Advisory Guideline DWA-M 386E

Thermal treatment of sewage sludge is in regard to quantity the most important disposal route in Germany. It is an important option for a safe, economically effi cient and environmentally sound sludge disposal. Since the late 1980ies, the percentage of sludges which are treated thermally has risen from about 12 % to more than 50 %. Almost half of these sludge quantities are treated in mono-incineration plants. About the same amount is co-incinerated in coal power plants. Co-incineration is discussed in detail in the Advisory Guideline DWA-M 387 “Thermal Treatment of Sewage Sludge – Co-Incineration in Power Plants”.

The objective of the Advisory Guideline DWA-M 386 is to give fundamental information for the technical realiza-tion and operation of plants for mono-incineration of sewage sludge. Based on fuel characteristics of sewage sludge various incineration systems, possibilities for heat recovery and emission reductions as well as treat-ment options for fl ue gas purifi cation are introduced. Furthermore, information on legal framework, on plant organisation and economic effi ciency is presented. Finally, several practical examples of mono-incineration plants are discussed. For planners and operators of mono-incineration plants, this Advisory Guideline shall supply a basis for the determination about concepts during the planning phase and for decisions on invest-ments for the construction of new plants. This Advisory Guideline also supplies important information for ma-chinery manufacturers and plant engineers. However, it does not give detailed dimensioning standards for a process engineering layout of the plant or parts of it.

ISBN 978-3-942964-95-1

German Association for Water, Wastewater and WasteDeutsche Vereinigung für Wasserwirtschaft, Abwasser und Abfall e. V.Theodor-Heuss-Allee 17 · 53773 Hennef · GermanyTel.: +49 2242 872-333 · Fax: +49 2242 872-100E-Mail: info@dwa.de · Internet: www.dwa.de

German DWASet of Rules

German Association for Water, Wastewater and WasteDeutsche Vereinigung für Wasserwirtschaft, Abwasser und Abfall e. V.

Thermal Treatment of Sewage Slugde– Mono-Incineration

December 2011

Thermische Behandlung von Klärschlämmen – Monoverbrennung

Publisher/Marketing:German Association for Water, Wastewater and WasteDeutsche Vereinigung für Wasserwirtschaft, Abwasser und Abfall e. V.Theodor-Heuss-Allee 17 · 53773 Hennef · GermanyTel.: +49 2242 872-333 · Fax: +49 2242 872-100E-Mail: info@dwa.de · Internet: www.dwa.de

Advisory Guideline DWA-M 386E

German DWASet of Rules

Thermal Treatment of Sewage Slugde – Mono-Incineration

December 2011

Thermische Behandlung von Klärschlämmen – Monoverbrennung

DWA-M 386E

2 December 2011 DWA Advisory Guideline

The German Association for Water, Wastewater and Waste (DWA) is strongly committed to the development of secure and sustainable water and waste management. As a politically and economically independent organisation it is professionally active in the field of water management, wastewater, waste and soil protection.

In Europe DWA is the association with the largest number of members within this field. Therefore it takes on a unique position in connection with professional competence regarding standardisation, professional training and information. The approximately 14,000 members represent specialists and executives from municipalities, universities, engineering offices, authorities and companies.

Imprint

Publisher and marketing: DWA German Association for Water, Wastewater and Waste Theodor-Heuss-Allee 17 53773 Hennef, Germany

Translation: Claudia Mayerl, Braunschweig

Printing (English version): Bonner Universitäts Buchdruckerei

ISBN: 978-3-942964-95-1

Printed on 100 % recycled paper

Tel.: Fax: E-Mail: Internet:

+49 2242 872-333 +49 2242 872-100 info@dwa.de www.dwa.de

© DWA Deutsche Vereinigung für Wasserwirtschaft, Abwasser und Abfall e. V., Hennef 2014 German Association for Water, Wastewater and Waste

All rights, in particular those of translation into other languages, are reserved. No part of this Advisory Guideline may be repro-duced in any form – by photocopy, digitalisation or any other process – or transferred into a language usable in machines, in particular data processing machines, without the written approval of the publisher.

DWA-M 386E

DWA Advisory Guideline December 2011 3

Foreword The DWA-Sub-Committee AK-3 “Energy-Related Reuse and Thermal Treatment” has dealt with special aspects of sewage sludge incineration in several working reports. Especially questions concerning emissions, as well as legal and economic aspects have been discussed in detail. The results have been published in the following technical reports in the DWA Journal KA Abwasser Abfall:

“Klärschlammverbrennung – Emissionen (Sewage Sludge Incineration – Emissions)“ (ATV 1995)

“NOx- und N2O-Emissionen bei der Verbrennung von Klärschlämmen (NOx and N2O Emissions Produced from Sludge Incineration)“ (ATV 1996)

“Emissionen von Quecksilber aus Klärschlammverbrennungsanlagen (Mercury Emissions from Sludge Incineration Plants)“ (ATV 1997a)

“Klärschlammverbrennung – Beseitigung oder Verwertung? (Sewage Sludge Incineration – Disposal or Reuse?)” (ATV

1997b)

„Kostenstrukturen und Schnittstellen von Anlagen zur thermischen Klärschlammverwertung (Cost Structures and Interfaces at Treatment Plants for Thermal Sludge Reuse)“ (ATV-DVWK 2001)

In this Advisory Guideline, results presented in the working reports have been summarized and updated and important aspects in regard to mono-incineration of sewage sludge have been added.

Co-incineration of sewage sludge in power plants will be dealt with in a second Advisory Guideline DWA-M 387 “Ther-mal Treatment of Sewage Sludge – Co-Incineration in Power Plants”.

DWA-M 386E

4 December 2011 DWA Advisory Guideline

Authors This Advisory Guideline has been elaborated by the DWA-Sub-Committee AK-3 “Energy-Related Reuse and Thermal Treat-ment”.

Members of the DWA-Sub-Committee AK-3 “Energy-Related Reuse and Thermal Treatment” are:

BASSE, Stefan Dr., Greppin

BUCK, Peter Dipl.-Ing., Heilbronn

DOMSCHKE, Thomas Dr.-Ing., Ludwigshafen

ELSTERMANN, Norbert Dipl.-Ing., Meerbusch

ESSER, Richard Dipl.-Ing., Bonn

HANßEN, Harald Dipl.-Ing., Hamburg

HASELWIMMER, Thomas Dipl-Ing., Stuttgart

HILLER, Georg Dipl.-Ing., Neu-Ulm

JASPER, Matthias Dipl.-Ing., Hannover

KAPPA, Sven Dipl.-Ing., Cottbus

KRISTKEITZ, Rainer Dipl.-Ing., Wuppertal

LEHRMANN, Falko Dipl.-Ing., Lünen (chairman)

LUDWIG, Paul Dipl.-Ing., Frankfurt am Main

MAURER, Martin Dipl.-Ing., Karlsruhe

OSTERTAG, Michael Dipl.-Ing., München

PETERS, Uwe Dipl.-Ing., Frechen

PIETSCH, Bernhard Dipl.-Ing., Berlin

SCHROTH, Herbert Dipl.-Ing., Stuttgart (resigned)

STEIER, Klaus Dr.-Ing., München

WERTHER, Joachim Prof. Dr.-Ing., Hamburg

WESSEL, Michael Dipl.-Ing., Essen

Guest contributions:

KANEFKE, Rico Dr., Leverkusen

Responsible in the DWA Head Office:

REIFENSTUHL, Reinhard Dipl.-Ing., Hennef Department Water Management, Waste and Soil

DWA-M 386E

DWA Advisory Guideline December 2011 5

Content Foreword ................................................................................................................................................................ 3 

Authors ................................................................................................................................................................ 4 

Content ................................................................................................................................................................ 5 

List of Figures ........................................................................................................................................................... 7 

List of Tables ............................................................................................................................................................ 7 

User Notes ................................................................................................................................................................ 8 

Introduction .............................................................................................................................................................. 8 

1  Scope ....................................................................................................................................................... 8 

2  Terms and Definitions ............................................................................................................................ 9 

2.1  General Information ................................................................................................................................. 9 

2.2  Definitions ............................................................................................................................................... 9 

2.3  Abbreviations and Symbols ...................................................................................................................... 10 

3  Fuel Characteristics of Sewage Sludge ................................................................................................. 11 

4  Drying as a Preliminary Step to Mono-Incineration ............................................................................. 12 

5  Sewage Sludge Conveying and Feeding ................................................................................................ 12 

5.1  Sludge Acceptance, Storage and Conveyance ........................................................................................... 12 

5.1.1  Mechanically Dewatered Sludge .............................................................................................................. 12 

5.1.2  Partially Dried Sludge .............................................................................................................................. 13 

5.1.3  Fully Dried Sludge ................................................................................................................................... 13 

5.2  Dosing and Feeding Systems for the Incinerator ...................................................................................... 16 

5.3  Safety Aspects for Sludge Storage ............................................................................................................ 17 

6  Incineration Systems .............................................................................................................................. 18 

6.1  Fluidized Bed Furnaces ............................................................................................................................ 18 

6.2  Multiple Hearth Furnaces ......................................................................................................................... 20 

6.3  Combination Multiple Hearth Fluid Bed Furnace ..................................................................................... 21 

6.4  Alternative Processes ................................................................................................................................ 21 

6.4.1  Grate Stoker Furnace ............................................................................................................................... 21 

6.4.2  Rotary Furnaces ....................................................................................................................................... 21 

6.4.3  Pyrolysis and Gasification ........................................................................................................................ 22 

6.4.4  Dust Firing Systems and Cyclone Furnaces .............................................................................................. 22 

6.5  Safety Aspects for Combustion Technology .............................................................................................. 22 

7  Waste Heat Recovery ............................................................................................................................. 23 

7.1  Waste Heat Recovery Options for Multiple Hearth Furnaces ................................................................... 23 

7.2  Waste Heat Recovery Options for Fluidized Bed Furnaces ....................................................................... 23 

7.3  Steam Turbine Process ............................................................................................................................. 25 

7.4  Mass and Energy Balances and Degree of Efficiency ............................................................................... 25 

7.4.1  Basics ....................................................................................................................................................... 26 

7.4.2  Losses ....................................................................................................................................................... 26 

7.4.3  Efficiency ................................................................................................................................................. 26 

DWA-M 386E

6 December 2011 DWA Advisory Guideline

7.4.4  Example Calculation ................................................................................................................................ 27 

7.4.5  Options for Optimization ......................................................................................................................... 28 

7.4.6  Energy Recovery According to Directive 2008/98/EC .............................................................................. 28 

8  Emissions and Flue Gas Purification .................................................................................................... 30 

8.1  Carbon Monoxides, Nitrogen Oxides, Organic Compounds ...................................................................... 30 

8.2  Dioxins and Furans .................................................................................................................................. 31 

8.3  HCl, HF, SO2, Dust, Heavy Metals ............................................................................................................ 32 

8.3.1  Wet Processes .......................................................................................................................................... 32 

8.3.2  Dry Processes ........................................................................................................................................... 32 

8.4  Practical Examples for Flue Gas Cleaning ................................................................................................ 33 

8.4.1  Multi-Stage Scrubbing Processes Using Caustic Soda Solution for Desulphurization ................................ 33 

8.4.2  Spray Dryer Absorber including Electrostatic Precipitator and Desulphurization with Caustic Soda Solution ... 34 

8.4.3  Spray Dryer Absorber with Fabric Filter, Limestone-Based Desulphurization and Production of Gypsum ...... 35 

8.5  Mercury and its Compounds at Incineration Plants .................................................................................. 35 

8.5.1  Oxidation Reactions of Mercury ............................................................................................................... 35 

8.5.2  Mercury Removal ..................................................................................................................................... 36 

8.5.2.1  Mercury Removal by Oxidation and Absorption ....................................................................................... 36 

8.5.2.2  Mercury Removal by Adsorption .............................................................................................................. 37 

8.5.2.3  Other Processes for Mercury Removal ...................................................................................................... 37 

8.6  Flue Gas Discharge ................................................................................................................................... 37 

9  Organisational Structure ....................................................................................................................... 38 

9.1  Qualification of Personnel ........................................................................................................................ 38 

9.1.1  Plant Operation ........................................................................................................................................ 38 

9.1.2  Maintenance ............................................................................................................................................ 40 

9.2  Shift Schedules ........................................................................................................................................ 40 

10  Aspects in Regard to Legal Requirements ........................................................................................... 41 

11  Waste ...................................................................................................................................................... 42 

11.1  Combustion Residues ............................................................................................................................... 42 

11.2  Phosphorus Recovery from Sludge Ashes ................................................................................................. 43 

11.3  Residues from Flue Gas Purification ......................................................................................................... 44 

12  Costs of Mono-Incineration of Sewage Sludge ...................................................................................... 44 

13  Practical Examples of Mono-Incineration Plants for Sewage Sludge ................................................. 47 

13.1  Main Wastewater Treatment Plant Stuttgart Mühlhausen ........................................................................ 47 

13.2  VERA Hamburg ........................................................................................................................................ 48 

13.3  INNOVATHERM Lünen ............................................................................................................................ 50 

13.4  Wuppertal Buchenhofen ........................................................................................................................... 51 

13.5  Currenta Leverkusen ................................................................................................................................ 52 

14  Locations of Mono-Incineration Plants ................................................................................................. 54 

EU and Federal Laws ................................................................................................................................................ 55 

Technical Guidelines ................................................................................................................................................ 55 

DIN Standards ............................................................................................................................................................ 55 

DWA Set of Rules ........................................................................................................................................................ 55 

Literature ................................................................................................................................................................ 56 

DWA-M 386E

DWA Advisory Guideline December 2011 7

List of Figures Figure 1: Fluidized bed furnace ................................................................................................................................. 18 

Figure 2: Multiple hearth furnace .............................................................................................................................. 20 

Figure 3: Combination multiple hearth fluid bed furnace........................................................................................... 21 

Figure 4: Forced circulation boiler ............................................................................................................................. 24 

Figure 5: Gravity circulation boiler ............................................................................................................................ 24 

Figure 6: Steam turbine cycle ..................................................................................................................................... 25 

Figure 7: T/s diagram of the Rankine cycle ................................................................................................................ 27 

Figure 8: Principle of staged combustion for minimizing nitrogen oxide emissions .......................................................... 30 

Figure 9: Dioxin and furan formation in dependency on the S/Cl ratio ...................................................................... 32 

Figure 10: Principle of dry flue gas purification ......................................................................................................... 33 

Figure 11: Wet flue gas scrubbing using caustic soda solution at the mono-incineration plant of BASF SE WWTP in Ludwighafen am Rhein, Location Frankenthal Pfalz, Germany ............................................................ 34 

Figure 12: Mercury in raw gas in dependency on chlorine content of sewage sludge ................................................. 35 

Figure 13: Sewage Sludge incineration plant Karlsruhe ............................................................................................. 36 

Figure 14: Sludge incineration plant Ulm-Steinhäule ................................................................................................. 37 

Figure 15: Organisational chart for operation and maintenance in regard to professional qualifications ................... 39 

Figure 16: Organisational chart for operation and maintenance in regard to plant structure ..................................... 39 

Figure 17: Description of process steps, definition of system boundaries ................................................................... 46 

Figure 18: Mono-incineration plant in Stuttgart Mühlhausen .................................................................................... 47 

Figure 19: Mono-incineration plant, Hamburg ........................................................................................................... 49 

Figure 20: Mono- incineration plant INNOVATHERM Lünen ..................................................................................... 51 

Figure 21: Mono-incineration plant Wuppertal Buchenhofen ..................................................................................... 52 

Figure 22: Mono-incineration plant Currenta Leverkusen .......................................................................................... 53 

List of Tables Table1: Technologies for sludge conveyance and their fields of application ............................................................... 14

Table 2: Constituents of sewage sludge ash ............................................................................................................... 42

Table 3: Capacity of mono-incineration plants sludge in Germany ............................................................................. 54

DWA-M 386E

8 December 2011 DWA Advisory Guideline

User Notes This Advisory Guideline has been produced by a group of technical, scientific and economic experts, working in an honorary capacity and applying the rules and procedures of the DWA and the Standard DWA-A 400. Based on judi-cial precedent, there exists an actual presumption that this document is textually and technically correct.

Any party is free to make use of this Advisory Guideline. However, the application of its contents may also be made an obligation under the terms of legal or administrative regulations, or of a contract, or for some other legal reason.

This Advisory Guideline is an important, but not the sole, source of information for solutions to technical problems. Applying information given here does not relieve the user of responsibility for his own actions or for correctly apply-ing this information in specific cases. This holds true in particular when it comes to respecting the margins laid down in this Advisory Guideline.

Introduction The first plant for mono-incineration of sewage sludge was put into operation in Germany in 1975 in the city of Düren. By the year of 2010, 22 additional plants had been constructed for the incineration of municipal and industrial sewage sludges in Germany (see Chapter 14: Table 3). The total capacity of these plants amounts to approx. 800,000 t of sewage sludge (total solids, TS) per year with municipal sewage sludges making up about 500,000 t TS of the total amount (as of spring 2011). Thus, approx. 25 % of the 2.0 million t TS pro-duced in Germany every year can be treated thermally in mono-incineration plants. These incineration plants mainly use fluidized-bed incinerators, more rarely multiple hearth furnaces, combination multiple hearth fluid bed furnaces, grate stoker furnaces, gasification or pyrolysis processes.

Except for Germany, mainly Belgium, the Netherlands, Great Britain, Austria and Switzerland use thermal treatment of sewage sludge in mono-incineration plants. Most incineration plants have been installed at munici-pal wastewater treatment plants. Others exist at chemi-cal industry sites, power plants or as central incineration plants at other locations with adequate infrastructure. The plants make an important contribution to disposal safety and environmental protection. Energy produced during incineration is reused in most cases for the gen-eration of steam and electricity and thus contributes to the power supply of the respective location.

1 Scope This Advisory Guideline presents fundamental infor-mation for the technical realization and operation of plants for mono-incineration of sewage sludge. Further-more, legal framework and aspects of economic efficien-cy shall be introduced.

For planners and operators of mono-incineration plants, this Advisory Guideline shall supply a basis

for deciding on investments for the construction of new plants as well as

for the determination of concepts and

for the selection of a suitable process technology for given particular conditions.

The Advisory Guideline also supplies important infor-mation for machinery manufacturers and plant engineers. However, it does not give detailed dimensioning stand-ards for a process engineering layout of the plant or parts of it.

Particular aspects of incineration of industrial sewage sludges (amongst others pollutant concentration, auto-ignition, mechanical characteristics) are manifold and will not be discussed in the Advisory Guideline.

This Advisory Guideline does not claim to represent all legal requirements and non-legislative rules and stand-ards, which might apply in every individual case.