employed for achieving the gas treatment in accordance to the specificationsmentioned in § 3.3.1 :- The DRY PROCESS- The SEMI-DRY PROCESS- The SEMI WET - WET PROCESS- The WET PROCESS

3.3.2.1 They all use successive unit operations which are:• The separation of the solid (fly ash and possibly neutralisation product) by filtration.

• The absorption and neutralisation of the acidic compounds.

• The gas filtration is achieved in electro - static precipitators (ESP) or fabric filters (FF). For the dryor semi-dry processes, fabric filters lead to a higher neutralisation yield as the gas-solid contact isenhanced on the filter cake.

• The neutralisation is achieved by :

- the injection of a dispersed solid neutralisation agent (dry process),

- the injection of a solution or a suspension of the neutralisation agent in such a way thatthe reaction products are recovered in a solid waste (semi-dry process),

- the contact of the raw gas with a solution or suspension of the neutralisation agent in agas / liquid reactor (sprayer, packed tower,...) leading to a liquid effluent (wet process).

• The complementary treatments of NOx and of PCCD/F are also achieved in the most recentincineration plants which have to meet the most severe regulations. These treatment arecommonly achieved by:-

- a gas-phase catalysed reaction of NOx with NH3,

- an activated carbon (AC) injection in the gas flow followed by a filtration of the ACcontaining PCDD/F and possibly mercury.


The activated carbon flow is generally controlled as a ratio of the neutralisation agent flow and theconsumed AC constitutes a solid residue to be handled. Nevertheless, the AC cleaning step has tobe used to meet the PCDD/F emission limit irrespective of the PVC content of the MSW.

3.3.2.2 Types of neutralisation agent commonly employed

� For the dry processes : CaO (calcium oxide), Ca(OH)2 (lime), CaCO3 (calcium carbonate) andNaHCO3 (sodium bi-carbonate) are possible materials which can be used. CaCO3 and CaO arenow hardly ever used because of the low efficiency of CaCO3 and the handling difficultiesassociated with CaO.

The quantity of neutralisation agent required will depend on the details of the gas specificationand the reactivity of the neutralisation agent..

This has led the suppliers of these chemicals to develop more reactive neutralisation agents suchas sodium bi-carbonate (or BICAR1 : NaHCO3) or the "Spongiacal"2 hydrated lime providing highspecific area and high porosity (refer to §7.2). The producers of these new neutralisation agentsclaim that the higher neutralisation efficiency of the reactants allows the simpler dry sytem to beused while still meeting the most severe requirements for gaseous effluent.

In order to use standard grade lime in respect with these specifications a process for recycling theneutralisation products after being crushed has been developed and comercialised.

� For the semi-dry processes : the semi-dry processes include the semi Wet - Wet where Ca(OH)2

is injected as a water suspension (lime-water) as well as the semi-dry system where Ca(OH)2 isfed as a dry powder in association to a water spray. Both systems produce dry residues.

� For the wet process ; NaOH and/or lime are principally used. Treatment of the liquid effluentrequires lime in any case for the precipitation of gypsum

Combination of NaOH (used in the scrubber) and of lime (in the water treatment) are generallyemployed (refer to Alkmaar, Spittelau , Vestforbraending and Bamberg incinerators).

3.3.2.3 Acids which can be neutralised

The neutralisation is used for dealing with the acid compounds (HCl, SOx, HF, HBr, POx...). mostlikely to be observed. NOx has a low reactivity with the neutralisation agent and therefore is onlypartly neutralised.

HCl is present in the raw gas at a level of 500 - 1200 mg/m3 and SOx at several hundred mg/m3

(check ranges used in the report) whereas the typical concentration of HF as well as of HBr is in therange of 3 - 10 mg/m3. This is well within the typical range of variation of the acid gas levelsmentioned above and hence needs no special consideration.

1 Trade Mark by Solvay

Capacities of Neutrec based Gas Treatment Systems :Belgium 470 t/year 2 plantsFrance 650 kt/year 10 plantsItaly 1 296 kt/year 15 plantsSpain 0.8 kt/year 1 plantGermany 20 kt/year 1 plant

[Sol 98]

2 Spongiacal is a trade Mark by Lhoist [Lho98]


In the case of MSW containing PVC, HCl and SOx are the principal acid compounds and will be theonly ones to be considered in the study. The corresponding chemical reactions which can occur withlime, soda, and bicarbonate are described in chapter 7.2.1.

3.3.3 Process description

3.3.3.1 DRY-PROCESS

Primar y oven

Air

BOTTOMASH

BOILERASH

HRB

Postcombustion

chamber

Heatrecover y

boiler

MSW

FF

FLYASH ANDNEUTRALISAT.

PRODUCTS

Fabricfilter

Air fan

Active carbon

Limestora ge

OFF.GAZ

Figure 3-1 Scheme : dry process GTS fed with lime and equipped with a single filtration step

The GTS-dry process comprises :• the solid sprayer which disperses the neutralisation agent - Ca(OH)2 or NaHCO3)- in the gas flow,• a reactor vessel located downstream aimed at ensuring the required contact time between the

solid and the gas in the case of Ca(OH)2,• a fabric filter or an ESP (Electric- Static Precipitator) for collecting the mixed fly ash and

neutralisation product and excess neutralisation agent, and to ensure efficient gas/solid contactfor complementing the chemical reactions.

The current filtration technologies allow the retention of all HMs -except Mercury- in the solid residuewhich allows the specification for Heavy Metals in the gas emission to be achieved.In case of NaHCO3 or "spongiacal" lime use, the neutralisation reactor is not necessary providingthat a fabric filter is used downstream. As an alternative, a two step gas filtration is sometimes usedin order to separate the different types of solid residues i.e fly ash and neutralisation products.With lime the neutralisation stage is operated at 130 / 150 °C.With NaHCO3 the upper temperature limit is imposed by the filter media, commonly 200 °C, and witha maximum of 250°C.

This process is used in the plants at Würzburg (Germany 1993), Novergie (France),Nordforbraending (Denmark) with lime and Reggio-Emilia (Italy) with NaHCO3 (refer to § 3.6.).


Recent dry processes with lime use the recycling of the neutralisation products separated in the filterto take profit of the excess of lime and thus reduce its consumption.

3.3.3.2 SEMI-DRY PROCESS

This category includes the real semi-dry GTS where the neutralisation agent is fed as a powderdownstream from a water spray, and the so-called semi-wet GTS where the neutralisation agentsare injected as a water solution or suspension. The semi-Dry Process leads to dry residues.

Air

Primar y oven

BOTTOMASH

BOILERASH

HRB

Postcombustion

chamber

Heatrecover y

boiler

MSW

FF

FLY ASH &NEUTRALISAT.

PRODUCTS

OFF.GAZ

Lime waterpréparation

Limestora ge

Neutralisationreactor

Fabricfilter

H2O

Figure 3-2 Scheme : Semi-wet process for Gas Treatment System which belongs to the semi-dry category

Figure 3-2 above describes the semi-wet process fed with a solution of lime- water. It differs from thedry process (with dry lime) only by the use of a lime suspension in water sprayed into the reactorvessel. Thanks to the temperature of the raw gas, the water is vaporised in the reactor and theneutralisation salts (chloride and sulphate) are recovered as a solid in the filter (ESP or FF) with thefly ash.The semi-dry category also includes the process called either semi-dry or conditioned dry process,which consists of a spray of dry lime powder downstream from a water spray.The management of the neutralisation products is the same than for the dry-process as it is also asolid. The quantities of residues nevertheless differ because the excess of neutralisation agentrequired is generally lower.The semi-dry process is used at Selchp (England), Toulon (France), Carrières-sur-Seine (France),Armargerforbraending (Denmark), Würzburg (Germany,1997) and Beveren (Belgium) (refer to §3.6).


3.3.3.3 WET PROCESS

The wet process comprises generally :

• a preliminary filtration (ESP) to remove the fly ash

• two successive scrubbers :

- The acid scrubber which is operated at about 50-70°C and, because of this a proportion of thewater contained in the gas is condensed. The liquid loop sometimes incorporates a heatexchanger for maintaining the operating temperature. More than 95 % of HCl is absorbed inthe liquid which becomes acidic (pH < 2 if no neutralisation agent is added).

- The neutral scrubber is generally fed with a NaOH solution (better than a Lime Watersuspension) for maintaining the pH value at 7 in order to remove SO2 and if required tocomplement the HCl neutralisation.

In most plants -like Antwerp (Belgium) and Spittelau (Austria)-, the liquid in the acid scrubber isadded with lime-water in order to maintain the pH value at about 3.

Air

MSW

Primaryoven

BOTTOMASH

FLYASH

HRB

ESP

Postcombustionchamber

Heatrecover yboiler

Electrostaticprecipitator

H2O

NaOH

Ca(OH)2

FILTERCAKES

LIQUIDEFFLUENTS

OFF.GAZ

NeutralScrubber

AcidScrubber

Watertreatment

Pressfilter

PF

Figure 3-3 Scheme : Wet process GTS (neutral scrubber fed with NaOH and water treatmentfed with lime)

In some incinerators (5 plants operated in Germany and 3 being constructed) the acid scrubber isonly fed with water in order to produce a concentrated HCl solution (33%) which can be purified andsold.

HMs present downstream from fly ash filtration are kept in the liquid phase except for mercury whichis only partly fixed in the acid solution of the acid scrubber and requires a complementary treatmentwith activated carbon. In some cases activated carbon is added to the liquid phase. In the watertreatment unit, HMs are further precipitated as hydroxides with pH values of 9 to 11 by the addition oflime which also precipitates the sulphates as gypsum.


3.3.3.4 SEMI WET - WET PROCESS

As the regulations in force in several European countries become increasingly severe for liquideffluent release, the semi wet - wet process has been derived from the wet System.

In the semi wet - wet process the neutralisation of HCl and SO2 is also achieved in two successivescrubbers. The liquid effluent is then sprayed in the gas and the liquid evaporated.

The calcium chloride crystallises with two moles of water and forms CaCl2, 2H2O. The free water inthe solid residue is between 0,5 and 2 %.This allows the conversion of a liquid effluent into a solid residue which is collected in theelectrostatic precipitator with the fly ash.

The neutralisation reactions and consequently the consumption of reagents are identical to those ofthe wet process.

In some plants, HMs are further precipitated as hydroxides with pH values of 9 to 11 by the additionof lime which also precipitates the sulphates as gypsum prior to being sprayed.

Air

MSW

Primary oven

BOTTOMASH

FLYASH

+ SALTS

HRB

ESP

Postcombustionchamber

Heatrecover yboiler Electrostatic

precipitator

Ca(OH)2H2O

OFF.GAZ

NeutralScrubber

AcidScrubber

Saltsspraydryer

NaOHH2O

SOLIDRESIDUES

Figure 3-4 Schematic representation of a semi wet - wet process (neutral scrubber fed withNaOH and water treatment fed with lime)

3.4 Regulatory limits of emissions from waste combustion

This is related to gas and liquid effluents and in some countries to solid residues. The gas emissionspecifications are the most defined and controlled and thus are the main concern for incinerationplant operators.

3.4.1 Hazardous waste incineration

The Directive 94/67/EC fixes the emission limits for gas and liquid effluents from Hazardous WasteIncineration as indicated in Annex A1.1. All EC member states have incorporated this Directive intheir regulations.


3.4.2 Municipal Solid Waste Incineration

The 369/89 EC directive for MSW was issued in 1989 and the next version is not yet in force.Although all EC states have applied the 369/89 EC directive in their own regulations, most of theEuropean States have already introduced more severe emission limits

As indicated in table of annex A1.1 :

• Four European States (Austria, Belgium, Germany, Netherlands) have imposed - for the HClemission limit - the requirements of 94.67/CE Directive for hazardous waste incineration (10mg/Nm3, 11 % O2).

• Italy and United Kingdom have fixed intermediate specifications (20 and 30 mg HCl/Nm3, 11 % O2

respectively).

• In Denmark, Sweden and France, the HCl limit in off-gas (50 mg/Nm3, 11 % O2) is still that of the89.369 Directive.

3.4.3 Application to PVC incineration

The presence of PVC in the waste to be incinerated mainly affects the HCl concentration in the rawgas. This influences the operation of the neutralisation step as the HCl concentration in the off-gashas an impact on the necessary quantity of neutralisation agent to be used and, therefore, on thequantity of the residues from the neutralisation step.

3.4.4 Specific Regulation related to solid residues

There is no European Directive in force in this field but most states have specific regulations andpractices as described in chapter 9.

3.5 Incineration capacities in EC and GTS process distribution

It was initially observed that data related to the capacities of the incinerators as a function of thecombustion process and also of the APC process were difficult to obtain and to analyse.

The technological progress for gas treatment as well as the revamping of old systems for meetingthe regulations in force are responsible for constant development of the incineration process.

The TNO and Juniper Studies were used for the identification of the distribution of incinerationcapacities as a function of combustion and APC processes.

3.5.1 Data about Waste generation and elimination in EC

The distribution of the Municipal Solid Waste according to the different ways of treatment in Europeis shown in annex A1.2. Different sources of data have been considered :

• EEWC report published 1997 (Juniper study) [Eew97]

• European Statistics from 1993-1996 published in 1997 by ISWA [Isw97 ]

• Latest data published by OECD from 1995 [Oec97]

• Eurostat report corresponding to data from 1993 [Eur97 ]

Total MSW generated in EC: 150 Million tons/year (OCDE 1995)

7 % composted

10 % recycled


21 % incinerated

52% landfilled

The OCDE source is related to the MSW final destination in 1995. At present, the situation is probably different

3.5.2 Combustion processes

The table in annex A1.3 shows that Grate Systems are used with about 90 % of the incinerators in

service in terms of capacity.

3.5.2.1 Hazardous waste incineration

Hazardous waste (HW) is defined as waste containing hazardous materials such as medical waste,chemical and petroleum industry wastes. The major proportion of hazardous wastes are burned inspecial plants and cement kilns and the rest is incinerated in MSW plants.

In the Würzburg plant (Germany), the composition of the feed stream during 1993 comprised about2.3% of hazardous waste (with 1% of Hospital Waste) [Mar95a, Mar98].

Table 3-1a - Incineration of Hazardous Waste - French data from 1995 and 1996(Source ADEME 1997)

French Data (ADEME) 1995 1996 Number ofPlants

Hazardous Waste Incinerated(kt/year)

% Total HW production

1193

78%

1288

80%

> 40

% Special Plants 54.1 50 15

% MSW Plants 1.7 1.5 2

% Cements Kilns 29.8 34.2 23

% Others 14.4 14.3 -

In the case of hazardous waste incineration in the EC, only the data base for France is available asshown in table 3.1. Regarding the total waste incinerated in France, hazardous waste representsonly about 12 % of the total.

Clinical Waste (Hospital Waste) constitutes the major fraction of hazardous waste as measured bythe PVC content. Clinical waste can be classified into general waste, similar to municipal solid waste,and specific waste containing pathological material. Because of this last fraction, it is common forhospitals to have their own waste incinerator.

Incineration of clinical waste has been banned in some European countries. In other states clinicalwaste is still most probably incinerated in small facilities on-site at the hospitals. No information couldbe collected about these installations.

In Germany, nearly all the hospital incinerators have been closed and most clinical waste isincinerated in larger facilities, e.g. hazardous waste incinerators or special ovens located atmunicipal waste incinerators.The German Technical Guidelines on Waste Disposal [TAA91] define comprehensive requirementson the disposal of 332 types of waste requiring particular supervision and on the relevant facilities,based on Best Practicable Means (BPM). The standards of the statistics in the industrial, but partly


also in the public sector have been changed during the last years which makes it difficult to comparestatistical data. Furthermore the industry has not disclosed their statistics for a number of years.

The available data according to the latest official waste statistics [Sta96, DPU96, UBA99] arecompiled in Table 3-2. In 1995 there were 32 hazardous waste combustion plants in operation with atotal of 55 lines. 80 % of the systems operated in 1995 were rotary kilns combined with a postcombustion chamber [Gle95]. The total capacity of these systems accounted for more than 90 %.15 % of the systems were combustion chambers used mainly for gaseous and liquid residues andonly approx. 5 % were other types of furnaces.

Table 3-1b Incineration of Hazardous Waste - German data from 1990 and 1995(Sources Sta96, UBA99, DPU96)

1990 [Sta96]

(public+industrial)

1993 [UBA99]

(public+industrial)

1995 [DPU96]

(public*)

1999 *

(public+industrial)

Production (kt/y) 9771 8080 1612

Incineration Plants (total) 28 32 30

Incineration Plants(public)

7 8

Incineration Plants(industrial acceptingpublic waste)

7

Incineration Capacity(kt/y)

800 1100 1200

incinerated wastecollected by publicbodies (kt/y)

547

* no data from industry available

Two- or even three-stage wet scrubbing systems are the preferred gas cleaning systems inGerman hazardous waste combustion plants. In one plant (AVR Hamburg) HCl and gypsum areproduced from the scrubbing solutions. One public and at least one small industrial plant areequipped with a semi Wet - Wet System. The industrial plant uses a NaOH solution in a spraydrier downstream of a cyclone and upstream of a fabric filter. An estimate of the split between thevarious gas cleaning systems is not available due to the fact that this information was notdisclosed by the industrial operators of hazardous waste combustion plants.


Table 3-2 Estimation of the Clinical Waste Incineration in EC[Wor94, Ens91, Eur97, Oec97, Edi97, Apv97]

COUNTRY Number ofplants

Total capacityktonne/y

AUSTRIA 50-60 3.1BELGIUM (1995) 42DENMARK 16.8France 30-40 175GERMANY 50ITALY 50-60LUXEMBOURG 0NETHERLANDS (1993) 78 0.7SPAIN 2SWEDEN (1989) 30SWITZERLAND 30UK 260Total EC 670

As it can be seen in table 3.2, the total Clinical Waste incineration capacity in EC represents only0.5% of the total amount of waste incinerated.

3.5.2.2 Municipal Solid Waste Incineration

The number of plants and the incineration capacities for each country issued from different sources[Isw97 , Oec97, Eew97, Eur97 ] are shown in Annex A1.4. Large differences in the number of plantsand their capacities exist because of the capacity criteria used for the data collection (Juniper[Eew97] and ISWA sources take into account only the plants with capacities greater than 10 or 30kt/year) and because of the constant development of the incinerator process.

3.5.3 GTS processes

The table 3.3 shows the distribution of incinerators in EC by the type of process for GTS [Eew97].

Tables in annex A1.5 give an idea of the growth of the GTS process capacities in different EC statesduring the last 30 years in order to adapt the incineration facilities to the increasingly severeregulations for gas emission.


Table 3-3 Gas treatment for MSWI plants in Europe : number and capacities for each type.

Distribution, per country, of the capacities and number of plants as a function of the GasTreatment Systems .

Number ofplants

Total MSWIncinerated

Gas Treatment Systems

COUNTRY KT/y Dry process Semi-dry process Wet process(including semi-wet-

wet process)Number Capacity Number Capacity Numb

erCapacity

Juniper Source 1997 KT/year

% KT/year

% KT/year

%

AUSTRIA 3 510 3 510 100

BELGIUM 17 2151 1 55 3 8 741 34 8 1355 63

DENMARK 26 2814 8 482 17 7 790 28 11 1469 52

FINLAND 1 50 1 50 100

FRANCE 77 10830 16 1439 13 18 2277 21 29 5493 51

GERMANY 57 13458 19 4217 31 38 9210 68

ITALY 32 3407 13 1106 32 1 84 3 18 2217 65

LUXEMBOURG 1 150 1 150 100

NETHERLANDS 11 3600 1 80 2 10 5163 98

NORWAY 5 440 2 225 51 3 215 49

SPAIN 7 1072 2 515 48

SWEDEN 15 2094 6 778 37 9 1310 63

SWITZERLAND 26 2722 1 85 23 2637 97

UK 7 2140 4 1140 53 3 1000 47

TOTAL EC 254 42276 46 5200 15 59 9704 23 126 26727 60Notes :1) wet/semi-dry processes have been included in the wet processes.

In France, 3 plants are equipped with semi-wet wet process for a capacity of 480 000Tonnes/year of MSW.In Belgium 5 plants are equipped with semi-wet/wet process.The following numbers of plants equipped with semi-wet/wet process have been identified forsome European countries as well as the corresponding capacities.

BELGIUM 5 plants 480 000 t/yr MSWFRANCE 3 plants 480 000 t/yr MSWGERMANY 33 plants 7 700 000 t/y

(5 plants with pure wet scrubbing for 1 510 000 t/y MSW)

2) Unidentified APC systems as well as APC systems at present being upgraded are responsible forthe possible difference between the total capacity and the sum of capacities in relation to APCsystems.

The distribution of APC systems when related to the sum of identified gas treatment processes leadsto the following : Dry processes : 14%

Semi-dry processes : 22%Wet processes (including semi-wet/wet) : 64%

Source : Updated Juniper 1997 (Plants capacities >30 kt/year) [Eew97]


In practice a lot of incineration plants have either been revamped or shut down. This last option hasbeen used especially in UK and France where several units, and particularly the small ones, wereclosed as their pollutant emissions could not be satisfactory reduced.

In order to appraise the reliability of the different data sources, they were compared with otherFrench data bases issued by ADEME and ALSTHOM. The table in annex A1.6 shows how thevalues differ as function of the year considered and of the criteria used for the data collection :Juniper only takes into account the incinerators with a capacity greater than 30 000 t/year, Alsthomneglects the plants with a capacity less than 10 000 t/y and ADEME considers all ranges of capacitybut does not specify the APC process.

It appears - according to figure in annex A1.6 - that the different sources are consistent and that thedifference in distribution could be explained by the different criteria used for data selection.

3.6 Selected incineration facilities used for experimental data collection

A preliminary literature survey allowed the identification of the incineration plants which wereconsidered as relevant for data collection. The selection was based on the need for pertinent resultsfrom the different GTS processes and for results collected in different European countries.

For the experimental part of the study the following incineration plants listed in table 3.4 were finallyselected and the available data from these were collected.

Table 3-4 Location and type of incineration plants selected

Plants LocationYear

NeutralisationAgent

Reference

DRY GTS PROCESSWürzburg (Germany) 1993 Lime [Eur94,Veh96, Mar94, Mar95a, Bra95]Novergie (France)(location not disclosed)

1991 Lime [Nov99]

Nordforbraending (Denmark) 1997 Lime [Isw97, Ols99, Hje96, Hje98]Pontivy (France) 1994 Lime [Rod98]

Reggio Emilia (Italy) 1996 Bicarbonate [Ben97, Ene96]SEMI-DRY GTS PROCESS

Würzburg (Germany) 1997 Lime [Mar98, Veh98, Veh97]Selchp (England) Lime [Blu98, Den95, Por91, Por94, Sel94]Amager-Forbraending(Denmark)

Lime [Hje98, Ras95]

Toulon (France) 1991 Lime [Apa91, Per99]Carrières (France) 1997 Lime [Apa97, Per99]Beveren (Belgium) 1997 Lime [Wat97, Wat98]

WET GTS PROCESSAlkmaar ( Netherlands) 1997 Lime/Soda [Rij93, Spa98]Bamberg (Germany) Lime/Soda [Ach96, Rei89]Vestforbraending (Denmark) Lime/Soda [Cri99, Hje96, Hje98, Ras95, Isw97]Spittelau (Austria) 1997 Lime/Soda [Rei99]Antwerpen (Belgium) 1997 Lime/Soda [Wat97, Wat98]

CLINICAL WASTE INCINERATOR - DRY GTS PROCESSCW Incinerator (Belgium) 1997 Bicarbonate [Hwi99]

The industrial waste incinerators of INDAVER (Antwerpen and Beveren) are also considered as itgives an idea of what happens in presence of high chlorine contents in the waste [Wat97, Wat98 ].


Horgen and Bazenheid [Baz95, Hor94 ] facilities have been also mentioned but not furtherconsidered in the study as Switzerland does not belong to EC.

The main characteristics of the selected plants are shown in table 3.5.


Table 3-5 Main characteristics of the incineration plants selected for the study

Type Initial Waste Bottom Ash Fly ash ( + Boiler ash) Neutralisation products Other effluents Off-Gasof Type Cl Mass Chlorine Mass Chlorine Mass S.R. Chlorine Mass Chlorine

Location ofincinerators

APC ofwaste

kg/t kg/tonne ofinitialwaste

Clkg/tash

Distribution% of

initial Cl

kg/tonne ofinitial waste

Clkg/tash

Distribution% of

initial Cl

kg/tonne ofinitial waste

Stoich.ratio

Clkg/t

product

Distribution % ofinitial Cl

kg/tonneof initialwaste

Clkg/t

liquid

Distribution % ofinitial Cl

Distribution %of

initial Cl

Dry Process Bottom ash Boiler ash Cyclone ash residues Filter ash residues % (mg/Nm 3)Würzburg (D) 1993 D

limeMSW 7.32 267 8.4 30.6 5.4 34.3 2.5 32.5 3.2 56.7 25.1 17.1 188 44 1.4 (23.5)

" Dlime

+PVC 7.65 188.6 9.01 22.2 3.6 33.4 1.6 40.4 61.4 32.4 25.9 183 62 1 (22.4)

" Dlime

+PVC 8.74 212.7 13. 31.7 3.9 50.5 2.2 42.9 53.2 26.1 20.5 198 46 1.1 (21.4)

Novergie (F) Dlime

MSW 7-9 3.6

Pontivy (F) Dlime

MSW+Ind.

6 -10 171 61

Nordforb. (DK) Dlime

MSW 5.3 187 11 39 2.1 40 220 61 0.1 (65)

Dry with BICARReggio Emilia (I) DB MSW+D

H6-9 280 3.9 14 23 40 12 - 1.2 - - 16 338 73 0.12 (5)

Clinical Incinerator(B)

DB CW 24.4 1.5 46.5 0.1 (9)

Semi-Dry Process Solid ash residues

Würzburg (D) 1997 SD MSW 6.17 295 9.25 13.7 2.1 11.34 2.8 20 3.7 29.73 157 75.5 0.37 (6)SELCHP (GB) SD MSW 6 300 3 15 - - - 40 2.2 127 84.9 - - - 0.1 (10)Carrières (F) SW MSW 5 - 6 192 15 24 2 14Toulon (F) SD MSW 8 - 10 40Amager-forb. (DK) SD MSW 5.4 280 45 2 (10)Beveren (B) SD MSW 260 21 40 (5)

Wet Process Fly ash (boiler +filter ) Neutralisation products (solid) Liquid effluents

Alkmaar (NL) W MSW 6.4 260 2.9 12. 14 66.4 14.3 7.6 dry 1.1 4.2 0.5 9 dry 517 73.1 0.1 (10)Bamberg (D) W MSW 6.9 296 3 13. 23 43 14.5 4 (1+3) dry 1.46 25/37 26 300 17 46.4 0.16 (3)Vestforb. (DK) W MSW 5.3 155 2.8 8 18.5 96 33.5 0.7 450 0.1 58 0.3 (2.5)Spittelau (A) 1997 W MSW 8.6 280 3.38 11 25 70 20 3 (1.2+1.8) 1.2 5.2/0.1 0.1 616 9.7 68.8 0.1 (1)Antwerpen (B) W Indust.1 48 290 3.2 1.9 34 16.9 1.2 41 1 17 1 2600 19 94 0.1 (2)

Indust.2 29 271 3.5 3.2 31 31.4 3.3 40 1 17 1 1830 15 92 0.1 (2)Horgen (CH) W MSW 6.9 250 3.4 10.7 34 82 40.3 8.8 7.7 0.6 176 19 48.3 0.3 (2)Bazenheid (CH) W MSW 250 5 10 120 28.3 (7)

PVC.P. 007 EPage 30

4. GENERAL ASPECTS ON PVC : COMPOSITION AND CONTENT IN WASTES

4.1 PVC composition and main applications

Vinyl chloride monomer was first produced by Renault in France in 1835 and its polymerisationwas recorded in 1872 by Baumann who exposed sealed tubes containing vinyl chloride to sunlight.[Bou94 ]

PVC is a chlorinated hydrocarbon polymer consisting of a linear carbon chain for which alternatecarbon atoms have one of their hydrogen atoms replaced by a chlorine atom. The chlorine in PVCrepresents 57% of the weight of the pure polymer without any additives. Pure PVC will bedesigned as "polymer" and the term "compound" will be used for the different types of PVCcompounds.

Depending on the final application the PVC formulation can vary substantially because of additivesthat are incorporated into the polymer such as filler, stabiliser, lubricant, plasticiser, pigment orflame retardant.

Building and construction : plasticised and rigid PVCPackaging : plasticised and rigid PVCWire, cables and elec. : plasticised PVCLeisure : plasticised and rigid PVCTransport : plasticised and rigidFurniture, office equipment : plasticised and rigidClothing, footwear : plasticisedDomestic appliances : rigid and plasticised

Clothing Footwear3%

Leisure4%

W ire, cable & Elec.9%

Packaging15%

Building & Const.54%

Furniture, Office Eq.3%

Transport3%

Dom estic appliances1%

Other uses8%

Figure 4-1 PVC - Main applications in EC [Sva98]

PVC compounds can be used for a large range of applications including films for packagingapplications, cable covering, bottles , pipes and profiles suitable for building applications, textilefibres and automotive applications. Figure 4.1 shows how the use of PVC was distributed in 1998amongst the different applications [Sva98].

Stabilisers contain metallic compounds ( such as Pb, Ba, Zn, Cd, Ca, Sn) as shown in table 4.1[Buh98 ]. Lead stabilisers in Europe comprise some 60% of the market, organotin (often thiotin)stabilisers comprise 10-15% with the rest being solid, liquid or paste combinations of calcium andbarium salts with zinc and until recently cadmium [Don96 ]. Cadmium in PVC has been banned for

PVC.P. 007 EPage 31

all applications except profiles [Swe96]. These different formulations may have significantlydifferent chemical and physical characteristics, because of the wide range of processes used andapplications.

Plasticisers which are used in flexible PVC applications are organic compounds and includephthalates and chlorinated paraffins.

Lubricants often contain calcium or lead as stearate salts.

Table 4-1 Typical Metal Content in PVC Products [Buh98]

Stabiliser Type PrincipalMetal

Metal Content (%) in PVC

Packaging OtherProducts

Lead compounds Pb Not used 0.5-2.5Organotins Sn 0.1-0.2 0.3-0.5Cadmium compounds(usage restricted by91/338/EEC)

CdBaPb

Not used 0.1-0.20.1-0.31.0-1.8

Barium/Zinc compounds(only for plasticisedapplications)

BaZn

Not used 0.1<0.1

Calcium/Zinc compounds CaZn

0.1<0.1

0.1<0.1

As shown in annex A2.1, the resin content- and consequently the chlorine content- are highlydependent on the formulation of the compounds. The chlorine concentration therefore varies from53% in rigid products (93% of PVC resin) to 34% in films (60% of PVC resin) and 25% in cablecovering (44% of PVC resin). This concentration can go down to 14% in flooring applications (25%of resin) but we will not include this application in our discussion since the waste goes generally tolandfill or recycling.

4.2 PVC materials in the EC - production and use of PVC

The total amount of PVC consumed globally in Europe was about 5594 ktonnes in 1997 comparedto a total plastic consumption of 25905 ktonnes [Ecv97 ]. Figure 4.2 shows the development of themarket and production capacity during the past 5 years. As shown in annex A2.2, thisconsumption of PVC is increasing and is predicted to reach about 5880 ktonnes in 2006 accordingto the estimates of the PVC industry [Ecv97 ]. From other sources [Sri93 ], this consumption levelwill be attained in 2000.

PVC.P. 007 EPage 32

Total PVC market in Western Europe

52755150

55305310

54245594

4000 4400 4800 5200 5600 6000

1992

1994

1996

kt

P V C p ro d u c t io n b y W e s te r n E u ro p e a nm a n u fa c tu re r s

4 7 8 5

4 6 8 5

5 2 4 5

4 9 1 0

5 2 4 9

5 5 2 8

4 0 0 0 4 4 0 0 4 8 0 0 5 2 0 0 5 6 0 0 6 0 0 0

1 9 9 2

1 9 9 3

1 9 9 4

1 9 9 5

1 9 9 6

1 9 9 7

k t

Figure 4-2 Bulk market and production of PVC Materials (Western Europe)(Statistics for Western Europe- Source Sofres Conseil for APME) [Evc97]

4.3 Service life of PVC products

As shown on table 4.2 the service life of PVC highly depends on the use of PVC product.

Packaging and medical applications together with small objects, will become solid waste within 2years after being purchased. These products will end up with the household wastes and thus willpossibly be incinerated according to the local policy in use.

Wall covering, flooring and footwear have a medium life (2-10 years) and could be partly disposedof with MSW as waste products or as non hazardous industrial and commercial waste.

Table 4-2 Distribution of PVC materials with regard to the PVC service life [Buh98]

Service Life Applications Life % wgt

Short Life Packaging, medical applications, stationery < 2 years 15 %

Medium Life Wall covering, flooring, footwear 2 - 10 years 17 %

Long Life Flooring, wire & cable covering, furniture,automotive

10 - 20 years 26 %

Extra LongLife

Pipes, window profiles, cables, roof liners > 20 years 42 %

PVC.P. 007 EPage 33

4.4 PVC in MSW to be incinerated

4.4.1 Global composition of Municipal Solid Waste

The composition of MSW is subject to some fluctuation across Europe. This is due to differencesin the definitions of MSW and to the different conditions encountered in countries (socialconditions, location, season...). In general, MSW includes household waste, bulky waste, minorcommercial and industrial waste (trade waste), and market and garden residual waste when notsorted at source.

Tables in annex A2.3 and A2.4 give an estimation of the mean MSW composition of the whole ECin 1995 (OECD source [Oec97]) and in 1992 (TNO Source [Rij93 ]) as well as of the fraction whichis sent for incineration [Oec97, Eew97 ].

Table 4-3 Average composition of MSW in EC and evolution[Eur97, Isw97, Rij93, Oec97 and Apm96] (cf. Annex A2.3)

MSW fractions in EC EUROSTAT 1993% by Weight

TNO 1992% by Weight

OCDE 1995% by Weight

APME 1996% by Weight

Putrescibles/Fines 37 33 37 35Paper 27 30 26,2 25Plastics 8,5 7,4 9 8Glass 9 8 9 9Metals 4,7 8 4,5 4Miscellaneous(textiles incl.)

13,8 13,6 14,3 19

% PVC in Plastics 10 10,7% PVC in MSW 0,74 0,86

Table 4.3 represents the average composition of MSW in the EC according to different sources[Eur97 , Gro93, Oec97, Apm96 ].

4.4.2 Elementary composition of MSW

The elementary composition of MSW depends directly on the development of MSW managementpractices and especially on the increasing use of sorting at source. A more recent compilation ofdata has been published by PWMI/TNO in 1993 [Gro92, Gro93, Rij93 ]. On this basis, anestimation of the average MSW composition is given in Table 4.4.

Table 4-4 Main elements distribution in MSW from EC in 1996[Gro92, Apm96]

MSW fractionsin EC

APME 1996% by Weight

Chlorine% wt

Sulphur% wt

Heavy Metalskg/t

Putrescibles/Fines 35 0.756 0.285 2.108Paper 25 0.369 0.252 0.561Plastics 8 2.364 0.023 1.241Glass 9 0.01 - 0.9665Metals 4 0.032 0.011 18.491Miscellaneous (textiles incl.) 19 1.0 0.36 4.4Total (%wt) 100 0.738 0.233 2.64

PVC.P. 007 EPage 34

The same information related to the waste compositions measured in different selectedincinerators are shown in table 4.5. The average chlorine content of 0.7% for these plants is closeto the average value for MSW in the EC. The maximum deviation is 19%. For sulphur thedeviation is more important (average of 29% and deviation max. of 74%)

Table 4-5 Typical data of chlorine, sulphur and heavy metals content in EC MSW

Location of Initial WasteIncinerators Type Cl S HMs

Date kg/t kg/t kg/tWürzburg (D) 1996 MSW 6.2 3.4 4.23

Reggio Emilia (I) 1995 MSW +HW 7.6 2.0 0.5Selchp (GB) 1996 MSW 6 2.0 0.4Alkmaar (NL) 1995 MSW 6.4 1.2 2.17

Toulon (F) 1991 MSW 9.6 0.6Amagerf. (DK) 1997 MSW 5.4 1.3Spittelau (A) 1997 MSW 8.6 4 1.7Pontivy (F) 1994 MSW 6-

101.3

Carrières (F) 1997 MSW 6 1 3.6Bamberg (D) 1994 MSW 7.5 4 3.16

Antwerpen (B) 1997 Industrial waste 48 6.7 -Horgen (CH) 1995 MSW 6.9 6.3

Average Value 7.2 3 2

Heavy Metals (HMs) and trace elements (Se, Te) considered in this study are those subject tolimitation by the 94/67-EC Directive related to Hazardous Waste Incineration. In Germany (TA1986, 17BImSchV), heavy metals are distributed among the following three classes as a functionof their volatility :

Class I : Mercury (Hg),

Class II : Cadmium (Cd) and Thallium (Tl),

Class III : As, Co, Ni, Sb, Pb, Cr, Co, Sn, Cu, Mn, V + trace elements (Se, Te).

4.4.3 Influence of PVC on MSW composition

The concentration of PVC in MSW which is incinerated varies from country to country in the EC.On the other hand the PVC materials present in MSW are not a single compound but a variety ofdifferent products with a large range of compositions.

The presence of PVC mainly affects the chlorine content, and possibly the Heavy Metals (HMs) -arising from the presence of lead, tin, cadmium, zinc, barium- and the organic additives (mainlyfrom phthalates).

In order to more easily appraise the influence of PVC on MSW composition, PVC material isusually classified in two categories, unplasticised and plasticised, depending on its application.Unplasticised PVC or PVC-U (e.g pipes, windows frames,) is a rigid, strong and weather-resistantmaterial while plasticised PVC or PVC-P (e.g cable covering, floor coverings, some packagingapplications.) is a flexible material which is produced by incorporating a plasticiser. Theelementary composition of each PVC type has been evaluated and the global PVC compositionevaluated as a function of the unplasticised to plasticised ratio.

PVC.P. 007 EPage 35

4.4.3.1 PVC influence on Chlorine content in MSW

According to different sources from literature review [Nie96, Rei91, Gro93, Rij93, Mar95, Gro98,Swe97], the composition and the distribution of the PVC-U and PVC-P fractions are presented intable 4.6.

Table 4-6 Literature review on PVC contribution to Chlorine content in MSW

Sources Nieuwenhuysen1996 [Nie96]

De Groot1993 [Gro93 ]

Reimann1991 [Rei91]

Rijpkema1993 [Rij93 ]

Rasmussen1995 [Ras95]

Mark 1995[Mar95]

PVC-P (%) 50 34 30 50 50PVC-U (%) 50 66 70 50 50% Cl in PVC (%) 41 45 50 41 48 40Total PVC inMSW

(%) 0.7 0.65 0.7 0.6 0.73 0.74

Contribution toCl content(kg Cl/tonneMSW)

SoftRigidTotalPVC

1.11.82.9

< 0.82.83.5 2.4

1.52

3.5 2.96

Total Cl inMSW

(kg/tonne)

7 7 6.4 5.3 7

Contribution ofPVC to Clcontent in MSW

(%) 41.4 50 38 66 42.4

As it can be seen in table 4.6, PVC waste contributes to 38 to 66% of the chlorine content inMSW. The rest comes mainly from putrescibles (17% : table salt), paper (11%) and miscellaneouscombustibles (30%) [Rij93 ]. (The selected values for the Cl-content and the PVC contribution to Clcontent in MSW have a large impact on the conclusions of the report)

4.4.3.2 PVC Influence on HMs content in MSW

Table 4-7 PVC contribution to elementary composition of MSW [Rij93]

Elementsfrom MSW

MSWkg/t or

g/t

PVC – V(%)

PVC -P(%)

PVC waste50% rigid

Contribution of 0.7%PVC toMSW composition

kg/t MSW (%)

Cl kg/t 7.4 51 32 41 2.9 (39%)

S kg/t 2.4 0 0 0 0 (0%)

Cd g/t 6.4 0.01 0.01 0.01 0.7 g/t MSW (11%)

Pb g/t 570 0.147 0.024

0.084 5.88 g/t MSW (1%)

As g/t 8.3 5.10-5 5.10-

55.10-5 3.10-4 g/t (4.10 -3%)

Sn g/t 4.4 0.0025 0 0.0012 8.410-3 (0.19%)

Zn g/t 710 0 0.045

0.022 1.6 g/t MSW (0.2%)

Other Metals g/t 1354 0.0396 0.037

0.038 2.7 g/t MSW (0.2%)

PVC.P. 007 EPage 36

The table 4.7 presents the PVC influence determined for a 50/50 PVC-U/PVC-P (and 0.7% PVCin MSW). It appears that the influence of PVC on heavy metal content in MSW is only significantfor cadmium as the PVC contribution to Cd concentration in MSW is about 11%. For lead, tin,arsenic and zinc, the PVC influence is lower than 1%. According to other sources (MSWcontaining a PVC-U fraction about 0.7%), lead from PVC contributes to approx. 6% [Rei91].

Some others sources mention different values for the PVC contribution to the lead content inMSW :

[Min 97] : 10 % of the lead in MSW comes from PVC in the Netherlands

[DEPA 98] : 6 % of the lead in incinerated MSW comes from PVC in Denmark

[MER 99] : 3 % of the lead in incinerated MSW comes from PVC in Sweden

The data show a large disparity that could be the subject of specific investigations. For thepurpose of the present study it will be assumed that PVC contribution to the lead content in MSWdoes not exceed 1 %.

4.5 PVC in hazardous industrial waste

As PVC is not at present defined in EC legislation as hazardous (it is not in the hazardous wastelist), it is not supplied voluntarily to Hazardous Industrial Waste incinerators as the treatment costis higher than that of MSW.

Even the larger quantities of PVC materials obtained from building demolition are not incineratedin Hazardous Waste Incinerators.

Some low concentration of PVC - 2% max. [Gov99 ] - can exist in Hazardous Waste due topackaging of the hazardous waste (PVC bottles, PVC films for protection...).

On the other hand the Hazardous Wastes contain high chlorine concentration (chlorinatedsolvents, polluted salt residues...) - 3 to 5% at Antwerpen [Wat98] - and the influence of PVC istherefore limited.

4.6 PVC influence on Clinical Waste (CW) composition

Table 4-8 PVC influence on Chlorine content in Clinical Waste

Waste CLINICAL WASTE MSWSources Belgium

1997 [Hwi99 ]ASME

1994 [Ran94]in EC

(cf. Chapter 5)

Total Cl in Waste (kg/tonne) 23 (10-35) 11-21 5-10

Total PVC inWaste

(%) 4.4 (1.4-7) 1.4-3.7 0.6-0.8

Cl content inPVC

(%) 43 (40-45) 43 40-50

PVCContribution toCl content

(kg Cl/tonneWaste)

17 ( 5 - 30) 6-16 2.5-3.5

PVC contributionto Cl in Waste

(%) 74 (50-86) 55-76 38-66

Table 4.8 contains the experimental results collected in a Belgium Clinical Waste Incinerator(location not disclosed) using a dry process with sodium bicarbonate. It shows that PVC influencesclinical waste more than MSW ; 50 to 86% of the chlorine is contributed by PVC to CW while 38 to66% of the chlorine is contributed by PVC to MSW.

PVC.P. 007 EPage 37

5. POST-USE PVC INCINERATION PRACTICE IN EC

As discussed previously, PVC waste material can be divided into different categories :

• Category 1 : Household waste ; this is mainly packaging (such as films, blister packs...), toys,small objects , do it yourself applications [Dem96]

• Category 2 : Small industry or retail outlets, electrical and electronic equipment, automotiveresidues

• Category 3 : Hospitals - small applications and equipment

• Category 4 : End of Life PVC from building demolition

The available types of incineration facilities to which PVC could be addressed are :

• MSW incinerators

• Hospital Waste incinerators

• Hazardous (industrial ) Waste incinerators

• Cement kilns

5.1 Co-incineration in cement kiln

In the cement industry, the co-combustion of the waste in the kiln is commonly used for economybut the cement process is not adapted to treat wastes containing PVC whatever its category.

Although the French regulation allows the use 1 or 2% of chlorine in the alternative fuel accordingto the location of its injection, in practice Cl content is limited in France to 0.3 to 0.5% in order toprevent plugging of the cyclones due to the crystallisation of chlorinated salts [Cha99].

For other cement processes (wet process) in Belgium [Deg99] the regulations allow a maximum of6% of chlorine in the waste but operators do not exceed 1% (preferably 0.1 to 0.5%) in order tomeet the specification for Cl content in the manufactured cement. Chlorine fed to the kiln isrecovered as salt with the dust from the ESP or FF Gas Filtration step. This dust is mixed with theclinker, Calcium Sulphate and other additives are used to manufacture the cement for which themaximum chlorine content is 0.1%.

As an example, the waste management in Antwerpen [Wat99] can be considered : plastics aresorted at source and the plastic waste sorted again to separate the material destined for recyclingand the refuse to be incinerated. According to the Cl content of this refuse it is either sent to thecement kiln (Cl<0.5%) or to the MSW incinerator (Cl>0.5%).

For the current practice described above - and for the required Cl content in the alternative fuel -the chlorine is recovered with the dust and mixed with the clinker. In conclusion co-incineration ofPVC in a cement kiln is limited in use because of the chlorine content but where it is used itproduces no residues.

5.2 Incineration of PVC material from categories 1 and 2

The material is mixed with MSW directly by the users then sent to landfill or to an MSWincinerator. The non-sorted plastics are also sent to an incinerator or to landfill with the waste.

PVC.P. 007 EPage 38

5.3 Incineration of PVC material from category 3 (Clinical waste)

Different practices are used in the different EC countries : Clinical Waste is incinerated either inspecific incinerators nationally distributed as in Italy or centralised as in Germany or to MSWincinerators [Isw97 ]. In this last case, the Clinical Waste ratio is 10% maximum as in ReggioEmilia, Milan (Italy) or Tronville-en-Barrois (France) [Isw97, Ens91, Ade98] .

As mentioned in § 4.6 Clinical Waste contains more PVC than MSW but nevertheless the totalClinical Waste incinerated is only 0.5% of the MSW incinerated [Wor94, Ens91, Eur97, Oec97,Edi97, Apv97 ].

5.4 Incineration of PVC material from category 4 (building demolition)

The operators of Industrial Hazardous Waste Incinerators (Indaver [Wau99], AVR [Gov99 ],Ecotechniek [Don99 ], Kommunckemi [Kri99 ], Cleanaway, HIM [Sch99 ], Rechen, SARP, TREDI...)were questioned. They also answered that such sorted PVC is not supplied to their plants(Hazardous Waste Incinerators) but to MSW Incinerators. PVC can be accidentally present inHazardous Industrial Waste and its concentration is always below 2% (by weight) [Gov99 ].

PVC from category 4 is therefore incinerated with MSW and a shredder is installed close to thebunker to deal with objects which are too large; such practice is used in the Beveren MSWincinerator.

5.5 Conclusions : type of waste where incineration is influenced by PVC

PVC has a minor influence on Hazardous Industrial Waste incineration and on cement kiln co -incineration.

PVC mainly influences the MSW characteristics.

For the continuation of this study, only the influence of PVC on MSW will be considered.

5.6 Basic point for further calculations

A reference PVC content in MSW will be used in the continuation of the study for theoreticalcalculations as well as for comparing the results collected from the different selected incinerators.Possible deviation from this reference waste will be considered for drawing the conclusionsconcerning the PVC influence on the Gas Treatment Residues quantities and composition.

Table 5-1 Reference Chlorine in MSW and PVC content[Nie96, Rei91, Gro93, Rij93, Mar95, Gro98, Swe97]

% by weight Upper Limits Lower LimitsTotal Cl content in MSW (%) 1 0.5PVC-U (%) 70 50PVC-P ratio (%) 50 30Cl content in PVC-U (%) 57 51Cl content in PVC-P (%) 40 32Total Cl from PVC in MSW (%) 0.66 0.2PVC contribution to Cl in MSW (%) 66 38

As a conclusion to the influence of PVC on MSW compositions it can be said that :

• The major influence of PVC on MSW composition is related to the chlorine content as about 38to 66% of the chlorine comes from PVC in the reference waste.

PVC.P. 007 EPage 39

• PVC influence on the HMs content in the waste is significant for cadmium as 11% of it comesfrom PVC. For other HMs PVC influence is lower than 1% and, therefore, not significant. Asalready mentioned the PVC influence on lead content is assumed to not exceed 1 %.

It should also be noted that PVC formulations are subject to continuing technical developments.This applies especially to the HMs and trace element content. Cadmium for example has beenbanned for all applications but profiles and its concentration in waste will therefore decreasecorrespondingly.

6. INFLUENCE OF PVC ON RAW-GAS COMPOSITION

6.1 Partitioning of elements between the Bottom Ashes and Raw-Gas

6.1.1 Definition of Raw-Gas

During the combustion of the waste in a grate system, the incoming material is distributedbetween two streams : bottom ash and raw gas.

Bottom ash is the solid material discharged from the grate. Raw gas is composed of two phases,a gaseous and a solid one. The constituents of the gaseous phase are nitrogen, the majorcombustion products CO2, H2O, residual oxygen, minor amounts of products of incompletecombustion (PIC), acid gases like HCl or SO2 and at high temperature volatilised metal or traceelement compounds.

The solids contain various materials:

• material mechanically carried over from the combustion chamber which comprises silicates andoxides species, e.g. CaO,

• neutralisation products of the primary alkaline fly ash and the acid gases, e.g. alkali and earth-alkali chlorides,

• condensation products of compounds initially volatilised inside the combustion chamber suchas metal chlorides, sulphides or oxides.

Whereas in old combustion plants high dust loads up to 5 g/m3 were common, modern plants arecharacterised by less stringent combustion and low dust loads down to < 2 g/m3.

6.1.2 Fundamentals of the thermal behaviour of elements

Various elements undergo different chemical reactions in the conditions found inside thecombustion chamber of a waste combustion facility. Major controlling parameters are thetemperature in the fuel bed and the local concentrations of reactants. Both parameters are notknown to the degree that would allow a reliable calculation of reactions on the basis of thermo-chemical data.

Furthermore, only a few data sets from operating waste combustion plants have been publishedthat give a more or less systematic overview of the fate of elements, their controlling mechanisms,and their effects on the residue quality [Ang90, Bel93, Dal93, Egg92, Mor98, Rei89b, Rei95,Rij96]. Hence a short theoretical consideration in combination with the results of respective andespecially designed experiments in the Karlsruhe test plant for municipal solid waste combustion,TAMARA, will be used in order to provide the basis for the following considerations.

PVC.P. 007 EPage 40

6.1.2.1 Partitionning of chlorine

The most stable oxidation state of chlorine under the conditions of waste combustion is -1. Thismeans that its major combustion products are chlorides with HCl as the most prominentcompound. The actual partitioning of chlorine is to a great extent influenced by the nature of thiselement in the waste stream. For typical municipal solid waste incinerated in a grate system thepartitioning given in Table 6-1 with 10 - 30 % staying in the bottom ash and the remainder enteringthe raw gas stream is found [Iaw97]. This range can be attributed to the actual mix of differentchlorine species in the waste.

Experiments in TAMARA revealed the expected distinctive variations in the partitioning forinorganic and organic chlorine species as can be seen from Figure 6-1 [Hun94]. Burning pre-treated municipal solid waste with a Cl concentration of 0.3 wt % (temperature approx. 950 °C)resulted in a division between bottom ash and raw gas of about 20%/80%. An increase in Cl loadby means of CaCl2 (to 0.4wt %) resulted in approx. 40 % of Cl staying in the bottom ash and theaddition of the thermally more stable NaCl (total Cl: 0.5 wt %) increased this fraction to more than50 %.

Figure 6-1 Influence of Inorganic Species on the distribution of the chlorine [Hun94]

The experiments show that inorganic chlorides added to the waste have a higher tendency to stayin the bottom ash than the chlorine from organic chlorine compounds. The latter are alreadydecomposed in the pyrolysis/gasification zone on the grate and form HCl which is released intothe gas phase.

In another experiment the Cl level in the TAMARA feed was increased from approx. 0.7 to morethan 3 wt % by addition of PVC containing waste plastics (temperature 1 050 °C). The Cl balanceof these experiments in Figure 6-2 documents shows that in the basic case with no plasticaddition, about 12 - 15 % of the waste stayed in the bottom ash. The Cl added by the PVCaddition entered mainly the gas phase whereas the portion in the bottom ash was only marginallyincreased.

PVC.P. 007 EPage 41

Figure 6-2 Distribution of Chlorine [Veh96a]

The graph shows that the Cl inventory in the fly ash increases with increasing Cl input and levelsoff at high Cl feed. The fly ash show a pH of 6 - 7 when brought into contact with water. This effectis typically seen in modern waste combustion plants where the dust load is very low and henceonly a limited amount of chlorides can be formed by neutralisation.

6.1.2.2 Partitioning of sulphur

Sulphur is not present in PVC and hence its partitioning is not expected to be altered by the extrafeeding of PVC. Sulphur species in the waste stream are sulphates or organic compounds thecombustion products of which are SO2, SO3, or sulphates. The partitioning of sulphur dependsalmost totally on the temperature in the fuel bed. In municipal solid waste combustion typically onethird of the inventory stays in the bottom ash and one third is as SO2 in the raw gas. If thecombustion temperature is increased a higher portion of sulphur enters the flue gas. Theexplanation is the limited thermal stability of sulphates. E.g. sulphates of trivalent heavy metalslike Fe or Al disintegrate at temperatures of 700 - 750 °C, and if water is present, at lowertemperatures. Even the abundant CaSO4, gypsum, starts decomposing at about 1050 °C.

6.1.2.3 Partitioning of heavy metals

In this chapter only the metals Cu, Zn, Cd, Sn, and Pb will be considered. These have beenselected due to their importance in the context of PVC combustion. All of these - like most of theheavy metals - are characterised by the relatively high volatility of their chlorides as is documentedby the respective vapour pressure curves in Figure 6-3.

The heavy metal with the highest volatility, mercury, is not shown in the graph. First of all it istypically not found in PVC and on the second hand all of its compounds are found in the gasphase at temperatures exceeding 400 °C. The same stays for the rather mobile trace elementarsenic the trichloride of which has a boiling point of 130.4 °C.

PVC.P. 007 EPage 42

Figure 6-3 Vapour pressure curves of selected metals, metal chlorides and metal oxides

(MSWC: municipal solid waste combustion, HWC: hazardous waste combustion)

The graph indicates that at temperatures typically found in municipal solid waste combustion thechlorides of Cu, Zn, Cd, Sn, and Pb - if they have been formed - are mainly present in the gasphase. Some metals like Zn, Cd, and Sn could also be evaporated in the metallic form which,however, has a lower formation probability under the overall oxidising conditions in the combustionchamber. At higher temperatures, e.g. in the combustion chamber of a hazardous wastecombustion plant, the oxides of Cd, Sn, and Pb may contribute to the volatility of the respectivemetals.

Tests performed in TAMARA burning homogenised municipal solid waste at a combustionchamber temperature of 900 °C resulted in the partitioning of the above mentioned heavy metalsshown in Figure 6-4. This partitioning could be verified by theoretical calculations and is in goodagreement with data published for full scale municipal solid waste incineration plants (compareTable 6-1). The gas phase carries only negligible amounts of the selected heavy metals. This is inline with the vapour pressure curves and leads to the conclusion that the emission of all heavymetals except mercury can be controlled by efficient dust removal. This is also valid for the traceelements As and Sb [Veh97a].

PVC.P. 007 EPage 43

Figure 6-4 Partitioning of selected elements in TAMARA at 900°C [Mel98]

In spite of its extremely volatile chloride Cu is a low volatile heavy metal and stays mainly in thebottom ash. Typically far less than 10 % is reported to be transferred into the raw gas. Zn and Pbhave similar thermal properties with approx. 30 - 40 respectively 45% being released into the rawgas. Data for Sn are less often found in literature and based on various TAMARA test results avolatilisation of approx. 80 % can be considered. For Cd in most cases 15-20 % only are found inthe bottom ash. The variation, however, is high and for full scale plants data of up to 45 % havebeen reported for a Danish municipal solid waste combustion plant [Dal93].

6.2 Element partitioning in full scale plants

6.2.1 Overview

Typical partitioning ranges of selected elements taken from published results from full scalemunicipal solid waste combustion plants have been compiled in Table 6-1. The table containsconcentration ranges published for municipal solid waste (MSW) and the inventory to be expectedin the raw gas calculated on the basis of the ranges of percent partitioning between bottom ashand gas. At the recommended raw gas temperatures of <= 200 °C at the boiler outlet all elementsother than S, Cl, and Hg are almost totally condensed on the particulate matter.

In the combustion step, it can be considered that the organic fraction of PVC is fully oxidised intoCO2 and H2O thus does not contribute to the formation of residues in the Gas Treatment Step.

Non organic elements present in the waste are distributed among Raw Gas and Bottom Ash : thisapplies notably to Chlorine, Sulphur and Heavy Metals.

The partitioning of these elements is described in the table 6.1. which presents the correspondingweight distribution of the species present in the initial MSW feed (Average Reference compositionof MSW in EC). Data collected from the selected incinerator plants in EC comprised in table 6.1,are in agreement with average data estimated for EC incinerators.

PVC.P. 007 EPage 44

Table 6-1 Literature data for distribution of main components from MSW over bottom ashand raw-gas

[Ang90, Egg92, Rei92, Veh92, Mar95, Rij96]

Elementsfrom MSW

MSW content kg/t Bottom ashwt % initial

Raw-Gaswt %initial

Raw-GasComposition

kg /tonneMSW

Cl kg/t 5 - 10 10-30 70-90 3 - 8S kg/t 1 - 4 40 - 70 30 - 60 0.5 - 2.5

HMs with lower volatility(Cr, Mn, Fe, Ni, Cu, Co)

1.34 91-98 2 - 9 0.02-0.12

HMs with middle volatility(Zn, As,Sn,Pb)PbZn

1.29

0.57 (0.25 -1)0.71 (0.5-1.5)

50-75

6367

25-50

3733

0.32-0.64

0.210.23

HMs with high volatility(Hg, Cd, Se, Te)HgCd

0.011

0.0045 (0.0018-0.005)0.0064 (0.006-0.011)

7-36

733

64-93

9377

0.7 - 0.01

0.0040.005

6.2.2 Case Studies

Data from specific municipal solid waste combustion plants on the evolution of chlorine - in theform of hydrochloric acid - in the raw gas as a function of the chlorine inventory in the waste fuelare plotted on the figure 6-5. In most facilities approx. 85 % of the total Cl shows up in the rawgas. This number is well in line with the results obtained in the test plant. There is one plant inWürzburg where only 70 % of the Cl are found in the raw gas. The reason for this significantlylower number is obviously the peculiar waste composition with only 55 wt % of typical MSW, largeamounts of sorting, recycling and production residues and the co-combustion of 3.5 - 8.5 wt % ofautomotive shredder residue and approx. 6 wt % of sewage sludge. Especially the latter materialintroduces high amounts of calcium into the incinerator which may be the reason for the unusuallyhigh amount of Cl in the bottom ash.

PVC.P. 007 EPage 45

Evolution of Chlorine content in Raw Gas with initial Chlorine content in MSW

Bamberg 1994

Alkmaar

Selchp

Würzburg0,7 % PVC

Würzburg1,15 % PVC

Reggio Emilia

Horgen

Bamberg1993

Selchp 0,51% PVC

0

1

2

3

4

5

6

7

0 1 2 3 4 5 6 7 8 9

Chlorine content in MSW (kg Cl/ton of MSW)

Chl

orin

eco

nten

tin

Raw

Gas

(kg

Clg

as/to

nin

itial

MS

W)

Würzburg0,80 %

Figure 6-5 Evolution of Chlorine content in Raw Gas with initial Chlorine content in MSW

There are data from two plants, Selchp and Würzburg, where limited amounts of PVC have beenadded to the waste. The graph 6.5 shows that as a first approach the distribution of the chlorinebetween bottom ash and raw gas stays constant. In both plants the PVC addition caused amaximum increase in chlorine inventory by only 20 %. Such moderate increases have nosignificant influence on the overall partitioning behaviour.

Evolution of Chlorine content in Raw Gas with initial Chlorine content in MSW

0

5

10

15

20

25

30

35

40

45

50

0 5 10 15 20 25 30 35 40 45 50

Chlorine content in MSW (kg Cl/ton of MSW)

Chl

orin

eco

nten

tin

Raw

Gas

(kg

Clg

as/to

nin

itial

MS

W)

Industrial wasteINDAVER (B)

MSW

Figure 6-6 Evolution of Chlorine content in Raw Gas with initial Chlorine content in thewaste

PVC.P. 007 EPage 46

The combustion temperature in hazardous waste combustion plants of the rotary kiln typeexceeds that in municipal solid waste combustion plants by typically 200 up to 400 °C. At suchhigh temperatures many inorganic chlorides decompose under the formation of HCl. Alkalichlorides can to a great extent evaporate (boiling points of NaCl and KCl appr. 1410 °C).Furthermore industrial waste often contains high loads of organically bound chlorine. Hence it canbe expected that in industrial waste combustion plants the chlorine is transferred into the raw gasto a greater extent than it is in municipal solid waste combustion plants. This can be verified by thedata shown in Figure 6-6.

For sulphur the results are more dispersed as the sulphur recovered in the raw gas representsfrom 30 to 60% of the initial sulphur quantity in the waste. It has, however, to be mentioned, thatthe data published from full scale waste combustion plants for sulphur are often inconsistent. Onereason is the difficulty to analyse the true sulphur concentration in the waste stream.

Table 6-2 comprises data for chlorine, sulphur and the sum of regulated heavy metals and traceelements obtained from full scale incineration plants in the EC.

Table 6-2 Experimental Data collected from incinerator plants in EC

Location of % Volatilisation from Initial WasteIncinerators Type Cl S HMs

Date % wt %wt % wtWürzburg (D) 1993 MSW 70 50 22Würzburg (D) 1997 MSW 82 28 13Reggio Emilia (I) 1995 MSW 86 55 12Selchp (GB) 1996 MSW 85 60 -Alkmaar (NL) 1995 MSW 88 55 20.5Nordforb (DK) MSW 61Bamberg (D) 1994 MSW 87 55 23Antwerpen (B) 1997 Industrial

waste(T>1050°C)

98 95 >98% (Hg, Cd)>50% (Pb,Zn)

>25% (Cu)Horgen (CH) 1995 MSW 89 - -

Average Value (%) 85 50 18Maximum Ratio in the Raw Gas 90 60 25Minimum Ratio in the Raw Gas 70 30 10

The situation at the INDAVER hazardous waste incineration plant in Antwerpen (cf. figure 6.2)refers to the effect of the combination of high chlorine concentration in the waste and hightemperature in the combustion chamber : at 1050°C about 2% of Cl and 5% of S only are retainedin the bottom ash in comparison with the average values of 15% and 50% encountered in MSWincineration (at 700 - 900°C).

The rather low volatility of sulphur in the Würzburg plant can again be traced back to the co-combustion of other waste types, especially of sewage sludge. Furthermore, the soil aroundWürzburg contains a lot of gypsum and hence a substantial part of the street sweepings and theyard and market waste may contribute to an unusually high extent to the sulphur concentration inthe bottom ash.

PVC.P. 007 EPage 47

6.3 Influence of PVC on the Volatilisation of Heavy Metals and Trace Elements

6.3.1 Fundamentals

PVC is an important source of chlorine in the waste and hence the influence of PVC on thethermal behaviour of heavy metals and trace elements is first of all one of an increased Cl load.The prominent role of chlorine in the volatilisation of metals and trace elements in wastecombustion has been discussed in chapter 6.2.2.3. Theoretically an enhanced Cl inventory in thefeed should promote the volatilisation of a number of elements due to an improved formation ofchlorides. This effect is indeed seen in results from the above mentioned co-combustion of PVCcontaining waste in the test facility TAMARA . The left graph in Figure 6-7 depicts the amount ofmetals found in the fly ash as a function of the Cl inventory in the otherwise unchanged waste fuel.The volatile heavy metals Zn, Cd, and Sn, the trace element Sb, and the more lithophilic metal Cushow a significant correlation of transfer into the fly ash with the Cl load in the feed stream.

In principle the same findings were made in other TAMARA experiments at a combustion chambertemperature of 950 °C (compare Figure 6-7, right graph). The variation in Cl input obtained inthese tests reflects more the range to be expected if increased amounts of PVC are fed into amunicipal solid waste combustion plant.

Figure 6-7 Volatilisation of selected elements in TAMARA vs. chlorine feed at 1050ºC (left,[Veh96a]) and 950 °C (right, [Veh95])

The findings indicate that in grate systems with increasing PVC content in the waste a moredistinctive transfer of volatile metals from the bottom ash into the filter ash has to be taken intoaccount. The effect is less pronounced for thermally mobile elements like Zn or Pb which are, to acertain extent, also mechanically carried over from the fuel bed. If the chlorine inventory is onlymoderately increased e.g. by some 20 - 30 % as is the case in full scale plants if limited amountsof PVC are co-combusted, the effects on the volatilisation of heavy metals and trace elementsstay limited, too. Volatilisation increases of 20 % percent will hardly be noticed considering thedifficulties in obtaining accurate element balances in technical plants.

The influence of chlorine on the mobilisation of heavy metals from the fuel bed has been indirectlyverified by annealing experiments [Veh99a]. Filter ash from a municipal solid waste combustionplant with a chloride concentration of 9.65 wt % were annealed at different temperatures in alaboratory oven for one hour. The graph on the left in Figure 6-8 shows the volatilisation of Cu, Zn,Cd, and Pb. The ranking of volatility does not follow the ranking expected from the vapourpressure curves of the metal chlorides. All the Cd is released at 900 °C. The evaporation of Pb,however, the chloride of which has about the same boiling point, is substantially retarded.Obviously there are species other than chlorides also present in the fly ash.

PVC.P. 007 EPage 48

Figure 6-8 Volatilisation of selected elements out of filter ash with 9.6 wt % Cl (up) and Znvolatilisation out of washed filter ash with successive addition of CaCl 2 (down) [Veh99a]

Washing of the filter ash removes almost the total chloride inventory. If the washed ash isannealed only a very limited volatilisation can be accomplished. This is documented for Zn in theright graph in Figure 6-8. Successive addition of chlorine in the form of CaCl2 improves thevolatility by the formation of ZnCl2.

The transfer of heavy metals from the fuel bed into the fly ash may increase the toxicity of the filterash. This residue stream, however, is in many European regulations classified as a wasterequiring special surveillance and hence a higher or lower load of heavy metals will not alter itsdisposal requirements.

On the other hand the enhanced volatilisation of ecotoxic elements from of the bottom ash is adesirable strategy in view of better compatibility with the regulations for the beneficial utilisation ofthis residue.

6.3.2 Full scale case Studies

As has been pointed out the separation of heavy metals and trace elements depends on :

- the temperature in the combustion chamber

- the composition or chemical form of the element in question in the waste feed,

- the preferred reactions of the element in the fuel bed, and

- the volatility of the generated species (oxide, chloride, sulphide, oxi-chloride, oxi-sulphide,metal)

PVC.P. 007 EPage 49

In the typical range of operation parameters encountered in municipal solid waste incineration thepartitioning of each element varies within relatively limited ranges and as the PVC does notinfluence significantly the heavy metal content in the waste - except for cadmium - the heavy metaland trace element content in the raw gas is not submitted to large variation [Ang90, Egg92,Rei92, Rei91, Veh92, Mar95, Rij96 ] :

The only data available in literature on the effects of PVC in full scale waste combustion plants inthe EC are the results of the APME sponsored experiments on the co-combustion of PVCcontaining mixed plastic waste in the municipal solid waste incineration plant at Würzburg inBavaria, Germany. The most important findings in the context of this study are compiled in Table6-3 and can be summarised

• Cadmium concentration increases of up to 10 % have been measured after PVC addition

• The lead concentration can be slightly increased in case of higher chlorine content in the waste(1 % max. increase). For lead distribution in the bottom ash and raw gas the combustiontemperature has a greater effect than the Cl concentration.

Thus the presence of PVC appears to have only a minor effect on the heavy metal and traceelement presence in the raw gas. The table shows the typical distribution between bottom ash andraw gas for the most sensible metals likely to be present. Lithophilic heavy metals with very lowvolatility such as Fe, Cr, Ni,... remain almost totally in the bottom ash. Traces found in the fly ashare mechanically carried over.

PVC.P. 007 EPage 50

Table 6-3 Influence of PVC on Heavy Metals distribution between Bottom Ash and RawGas

ElementsFrom MSW Würzburg

StandardMSW

content

% from PVCin standard

MSW

MSW0.7% PVC

MSW0.8% PVC

MSW1.15% PVC

Cl kg/t 7.32 43% 7.32 7.76 9.26% of Heavy Metals

in Raw Gas from initial wasteTotal HMs kg/t 3.25 0.3% 24% 35% 34%HMs with high volatilityHg g/tCd g/t

4.511

0.015%11%

92%49%

98%56%

92%66%

HMs with middlevolatilityPb g/tZn g/t

570710

1%0.2%

6%27%

3%27%

6%27%

HMs with low volatilityCu g/tCr g/tSn g/t

5002504.4

0.2%0.2%0.2%

0.3%2.4%11%

0.5%0.8%10%

0.8%3.4%18%

The results obtained from the EC funded project MELODI (BRPR-CT95-0011) are in agreementwith the above conclusions : the project was related to the prediction of HMs behaviour inincineration processes, and for the validation of the model, experimental results were collectedfrom an industrial plant (INDAVER), a pilot plant (FZK) or on a laboratory scale (INASMET).

It showed that the metals studied (Hg, Cd, Zn, Pb, Fe, Ni, Cu) require either high temperatures(above 1000°C) or high chlorine ratios in the waste to be significantly transferred from the bottomash to the fly ash.

This transfer of Heavy Metals from bottom ash to fly ash was the objective of the industrial partneras it was considered to be more important to remove HMs from the bottom ash even if it causesa HMs increase in the fly ash : bottom ash accounts for 300 kg/tonne of MSW and fly ash for 25kg/tonne of MSW.

6.4 Influence of PVC on organic pollutants in the Raw Gas

According to the operating conditions in the combustion step (temperature, oxygen content andresidence time) it can be stated that the organic fraction of PVC additives are fully converted intoCO2 and H2O.

The debate concerning the influence of PVC on the formation of PCDD/F is beyond the scope ofthis study but has been subject to a number of studies.

The above shows that PVC has a low effect on the presence of pollutants in the Gas Treatmentresidues :

• The organics-such as phthalates- are converted into CO2 and H2O

• The Heavy Metals brought by PVC into MSW:

PVC.P. 007 EPage 51

Cadmium emanating from PVC is mainly transported to Gas Treatment residues thus the 10%increase of Cadmium in MSW makes a 10% increase in Gas Treatment Residues

Lead in MSW due to PVC (1.03% cf Pb in MSW), is distributed between bottom ash and Raw Gashence the influence of PVC on lead presence in Gas Treatment Residues is too low to be takeninto account.

7. EVALUATION OF THE INFLUENCE OF PVC ON THE QUANTITY OF RESIDUES FROM

GAS TREATMENT

As already described, the possible Gas Treatment Residues are :

• The fly ash which is recovered downstream from the Heat Recovery Boiler. It comprises theboiler ash and the filter ash. About 14 to 34 kg of fly ash are produced from 1 tonne of MSW

Some processes (dry or semi-dry) do not have specific filtration for fly ash which is collected withthe Neutralisation Products.

• The neutralisation products which can be solid or liquid according to the type of process :- Solid product for dry and semi-dry process (mainly mixed with the fly ash).- Solid product for semi-dry / wet process.- Solid product (filter cake) and liquid effluent for wet process.

The neutralisation products are mainly composed of the neutralisation salts (NaCl, CaCl2,CaOHCl,…) according to the neutralisation agent employed as well as the required excess(NaOH, Ca(OH)2, Na2CO3).

7.1 The Fly ash : Its effect on Cl balance, and the influence of PVC on its quantity

7.1.1 Fly ash flow

As mentioned in table 3.5, fly-ash (boiler and filter ash) represent about 14 to 34 kg per tonne ofMSW.

No significant influence of PVC presence in the initial waste on the quantity of fly ash could beidentified as shown in table 3.5.

The quantity of fly ash is mostly dependent on the technology and operation of the combustionstep as these determine the carry-over of solid particles in the raw gas.

7.1.2 The role of fly ash in the chlorine balance

Due to the presence of Alkali or Alkaline Earth Metal Oxides in the fly ash it is mostly basic :washing with water commonly leads to a pH of 10 to 13 in the liquid.

Fly ash is thus responsible for the neutralisation of a part of the Cl present in the raw gas as HClirrespective of the management of the fly ash (separate filtration or filtration with the neutralisationproducts).

When fly ash is separately filtered its chlorine content can be measured : this represents 11 to15 % of the Cl present in the waste. This Cl does not,therefore, need to be neutralised as it isrecovered as chlorine salts.

PVC.P. 007 EPage 52

7.2 Gas neutralisation

This step of the Gas Treatment is the most influenced by the presence of PVC in the waste :achlorine increase in the raw gas is the major effect of PVC incineration and larger quantities of Clhave to be neutralised in order to meet the emission limits in force.

In this part of the study, the information already mentioned concerning the GTS, the MSWcomposition and flows as well as the Raw Gas composition is used to evaluate the quantities ofGas Treatment residues as a function of the type of neutralisation agent and of the processemployed.

The object of gas neutralisation is to remove all the acid species from the Raw Gas : this appliesprincipally to HCl and SOx but also to other acids (HF, HBr, POx...) which can be present at lowerconcentration. In the framework of the present study only HCl and SOx will be considered.Though PVC only has an influence on chlorinated compounds in the Raw Gas, the presence ofSOx has to be taken into consideration as SOx neutralisation occurs simultaneously with that ofHCl. One of the main targets of the study is therefore to determine what part of the neutralisationstep requirement is attributable to HCl . This is because the neutralisation agent supply is aimedat meeting the emission limits for all pollutants present in the Raw Gas.For this purpose the chemical reactions involved in the Neutralisation Step will first be consideredfor HCl and SOx as well as for the corresponding products. The required amount of NeutralisationAgent (NA) which needs to be used to meet the gas emission limits will then be evaluated fromexperimental results as the practical data differs from that predicted by theoretical work : excessof NA is necessary and depends on the GTS process as well as on the nature of the reagent. Thecorresponding part of Neutralisation products and Neutralisation Agent excess attributable to PVChas then to be determined.

7.2.1 Nature of Neutralisation agent / Chemical reactions

Neutralisation with lime

Reactions with HCl :

• In dry,and semi dry systems:

HCl + Ca(OH)2 → CaOHCl + H2O (1)HCl + CaOHCl → CaCl2 + H2O (2)

This means that in presence of lime excess only Hydroxichloride CaOHCl is formed. Furthermoreit has been observed that CaCl2 and Ca(OH)2 - when mixed together - react to formHydroxichloride CaOHCl. [Al 97], [Joz 95].

On the other hand to form CaCl2 a two stage reaction scheme is needed.

Calcium oxichloride crystallises with one mole of water forming CaOHCl,1H2O.

The quantity of water associated with calcium chloride CaCl2 can vary as a function of the processemployed to dry the salt as well as the corresponding temperature:

In the case of spray drying at a temperature below 130°, CaCl2 crystallises with two moles of waterforming CaCl2,2H2O

For spray drying operated above 130°C,CaCl2, H2O can also be present

For calcium chloride drying by external heat transfer CaCl2,6H2O has to be considered

In the solid salt from spraying systems, 0.5 to 2% of free water is present in the solid residue.

PVC.P. 007 EPage 53

For the follow up of the study it will be assumed that the gas treatment residue is handledproperly. This means that is collected in proper packages(big bags or drums) and not stored in theopen in order to prevent any extra water impregnation from rain or atmospheric humidity. CaCl2 isknown to be hygroscopic and used for ambient air drying. The same hygroscopic behaviour hasnot been reported for CaOHCl

The general reaction Ca(OH)2 +2HCl → CaCl2,2H2O is commonly referred to in the literature andwill be used for simplification in the follow-up of the study.

It does not affect the quantity of the solid recovered after the neutralisation,

• In wet processes

In the presence of liquid, removal of HCl from the Raw Gas does not require neutralisation : HCl issoluble enough to be absorbed in the liquid forming an acid solution :

HClgas → (HCl)solution → H+ + Cl-

As mentioned on page 15, in some German Incinerators, HCl is recovered as a solution to bevalorised. This of course drastically limits the quantities of the residues attributable to PVC (only 5plants are equipped with this process).

In the other plants using a wet process, the liquid flowing through the acid scrubber is commonlyset at pH of 3 by controlled supply of lime water.

In the other hand the neutral scrubber is operated at pH of 7 due to injection of NaOH

The liquid effluents collected from the two scrubbers is collected and brought to pH of 10 to 11with lime in order to:

• precipitate the sulphate as gypsum

• precipitate the HMs as hydroxide

Addition of sulphide salt and flocculation agents is also employed to complement the HMsprecipitation and enhance the decantation.

In such a process, HCl is mainly neutralised by lime as its absorption occurs mainly in the firstscrubber and its neutralisation ends up in the water treatment.

The same process are exploited in the semi wet - wet process.

For other current wet processes the acid effluent of scrubber 1 is mixed with that of scrubber 2and then further treated to pH 10 -11 with lime in order to :

• precipitate the sulphate as gypsum• precipitate the HMs as hydroxides

The liquid effluent - containing the soluble chloride salts - is then either released to theenvironment or evaporated for separating the salts. This can be achieved either by external heatsupply or by spraying the liquid in the raw gas as used in the semi Wet - Wet System.

• In the semi-wet wet process, HCl is neutralised in the wet scrubber as in the wet process, thenthe liquid is sprayed into the gas stream.

CaCl2 present in the liquid is converted into dry CaCl2,2H2O. Possible treatment of the liquid canbe carried out prior its evaporation in the spraying equipment as in the Alkmaar plant.

Reactions with sulphur oxides :

PVC.P. 007 EPage 54

Sulphur oxides consist of a mixture of SO2 and SO3 labelled SOx.

• In the dry or semi-dry process :

Both oxides react with lime to form calcium sulphite or calcium sulphate.

SO2 + Ca(OH)2 → CaSO3 + H2OSO3 + Ca(OH)2 → CaSO4 + H2O

The reaction with SO3 is faster than with SO2. In the presence of oxygen, sulphite is progressivelyconverted to sulphate :

CaSO3 + 1/2O2 → CaSO4

Both Ca sulphite or sulphate crystallise with 2 moles of water CaSO3, 2H2O, CaSO4, 2H2O

For the present study the following reaction has been considered :

SO2 + Ca(OH)2 + 1/2 O2 + H2O → CaSO4 + 2H2O

• In the wet and semi wet - wet processes :

SO2 is first dissolved in the liquid but unlike HCl its dissociation into ions requires a minimum pHlevel to lead to the following reactions :

H2O + SO2 ↔ HSO3- + H+ KA1 = 1,5.10-2

HSO3- ↔ H+ + SO3

-- KA2 = 1.10-7

As sulphite acid is not so strong as HCl, at low pH values SO2 is stable in the liquid and thereforeSO2 removal from gas is only driven by the Gas Liquid equilibrium.

This explains why SO2 is mainly absorbed in the neutral scrubber as at pH = 7 it is transformedinto sulphide salts. These are then oxidised into sulphates in presence of air or oxygen excess.

Neutralisation with Sodium Bicarbonate :NaHCO3 is only used in the dry process in the form of powder. NaHCO3 is ground just beforebeing injected to achieve a solid with a high porosity and specific area.

Reactions with HCl : HCl + NaHCO3 → NaCl + CO2 + H2O

The excess of bicarbonate is transformed into carbonate :

2NaHCO3 → Na2CO3 + H2O + CO2

168 g of NaHCO3 excess lead to 106 g of carbonate Na2CO3 and this therefore reduces thequantity of residues produced.No crystallisation water has been measured neither for NaCl nor for NaHCO3 and Na2CO3

Reactions with SOx : 2NaHCO3 + SO2 → Na2SO3 + H2O + 2CO2

2NaHCO3 + SO3 → Na2SO4 + H2O + 2CO2

Here again the reaction with SO3 is faster that with SO2. In general the reaction is faster than withlime. The intermediate formation of NaHSO3 could exist but this compound has never beenidentified in the residues.

The excess of NaHCO3 is transformed in Na2CO3 has already been mentioned. Na2SO3 isoxidised into Na2SO4 in presence of oxygen from the gas and in the residue only Na2SO4 can beidentified :

Na2SO3 + 1/2 O2 → Na2SO4

Neutralisation with NaOH :

PVC.P. 007 EPage 55

Some atypical applications with dry or semi-dry process exist. NaOH is more commonly used inthe wet process, despite its higher cost. Nevertheless NaOH in such cases is used together withlime, which is necessary to obtain precipitated gypsum : in Alkmaar NaOH is used in the neutralscrubber and lime is added at the liquid effluent treatment stage.

Reaction with HCl : NaOH + HCl → NaCl + H2O

Reaction with SOx :

SO2 + NaOH → NaHSO3 NaOH + SO3 → NaHSO4

NaHSO3 + NaOH → Na2SO3 + H2O NaHSO4 + NaOH → Na2SO4 + H2O1/2 O2 + Na2SO3 → Na2SO4

Neutralisation with calcium carbonate CaCO 3 :This method is only rarely used for wet processes as it is not reactive enough for meeting the off-gas specifications in dry processes.

7.2.2 Required quantities of Neutralisation Agents / Stoichiometric Ratio SR

As already mentioned, in order to meet the gas emission limits, the required quantities ofneutralisation agents are greater than those corresponding to the stoichiometry of the chemicalreactions considered previously.

To measure the neutralisation agent (N.A.) excess, the Stoichiometric Ratio (S.R.) is commonlyused :

SR =quantity of NA effectively used

quantity of NA corresponding to the stoichiometry

As the neutralisation agent is supplied to the system to meet all the limits in force for gasemission, the experimental data give the total neutralisation agent consumption and thus enablethe evaluation of the overall S.R. for both HCl and SO2.

The example of Würzburg 1997 can be considered : the gas at the neutralisation stage contains4.9 kg of Cl and 0.8 kg of S per tonne of MSW. This leads to the stoichiometric NA quantities :

Ca(OH)2 + 2 HCl →→→→ CaCl2 + 2 H2O

Molecular weight Cl 74 2 x 35,5 111 36

kg/tonne MSW 4,9 5,11 7,66 2,48

SO2 + Ca(OH)2 + 1/2 O2 →→→→ CaSO4 + H2O

Molecular weight S 32 74 16 136 18

kg/tonne MSW 0,8 1,85 0,2 3,4 0;45

PVC.P. 007 EPage 56

Ca(OH)2 for HCl and SO2 stoichiometric neutralisation : 6,957 kg/tonne of MSWCa(OH)2 effectively employed : 19,6 kg/tonne of MSW

Overall S.R. = 19,6/6,96= 2,8

To evaluate the impact of PVC on the neutralisation agent consumption and thus on the quantityof residues, it is necessary to evaluate the specific SR for HCl and SO2 or the contribution of HClto the overall SR.

The S.R. required as a function of the HCl neutralisation yield to meet the gas limits has also to beconsidered. It was attempted to use yield versus SR relations as described in figure 7.1 for theWürzburg 1997 campaign.

It has been nevertheless observed that this type of curve is only valid for the plant considered asexperimental points from other plants do not fit with the curve.

It was therefore decided to use fixed S.R. ranges and then consider the evaluated values inregard to the measured HCl yield or HCl content in the raw gas in comparison with thecorresponding next regulation limit (10 mg HCl/Nm3).

7.2.2.1 S.R. required for wet process and semi Wet - Wet process

In these processes no excess of Neutralisation Agent is required for the neutralisation of HCl. Asmentioned, HCl treatment can be achieved by HCl absorption in water and SO2 only requires aneutral pH to be neutralised.

As mentioned in § 7.2.1 HCl removal from Gas can be achieved by a HCl absorption in water andSO2 requires only a neutral pH. This means that substoichiometric conditions could be used forHCl and this is valid in case of HCl recovery from GTS. Otherwise HCl has to be neutralisedbefore the release of the liquid effluent.

The required precipitation of Heavy Metals Hydroxides in the water treatment is thus the onlyreason to have Overall SR values greater than 1, but this should not be attributed to PVC as itscontribution to the heavy metals content in the Neutralisation Products is negligible (refer tochaptr.8).

For wet processes, the presence of PVC in MSW can thus be considered as responsible for theproduction of the stoichiometric quantity of CaCl2 or NaCl in the liquid effluent.

7.2.2.2 Specific SR for HCl and SO 2 in dry and semi-dry processes

As already mentioned, in dry or semi-dry processes the neutralisation mechanism differs fromthose in wet process where reactions occur in the liquid.

In dry or semi-dry process a first step in the mechanism consists into a chemisorption of theNeutralisation Agent (chemisorption is an absorption of the gases enhanced by chemical bondingbetween the gaseous and solid states).

This first step is in some case limiting and it causes the difference of reactivity between HCl andSO2. HCl provides two advantages in comparison with SO2 : its size is small- this facilitates theGas-Solid contact in the pores- and it has an important dipolar moment as the electronegativity ofH and Cl atoms is widely different.

In order to compensate for the spatial factor of SO2, high porosity Neutralisation Agents havebeen developed such as BICAR (Sodium Bicarbonate) or Spongiacial (high Porosity Lime).

PVC.P. 007 EPage 57

Specific SR for HCl and SO2 neutralisation with lime :

Specific SR have been evaluated by different authors such as D. Reimann [Rei91], T.H.Christensen [Chr98 ], and D. Pauli [Pau89].

Table 7-1 Specific stoichiometric ratio for HCl and SO 2 neutralisation with lime

SPECIFIC STOICHIOMETRIC RATIO FOR HCl AND SO 2

D. Reimann D. Pauli T.H.Christensen

HCl SO2 HCl SO2 HCl

Dry Process with lime 1,1 - 1,5 1,8 - 3,5 1,1 - 1,5 1,8 - 4 1.5 - 2

Semi-dry Process with lime

Semi Wet - Wet Process withlime

1,1 - 1,5 1,3 - 2,6 1,1 - 1,5

1,1 - 1,5

1,8 - 3

1,3 - 2,6

1.05 - 2

Wet Process 1,05 - 1,15 1,05 - 1,15

It has to be first noted that most authors and incinerators operators confirm the S.R. values for thewet process (refer to § 7.2.2.1).

For the dry and semi-dry processes it is therefore clear that an excess of Neutralisation Agent isnecessary as the specific S.R. values are greater than 1. This reflects the reaction limitationsmentioned above.

The influence of SO2 on the HCl neutralisation has been specifically described thanks toexperiments achieved in Würzburg [Kur99 ]. The results are plotted on the curves of figure 7.1and in annex A3.5. They show the relation between HCl yield (yield related to HCl neutralisation)and Overall Stoichiometric Ratio for different SO2 content in the Raw Gas.

PVC.P. 007 EPage 58

98,0

98,2

98,4

98,6

98,8

99,0

99,2

99,4

99,6

99,8

100,0

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0

Global Stoichiometric Ratio (S.R. = [Effective N.A, Supply]/[NA for HCl+SO2 at stoichiometry])

HC

lneu

tral

isat

ion

yiel

d(%

)

SO2=120 mg/Nm 3

SO2=1200 mg/Nm 3

SO2=400 mg/Nm 3

Figure 7-1 Transformation of Würzburg/Noell Curves in the relation between HCl yieldand Overall SR

[Kur99] (cf. annex A3.5)

This proves the influence of SO2 on HCl neutralisation as the higher the SO2 content the higherthe Overall SR for reaching the same HCl yield.

Specific SR for HCl and SO2 neutralisation with Sodium Bicarbonate :

For the determination of the specific stoichiometric ratios for HCl and SO2 with NaHCO3, nosatisfactory data could be identified in the literature.

Rather than not considering bicarbonate in the follow up of the study, it was decided to use non-published results such as evaluations from operators of incineration plants as well as from thebicarbonate suppliers.:

Due to the large specific area of bicarbonate, the steric limitation to SO2 neutralisation is obviouslylower than for lime. It is confirmed by experimental overall stoichiometric ratios which are between1.05 to 1.5 as measured in different incineration plants.

Nevertheless the concurrence of HCl and SO2 neutralisation still exists and SO2 is likely to requiremore excess of bicarbonate.

A realistic evaluation for HCl specific S.R. is close to 1.05 : this can be considered as a maximumas plants already operate successfully with an overall S.R. of 1.05.

7.2.2.3 Comparison with experimental results collected from the selected incinerators -

Appraisal of the validity of HCl stoichiometric ratio

Table 7-2 shows the overall SR as measured in the different incineration facilities as well as thecorresponding gas emissions in terms of HCl and SO2.

PVC.P. 007 EPage 59

Table 7-2 shows that :

- the dry process with standard grade lime -and without recycle of neutralisation products- is notlikely to meet the most severe specification for HCl release with the gas effluent (10 mg/Nm3)whatever the excess of lime.

This explains why Würzburg and Nordforbraending have replaced the dry System with lime bya semi-dry process.

(conditioned dry processes are not considered as dry processes but as semi-dry systems)

- the dry process with bicarbonate results in meeting the 10 mg/Nm3 emission for HCl.

- the semi-dry process with standard lime also results in meeting the 10mg/Nm3 specification forHCl.

- all the selected incinerators equipped with a wet (or semi wet - wet) process fully meet the10 mg/Nm3 limit for HCl concentration in the off gas.

Table 7-2 Overall S.R. and Gas Emissions measured for the different selected incinerators

Plants Location Year Neutralisation Off-Gas Emissions (mg/Nm 3) Overall

Agent HCl SO 2 SR

DRY GTS PROCESSWürzburg (Germany) 1993 Ca(OH) 2 23.5 19 3.2

Novergie (France) 1991 Ca(OH) 2 31 15 3.6

Nordforbraending (Denmark) 1997 Ca(OH) 2 65 300 2.1

Reggio Emilia (Italy) 1996 NaHCO 3 5 2 1.2

SEMI-DRY GTS PROCESSWürzburg (Germany) 1997 Ca(OH) 2 6 3 2.8

Selchp (England) 1996 Ca(OH) 2 7 14 2.2

Amager-Forbraending(Denmark)

1997 Ca(OH)2 14 75 2

Toulon (France) 1991 Ca(OH) 2 30 40 2

Carrières (France) 1997 Ca(OH) 2 15 14 2

Beveren (Belgium) 1997 Ca(OH) 2 30 40 2.2

WET GTS PROCESSAlkmaar ( Netherlands) 1997 NaOH/Ca(OH) 2 5 30 1.1

Bamberg (Germany) 1994 NaOH/Ca(OH) 2 2 7 1.5

Vestforbraending (Denmark) 1997 NaOH/Ca(OH) 2 2.5 50 1.1

Spittelau (Austria) 1997 NaOH/Ca(OH) 2 1 4 1.1

Antwerpen (Belgium) 1997 NaOH/Ca(OH) 2 2 20 1

CLINICAL WASTE INCINERATOR - DRY GTS PROCESSCW incinerator (Belgium) 1997 NaHCO 3 9 13 1.5

PVC.P. 007 EPage 60

Table 7-3 Experimental and Theoretical Results from Full Scale PlantsN.A. quantities from Dry Gas Treatment Process

Reggio Belgium Würzburg Nordforb, NovergieDRY Location Emilia Clinical waste

PROCESS Date 1996 1996 1993 1997 1991Process Category Dry Dry Dry Dry Dry

Real Process Applied Dry Dry

Neutralisation Agent NaHCO3 Ca(OH)2

Gas to Cl 5,6 17,1 5,1 3,2 6,0 8,1neutralisation S 1,0 1,1 1,7 2,2 0,5 0,5

kg/t MSW Cl+S 6,6 18,2 6,8 5,4 6,5 8,6

Neutralisation Agent kg/t MSW 22,2 68,6 29,5 17,8 26,9 19,2(measured flow) NaHCO3 or Ca(OH)2

Stoichiometric ratio for HCl SR HCl 1,05 1,05 2,0 2,0 2,0 2,0Calculated N.A. required kg NA / kg Cl 2,48 2,48 2,08 2,08 2,08 2,08

kg NA / ton MSW 13,9 42,4 10,6 6,7 12,6 16,9

Stoichiometric ratio for SO2 SR SO2 1,3 1,3 4,0 4,0 4,0 4,0Calculated N.A. required kg NA / kg SO2 6,83 6,83 9,25 9,25 9,25 9,25

kg NA / ton MSW 6,8 7,3 15,7 20,4 4,6 4,6

Total NA required for Cl + S kg / ton MSW 20,7 49,7 26,3 27,1 17,2 21,5

Consistency oftheoritical and. Total calculated required NA % 93% 72% 89% 152% 64% 112%

experimental Results Total measured NACO

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Table 7-4 Experimental and Theoretical Results from Full Scale PlantsN.A. quantities from Semi-Dry Gas Treatment Process

SEMI DRY Location Wurzburg Carrières Toulon SelchpAmager-Forbraending Beveren

PROCESS Date 1997 1997 1991 1996 1997 1997Process Category Semi Dry

Neutralisation Agent Ca(OH)2

Real Process Applied Semi Dry Semi Wet Semi DrySemi Dry Semi Dry Semi Wet

Gas to Cl 4,9 3,4 4,2 6,7 5,2 3,8 3,8 4,9neutralisation S 0,8 0,4 0,5 0,3 1,0 0,6 0,6 1,5

kg/t MSW Cl+S 5,7 3,8 4,7 7,0 6,2 4,4 4,4 6,4

Neutralisation Agent kg/t MSW 19,6 8,9 19,9 15,6 17,0 10,8 13,1 18,9(measured flow) Ca(OH)2

Stoichiometric ratio for HCl SR HCl 1,7 1,7 1,7 1,7 1,7 1,7 1,7 1,7Calculated N.A. required kg NA / kg Cl 1,77 1,77 1,77 1,77 1,77 1,77 1,77 1,77

kg NA / ton MSW 8,7 6,0 7,4 11,9 9,2 6,7 6,7 8,7

Stoichiometric ratio for SO2 SR SO2 4,0 4,0 4,0 4,0 4,0 4,0 4,0 4,0Calculated N.A. required kg NA / kg SO2 9,25 9,25 9,25 9,25 9,25 9,25 9,25 9,25

kg NA / ton MSW 7,4 3,7 4,6 2,8 9,3 5,6 5,6 13,9

Total NA required for Cl + S kg / ton MSW 16,1 9,7 12,1 14,6 18,5 12,3 12,3 22,5

Consistency oftheoritical and. Total calculated required NA % 82% 109% 61% 94% 109% 114% 94% 119%


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PVC.P. 007 EPage 61

In Würzburg the Neutralisation products are partly recycled to the Neutralisation reactor in order tobenefit from the excess of lime still present. This is responsible for a local Stoichiometric Ratiohigher than calculated as a function of the lime supply as well as for a certain uncertainty in theresults shown above.

Table 7-5 Experimental and Theoretical Results from Full Scale PlantsN.A. quantities from Wet and Semi Wet-Wet Gas Treatment Process

Alkmaar Bamberg Vestfor Spittelau AntwerpenWET / SEMI WET-WET Location braending

PROCESS Date 1995 1994 1997 1997 1997Process Category Wet Wet Wet Wet Wet

Real Process AppliedSemi wet-wet wet wet wet wet

Neutralisation Agent NaOH/CaOH2

Gas to Cl 4,7 5,3 3,2 5,9 46,5neutralisation S 0,7 2,0 0,5 0,8 6,4

kg/t MSW Cl+S 5,4 7,3 3,7 6,7 52,9

Neutralisation Agent kg/t MSW 7,8 14,8 4,9 8,7 63,2(measured flow) NaHCO3 or Ca(OH)2

NA proportions CaOH2 0,75 0,75 0,75 0,88 0,75

NaOH 0,25 0,25 0,25 0,12 0,25

Stoichiometric ratio for HCl SR HCl 1,10 1,10 1,10 1,10 1,10Calculated CaOH2 required kg CaOH2/ kg Cl 1,15 1,15 1,15 1,15 1,15

kg CaOH2 / ton MSW 5,4 6,1 3,7 6,8 53,3

Stoichiometric ratio for SO2 SR SO2 1,10 1,10 1,10 1,10 1,10Calculated CaOH2 required kg CaOH2 / kg S 2,54 2,54 2,54 2,54 2,54

kg CaOH2 / ton MSW 1,8 5,1 1,3 2,0 16,3

Stoichiometric ratio for HCl SR HCl 1,10 1,10 1,10 1,10 1,10Calculated NaOH. required kg NaOH / kg Cl 1,24 1,24 1,24 1,24 1,24

kg NaOH / ton MSW 5,8 6,6 4,0 7,3 57,6

Stoichiometric ratio for SO2 SR SO2 1,10 1,10 1,10 1,10 1,10Calculated NaOH. required kg NaOH / kg S 2,75 2,75 2,75 2,75 2,75

kg NaOH / ton MSW 1,9 5,5 1,4 2,2 17,6

Total NA required for Cl + S kg / ton MSW 7,3 11,4 5,0 8,9 71,0taking into account % NA

Consistency oftheoritical and. Total calculated required NA % 94% 77% 103% 102% 112%


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PVC.P. 007 EPage 62

Validity of the S.R. range for HCl :

In order to evaluate the validity of the specific SR for HCl (and for SO2) indicated in table 7-1, theSR values have been applied to the calculation of the required volume of NA and the resultscompared with the measured ones:

The results are shown in table 7-3, 7-4, 7-5 for the different gas treatment processes:

The first two lines show the measured quantities for

• Cl and S quantities in the gas to be neutralised

• the neutralisation agent measured volume.

The three following lines show the results of the calculation of the NA quantities used specificallyfor HCl and SO2 neutralisation related to the corresponding SR values:

for the dry process with lime for instance:

SR HCl = 2 2HCl + 2Ca(OH)2 � CaCl2,2H2O + Ca(OH)2

1 kg of Cl requires 2,08kg of Ca(OH)2

5,1 kg of Cl requires 10,61kg of Ca(OH)2

SR SO2 = 4 SO2+ 4Ca(OH)2 + ½ O2 +H2O� CaSO4,2H2O + 3Ca(OH)2

1 kg of S requires 9,25kg of Ca(OH)2

1,7 kg of S requires 15,725kg of Ca(OH)2

Total calculated NA : 10,61 + 15,725 = 26,33 kg

Total measured NA : 29,5kg

Consistency : (26,33/29,50)*100 = 89,3% ~ 89%

For bicarbonate, the following reactions drive the neutralisation:

SR HCl = 1,05 HCl + 1,05NaHCO3 � NaCl + 1,025CO2 + 1,025 H2O + 0,025Na2CO3

1 kg of Cl requires 2,48kg of NaHCO3

SR SO2 = 1,3 SO2 + 2,6NaHCO3 � Na2SO4 + 2,3CO2 + 1,3 H2O + 0,3Na2CO3

1 kg of S requires 6,83kg of NaHCO3

For the dry process with standard grade lime, the upper limits of the SR ranges for HCl and SO2

have to be used for obtaining a consistency considered as satisfactory.

The dry process with bicarbonate can be described with the SR values of 1,05 for HCl and 1,3 forSO2.

For the semi-dry process with lime the SR of 1,7 for HCl and 4,0 for SO2 were selected as theyallow for correct consistency of theoretical results with experimental ones.

For the wet (and semi wet - wet) processes, SR of 1,1 for both HCl and SO2 lead to calculationsconsistent with experimental results.

The table below summarises the SR values considered as valid for HCl neutralisation.

PVC.P. 007 EPage 63

Table 7-6 HCl Stoichiometric Ratio for the different Gas Treatment process

Dry with lime *: SR (HCl) = 2

Dry with Bicar : SR (HCl) = 1.05

Semi-Dry with lime * SR (HCl) = 1.7

Wet and Semi Wet - Wet with lime *: SR (HCl) = 1.1

* Standard grade lime

Validity of the Method based on a fix range for HCl S.R. :

The method has been shown to be valid for HCl yields in between 86 to 99.5% for dry processwith lime and 95 to 99.3% for semi-dry process with lime.

At the same time, the method has been shown to be valid for chlorine content in the waste from4.9 to 11.6 kg/tonne MSW (corresponding to 3.2 to 8.1 kg in the Raw Gas per tonne of MSW).

This means that the method used to evaluate the quantity of residues is valid for chlorine arisingfrom the presence of PVC up to 7.6 kg/tonne MSW, and thus for an increase of the averageChlorine content related to the PVC from 3 to 7.6 kg/tonne MSW (i.e. a 150% increase).

To check these results, other experimental data from Würzburg have been assessed. Thecorresponding results were plotted on a series of curves showing the chlorine neutralisation yieldas a function of Overall S.R. shown on figure 7.1.

It appears that a 50% increase of the PVC content in the waste imposes a higher HCl yield (99.2%instead of 99.0%) and therefore a global stoichiometric ratio increase from 1.1 to 1.2 (for400mg/Nm3 of SO2) thus a specific HCl SR increase from 1.1 to 1.5 as the increase of Ca(OH)2

consumption is devoted to only HCl neutralisation (PVC content in MSW of 1.05 for Cl ratio inPVC of 43%).

This confirms that the fixed range for HCl S.R. is still valid for PVC increases up to 50%.

The relation between HCl yield and Overall S.R. established at Würzburg is nevertheless notapplicable to all plants even if they belong to the same category (dry, semi-dry, wet). If PVC issubmitted to variations greater than 50% it will be necessary- a) to establish the relation betweenHCl yield and overall S.R for each plant considered and b) to run specific tests with different Cland S content in the waste.

PVC.P. 007 EPage 64

7.3 Contribution of PVC to the production of residues and to the neutralisation agent

consumption

According to the results and discussion above the following summary tables have beenestablished :

Table 7-7 Influence of PVC on the quantity of residues

DRY SEMI-DRY WET SEMI WET -WET

Neutralisation Agent. Lime BICAR Lime Lime Lime

S.R. HCl 2 1.05 1.7 1.1 1.1

Cl kg min 0.25

per kg max 0.53

of PVC average 0.45

Residues (kg) min 0,78 0,46 0,70 0 0.54

max 1.65 0.97 1.48 0 1.15

(per kg of PVC) average 1,40 0,82 1,26 0 0.98Liquid effluent (dry material)(kg per kg of PVC)

0 0 0 0.42 to 0.88 0

Table 7-8 Influence of PVC on the consumption of neutralisation agent


Neutralisation Agent.(NA)

Lime BICAR Lime Lime Lime

S.R. HCl 2 1.05 1.7 1.1 1.1

kg NA / kg Cl 2.08 2.48 1.77 1.15 1.15

Cl kg min 0.25

per kg max 0.53

of PVC average 0.45

NA kg min 0.52 0.62 0.44 0.29 0.29

per kg max 1.11 1.32 0.94 0.61 0.61

of PVC average 0.94 1.12 0.79 0.52 0.52

PVC.P. 007 EPage 65

8. EVALUATION OF THE INFLUENCE OF PVC ON THE HAZARDOUSNESS OF THE

RESIDUES

8.1 PVC influence on the composition of the residues

The effect of PVC on the composition of the residues reflects the PVC influence on the Raw Gascomposition (refer to chapter 6) as most of the pollutants present in the Raw Gas are recovered inthe Gas Treatment residues or liquid effluents in order to comply with the Gas Emission limits.

According to the possible Gas Treatment Processes, the pollutants are present in the differentresidues and effluents which belong to the following categories :

• Fly ash (Boiler Ash, Cyclone Ash, Filter Ash) : solid residue• Neutralisation products : solid residue• Neutralisation effluent : liquid• Filter cake from treatment of liquid : solid residue• Gas effluent

In most of the dry and semi-dry systems a single residue is produced which contains both fly ashand Neutralisation products.

In the wet process, Fly ash, liquid effluent and filter cake are generated separately.

When a double filtration step is used (as for some dry processes with bicarbonate or some semi-wet systems) Fly ash and Neutralisation products are recovered separately.

8.1.1 PVC influence on fly ash composition

The attached table in Annex A4.1 indicates the composition of fly ash collected from differentincineration plants.

Chlorine Content:

As already mentioned, fly ash contributes between 11 to 15% of the neutralisation of the HCl andits chlorine content is consequently subject to variations as a function of the Cl content in thewaste.

The table in Annex A4.1 shows that the chlorine concentration in fly ash varies between 1.8 to13.2%. This is consistent with the range of 4.0 to 10.2% seen in table A.7.1 in Annex 7.

Heavy Metals content:

When fly ash is separately collected it contains almost all the HMs from the Raw Gas except forMercury:

• Mercury concentrations in fly ash are low (see table A.7.2 in Annex 7) but higher inNeutralisation Products. Efficient removal of Mercury from the Flue Gas requires addition ofactivated carbon (Dry or Semi-dry Systems).

• Cadmium is almost totally present in the fly ash

• Lead is recovered in the fly ash except in the bicarbonate - dry process - for which the filtrationis operated at higher temperature (200 °C instead of 130 °C with lime).

PVC.P. 007 EPage 66

As mentioned in chapter 6, except for Cadmium, the influence of PVC in the waste on the HMconcentration in the Raw Gas is less significant. Table in annex A4.1 confirms this assumption asno relation can be drawn between Chlorine and HMs (except for Cd) in the fly ash.

Organic Contents:

Fly ash can contain unburned material and PCDD/F present in the raw gas (refer to 6.4).

8.1.2 PVC influence on the composition of Neutralisation Products

Major components :

The major components of the neutralisation products are the salts from the neutralisation reactionas well as the excess neutralisation agent. The composition of the neutralisation products istherefore obviously dependent on the type of neutralisation agent used for Gas Treatment.

In order to evaluate the influence of PVC on the behaviour of solid residues, the composition andquantities of neutralisation products have been estimated for MSW with and without PVC and forthe different gas treatment processes. The calculation and results are shown in Annex 6.

Dry, semi-dry and semi wet-wet processes with lime lead to the following major components:

Ca(OH)2 excessCaOHCl, H2OCaCl2, H2OCaSO4, 2H2O

The dry process with bicarbonate results in the following major components:

NaClNa2CO3

Na2SO4

The wet process leads to :

NaCl, CaCl2 in solution in the liquid effluent when lime is used in the first scrubber and inwater treatment and NaOH in the second neutral scrubber

CaSO4 is recovered in the filter cake. The excess of base (Ca(OH)2) is neutralised beforereleasing the liquid effluent (Hydrochloric acid is commonly used on purpose).

Heavy Metals and Trace Elements :

When fly ash is mixed with neutralisation products (dry and semi-dry systems with lime) the HMsand trace elements (except Mercury) are almost fully recovered in the solid residue.

For the wet process fly ash filtration is generally achieved in an electrostatic precipitator for whichthe filtration yield is in 96 to 99 % depending on particle size. The filter cake thus contains 1 to 4 %of the less volatile Heavy Metals and a large part of the cadmium and all the absorbed mercury onactive carbon which is commonly added to the filter cake for disposal.

PVC.P. 007 EPage 67

8.2 PVC INFLUENCE ON THE HAZARDOUSNESS OF THE RESIDUES

8.2.1 Approach

The purpose of this part of the study is to attempt to quantify the hazardousness of the airpollution control (APC) residues, which can be attributed to the PVC in the waste fed to theincinerator. Due to the lack of directly comparable data (i.e. on the hazardousness of residuesfrom incineration of the same type of waste with and without PVC), this is a difficult task to whichno definite solution can be given. However, based on a) the results of the previous sections of thisstudy, b) some additional information on the composition and behaviour of the residues and c) anumber of assumptions, some scenario calculations can be made to illustrate and exemplify theinfluence of PVC incineration on the potential impact of the residues on the environment.

The evaluation will include the following:

• Discussion of the concept of hazardousness as applied to APC residues

• Discussion of management options and practices for APC residues

• Composition and leaching data for APC residues

• Scenario definitions and calculations

8.2.2 Discussion of the concept of hazardousness applied to APC residues

APC residues from MSW incineration are all classified as hazardous waste in EC legislation. Theyare all on the hazardous waste list (EWC code 1901, Council Decision of 22 December 1994,94/904/EC). The list includes fly ash (190103), boiler dust (190104), filter cake from gas treatment(19105), aqueous liquid waste from gas treatment and other aqueous liquid wastes (190106),solid waste from gas treatment (190107) and spent carbon from flue gas treatment (190110). Theplacement on the list is based on the list of properties of wastes, which render them hazardous(Annex III to the Council Directive on hazardous waste, 91/689/EEC). These properties, H1through H14, are in most cases described as general, intrinsic properties and not related tospecific management scenarios (e.g., transport, handling, storage, treatment, landfilling, reuse).However, the inclusion in the list implies that the wastes are considered to display one or more ofthe above properties and this does not have to be demonstrated by any testing in a particularcase.

According to the recently adopted Council Directive on the landfill of waste (1999/31/EC), wastewhich is classified as hazardous waste according to Directive 91/689/EEC should be placed inhazardous waste landfills, provided the acceptance criteria of Annex II to the Landfill Directive arecomplied with. However, these acceptance criteria are to be developed over the next 2-3 years bythe Technical Adaptation Committee and are thus not yet available. In the meantime, nationalregulations will continue to apply.

All EC member states define APC residues as hazardous waste in accordance with Directive91/689/EEC, and they are typically placed in hazardous waste or special waste landfills. Ingeneral, the permission to place treated or untreated APC residues in a special or hazardouswaste landfill requires compliance with criteria based on the composition of the residues and/orthe leaching behaviour of the residues, i.e. the results of some regulatory leaching test.

In the previous part of the study it was found that the most important effects of incineration of PVCon the APC residues appear to be a substantial increase in the content of chlorides, a significantincrease in the content of Cd (approximately 10 %) and possibly a less significant increase in thecontent of Pb and Zn in the residues. However, in particular the additional chloride content caused

PVC.P. 007 EPage 68

by the incineration of PVC may be expected to have an influence on the environmental propertiesof the residues. This influence is likely to be more quantitative than qualitative in nature. It mayhave a direct effect on the leaching properties of the residues and a more indirect effect on theenvironment due to the fact that a larger mass of residues must be handled and managed.

Some of the effects on the leaching properties will be discussed in sections 8.2.4 and 8.2.5.

8.2.3 Management options and practices for APC residues

GeneralMost of the APC residues generated by incinerators in the EC are landfilled with or without priortreatment. Very little utilisation of APC residues takes place, except in the Netherlands, whereapproximately 30 to 50 % of the MSWI fly ash generated is used as a filler in asphalt(Bor94 ;Van99).

As mentioned above, the residues are normally placed in hazardous or special waste landfills withleachate collection systems. In some countries, e.g. France, the residues must be stabilised (bysolidification and/or chemical stabilisation) prior to or during disposal. In Germany, some APCresidues may still be placed in landfills, but most are placed underground in old salt caverns orpumped into old coal mines as a cement grout admixture. Some countries, e.g. Denmark and theNetherlands, are currently considering residue management options and investigating varioustreatment concepts and processes. In the meantime, the residues are placed in temporary storagefacilities or landfills or exported to the German underground facilities or the Norwegian treatmentand storage facility at Langøya (where alkaline dry and semidry residues are mixed with wastesulphuric acid and landfilled in a deep, former limestone quarry as an impure gypsum product).

Fly ashFly ash, i.e. the particulate material collected by electrostatic precipitators or fabric filters upstreamof the acid gas cleaning systems at wet scrubber systems and sometimes also at dry and semidrysystems, is generally classified and treated in much the same way as the dry and semidryresidues containing the fly ash are. They are placed in hazardous waste landfills with or withoutprior treatment. The most common treatment form in the EC member states is probablysolidification/stabilisation with hydraulic binders (cement or cement-like substances) oftensupplemented with the admixing of various additives. This is done e.g. in Austria, Belgium,Germany and France (Veh97c , Vra99, Fly97 ). In some cases the fly ash is washed prior tosolidification/stabilisation to remove the readily soluble salts (mostly chlorides). This is done inSwitzerland (Veh97c ). Methods for chemical stabilisation of fly ash with phosphates, carbondioxide, ferrous sulphate and other chemicals (with or without prior washing of the ash) are underdevelopment but not yet in general use. In some member states, e.g. Germany and Denmark, flyash pre-collected at incinerators with wet scrubbing systems is mixed with the sludge fromtreatment of the scrubber water and landfilled (Fly97 ). The purpose of this treatment should be forthe fly ash to absorb excess liquid from the sludge and for the sludge to bind/reduce some of thepotentially soluble trace elements in the fly ash, thereby reducing their leachability. Moresophisticated treatment methods such as the so-called «3-R» (Rauchgas-Reinigung mitRückstandsbehandlung) process in which the fly ash is extracted with the acid scrubber waterfrom the wet scrubbing process and subsequently fed back on the grate to be sintered, are only inuse commercially at very few incinerators (Veh99). High temperature treatment methods such asmelting and vitrification are currently not being applied to fly ash in full scale in Europe due to thehigh energy requirements and the technical difficulties involved.

PVC.P. 007 EPage 69

Residues from dry and semidry processesThere is no qualitative difference between the composition and the management options andpractices for residues from the dry and semidry processes, respectively. The only difference isthat due to the higher stoichiometric ratio, the dry residues generally have a higher content ofunreacted neutralisation agents than the semidry residues have. In this chapter, dry and semidryresidues will therefore be discussed together. As described in the previous parts of the report, it isquite common to collect the excess neutralisation agents and the reaction products from the dryand semidry processes together with the fly ash. In some countries, e.g. Belgium, the fly ash ispre-collected upstream of the acid gas cleaning systems, and the dry and semidry residuesconsists of reaction products and excess neutralisation agents with only very small amounts of flyash. With few exceptions (most notably Hg), most of the contaminants and trace elements areassociated with the fly ash, and the fly ash containing residues from the dry and semidryprocesses may therefore be regarded as fly ash diluted with reaction products and excessneutralisation agents (+ some extra Hg). Several processes have been designed to recovercalcium chloride and sodium chloride from the dry and semidry APC residues, but to the best ofour knowledge, few or none of these processes are currently used commercially (Fly97 ).

The dry and semidry residues are generally placed in hazardous or special landfills with or withoutsolidification/stabilisation (Belgium, France, Great Britain, Sweden) or they are stored in old saltmines (Austria, Germany). In the Netherlands and Denmark, the residues are placed in temporarystorage, awaiting the development of appropriate technology and new regulations. As mentionedpreviously, part of the residues produced in Denmark are exported to a Norwegian treatment andlandfilling facility. The same solidification/stabilisation methods (cement and other additives) thatare used for fly ash are also applied to the residues from the dry and semidry processes. Theamounts of cement and other additives necessary are higher and the results in terms of stabilityand reduction of the leachability of contaminants as well as economics are less satisfactory thanfor fly ash because of the high contents of soluble salts (Fly97 , Veh97c ). The most promisingstabilisation processes for dry and semidry residues are based on initial or simultaneous removalof the soluble salts by an aqueous extraction followed by the actual stabilisation step. Thiswashing operation produces a saline extract with a content of trace elements, which must betreated prior to discharge. The technical and economical problems associated with hightemperature treatment (melting and vitrification) of dry and semidry residues are even morepronounced than for fly ash and no such processes are in commercial operation.

Residues from the wet processIn the wet process the fly ash is always pre-collected upstream of the wet scrubber(s). The wastestreams from the process may consist partly of sludge from treatment of the wastewater andpartly of treated wastewater containing the soluble salts, mostly the chlorides. The purpose of thewastewater treatment is to reduce the content of trace elements in the wastewater to a very lowlevel. In some EC member states (e.g. Denmark) where most of the MSW incinerators are locatednear the sea, the discharge of treated, saline wastewater with a low content of trace elements isgenerally not considered problematic. In other member states where most or all incinerators arelocated inland, far away from the sea, the discharge of saline wastewater may not be acceptable,and in those cases the wastewater from the scrubbing system is evaporated to produce a dryresidue consisting of salts and various impurities. This is e.g. common practice in Austria,Germany and the Netherlands (semi wet-wet system). At a few incinerators HCl is recovered fromthe acid scrubber effluent by distillation (Veh97c ). It is also possible to recover gypsum byseparate treatment of the wastewater from the second scrubbing stage in two-stage scrubbingsystems.

The management options for the fly ash has been described above. The dry solids from theevaporation of the wastewater are treated similarly to the dry and semidry residues (without flyash) as described in section 10.3.3. The sludge from treatment of the wastewater from the wetscrubber will often appear as a filter cake, which may be landfilled at a special or hazardous waste

PVC.P. 007 EPage 70

landfill after stabilisation or mixing with fly ash. The treated wastewater is discharged to thesewage system or directly into a receiving water body.

8.2.4 Composition and leaching data for APC residues

It is not possible to find reliable and useful composition and leaching data for all the different typesof treated residues. This is partly due to the general reluctance of operators of incinerators andlandfills to publish such data, partly due to the fact that while many of the analytical and testingmethods required by various regulations may be used for classification of the residues, they arenot necessarily very useful in describing the actual behaviour of these residues after disposal.Furthermore, in many cases APC residues from MSW incinerators are not tested or characterisedat all since they are classified on the basis of their origin alone and taken to designated landfillswith or without treatment.

In spite of this, a fair amount of information exists on the general composition and the generalleaching properties of the major types of APC residues. The sources of this information areprimarily research projects, general knowledge on the leaching behaviour of waste materials (seee.g. HJE97) and the limited amount of data available from monitoring of the quality (and quantity)of APC residue landfills. Some of the important factors influencing the leaching properties ofwaste materials which are relevant in this context are pH, carbonation, reduction/oxidation (redox)potential, chloride complexation and the progression of the leaching. The latter is often expressedin terms of the liquid to solid (L/S) ratio, i.e. the ratio between the amount of APC residue and theamount of water that has passed through the residue (and become leachate) at any time.

For a thorough discussion of these factors and their influence on the leaching behaviour of APCresidues, please refer to IAW97, Hje97 and Hje98c . Briefly it can be mentioned that the pH offresh APC residues from the dry and semidry processes and in general also of fly ash is high withbuffering capacities decreasing in the order: dry residue, semidry residue, fly ash (the bufferingcapacity is a measure of the ability of a material to withstand pH changes imposed by acid (in thiscase) or alkaline attack). The high pH (often above 12) favours the leaching of lead and zinc whichare both amphoteric with minimum solubilities in the approximate range of pH = 8 – 10. Cadmium,however, exhibits very low solubility at high pH and increasing solubility with decreasing pH. Cdleachability is still fairly low at pH = 8. When wet and exposed to ambient conditions, particularlyatmospheric air, the alkaline dry and semidry residues will absorb carbon dioxide and becomecarbonated, i.e. the hydroxides will react with the carbon dioxide to form carbonates. The majoreffect will be a gradual decrease in pH to approximately 8-9 while the most of the bufferingcapacity is retained but shifted to a lower pH. Consideration of changes in redox potential may beparticularly relevant to sludges from treatment of the scrubbing liquid from the wet process, sincethey consist partly of reduced organic reagents such as trimercaptotriazine (TMT). The long termstability and leaching behaviour of these materials when exposed to ambient (generally oxidising)conditions are not well known. Both cadmium and lead are subject to increases in solubility due tochloride complexation at high chloride concentrations. This is only relevant during the initial stagesof the leaching process where the highest concentrations of chlorides are seen in the leachate.The initial leachates from dry and semidry residues will often be very alkaline, and it will difficult todistinguish between the increases in solubility of lead caused by high pH and by high chlorideconcentrations, respectively. For cadmium, however, a high chloride concentration may cause anincrease in solubility/leachability even at high pH values. The effect will disappear relatively earlyin the leaching process as the chloride concentration decreases with increasing L/S (Hje98a).

For the purpose of illustration, general elemental composition data for fly ash, dry and semidryresidues containing fly ash and sludge from treatment of the wastewater from the wet process(without fly ash) are presented in Annex 7.1. The source of the data which are based on chemicalanalysis of residues from incinerators in several European countries and the USA and Canada, isIAW97. It must be assumed that the waste incinerated has contained whatever amount of PVCwas normal for the various locations at the time of sampling of the residues.

PVC.P. 007 EPage 71

No data are available on the composition of APC residues from incineration of waste without PVC.A demonstration of the difference between the residues resulting from incineration of wastewithout and with PVC, respectively, must therefore be based partly on theoretical considerations.Since the previous part of the study has shown that only the contents of chlorides and cadmium inthe APC residues are affected significantly by the incineration of PVC, the distinction betweenresidues from incineration of waste with and without PVC, respectively, will be based primarily onthe mass balance calculations shown in Annex 6 and the sources of the data in Annex 7.

Whereas the doubling of the chlorides in the flue gas and the corresponding residues caused bythe presence of PVC in the waste feed will have a noticeable effect both on the quantity and thequality of the residues, particularly in relation to the leaching properties, the 10 % increase incadmium content will be much harder to detect and verify (according to Annex 7.1 there is a 100%difference between the 25% and the 75% percentiles for Cd content in fly ash and dry/semidryresidues, and a 300% difference for sludge from the wet process).

There is no direct relationship between the total content of Cd and the leachability of Cd (see e.g.IAW97 or Hje97), and a 10% increase in total content of Cd in the residues will not necessarilylead to a 10% increase in the leachable amount of Cd. The leachability depends on the chemicalnature of the cadmium and the leaching conditions. However, from a theoretical point of view, theincreased content of chloride may, as described above, cause a certain increase in the leachabilityof Cd: Most of the leaching of Cd from landfilled APC residues will occur during the initial stagewhen the chloride concentration is highest, because of the formation of soluble chloride/cadmiumcomplexes. This will occur only at very low L/S values and very high chloride concentrationsbecause the pH is generally high and does not favour leaching of Cd. It is not possible to quantifythis potential effect but it is not likely to cause a qualitative change of the properties of theleachate. The «natural» variation of the chloride content in the residues is also substantial, butsince practically all chloride present will be leachable, there is a more direct relationship betweentotal content and leachable amount for chlorides than for Cd and most other elements. In leachingexperiments such as e.g. column leaching tests, the leachable part of the Cd will usually notexceed a few percent of the total Cd content.

Some leaching data for residues from the dry, semidry and wet processes are presented in Annex7.3. The data, which have been produced by VKI, are the results of laboratory leaching tests, andthey have later been confirmed by large scale lysimeter leaching tests (Fly97 ). Column (andlysimeter) leaching tests can to a certain extent be regarded as simulating the leaching processesthat might occur in a landfill, but the tests are accelerated and do not take ageing effects (e.g.carbonation and oxidation) into account. The Annex also contains some leachate monitoring datafrom a Danish landfill for APC residues from MSW incinerators. The leaching data are of courserepresentative of the incineration of waste with whatever content of PVC there was at the time ofsampling of the residues (late 1989 to 1997). It may be assumed that the content of PVC wastypical for municipal solid waste. The column leaching data are used in the scenario calculations inSection 8.2.5.

8.2.5 Scenario definitions and calculations

Due to the lack of availability of APC residues representing the situation where no PVC isincinerated, no direct comparisons of the hazardousness of the various types of residuesproduced with and without incineration of PVC can be made. Instead an attempt will be made toillustrate the hazardousness of the residues in the two situations in terms of the expectedproperties of the leachate or the expected amounts of key component(s) leached when theresidues are landfilled under certain conditions. This will be done by means of scenariocalculations.

The scenarios considered will be based on incineration of 1 million tonnes of waste with andwithout PVC, respectively, and landfilling of the resulting APC residues. The following APCprocesses are considered: The dry process, the semidry process and the wet process. For the wet

PVC.P. 007 EPage 72

process, both the disposal of fly ash alone and of fly ash mixed with the sludge/filter cake areconsidered. The scenario with fly ash alone is thus not complete (the sludge/filter cake is notaccounted for) but it serves to illustrate the difference between the leachate obtained from jointdisposal of sludge and fly ash and separate disposal of the fly ash. The incomplete fly ashscenario would also cover the fly ash part of the residues from the semiwet-wet process. There is,however, no landfill scenario to cover the landfilling of those parts of the residues from thesemiwet-wet process resulting from the evaporation of the scrubber effluent (the acid gas cleaningresidues). The reason for this is partly, that no suitable leaching data are available on thismaterial, partly that it would make little sense to place this almost totally soluble material in alandfill with percolation of water.

The estimates of the various amounts of the various components of the APC residues resultingfrom incineration of 1 tonne of waste without and with PVC, using the different APC processes(including the semiwet-wet process), are listed in table 8.1. The table also shows the relativeincrease of the amount of each component caused by incineration of PVC.

The masses of the acid gas cleaning residues shown in table 8.1 have been calculated from thedata shown in Annex 5 adjusted with the amount of Cl present in the fly ash (1.2 and 2.4 kg/ton ofwaste without and with PVC, respectively). This is done because of the inconsistency between thedata available – the calculations of the masses of the gas cleaning residues in annex 5. Assumesthat all the chlorine is captured in the acid gas cleaning residues and the data on fly ash assumesa content of 9.4 % (w/w) of Cl in the fly ash (see below).

Table 8-1 – The estimated amounts of residues or residue components from various APCprocesses resulting from incineration of 1 tonne of waste without and with PVC.

Residue Amount produced per tonne ofwaste incinerated (kg)

Increase caused byincineration of PVC

% (w/w)Without PVC With PVC

Dry process:Acid gas cleaning residueFly ashAcid gas cleaning residue + fly ash

19.523.843.3

26.725.051.7

+ 37+ 5.0+ 19

Semidry process:Acid gas cleaning residueFly ashAcid gas cleaning residue + fly ash

19.723.843.7

25.725.050.7

+ 31+ 5.0+ 16

Wet process:Fly ashFilter cakeFilter cake + fly ash

23.84.3

28.1

25.04.3

29.3

+ 5.0+ 0+ 4.3

Semiwet-wet process:Acid gas cleaning residueFly ashAcid gas cleaning residues + FlyAsh

9.923.833.7

14.425.039.4

+ 45+ 5.0+ 17

The data in table 8.1 are based on the S.R. values and PVC contents presented in Annex 5 andthe fly ash quantities and properties described below.

The landfill scenarios represent disposing of the appropriate amounts of the various residues in alandfill with an average height of 10 m and calculating the amounts of selected key componentsleached from each residue over a period of approximately 50 years. The annual rate of infiltrationof precipitation is set to 250 mm and the average dry densities of the packed residues are all

PVC.P. 007 EPage 73

estimated at 1.3 tonnes/m3. Since the heights of the landfills are fixed, landfilling of differentamounts of residues will result in landfills with different surface areas and, consequently, differentrates of production of leachate.

The amounts of the various types of residues produced by the incineration of 1 million tonnes ofwaste are estimated on the basis of the calculations shown in table 8.1. The results are shown in8.2. The amount of fly ash produced by all APC processes is assumed to be 25 kg/tonne wasteincinerated with PVC in the waste. This corresponds to an average value as the quantity of fly ashis related to the type of primary combustion and post-combustion chambers as well as to theoperating conditions applied. The fly ash (boiler and filter ash) values indicated for the wetprocesses in table 3.5 are in accordance to this average : 10 to 35 kg/ton MSW, average 24kg/ton MSW. It is further assumed that the fly ash from incineration without PVC contains only 50percent of the chloride present in fly ash from incineration of waste with PVC (it should be notedthat this is not supported by data). Based on actual data (Hje93) the content of chloride in the flyash from incineration of waste with PVC is set at 9.4% (by weight). The estimation of the amountsof neutralisation residues produced is based on the assumption that the waste contains 7.0 kgCl/tonne in the presence of PVC and 3.5 kg Cl/tonne without PVC (see Annex 6).

Table 8-2 - The estimated amounts of the various residues produced in terms of kg/tonneof waste incinerated and tonnes per million tonnes of waste incinerated.

RESIDUE Incineration without PVC Incineration with PVC

kg/tonne waste tonnes/milltonnes waste

kg/tonne waste tonnes/milltonnes waste

Dry residue(including fly ash)

43.3 43300 51,7 51700

Semidry residue(including fly ash)

42.6 42600 50.2 50200

Wet (filter cake +fly ash)

28.1 28100 29.3 29300

Fly ash 23.8 23800 25.0 25000

The amount of leachate produced each year and over a period of 50 years may be calculated byfirst calculating the surface area of each of the landfills and then multiplying the surface area bythe annual rate of infiltration (250 mm) and finally multiplying the result by 50 years. The results ofthese calculations are presented in table 8.3.

The liquid to solid ratio (L/S) corresponding to t = 50 years can be calculated from the followingequation :

L/S = t/(d x H/I)

where d is the dry bulk density of the landfilled residue, H is the height of the landfill and I isannual rate of infiltration of precipitation. For t = 50 years, d = 1.3 t/m3, H = 10 m and I = 250mm/year, L/S = approximately 1 l/kg.

PVC.P. 007 EPage 74

Table 8-3 – The estimated amounts of leachate produced annually and over the period of50 years from the landfills containing the APC residues resulting from incineration of 1

million tonnes of waste.

RESIDUE Incineration withoutPVC

Leachate production

Incineration with PVC

Leachate production

PVC influenceon leachateproduction

m3/year m3over 50years

m3/year m3over 50years

% (vol/vol)

Dry 833 41635 993 49663 + 19

Semidry 818 40913 964 48221 +18

Wet + fly ash 540 27019 563 28173 +4.3

Fly ash 458 22885 481 24038 + 5.0

The composition of the leachate is estimated using the results of column leaching tests carried outby VKI on dry residues from I/S Nordforbrænding, semidry residues from I/S Amagerforbrænding,wet scrubber sludge mixed with fly ash from Gothenborg (Hje92) and fly ash from I/SVestforbrænding (Hje93). The results of these tests are expressed as leachate composition andaccumulated leached amounts of various components as a function of L/S. The accumulatedleached amounts of chloride, sulphate, calcium, sodium, potassium, cadmium and lead atL/S = 1 l/kg are calculated and listed in table 8.4. These values are assumed to represent theleaching properties of the residues resulting from the incineration of waste with PVC.

In table 8.4, it is assumed that the amounts of chloride leached from the residues at L/S = 1 l/kgare reduced by 50% if the PVC is removed from the waste prior to incineration. The counterionsNa and K are also reduced to 50 % whereas this is not done for sulphate since this componentmay be solubility controlled by Ca. The estimated of the amount of Ca leached from the residuesfrom incineration of waste without PVC is based on an ion balance calculation involving Na+, K+,Ca2+, Cl- and SO4

2-. For Cd it is assumed that a 10% increase on a mass balance basis leads to a10% increase in leachability, see below. Because of the difference in total amount of residueproduced when 1 tonne of waste with and without PVC, respectively, is incinerated, the amount ofCd leached on a mg/kg residue basis may appear higher for residues produced withoutincineration of PVC than for residues produced with incineration of PVC, although the total amountof Cd leached from the residues will be highest for incineration of 1 tonne of waste with PVC. ForPb, solubility control is assumed, and the leached amounts are the same on a g/t residue basisboth with and without incineration of PVC.

The estimated resulting accumulated leached amounts of the selected components are shown intable 8.5 for landfills for all 4 types of residues resulting from incineration of waste with and withoutPVC. The figures in the table represent the amounts leached over a period of 50 years from alandfill containing the residues from incineration of 1 million tonnes of waste. The results in table8.5 have been obtained by multiplying the accumulated leached amounts in table 8.4 by theappropriate masses of residues produced per million tonnes of waste incinerated (table 8.2).

PVC.P. 007 EPage 75

Table 8-4 – Estimated accumulated amounts of selected components leached from thelandfilled residues resulting from the burning of waste with and without PVC at L/S = 1 l/kgcorresponding to a period of 50 years. Unit: g/tonne residue.

ComponentDry residue

(incl. FA)Semidry residue

(incl. FA)Wet + fly ash Fly ash (FA)

withoutPVC

withPVC

withoutPVC

withPVC

withoutPVC

withPVC

withoutPVC

withPVC

g/t g/t g/t g/t g/t g/t g/t g/t

ChlorideSulphateCaNaKCdPb

1190001300

530008900

130000.463400

2000001300

8900015000220000.433400

65000140

320007700

100000.1715

130000140

5600013000170000.1615

290002400350099009900

0.000380.00045

5500024005400

19000190000.0004

0.00045

4900030005900

1500019000

7.09.1

9400030005800

2900037000

7.39.1

Table 8-5 – Estimated amounts of components leached over a period of 50 years from alandfill containing the APC residues resulting from the incineration of 1 million tonnes of

waste without and with PVC, respectively.

ComponentDry residue

(incl. FA)Semi-dry residue

(incl. FA)Wet + FA Fly ash (FA)

withoutPVC

withPVC

withoutPVC

withPVC

withoutPVC

withPVC

withoutPVC

withPVC

tonnes tonnes tonnes tonnes tonnes tonnes tonnes tonnes

ChlorideSulphateCaNaKCdPb

520056

2300390570

0.020150

1030067

4600780

11000.022180

33006.0

1300330430

0.0070.64

65007.0

2800650850

0.0080.75

8106797

280280

0.0000110.000013

160070

160560560

0.0000120.000013

120071

1403604600.170.22

240075

1507309300.180.23

From table 8.5 it can be seen that for all the APC processes, a substantially larger amount of saltsmay be expected to leach from the residues from incineration of PVC containing waste than fromresidues from incineration of waste not containing PVC, when the residues are landfilled. Forchloride, Na, K (and for dry and semidry residues also Ca) the amounts leached are doubled dueto the incineration of PVC. Although there might also be a modest increase in the amounts of Cdleached, this cannot be sustained by data. However, in the calculation for the scenarios involvingresidues from combustion of waste not containing PVC, the release of Cd is simply set to 91 % ofthat calculated for residues from combustion of waste containing PVC. There is no directrelationship between the total content and the leachable amount of Cd but the increase in theleached amount of Cd is intended to demonstrate an effect of the 10% increase in total content ofCd in the fly ash, which may be expected when PVC-containing waste is combusted. In view of theuncertainties involved in these calculations, the differences between the amounts of Cd leachedfrom the landfilled residues from combustion of waste with and without PVC, respectively, cannotbe regarded as significant. This is probably also true for sulphate and Pb, which are both assumedto be solubility controlled.

PVC.P. 007 EPage 76

It should be kept in mind that the scenario calculations are based on a mixture of theoreticalconsiderations and concrete leaching data based on laboratory testing of specific residues underconditions, which may not be fully representative of the conditions existing in a real landfill, andthe results should therefore be regarded only as a semi-quantitative illustration of the order ofmagnitude of the expected effects of PVC incineration on the properties of APC residues. Theresults should hence not be regarded as exact representations of the «truth» and should not bequoted out of context.

For the wet process PVC incineration will also cause a doubling of the concentration of salts(chlorides of sodium and calcium) in the wastewater stream which may either be treated toremove trace elements or evaporated to produce an impure salt residue.

In summary, the presence of PVC in the municipal solid waste (MSW) may be expected to havethe following effects on the APC residues from MSW incinerators:

• The quantity of residues, both in terms of mass and volume, will increase (see table 8.1 and8.2);

• The quantity of leachate produced from landfills containing residues from incineration of wastewith PVC will be larger than the quantity of leachate produced from landfills containingresidues from incineration of waste without PVC, all other conditions equal (see table 8.3);

The composition and leachability of the residues will change somewhat as a result of theincineration of PVC. When the residues are landfilled, this may be expected roughly to cause adoubling of the amounts of salts (mostly chlorides of Ca, Na and K) leached from the residues andpossibly a slight increase in the amounts of Cd and Pb leached (see table 8.5). The estimateddifferences for the leaching of Cd and Pb do, however, fall within the range of uncertainty of theestimations.

9. INFLUENCE OF PVC ON THE COST OF INCINERATION

9.1 Introduction ; Approach

The purpose of this part of the study is to identify the cost for PVC incineration, including themanagement of the residues.

As the PVC is never incinerated specifically, there is no reference for single end of life PVC cost.

The costs aspects related to the influence of PVC incineration on the residues from GasTreatment are evaluated as marginal costs with considering that PVC is added to the waste(MSW) in a rather low proportion (The PVC content in MSW has been identified for the currentsituation to be in the range of 0.60% to 0.74%).

This means that investment costs -as an example- attributable to PVC will only be considered inso far as the presence of PVC in the waste could require special equipment - or special materials -in the Gas Treatment section.

The same approach will be applied to manpower, and further fixed costs.

The neutralisation agent (N.A.) cost due to PVC is determined in accordance to the GasTreatment process and to the corresponding required excess which has been evaluatedpreviously.

The cost for the management of the Gas Treatment residues attributable to PVC is evaluated inrespect with the final destination of the residue.

The data provided by the European incinerators and by the N.A. providers is displayed in thischapter and validated by the literature.

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9.2 PVC influence on the investment costs of the plant

9.2.1 Equipment sizing

The incineration plants are designed in accordance to the power of the primary combustionchamber rather than to the waste flow to be burned.

In any case, the PVC proportion in MSW is too low to have a significant influence on the gas flowleaving the combustion stage and, therefore, on the size of the plant.

9.2.2 Material choice for the equipment

Because of corrosion due to chlorine resulting from the presence of PVC the most vulnerable partof the incineration plant is the Heat Recovery Boiler, and the question could arise whether thepresence of PVC could mean that it was necessary to use more expensive alloys for the boilerconstruction.

The answer to this question has been obtained by the literature review and by direct contacts withoperators involved in MSW incineration (Cl from 0.64% to 0.70%) as well as in Hazardous Waste(HW) incineration (Cl up to more than 4%).

INDAVER (Antwerpen plant for HW and Beveren for MSW) answered that for both incinerationunits (hazardous waste and municipal waste), the same alloys are used in the boiler. In addition,the maximum steam temperature is controlled to prevent corrosion due to chlorine. This is usuallyheld at 280ºC with a maximum temperature of 300ºC.

The presence of PVC in the waste therefore does not influence the equipment costs provided thatthe steam temperature is controlled.

9.3 PVC influence on the operating costs of the plant

The operating costs does not include the costs of the management of the residues from GasTreatment (considered in paragraph 9.4).

9.3.1 Neutralisation Agents consumption and cost

As explained in previous chapter, the chlorine arising from the presence of PVC has to beneutralised and this causes the consumption of neutralisation agents including any requiredexcess aimed at meeting the gas effluent limits.

In order to identify the current costs of neutralisation agents and additives, the incineratoroperators were directly questioned. Their answers are listed below :

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Table 9-1 Neutralisation Agents (N.A.) prices ( ∈∈∈∈/tonne)

Ca(OH)2 (countedas CaO)

NaOH BICAR

France 85.8 (1) 125.9 (1) 190.6

Netherlands 62.9 (2) 113.6 (2)

Austria 55.7 (3) 156.2 (3)

Germany 77.7 (5) 105 (5)

Italy (56.0) 213.4 192.1

Great Britain 90.5 (4)

N.A. Average Cost(∈∈∈∈/tonne)

74.5 142.8 191.3

(1) Benesse-Maremne (2) Alkmaar (3) Spittelau (4) Confidential source (5)

Bamberg

In order to evaluate the cost of the neutralisation attributable to PVC, the S.R. values for PVC-issued HCl evaluated in chapter 7 are used as follows.

It should be noted that this study describes the current situation and includes experimental datafor which the HCl concentration in the off-gas is sometimes much higher than the gas emissionlimit of 10mg/Nm3 for HCl. This applies particularly to the dry system with standard grade lime (andwithout recycling of neutralisation products) as it is unlikely to enable the dry process to meet thisspecification.

Consequently, the cost for the lime consumption in dry-process has to be considered only as anindication as it would not be technically possible to meet a limit of 10 mg HCl/Nm3.

The other Gas Treatment Processes are known to be able to comply with the 10 mg HCl/Nm3

limit.

Table 9-2 Neutralisation Agents costs per tonne of PVC in MSW

N. A.

Nature

S.R.

(HCl)

N.A. quantity per tonneof PVC (tonne)

N.A. cost per tonne of PVC(∈∈∈∈)

min max average min max average

Dry BICAR 1.05 0.62 1.32 1.12 118.6 252.5 214.3

Ca(OH)2 * 2.00 0.52 1.11 0.94 38.7 82.7 70

Semi Dry * Ca(OH)2 1.70 0.44 0.94 0.79 32.8 70.0 58.9

Wet Ca(OH)2 1.10 0.29 0.61 0.52 21.6 45.4 38.7

Semi Wet –Wet

Ca(OH)2 1.10 0.29 0.61 0.52 21.6 45.4 38.7

* these Gas Treatment Systems generally result in gas emissions over the next European limit.

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Average NA quantities and costs are related to the average Cl content in PVC of 45%

9.3.2 Maintenance costs/Heat recovery yield

As mentioned in § 9.2.2. the chlorine presence in the raw gas supplied to the Heat RecoveryBoiler makes it necessary to limit the steam temperature below 300 °C in order to preventcorrosion due to the formation of iron chloride.

Consequently the steam pressure in the Heat Recovery Boiler is generally maintained at about 40bar in MSW incineration facilities. According to the operators that have been questioned, if theseconditions are maintained no particular corrosion problems have been experienced.

On the other hand the limitation of the pressure of the steam has an effect on the efficiency of thesteam turbine and, thus, on the yield of electricity recovery from MSW.

In comparison the situation of the coal fired power plants are often considered : the low chlorinecontent in the coal allows the combustion gas to contain 30 times less HCl than in MSWincinerators and therefore minimises the high temperature corrosion risk. Coal fired power plantscommonly use a 100 bar (or more) steam pressure for a higher electricity yield in the steamturbine.

As already mentioned PVC is responsible for 38 to 66 % of the chlorine content in MSW and thequestion arises about the corrosion risks if no PVC is present in the waste. According to operatorsit is not likely that the steam pressure could exceed 50 bar in the absence of PVC in MSW.

In case of cogeneration - as used in the recent incinerator facilities - the lower electricity yielddoes not affect the global heat recovery but the electricity / heat ratio only.

9.3.3 Other costs

Manpower : since the PVC content in MSW is lower than 1%, the PVC presence in MSW does notinvolve any particular manpower requirement.

Electricity and Utilities : same as above.

9.4 PVC influence on the cost of the management of residues to their final destination

9.4.1 Final destination of the residues in Europe

According to the national policies and corresponding regulations in force, the Solid Residues fromGas Treatment can be stabilised by a cement-based binding, and then stored in different finaldestinations as shown below:

Belgium : Class 1 special landfill for non-stabilised residues in FlandersClass 2 landfill for stabilised residues in Wallonia

France : special landfill disposal (class 1) after stabilisation to meet the leaching criteria

Netherlands : landfill

Germany : salt mines storage

Austria : salt mines storage

Italy : landfill after stabilisation

Great Britain : landfill

PVC.P. 007 EPage 80

Denmark : on-site landfill (situation at Kommunekemi) or sent to Norway

9.4.2 Costs of storage for the residues

The table below shows the different costs for the management of the solid residues from GasTreatment (fly ash, neutralisation salts, filter cake) up to their final destination. This includes thecost of stabilisation when required.

Table 9-3 Solid residues storage costs ( ∈∈∈∈/tonne)

Country Nature of theresidues

Stabilisationrequired

Type of finalstorage

cost ( ∈∈∈∈/tonne)

Belgium (Wallonia) Fly ash and Salts Yes Landfill Class 2 155

France All solid residues Yes Landfill Class 1 210 to 240

Italy All solid Yes Landfill Class 2 135 to 160

Netherlands Fly ashNeutralisation Salts

Filter cake

NoNoNo

Landfill110100100

Germany Fly ash / Salts

Filter cake

No

No

Salt Mines 100 to 130

50

Austria Fly ash

Filter cake

No

No

Salt Mines 130

460

Great Britain Fly ash and Salts No Landfill 75

Belgium (Flandres) Fly ash and Salts No Landfill Class 1 120 to 130

Denmark Fly ash and Salts No Landfill 80

The table shows a large range for the cost for residue disposal. Two categories can benevertheless considered according to the need to stabilise the residue prior to storing it in its finaldestination.

The following average price will be applied for the cost evaluation of PVC treatment per tonne ofresidues :

- with stabilisation : 175 ∈∈∈∈/tonne- without stabilisation : 105 ∈∈∈∈/tonne

9.4.3 Cost for the management of residues from gas treatment up to their final destination

The contribution of PVC to the quantity of the solid residues depends - as already mentioned - onthe type of Gas Treatment Process :

• For dry and semi-dry systems, PVC contributes to the residue formation because of thechlorine and thus to the quantity of salts after gas neutralisation.

• For the wet process, the PVC contribution to solid residue (filter cake) is not significant as thefilter cake mainly consists of gypsum obtained by the precipitation of sulphates with calcium:The Spittelau Analysis of filter cakes shows:

550 mg/kg for Pb thus 778 mg of Pb(OH)2

25 mg/kg for Cd thus 60 mg of Cd(OH)2

If all Pb and Cd came from PVC, this should represent 0.08% of the filter cake (dry substance).Thus, in the wet process, there is no solid Gas Treatment residue attributable to PVC.

PVC.P. 007 EPage 81

Since there is currently no regulation concerning the release of chlorides into rivers, the liquideffluents due to PVC do not contribute to any additional cost when a wet Gas Treatment System isemployed. [Abp99,Rei99 ]

• For the semi wet-wet process PVC contributes to the residues as the salts present in the liquideffluents are dispersed in the gas flow

Using the results of chapter 7 for the appraisal of the quantity of residues as a function of the GasTreatment process, the corresponding contribution of PVC to the costs of management of theresidues can be evaluated as follows :

Table 9-4 Cost of management of the residues per tonne of PVC

GTS System Dry Semi-Dry Wet Semi-wet / Wet

NA nature Ca(OH)2 BICAR Ca(OH)2 Ca(OH)2 Ca(OH)2

Residue produced min 0.78 0.46 0.70 0 0.54max 1.65 0.97 1.48 0 1.15

per tonne of PVC(tonne)

average 1.40 0.82 1.26 0 0.98

Management cost of residues(∈/tonne)

175 with stabilisation105 without stabilisation

min maxaverage

min maxaverage

min maxaverage

min maxaverage

min maxaverage

Cost ofmanagement of

withoutstabilisation

80 to 175150

50 to10085

75 to 155 130 0 60 to 120105

the residue∈∈∈∈ per tonne PVC

withstabilisation

140 to 290245

80 to 170145

120 to 260220

0 95 to 200170

9.5 Heat recovery profit attributable to PVC

About 80 to 85% of energy content of PVC (20.9 MJ/kg / for pure PVC [Hil.82]) can be recoveredin the Heat Recovery Boiler : 5% loss of Energy is due to unburned material and 10 to 15% to theunrecovered heat of the flue gas.

The possible selling price of heat (mid-pressure steam) were identified as :10.7 ∈/MWh in France10.9 ∈/MWh in Italy12.5 ∈/MWh in Belgium

1 tonne of pure PVC resin could therefore be valorised at 56 ∈:tonne of PVC;

In fact the PVC compound contains 44 to 93 % of PVC resin and the remainder is composed oforganic compounds with a higher calorific value, and also of mineral compounds without anycalorific value. It seems thus relevant to take into account the following value of 50 ∈∈∈∈/tonne ofPVC (polymer) for heat valorisation.

In the case of electricity production the energy efficiency of the complete system (including heatboiler and steam turbine) is only of 20 to 25 % but the electricity is valorised at a market price ofabout 0,030 ∈/kWh.

Base on the same calculation as before, PVC can be valorized for 4,2 to 5,2 MJ/kg of pure resin(1,2 to 1,4 kWh) thus for a price of 36 to 42 ∈/tonne of PVC product (overage ~ 40 ∈/tonne PVC).

As most of the plants are equipped with energy recovery produce electricity, the heat recoveryfrom PVC will be considered at 36 to 42 ∈/tonne of PVC product.

PVC.P. 007 EPage 82

9.6 Total cost related to PVC incineration ( ∈∈∈∈/tonne of PVC)

In order to evaluate the influence of PVC on the cost of the Gas Treatment System, two different

figures will be considered :

• MSW with no PVC, thus with a chlorine content of 3,5 kg Cl/t MSW (table 9-5a)

• PVC product with a chlorine content of 0,25 to 0,53 % (table 9-5 b)

This will allow the effect of the substitution of 1 kg of waste with 1 kg of PVC as shown in table 9-

5cTable 9-5a - Cost for the treatment of the gas from the incineration

of 1 tonne MSW free of PVCDry System Semi-Dry Wet Semi Wet -

WetCa(OH)2 BICAR Ca(OH)2 Ca(OH)2 Ca(OH)2

Cl per kg of MSW (kg) 0,0035Investment Cost 0 0 0 0 0Manpower 0 0 0 0 0NA cost 1,0 3,0 0,8 0,5 0,5Finaldisposal


2,1 1,2 1,8 0 1,5

of residues withstabilisation

3,4 2,0 3,1 0 2,4

Liquid effluent release - - - 0 -TOTAL Without

stabilisation3,1 4,2 2,6 0,5 1,9

EXPENSE Withstabilisation

4,4 5,0 4,9 0,5 2,9

Heat recovery valueKJ/kg

10 MJ for 1 kg MSW → 2 to 2,5 MJ/kg MSW converted intoelectricity

Heat recovery value∈/tonne

- 17 to - 20 (average : - 18,5)

Final Withoutstabilisation

- 15,4 - 14,3 - 15,9 - 18 - 16,6

Cost Withstabilisation

- 14,1 - 13,5 - 13,6 - 18 - 15,6

Note : the ranges of cost for the PVC are attributable to the range of chlorine content in the PVC.

PVC.P. 007 EPage 83

Table 9-5 b - Cost for the treatment of gas from 1 tonne PVC incineration

Dry System Semi-Dry Wet Semi Wet - WetCa(OH)2 BICAR Ca(OH)2 Ca(OH)2 Ca(OH)2

Cl per kg of PVC (kg) 0.25 to 0.53 (min - max)0.45 (average)

Investment Cost 0 0 0 0 0Manpower 0 0 0 0 0NA cost 39 – 83 119 - 252 33 - 70 22 - 45 22 - 45

70 214 59 39 39Finaldisposal


80 – 175150

50 - 10085

75 - 155130

0 60 - 120105


140 – 290245

80 - 170145

120 - 260220

0 95 - 200170

Liquid effluent release - - - 0 -TOTAL without

stabilisation120 – 260

210170 - 350

300110 - 230

18520 - 50

4080 - 170

135EXPENSE with


310200 - 420

360155 - 330

27020 - 50

40120 - 250

205Heat recovery value (*) 40Final without


170130 - 310

26070 - 190

145(-20) - 10

(0)40 - 130

95Cost with


270160 - 380

320115 - 290

230(-20) - 10

(0)80 - 210

165

Table 9-5 c - Additional cost related to the substitution of 1 tonne MSW by 1 tonne of PVC

Dry System Semi-Dry Wet Semi Wet - WetCa(OH)2 BICAR Ca(OH)2 Ca(OH)2 Ca(OH)2

Cl per kg of PVC (kg) 0.25 to 0.53 (min - max)0.45 (average)

Investment Cost 0 0 0 0 0Manpower 0 0 0 0 0NA cost 38 – 82 116 - 249 32 - 69 22 - 45 22 - 45

69 211 58 39 39Finaldisposal


78 – 173148

49 - 9984

73 - 153128

0 58 - 128103


137 – 287242

78 - 168143

117 - 257217

0 93 - 198168

Liquid effluent release - - - 0 -TOTAL without


217165 - 348

295105 - 222

18620 - 50

4078 - 168

142EXPENSE with


311194 - 417

355149 - 326

26520 - 50

40117 - 247

207Heat recovery value (*) - 21,5Final without


196144 - 327

27484 - 206

165(-1) - 29 -

1957 - 147

121Cost with


290172 - 396

334127 - 305

244(-1) - 29 -

1996 - 226

186

PVC.P. 007 EPage 84

The above results show the effect on the substitution of 1 kg of MSW by 1 kg of PVC on the costof the gas treatment.

In order to link the influence on cost on the PVC content in MSW another way to show the resultsis presented below.

It is based on the determination of the increase of the Gas treatment cost when the PVCcontribution to chlorine content in MSW goes from the lowest value of the range identified in table4.6 (38 %) up to the upper one (66 %). The cost for landfilling residues corresponds to that ofstabilisation.

• The Gas Treatment cost is first calculated for the lowest PVC content according to the followingcharacteristics of MSW corresponding to the Rijpkema data [Rij 93] (refer to table 4.6)

Total Cl in MSW : 5.6 kg per tonne

Chlorine from PVC in MSW : 2.1 kg per tonne

PVC contribution to Cl in MSW : 38 %

Sulphur content in MSW : 2.2 kg per tonne (average value from selected plants)

For this first calculation the gas treatment is calculated for the neutralisation of HCl and SO2.

The overall stoichiometric ratios are used on purpose for HCl and SO2.neutralisation

• The second figure of the scenario corresponds to a PVC increase in the same MSW up to the66 % contribution of PVC to the Cl content in MSW :

Total Cl in MSW : 10.2 kg per tonne

Chlorine from PVC in MSW : 6.7 kg per tonne

Additional Cl due to PVC increase : 4.6 kg/tonne

PVC contribution to Cl in MSW : 66 %

Sulphur content in MSW : unchanged

For the second calculation the specific Stoichiometric Ratios for HCl as identified in table 7.6are used for the different Gas Treatment processes

The cost increase should be lowered - for each Gas Treatment Process - by 0.5 ∈/tonne inorder to take into account the heat valorisation of PVC.

PVC.P. 007 EPage 85

Table 9-6 Effect on the cost of Gas Neutralisation due to the PVC increase in MSW in therange of PVC contribution to Cl in MSW (38 % to 66 %)

Gas Treatment costfor a MSW

PVC issued Cl : 38%

Additional GTcost in case ofPVC increase

PVC issued Cl :66%

Total Cl(kg) per tonne of MSW 5.6 10.2PVC contribution to Cl in MSW (kg/tonne MSW) 2.1 6.7Additional Cl due to PVC increase (kg/tonne MSW) - 4.6S in MSW 2.2 unchanged : 2.2

Overall S.R. 2.8 2Total N.A. (kg/tonne MSW) 30.60 9.6

DRY SYSTEM Cost ∈/tonne MSW 2.28 0.71Ca(OH)2 Total residues (kg/tonne

MSW)43.1 14.3

Cost ∈/tonne MSW 7.5 2.5Total Cost 9.8 3.2Overall S.R. 1.2 1.05Total N.A. (kg/tonne MSW) 30.1 11.4

DRY SYSTEM Cost ∈/tonne MSW 5.7 2.2NaHCO3 Total residues (kg/tonne

MSW)22.1 7.9


SEMI DRY SYSTEM Cost ∈/tonne MSW 1.71 0.61Ca(OH)2 Total residues (kg/tonne

MSW)35.4 12.9


WET SYSTEM Cost ∈/tonne MSW 0.90 (lime) 0.40 (lime)Ca(OH)2 Total residues (kg/tonne

MSW)0 0

Cost ∈/tonne MSWTotal Cost 0.90 0.4Overall S.R. 1.1 1.1

SEMI WET - Total N.A. (kg/tonne MSW) 12.3 5.5WET SYSTEM Cost ∈/tonne MSW 0.91 (lime) 0.41 (lime)Ca(OH)2 Total residues (kg/tonne

MSW)23.4 9.1

Cost ∈/tonne MSW 4.1 1.6Total Cost 5.0 2.0

PVC.P. 007 EPage 86

In table 9.6 above, the first column shows the neutralisation agent consumption andcorresponding residue quantities for both HCl and SO2 neutralisation. This reflects therefore theeffective situation in Gas Treatment systems as the calculation uses the overall stoechiometricratios measured in the different incineration plants which were selected

The second column shows the effect of a PVC increase in the waste - for a constant sulphurcontent - and calculations are consequently based on the specific SR for HCl as identified in table7.6.

10. CONCLUSIONS

The following conclusions are drawn from the present study :

• End of life PVC, when disposed of by incineration, mainly involves Municipal WasteIncinerators, as neither Hazardous Waste Incineration plants or cement kilns treat PVC richwastes. PVC is also present in Hospital Waste and influences the operation of the GasTreatment stage as for MSW incineration.

• Because of the wide range of uses for PVC materials, and correspondingly wide range ofmechanical properties, the PVC polymer content varies from 44% to 93%, and subsequentlythe Cl content in PVC varies from 25 to 53 %.

• The influence of PVC on MSW composition is mainly related to the chlorine content of thewaste sent to incineration : PVC is responsible for 38 to 66 % of the chlorine content in MSW(total Cl in MSW containing PVC: 5,3 to 7 kg Cl / tonne MSW).

• PVC also influences the Heavy Metals (HMs) content in the MSW : this is mainly Cadmium as10% of Cd in MSW is attributable to PVC, but this situation is being changed as Cadmiumadditives are only permitted in profiles. In the current temperature range of combustion step forMSW incineration, the higher chlorine content has no significant effects on the transfer of otherHeavy Metals and trace elements from bottom ash to gas treatment residues.

• The presence of PVC in MSW has a direct effect on the quantity of chlorine in the raw gas andtherefore on the corresponding necessary gas treatment efficiency. The higher chlorine contentin the gas requires additional neutralisation agent supply and therefore affects the quantity ofresidues or effluents generated by the different Gas Treatment Systems (dry, semi-dry, wetand semi wet-wet) as shown in Table 10-1. The quantities of residues attributable to the PVCare in scenarios where the most severe emission limits for HCl (10 mg/Nm3) are met, exceptfor the dry process with standard grade lime which is not likely to meet this specification.

PVC.P. 007 EPage 87

Table 10-1 Influence of PVC on the quantity of residues


Neutralisation Agent. Lime BICAR Lime Lime LimeS.R. HCl 2 1.05 1.7 1.1 1.1Cl (kg) per min 0.25kg of PVC max 0.53

average 0.45

NA (kg) min 0.52 0.62 0.44 0.29 0.29

Per max 1.11 1.32 0.94 0.61 0.61

kg of PVC average 0.94 1.12 0.79 0.52 0.52

Residues (kg) min 0,78 0,46 0,7 0 0.54

(per kg of PVC) max 1.65 0.97 1.48 0 1.15

average 1.40 0.82 1.26 0 0.98Liquid effluent (dry

material)(kg per kg of PVC)

0 0 0 0.42 to 0.88 0

• Gas Treatment Residues relating to the use of PVC are mainly composed of chlorine salts andneutralisation agent excess. According to the Gas Treatment System these can be eithersodium salts NaCl, Na2CO3,(dry process with sodium bicarbonate, wet process with sodiumhydroxide) or calcium compounds CaCl2, CaOHCl, Ca(OH)2 (for processes using lime).

• The costs for PVC incineration can be evaluated as a marginal cost :

The PVC content in MSW is rather low and the presence of PVC in the waste does not requirea) larger size equipment for gas treatment, b) the use of particular materials or c) extramanpower.The presence of PVC involves a specific consumption of neutralisation agent and isresponsible for the generation of neutralisation products These two topics lead to specificcosts due to N.A. consumption and to residues management up to their final destination(mostly landfill).

The additional cost for PVC incineration, for a PVC chlorine content in PVC from 0.25 to 0.53%,depends on the Gas Treatment System as well as on the practice used for the management ofthe residues with or without stabilisation of the residue prior to its storage in landfill.

PVC.P. 007 EPage 88

Additional Cost for PVCincineration

Dry System Semi-Dry Wet Semi-Wet,Wet

∈/tonne of PVC Lime SodiumBicarbonate

Lime Lime / NaOH Lime / NaOH

min maxaverage

min maxaverage

min maxaverage

min maxaverage

min maxaverage

Without stabilisation of theresidue

95 – 234196

144 - 327274

84 - 206165

(-1) - 2919

57 - 147121

With stabilisation of theresidue

154 - 347290

172 - 396334

127 - 305244

(-1) - 2919

96 - 226186

The liquid effluents from wet processes have to comply with the regulations in force. In severalEC countries - such as Belgium or Germany - the release of salts in liquid effluents is submittedto more severe restrictions and Gas Treatment processes are being adapted to produce onlysolid residues.

• APC residues are classified as hazardous waste according to the directive 91/689/EC and thepresence of PVC in the waste is unlikely to cause any change in this classification.

APC residues -with or without PVC- have therefore to be managed correspondingly and placedin Hazardous Waste storage (landfill) providing that the residues comply with the acceptancecriteria.

The influence of PVC on the hazardousness of the Gas Treatment residues is difficult toquantify due to the lack of reliable data related to leachate compositions and quantitiescorresponding to different storage scenarios.

Calculations have been performed to estimate the quantity and quality of leachate generated inlandfills containing residues from different APC processes with and without PVC in the waste.

The calculations indicate that PVC incineration may be responsible for an increase in theamount of leachate generated from the landfilled residues corresponding to:

• 19 % for the dry process• 18 % for the semi-dry process• 4.3 % for the wet process• 15.0 % for the semi wet-wet process

For all residues, the incineration of PVC (which concentration in MSW is 0.6 to 0.8 %) appearsto increase the content of leachable salts (primarily chlorides of Ca, Na and K) by a factor of 2.There is no data showing that the leaching of trace elements/heavy metals will increasesignificantly as a result the incineration of PVC. There is a theoretical possibility that theleaching of, for example, cadmium may increase due to increased chloride complexationcaused by PVC incineration but no data are available to substantiate this.

PVC.P. 007 EPage 89

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