Air Pollution Prevention and Control

Air Pollution Prevention and Control

Bioreactors and Bioenergy

Edited by

CHRISTIAN KENNES AND MARIA C. VEIGADepartment of Chemical Engineering, University of La Coruna, Spain

A John Wiley & Sons, Ltd., Publication

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Library of Congress Cataloging-in-Publication Data

Air pollution prevention and control : bioreactors and bioenergy / edited by Christian Kennes and M. C. Veiga.pages cm

Includes bibliographical references and index.ISBN 978-1-119-94331-0 (cloth)1. Air–Pollution. 2. Air–Purification. 3. Bioreactors. 4. Biomass energy. I. Kennes, C. II. Veiga, M. C.

TD883.A57182 2013628.5′36–dc23

2012041074

A catalogue record for this book is available from the British Library.

ISBN: 9781119943310

Typeset in 10/12pt Times by Laserwords Private Limited, Chennai, India

Contents

List of Contributors xvii

Preface xix

I FUNDAMENTALS AND MICROBIOLOGICAL ASPECTS 1

1 Introduction to Air Pollution 3Christian Kennes and Marıa C. Veiga1.1 Introduction 31.2 Types and sources of air pollutants 3

1.2.1 Particulate matter 51.2.2 Carbon monoxide and carbon dioxide 61.2.3 Sulphur oxides 71.2.4 Nitrogen oxides 71.2.5 Volatile organic compounds (VOCs) 91.2.6 Odours 101.2.7 Ozone 111.2.8 Calculating concentrations of gaseous pollutants 11

1.3 Air pollution control technologies 111.3.1 Particulate matter 111.3.2 Volatile organic and inorganic compounds 121.3.3 Environmentally friendly bioenergy 17

1.4 Conclusions 17References 17

2 Biodegradation and Bioconversion of Volatile Pollutants 19Christian Kennes, Haris N. Abubackar and Marıa C. Veiga2.1 Introduction 192.2 Biodegradation of volatile compounds 20

2.2.1 Inorganic compounds 202.2.2 Organic compounds 21

2.3 Mass balance calculations 242.4 Bioconversion of volatile compounds 25

2.4.1 Carbon monoxide and carbon dioxide 252.4.2 Volatile organic compounds (VOCs) 26

2.5 Conclusions 27References 27

vi Contents

3 Identification and Characterization of Microbial Communities in Bioreactors 31Luc Malhautier, Lea Cabrol, Sandrine Bayle and Jean-Louis Fanlo3.1 Introduction 313.2 Molecular techniques to characterize the microbial communities in bioreactors 32

3.2.1 Quantification of the community members 323.2.2 Assessment of microbial community diversity and structure 343.2.3 Determination of the microbial community composition 393.2.4 Techniques linking microbial identity to ecological function 403.2.5 Microarray techniques 413.2.6 Synthesis 42

3.3 The link of microbial community structure with ecological function in engineeredecosystems 423.3.1 Introduction 423.3.2 Temporal and spatial dynamics of the microbial community structure under

stationary conditions in bioreactors 433.3.3 Impact of environmental disturbances on the microbial community structure

within bioreactors 453.4 Conclusions 47References 47

II BIOREACTORS FOR AIR POLLUTION CONTROL 57

4 Biofilters 59Eldon R. Rene, Marıa C. Veiga and Christian Kennes4.1 Introduction 594.2 Historical perspective of biofilters 594.3 Process fundamentals 604.4 Operation parameters of biofilters 62

4.4.1 Empty-bed residence time (EBRT) 624.4.2 Volumetric loading rate (VLR) 634.4.3 Mass loading rate (MLR) 634.4.4 Elimination capacity (EC) 634.4.5 Removal efficiency (RE) 634.4.6 CO2 production rate (PCO2

) 634.5 Design considerations 64

4.5.1 Reactor sizing 644.5.2 Irrigation system 664.5.3 Leachate collection and disposal 66

4.6 Start-up of biofilters 684.7 Parameters affecting biofilter performance 70

4.7.1 Inlet concentrations and pollutant load 704.7.2 Composition of waste gas and interaction patterns 714.7.3 Biomass support medium 724.7.4 Temperature 754.7.5 pH 784.7.6 Oxygen availability 794.7.7 Nutrient availability 80

Contents vii

4.7.8 Moisture content and relative humidity 814.7.9 Polluted gas flow direction 834.7.10 Carbon dioxide generation rates 834.7.11 Pressure drop 85

4.8 Role of microorganisms and fungal growth in biofilters 874.9 Dynamic loading pattern and starvation conditions in biofilters 894.10 On-line monitoring and control (intelligent) systems for biofilters 93

4.10.1 On-line flame ionization detector (FID) and photo-ionization detector (PID)analysers 93

4.10.2 On-line proton transfer reaction–mass spectrometry (PTR-MS) 944.10.3 Intelligent moisture control systems 944.10.4 Differential neural network (DNN) sensor 95

4.11 Mathematical expressions for biofilters 954.12 Artificial neural network-based models 97

4.12.1 Back error propagation (BEP) algorithm 974.12.2 Important considerations during neural network modelling 994.12.3 Neural network model development for biofilters and specific examples 103

4.13 Fuzzy logic-based models 1054.14 Adaptive neuro-fuzzy interference system-based models for biofilters 1084.15 Conclusions 111References 111

5 Biotrickling Filters 121Christian Kennes and Marıa C. Veiga5.1 Introduction 1215.2 Main characteristics of BTFs 122

5.2.1 General aspects 1225.2.2 Packing material 1235.2.3 Biomass and biofilm 1265.2.4 Trickling phase 1265.2.5 Gas EBRT 1285.2.6 Liquid and gas velocities 129

5.3 Pressure drop and clogging 1305.3.1 Excess biomass accumulation 1305.3.2 Accumulation of solid chemicals 133

5.4 Full-scale applications and scaling up 1345.5 Conclusions 135References 135

6 Bioscrubbers 139Pierre Le Cloirec and Philippe Humeau6.1 Introduction 1396.2 General approach of bioscrubbers 1406.3 Operating conditions 141

6.3.1 Absorption column 1426.3.2 Biodegradation step – activated sludge reactor 143

6.4 Removing families of pollutants 143

viii Contents

6.4.1 Volatile organic compound (VOC) removal 1446.4.2 Odor control 1466.4.3 Sulfur compounds degradation 146

6.5 Treatment of by-products generated by bioscrubbers 1486.6 Conclusions and trends 148References 149

7 Membrane Bioreactors 155Raquel Lebrero, Raul Munoz, Amit Kumar and Herman Van Langenhove7.1 Introduction 1557.2 Membrane basics 156

7.2.1 Types of membranes 1567.2.2 Membrane materials 1597.2.3 Membrane characterization parameters 1597.2.4 Mass transport through the membrane 160

7.3 Reactor configurations 1637.3.1 Flat-sheet membranes 1647.3.2 Tubular configuration membranes 1657.3.3 Membrane-based bioreactors 166

7.4 Microbiology 1667.5 Performance of membrane bioreactors 168

7.5.1 Membrane-based bioreactors 1687.5.2 Bioreactor operation: Influence of the operating parameters 169

7.6 Membrane bioreactor modeling 1707.7 Applications of membrane bioreactors in biological waste-gas treatment 172

7.7.1 Comparison with other technologies 1727.8 New applications: CO2 –NOx sequestration 173

7.8.1 NOx removal 1737.8.2 CO2 sequestration 176

7.9 Future needs 177References 178

8 Two-Phase Partitioning Bioreactors 185Hala Fam and Andrew J. Daugulis8.1 Introduction 1858.2 Features of the sequestering phase – selection criteria 1868.3 Liquid two-phase partitioning bioreactors (TPPBs) 187

8.3.1 Performance 1878.3.2 Mass transfer 1898.3.3 Modeling and design elements 1948.3.4 Limitations and research opportunities 196

8.4 Solids as the partitioning phase 1978.4.1 Rationale 1978.4.2 Performance 1978.4.3 Mass transfer 1988.4.4 Modeling and design elements 1998.4.5 Limitations and research opportunities 200

References 200

Contents ix

9 Rotating Biological Contactors 207R. Ravi, K. Sarayu, S. Sandhya and T. Swaminathan9.1 Introduction 207

9.1.1 Limitations of conventional gas-phase bioreactors 2089.2 The rotating biological contactor 209

9.2.1 Modified RBCs for waste-gas treatment 2109.3 Studies on removal of dichloromethane in modified RBCs 213

9.3.1 Comparison of different bioreactors (biofilters, biotrickling filters, andmodified RBCs) 215

9.3.2 Studies on removal of benzene and xylene in modified RBCs 2169.3.3 Microbiological studies of biofilms 217

References 219

10 Innovative Bioreactors and Two-Stage Systems 221Eldon R. Rene, Marıa C. Veiga and Christian Kennes10.1 Introduction 22110.2 Innovative bioreactor configurations 222

10.2.1 Planted biofilter 22210.2.2 Rotatory-switching biofilter 22310.2.3 Tubular biofilter 22410.2.4 Fluidized-bed bioreactor 22510.2.5 Airlift and bubble column bioreactors 22710.2.6 Monolith bioreactor 22910.2.7 Foam emulsion bioreactor 23110.2.8 Fibrous bed bioreactor 23310.2.9 Horizontal-flow biofilm reactor 234

10.3 Two-stage systems for waste gas treatment 23510.3.1 Adsorption pre-treatment plus bioreactor 23510.3.2 Bioreactor plus adsorption polishing 23710.3.3 UV photocatalytic reactor plus bioreactor 23710.3.4 Bioreactor plus bioreactor 240

10.4 Conclusions 242References 243

III BIOPROCESSES FOR SPECIFIC APPLICATIONS 247

11 Bioprocesses for the Removal of Volatile Sulfur Compounds from Gas Streams 249Albert Janssen, Pim L.F. van den Bosch, Robert C. van Leerdam,and Marco de Graaff11.1 Introduction 24911.2 Toxicity of VOSCs to animals and humans 25011.3 Biological formation of VOSCs 25111.4 VOSC-producing and VOSC-emitting industries 252

11.4.1 VOSCs produced from biological processes 25211.4.2 Chemical processes and industrial applications 25211.4.3 Oil and gas 253

11.5 Microbial degradation of VOSCs 253

x Contents

11.5.1 Aerobic degradation 25311.5.2 Anaerobic degradation 25411.5.3 Degradation via sulfate reduction 25511.5.4 Anaerobic degradation of higher thiols 25511.5.5 Inhibition of microorganisms 256

11.6 Treatment technologies for gas streams containing volatile sulfur compounds 25611.6.1 Biofilters 25611.6.2 Bioscrubbers 258

11.7 Operating experience from biological gas treatment systems 26111.7.1 THIOPAQ process for H2S removal 266

11.8 Future developments 266References 266

12 Bioprocesses for the Removal of Nitrogen Oxides 275Yaomin Jin, Lin Guo, Osvaldo D. Frutos, Marıa C. Veiga and Christian Kennes12.1 Introduction 27512.2 NOx and N2O emissions at wastewater treatment plants (WWTPs) 276

12.2.1 Nitrification 27612.2.2 Denitrification 27612.2.3 Parameters that affect the formation of nitrogen oxides 277

12.3 Recent developments in bioprocesses for the removal of nitrogen oxides 27912.3.1 NOx removal 27912.3.2 N2O removal 285

12.4 Challenges in NOx treatment technologies 28712.5 Conclusions 288References 288

13 Biogas Upgrading 293M. Estefanıa Lopez, Eldon R. Rene, Marıa C. Veiga and Christian Kennes13.1 Introduction 29313.2 Biotechnologies for biogas desulphurization 294

13.2.1 Environmental aspects 29413.2.2 The natural sulphur cycle and sulphur-oxidizing bacteria 29413.2.3 Bioreactor configurations for hydrogen sulphide removal at laboratory scale 29513.2.4 Case studies of biogas desulphurization in full-scale systems 302

13.3 Removal of mercaptans 30613.4 Removal of ammonia and nitrogen compounds 30713.5 Removal of carbon dioxide 30813.6 Removal of siloxanes 30913.7 Comparison between biological and non-biological methods 31113.8 Conclusions 311References 315

Contents xi

IV ENVIRONMENTALLY-FRIENDLY BIOENERGY 319

14 Biogas 321Marta Ben, Christian Kennes and Marıa C. Veiga14.1 Introduction 32114.2 Anaerobic digestion 321

14.2.1 A brief history 32114.2.2 Overview of the anaerobic digestion process 323

14.3 Substrates 32814.3.1 Agricultural and farming wastes 32814.3.2 Industrial wastes 32914.3.3 Urban wastes 33314.3.4 Sewage sludge 333

14.4 Biogas 33414.4.1 Biogas composition 33414.4.2 Substrate influence on biogas composition 335

14.5 Bioreactors 33514.5.1 Batch reactors 33714.5.2 Continuously stirred tank reactor (CSTR) 33714.5.3 Continuously stirred tank reactor with solids recycle (CSTR/SR) 33714.5.4 Plug-flow reactor 33714.5.5 Upflow anaerobic sludge blanket (UASB) 33714.5.6 Attached film digester 33814.5.7 Two-phase digester 338

14.6 Environmental impact of biogas 33814.7 Conclusions 339References 339

15 Biohydrogen 345Bikram K. Nayak, Soumya Pandit and Debabrata Das15.1 Introduction 345

15.1.1 Current status of hydrogen production and present use of hydrogen 34615.1.2 Biohydrogen from biomass: present status 346

15.2 Environmental impacts of biohydrogen production 34615.2.1 Air pollution due to conventional hydrocarbon-based fuel combustion 34615.2.2 Biohydrogen, a zero-carbon fuel as a potential alternative 348

15.3 Properties and production of hydrogen 34815.3.1 Properties of zero-carbon fuel 34815.3.2 Biohydrogen production processes 350

15.4 Potential applications of hydrogen as a zero-carbon fuel 36315.4.1 Transport sector 36315.4.2 Fuel cells 366

xii Contents

15.5 Policies and economics of hydrogen production 37115.5.1 Economics of biohydrogen production 372

15.6 Issues and barriers 37315.7 Future prospects 37415.8 Conclusion 375Acknowledgements 375References 375

16 Catalytic Biodiesel Production 383Zhenzhong Wen, Xinhai Yu, Shan-Tung Tu and Jinyue Yan16.1 Introduction 38316.2 Trends in biodiesel production 384

16.2.1 Reactors 38416.2.2 Catalysts 389

16.3 Challenges for biodiesel production at industrial scale 39316.3.1 Economic analysis 39316.3.2 Ecological considerations 393

16.4 Recommendations 39416.5 Conclusions 395References 395

17 Microalgal Biodiesel 399Hugo Pereira, Helena M. Amaro, Nadpi G. Katkam, Luısa Barreira,A. Catarina Guedes, Joao Varela and F. Xavier Malcata17.1 Introduction 39917.2 Wild versus modified microalgae 40217.3 Lipid extraction and purification 404

17.3.1 Mechanical methods 40517.3.2 Chemical methods 406

17.4 Lipid transesterification 40717.4.1 Acid-catalyzed transesterification 40817.4.2 Base-catalyzed transesterification 40817.4.3 Heterogeneous acid/base-catalyzed transesterification 41017.4.4 Lipase-catalyzed transesterification 41017.4.5 Ionic liquid-catalyzed reactions 411

17.5 Economic considerations 41217.5.1 Competition between microalgal biodiesel and biofuels 41217.5.2 Main challenges to biodiesel production from microalgae 41317.5.3 Economics of biodiesel production 414

17.6 Environmental considerations 41517.6.1 Uptake of carbon dioxide 41617.6.2 Upgrade of wastewaters 41617.6.3 Management of microalgal biomass 417

17.7 Final considerations 418

Contents xiii

17.7.1 Current state 41817.7.2 Future perspectives 418

Acknowledgements 420References 420

18 Bioethanol 431Johan W. van Groenestijn, Haris N. Abubackar, Marıa C. Veiga and Christian Kennes18.1 Introduction 43118.2 Fermentation of lignocellulosic saccharides to ethanol 432

18.2.1 Raw materials 43218.2.2 Pretreatment 43418.2.3 Production of inhibitors 43918.2.4 Hydrolysis 43918.2.5 Fermentation 440

18.3 Syngas conversion to ethanol – biological route 44118.3.1 Sources of carbon monoxide 44118.3.2 The Wood–Ljungdahl pathway involved in the bioconversion of carbon

monoxide 44518.3.3 Parameters affecting the bioconversion of carbon monoxide to ethanol 446

18.4 Demonstration projects 45018.5 Comparison of conventional fuels and bioethanol (corn, cellulosic, syngas) on air

pollution 45118.6 Key problems and future research needs 45518.7 Conclusions 456Acknowledgements 456References 456

V CASE STUDIES 465

19 Biotrickling Filtration of Waste Gases from the Viscose Industry 467Andreas Willers, Christian Dressler and Christian Kennes19.1 The waste-gas situation in the viscose industry 467

19.1.1 The viscose process 46719.1.2 Overview of emission points 46819.1.3 Technical solutions to treat the emissions 46919.1.4 Potential to use biotrickling filters in the viscose industry 470

19.2 Biological CS2 and H2S oxidation 47119.3 Case study of biological waste-gas treatment in the casing industry 472

19.3.1 Products from viscose 47219.3.2 Process flowsheet of fibre-reinforced cellulose casing (FRCC) 47319.3.3 Alternatives for biotrickling filter configurations 47319.3.4 Characteristics of the CaseTech plant 47519.3.5 Description of the BioGat installation 47519.3.6 Performance of the BioGat process 475

xiv Contents

19.4 Conclusions 484References 484

20 Biotrickling Filters for Removal of Volatile Organic Compoundsfrom Air in the Coating Sector 485Carlos Lafita, F. Javier Alvarez-Hornos, Carmen Gabaldon,Vicente Martınez-Soria and Josep-Manuel Penya-Roja20.1 Introduction 48520.2 Case study 1: VOC removal in a furniture facility 486

20.2.1 Characterization of the waste-gas sources 48620.2.2 Design and operation of the system 48720.2.3 Performance data 48820.2.4 Economic aspects 490

20.3 Case study 2: VOC removal in a plastic coating facility 49120.3.1 Characterization of the waste-gas sources 49220.3.2 Design and operation of the system 49220.3.3 Performance data 49320.3.4 Economic aspects 495

Acknowledgements 496References 496

21 Industrial Bioscrubbers for the Food and Waste Industries 497Pierre Le Cloirec and Philippe Humeau21.1 Introduction 49721.2 Food industry emissions 498

21.2.1 Identification and quantification of waste-gas emissions 49821.2.2 Choice of the technology 49821.2.3 Design and operating conditions 50021.2.4 Performance of the system 503

21.3 Bioscrubbing treatment of gaseous emissions from waste composting 50321.3.1 Waste-gas emissions: nature, concentrations, and flow 50321.3.2 Choice of the gas treatment process 50421.3.3 Design and operating conditions 50521.3.4 Gas collection system 50721.3.5 Gas treatment system 50821.3.6 Performance of the overall system 509

21.4 Conclusions and perspectives 510References 510

22 Desulfurization of biogas in biotrickling filters 513David Gabriel, Marc A. Deshusses and Xavier Gamisans22.1 Introduction 51322.2 Microbiology and stoichiometry of sulfide oxidation 514

22.2.1 Microbiology of sulfide oxidation 51422.2.2 Stoichiometry of sulfide biological oxidation 515

22.3 Case study background and description of biotrickling filter 517

Contents xv

22.3.1 Site description 51722.3.2 Biotrickling filter design 517

22.4 Operational aspects of the full-scale biotrickling filter 51922.4.1 Start-up and biotrickling filter performance 51922.4.2 Facing operational and design challenges 520

22.5 Economic aspects of desulfurizing biotrickling filters 522References 522

23 Full-Scale Biogas Upgrading 525Jort Langerak, Robert Lems and Erwin H.M. Dirkse23.1 Introduction 52523.2 Case 1: Zalaegerszeg, PWS system with car fuelling station 526

23.2.1 Biogas composition and biomethane requirements at Zalaegerszeg 52623.2.2 Plant configuration at Zalaegerszeg 526

23.3 Case 2: Zwolle, PWS system with gas grid injection 52923.3.1 Biogas composition and biomethane requirements at Zwolle 53123.3.2 Plant configuration at Zwolle 531

23.4 Case 3: Wijster, PWS system with gas grid injection 53423.4.1 Biogas composition and biomethane requirements at Wijster 53423.4.2 Plant configuration at Wijster 534

23.5 Case 4: Poundbury, MS system with gas grid injection 53623.5.1 Biogas composition and biomethane requirements at Poundbury 53723.5.2 Plant configuration at Poundbury 537

23.6 Configuration overview and evaluation 53923.7 Capital and operational expenses 540

23.7.1 Zalaegerszeg 54023.7.2 Zwolle 54123.7.3 Wijster 54123.7.4 Poundbury 54123.7.5 Overview table of capital and operating expenses 541

23.8 Conclusions 542References 543

Index 545

List of Contributors

Haris N. Abubackar, Department of Chemical Engineering, University of La Coruna, Spain

Marta Ben, Department of Chemical Engineering, University of La Coruna, Spain

F. Javier Alvarez-Hornos, Department of Chemical Engineering, University of Valencia, Spain

Helena M. Amaro, CIIMAR/CIMAR – Interdisciplinary Centre of Marine and Environmental Research,University of Porto, Portugal and ICBAS – Institute of Biomedical Sciences Abel Salazar, Universityof Porto, Portugal

Luısa Barreira, CCMAR – Centre of Marine Sciences, University of Algarve, Portugal

Sandrine Bayle, Ecole des Mines d’Ales, Laboratoire Genie de l’Environnement Industriel, France

Lea Cabrol, Ecole des Mines d’Ales, Laboratoire Genie de l’Environnement Industriel, France andEscuela de Ingenierıa Bioquımica, Chile

Debabrata Das, Indian Institute of Technology Kharagpur, India

Andrew J. Daugulis, Department of Chemical Engineering, Queen’s University, Canada

Marco de Graaff, Wetsus, Centre of Excellence for Sustainable Water Technology, WageningenUniversity, The Netherlands

Marc A. Deshusses, Department of Civil and Environmental Engineering, Duke University, USA

Erwin H.M. Dirkse, DMT Environmental Technology, The Netherlands

Christian Dressler, Lenzing Technik GmbH, Austria

Hala Fam, Department of Chemical Engineering, Queen’s University, Canada

Jean-Louis Fanlo, Ecole des Mines d’Ales, Laboratoire Genie de l’Environnement Industriel, France

Osvaldo D. Frutos, Department of Chemical Engineering, University of La Coruna, Spain

Carmen Gabaldon, Department of Chemical Engineering, University of Valencia, Spain

David Gabriel, Department of Chemical Engineering, Universitat Autonoma de Barcelona, Spain

Xavier Gamisans, Department of Mining Engineering and Natural Resources, Universitat Politecnica deCatalunya, Spain

A. Catarina Guedes, CIIMAR/CIMAR – Interdisciplinary Centre of Marine and EnvironmentalResearch, University of Porto, Portugal

Ling Guo, Department of Chemical Engineering, University of La Coruna, Spain

Philippe Humeau, Centre Scientifique et Technique du Batiment (CSTB), Aquasim, France

Albert J.H. Janssen, Sub-department of Environmental Technology, Wageningen University,The Netherlands

Yaomin Jin, Department of Chemical Engineering, University of La Coruna, Spain

Nadpi G. Katkam, CCMAR – Centre of Marine Sciences, University of Algarve, Portugal andITQB – Institute of Chemical and Biological Technology, New University of Lisbon, Portugal

Christian Kennes, Department of Chemical Engineering, University of La Coruna, Spain

Amit Kumar, Department of Sustainable Organic Chemistry and Technology, Gent University, Belgium

xviii List of Contributors

Carlos Lafita, Department of Chemical Engineering, University of Valencia, Spain

Jort Langerak, DMT Environmental Technology, The Netherlands

Raquel Lebrero, Department of Chemical Engineering and Environmental Technology, ValladolidUniversity, Spain

Pierre Le Cloirec, Ecole Nationale Superieure de Chimie de Rennes (ENSCR), France

Robert Lems, DMT Environmental Technology, The Netherlands

M. Estefanıa Lopez, Department of Chemical Engineering, University of La Coruna, Spain

F. Xavier Malcata, CIIMAR/CIMAR – Interdisciplinary Centre of Marine and Environmental Research,University of Porto, Portugal

Luc Malhautier, Ecole des Mines d’Ales, Laboratoire Genie de l’Environnement Industriel, France

Vicente Martınez-Soria, Department of Chemical Engineering, University of Valencia, Spain

Raul Munoz, Department of Chemical Engineering and Environmental Technology, ValladolidUniversity, Spain

Bikram K. Nayak, Indian Institute of Technology Kharagpur, India

Soumya Pandit, Indian Institute of Technology Kharagpur, India

Josep-Manuel Penya-Roja, Department of Chemical Engineering, University of Valencia, Spain

Hugo Pereira, CCMAR – Centre of Marine Sciences, University of Algarve, Portugal

R. Ravi, Department of Chemical Engineering, Annamalai University, Chidambaram, India

Eldon R. Rene, Department of Chemical Engineering, University of La Coruna, Spain

S. Sandhya, National Environmental Engineering Research Institute, Neeri Zonal Laboratory, India

K. Sarayu, National Environmental Engineering Research Institute, Neeri Zonal Laboratory, India

T. Swaminathan, Chemical Engineering Department, Indian Institute of Technology Madras, India

Shan-Tung Tu, School of Mechanical and Power Engineering, East China University of Science andTechnology, Shanghai, China

Pim L.F. van den Bosch, Sub-department of Environmental Technology, Wageningen University,The Netherlands

Johan W. van Groenestijn, TNO, Zeist, The Netherlands

Herman Van Langenhove, Department of Sustainable Organic Chemistry and Technology, GentUniversity, Belgium

Robert C. van Leerdam, Sub-department of Environmental Technology, Wageningen University,The Netherlands

Joao Varela, CCMAR – Centre of Marine Sciences, University of Algarve, Portugal

Marıa C. Veiga, Department of Chemical Engineering, University of La Coruna, Spain

Zhenzhong Wen, School of Energy and Power Engineering, University of Shanghai for Science andTechnology, Shanghai, China

Andreas Willers, CaseTech GmbH, Bomlitz, Germany

Jinyue Yan, School of Chemical Science and Engineering, Royal Institute of Technology, Stockholm,and School of Sustainable Development of Society and Technology, Malardalen University, VasterasSweden

Xinhai Yu, School of Mechanical and Power Engineering, East China University of Science andTechnology, Shanghai, China

Preface

Planet Earth is made up of three major natural compartments: air, water and soil. Pollution of thosecompartments will negatively affect human beings, as well as other living organisms and ecosystems.Therefore, air pollution has become an ever-increasing concern over recent decades. The metabolic activ-ity and healthy development of most mammals relies on the availability of clean air. Oxygen – one ofthe major components of air – is necessary in the breathing process. The presence of pollutants in theatmosphere, such as carbon monoxide, may inhibit the role of oxygen in metabolic processes, while otherpollutants, either organic or inorganic, may exhibit toxic and carcinogenic properties in humans. Plants,microorganisms, as well as buildings are all susceptible to the presence and undesirable effects of volatilepollutants. Two major ways to reduce and control such pollution problems are, on one side, the devel-opment of treatment technologies allowing the removal of pollutants from the atmosphere or even fromanaerobic gases, and, on the other side, the use of cleaner (bio)fuels. This book focuses on biotechnologi-cal alternatives to deal with air pollution problems based on the optimization of bioreactors for pollutioncontrol (as end-of-pipe treatment technologies) and on the development of biofuels with reduced environ-mental impact (as a more preventive alternative). This is the first reference work offering a comprehensiveoverview of those different aspects.

In Part I, fundamental and microbiological aspects are addressed. Chapter 1 describes the major differenttypes of volatile pollutants, their characteristics and environmental impact, as well as the major emittingsources. Biological and nonbiological treatment technologies are briefly discussed as well as some aspectsrelated to bioenergy. Chapter 2 discusses biodegradation and biotransformation processes. It first deals withthe main biodegradation processes of pollutants described in Chapter 1, then focuses on the possibilitiesof bioconversion – rather than biodegradation – of some of those volatile pollutants to useful products,which is a quite new approach in the field of air pollution and could improve cost-effectiveness. Chapter 3addresses basic microbiological aspects useful in the field of air pollution prevention and control. Molec-ular techniques and methods for the quantification of microbial populations and microbial diversity areexplained.

Part II gives an overview of all major bioreactors currently available for air pollution control. It doeslargely focus on bioreactors that are already being used in field applications and have proven their efficiency,but it also describes some bioreactors that are still in the development stage and that have, so far, beenstudied at only the laboratory- or pilot- scale. Biofilters, which represent one of the most extensivelyused bioreactors for air pollution control, are described in details in Chapter 4, focusing largely on recentinformation and data that have not previously been reviewed. Chapter 5 explains the fundamentals ofbiotrickling filters and offers an overview of recent aspects studied and reported in the literature overthe past decade, as well as information on full-scale reactors based on the authors’ practical experience.Bioscrubbers, detailed in Chapter 6, are hybrid processes combining a scrubber, as a first stage, with abioreactor, in a second stage. Important aspects of both the biological and nonbiological steps are described.Membrane bioreactors (Chapter 7) and two-phase partitioning bioreactors (Chapter 8) have not yet beenimplemented in full-scale applications for waste-gas treatment, contrary to the bioreactors explained inChapters 4–6. The basic principles of operation of those systems are detailed as well as aspects relatedto different membranes and liquid- and solid-partitioning phases that can be used in those applications.A very limited number of pilot- and full-scale plants have been built in the case of rotating biological

xx Preface

contactors (RBCs) (Chapter 9). So far, the latter are not very popular in the field of air pollution control. Anoverview of recent research on RBCs is presented. Chapter 10 deals, on one side, with two-stage and hybridsystems and, on the other side, with innovative bioreactors. Innovative systems have mainly been studiedat the research and/or early development stage. However, hybrid and two-stage bioreactors have alreadybeen used in the field. They allow tackling challenging aspects that cannot easily be solved with moreconventional systems. They may present some advantages for specific applications where the performancereached in single reactors would not be sufficient enough. Multistage processes may combine severalbiological reactors or may, otherwise, combine both biological and nonbiological techniques, similarly asin the case of bioscrubbers described in Chapter 6.

Part III focuses on two specific applications in Chapters 11 and 12, namely, the removal of sulphurcompounds and nitrogen compounds from gases, mainly SOx and other organic or inorganic sulphurcompounds (Chapter 11) as well as NOx (Chapter 12).

Biofuels production and their environmental impact represent the topics of Part IV. Several different(bio)fuels are currently being considered as interesting alternatives to the conventional energy sourcesproduced in fossil fuel industries. Not all different known biofuels could be included in this book; but thebest known and most common ones are described, and whenever possible we offer information on theirenvironmental impact, mainly in terms of air pollution, as well as data on economic aspects. In many cases,biofuels can be obtained from waste, pollutants or renewable resources. Biogas production is addressed inChapter 14. Different feedstock and bioreactor configurations suitable for biogas production are described,as well as that biofuel’s environmental impact. Chapter 15 deals with biohydrogen production and therole of bacteria and algae in different biotransformation reactions for hydrogen production, addressingmainly photo-fermentation and dark fermentation technologies. Chapters 16 and 17 both focus on biodiesel,obtained either through catalytic processes (Chapter 16) or through bioprocesses by means of microalgae(Chapter 17). The last chapter of Part IV describes cellulosic bioethanol production through pre-treatmentand subsequent fermentation of lignocellulosic material, and on the anaerobic bioconversion of waste gasesand synthesis gas into ethanol. Information is also given on demonstration projects and recent full-scaleapplications, as well as on economic and environmental aspects.

Part V concludes the book with applied information and the description of some case studies. Thenumber of case studies presented here had to be limited for this one-volume book to remain a reasonablelength. Pilot-scale and full-scale bioreactors are described in details.

Finally, Christian Kennes would like to take advantage in this introduction to thank the Wiley team forinviting him to prepare this book and for their very efficient assistance and support in this joint endeavour.Acknowledgments are also due to the different agencies and industries collaborating in our research on airpollution control and bioenergy; and more specifically to the Spanish Ministry of Science and Innovation(Project CTM2010-15796 to CK) and European FEDER funds for providing financial support. Publicationof this reference work would not have been possible without the efficient contribution and thoroughcollaboration of many colleagues and friends who agreed to write excellent chapters.

Christian KennesMarıa C. Veiga

La Coruna, Spain, 2012

Part IFundamentals and Microbiological Aspects

1Introduction to Air Pollution

Christian Kennes and Marıa C. Veiga

Department of Chemical Engineering, University of La Coruna, Spain

1.1 Introduction

This book describes the different biodegradation processes and bioreactors available for air pollution controlas well as other alternatives for reducing air pollution, mainly by using more environmentally friendly fuelsand biofuels, such as ethanol, hydrogen, methane or biodiesel. Only the bioreactors and (bio)fuels mostwidely used or studied over the past decade are reviewed in this book. Bioreactors, for which not muchsignificant research or many new developments have occurred over the past decade, have been describedin other book chapters [1] and are not included in this book.

1.2 Types and sources of air pollutants

Two major groups of pollutants can be considered in terms of air pollution: particulate matter and gaseouspollutants. The latter may be subdivided into volatile organic compounds (VOCs) and volatile inorganiccompounds (VICs). The best available treatment technology will depend on the composition and othercharacteristics of the emissions to be treated. The most significant contaminants and their origin are shownin Figure 1.1, in terms of emission percentages, in 2006 by source category for the 27 member states ofthe European Union. The member states are (year of entry in brackets) Austria (1995), Belgium (1952),Bulgaria (2007), Cyprus (2004), Czech Republic (2004), Denmark (1973), Estonia (2004), Finland (1995),France (1952), Germany (1952), Greece (1981), Hungary (2004), Ireland (1973), Italy (1952), Latvia(2004), Lithuania (2004), Luxembourg (1952), Malta (2004), The Netherlands (1952), Poland (2004),Portugal (1986), Romania (2007), Slovakia (2004), Slovenia (2004), Spain (1986), Sweden (1995) and theUnited Kingdom (1973).

Air Pollution Prevention and Control: Bioreactors and Bioenergy, First Edition. Edited by Christian Kennes and Marıa C. Veiga.c© 2013 John Wiley & Sons, Ltd. Published 2013 by John Wiley & Sons, Ltd.

4 Air Pollution Prevention and Control

From left to right:

→ Stationary sources: Combustion processes

→ Stationary sources: Industrial, non combustion processes

→ Mobile sources: Road and nonroad origin

→ Waste disposal

→ Miscellaneous (including agriculture)

P.M 2.5

CO

NH3

VOC

Air

pol

luta

nt

NOx

SO2

0 10 20 30 40 50

50.6 20.6 18.7 6.6

0.4

3.5

43.7

0.5

2.7

12.1 52.7

42.8

90.2 6.4 3.25

4.3 51.5

29.9 1 4.3

0.2 1.2

0.050.1

1.9 93.5

1.4

10 42.6 3.3

Percent of emission60 70 80 90 100

Figure 1.1 Distribution of EU-27 total emission estimates for different pollutants, by source category, in 2006.

Table 1.1 and Table 1.2 compare the annual emission estimates for both the European Union (EU-27) andthe United States, considering anthropogenic land-based sources only [2]. Natural sources of emission andother possible sources such as navigation have not been included, as comparable information for Europe(EU-27) and the United States often could not be obtained. Although some recent data were sometimesnot available for the United States and needed to be extrapolated [2], it is still possible and accurate toconclude that the results follow in both cases a similar trend for the different pollutants, in terms of both therelative total emission of each pollutant and the source of pollution. However, some differences may stillbe found when analysing the tables in detail, mainly in the case of carbon monoxide (CO) emission. Forexample, in Europe, almost 43% of CO emissions come from mobile sources (vehicles and transportationin general), while this represents as much as 85% in the United States. Conversely, CO from combustionsources represents about 44% in Europe, while it is only 7% in the United States.

Introduction to Air Pollution 5

Table 1.1 2006 emission estimates for different pollutants, by source category, in the European Union (EU-27)(106 kg yr−1). Reprinted under the terms of the STM agreement from [2] Copyright (2012) Elsevier Ltd.

Category CO NH3 VOC NOx PM2.5 SO2

Stationary sources: combustion 22 979 33 1 831 7 175 1 619 13 868Stationary sources:noncombustion 5 254 167 7 954 721 660 980Mobile sources 22 421 86 4 511 8 642 598 501Waste treatment and disposal 1 726 121 148 36 114 14Miscellaneous (mainly agriculture) 224 5 885 657 197 211 8Total 52 604 6 292 15 101 16 771 3 202 15 371

% of total 48.1 5.8 13.8 15.3 2.9 14.1

Table 1.2 2006 emission estimates for different pollutants, by source category, in United States (106 kg yr−1).Reprinted under the terms of the STM agreement from [2] Copyright (2012) Elsevier Ltd.

Category CO NH3 VOC NOx PM2.5 SO2

Stationary sources: combustion 5 619 63 843 6 206 1 150 12 026Stationary sources:noncombustion 3 009 205 7 960 1 724 758 2 708Mobile sources 69 735 291 6 913 10 810 962 499Waste treatment and disposal 1 416 25 375 131 241 27Miscellaneous (mainly agriculture) 1 949 3 679 495 61 561 20Total 81 728 4 263 16 586 18 932 3 672 15 280

% of total 58.2 3.0 11.8 13.5 2.6 10.9

1.2.1 Particulate matter

Particulate matter can be defined as a small solid or liquid mass in suspension in the atmosphere. Pri-mary particles are directly emitted from a polluting source, while secondary particles are formed in theatmosphere as a result of reactions or interactions between pollutants and/or compounds present in theatmosphere, usually volatile organic compounds, nitrogen oxides or sulphur oxides as well as water. A waterdroplet of acid rain, carrying sulphuric acid (H2SO4) or nitric acid (HNO3) produced from nitrogen oxides(NOx) or sulphur oxides (SOx), would be classified as particulate matter. Different terms can be used forparticles (e.g. dust, smoke, mist or aerosol) depending on their nature and characteristics.

Although many particles are not spherical, for the sake of simplicity and for engineering calculations,nonspherical particles are often assimilated to spheres of the same volume as the original particle. Particlesize, then, refers to the corresponding particle diameter.

Typically, the size (diameter) of particulate matter found in polluted air or waste gases may vary betweenabout 10−2 μm and a few hundreds of micrometres (10+2 μm), although smaller and larger particles mayalso be found. Larger particles do, however, settle quite fast, and in that way are quickly eliminatedfrom the atmosphere. In order to give an idea of the scale, 10−2 μm is a common size for viruses, whilecoal particles, flour or cement dust may be around 10+2 μm. The sizes of the latter may, however, vary

6 Air Pollution Prevention and Control

considerably, between only a few micrometres and about 1 mm. The same is true for water droplets, forexample mist or raindrops, with sizes ranging between a few micrometres up to more than 1 mm. Particlesof 10μm are considered large particles. Particulate matter is classified as PM10 for sizes up to 10μm, andPM2.5 for smaller sizes up to 2.5μm.

The effect of particles on health is more important in the case of smaller particles, for instance thosebelow 2.5μm, as they will more easily reach the lungs than larger particles. Some particles may carry heavymetals and carcinogenic molecules. They can also cause disorders of the respiratory system, asthma, bron-chitis and even heart problems. Besides, particles can reduce visibility and be involved in acid precipitations,or acid rain , described later in this chapter.

1.2.2 Carbon monoxide and carbon dioxide

According to data of the European Environment Agency and the US Environmental Protection Agency(EPA), the highest emission of gaseous pollutants to the atmosphere corresponds to emissions of CO, inboth the European Union and the United States (Table 1.1 and Table 1.2). Close to 50%, or somewhat more,of the total anthropogenic emission of pollutants corresponds to CO. Large amounts may be produced bynatural sources as well. On average, mobile sources account for about 85% of the total CO emissions in theUnited States. It reaches 42.6% in Europe; another 43.7% come from combustion processes in stationarysources (Figure 1.1). Considering that a large part of mobile sources are vehicles such as cars and trucks,it becomes obvious that CO pollution will be more significant in urban areas. As mentioned, the secondlargest source of CO emission, after motor vehicle exhaust, corresponds to stationary combustion processesand other industrial production processes. Its main origin is the incomplete combustion of fossil fuels orother materials such as wood. Combustion is the result of a reaction between oxygen and a fuel. Carbondioxide, water and heat will be produced if the reaction is complete and if the fuel contains only carbon,hydrogen and, eventually, oxygen atoms, such as in the example of methane (a major chemical present innatural gas):

CH4 + 2 O2 → 2 H2O + CO2 (1.1)

Carbon monoxide, instead of carbon dioxide, will be formed when the combustion is not complete, asshown in this reaction:

CH4 + 1.5 O2 → 2 H2O + CO (1.2)

Several reasons may be involved in this incomplete reaction. The most important ones are the amountof available oxygen, temperature, reaction time and turbulence. The theoretical amount of oxygen neededfor complete combustion can be calculated from the stoichiometric equation. However, some excess airis generally recommended for ensuring complete oxidation, but not too much, since excess air needs tobe heated as well. Increasing the temperature and residence time in the combustor will be favourable tocomplete combustion, as well as increasing turbulence in order to achieve intimate mixing between theoxygen and fuel.

Carbon monoxide is not of significant concern in terms of its impact on the environment, but it isflammable and, above all, highly toxic when inhaled. It is an odourless and colourless gas. Therefore,its presence is difficult to detect in closed environments. Prolonged exposure to concentrations above50–100 ppmv will cause fatigue, nausea and headache, while several hours of exposure to concentrationsexceeding 400–500 ppmv will gradually lead to dizziness and death. Carbon monoxide combines withhaemoglobin (Hb) in the blood and in that way prevents haemoglobin from transporting oxygen from therespiratory organs to the tissues. The affinity between CO and Hb is much stronger than that between Hband oxygen.

Introduction to Air Pollution 7

Similarly to CO, the major source of carbon dioxide (CO2) is combustion. It is only recently that CO2has been considered a compound of environmental concern. Pollutants such as CO2, methane and nitrogenoxides are all greenhouse gases, supposed to play a key role in global temperature changes. The averageresidence time of CO2 at concentrations typically found in the atmosphere is about 15 years, while it isabout 10 weeks for the much more reactive CO molecule. The concept of residence time of a species inthe atmosphere is similar to the residence time of a molecule in a continuous reactor. It is the average timethat species spends in the atmosphere before disappearing, for example through chemical or photochemicalreactions. Such difference in residence time between CO and CO2 justifies the negligible increase of theCO concentration in the air over the past century compared to CO2. Actually, one major product formedfrom atmospheric CO is CO2. The normal concentration of CO2 in nonpolluted air currently is around380 ppmv, whereas it hardly reached 300 ppmv a century ago.

1.2.3 Sulphur oxides

Sulphur oxides (SOx) include both sulphur dioxide (SO2) and sulphur trioxide (SO3). Sulphur dioxideappears in larger amounts than SO3 in combustion gases and is largely released during the combustion offossil fuels, mainly coal, in stationary sources, according to the following equations:

S + O2 → SO2 (1.3)

SO2 + 0.5 O2 → SO3 (1.4)

As shown in Figure 1.1, stationary combustion processes represent by far the major source of SO2,with around either 80% or 90% of the total SOx emissions, respectively, in the United States and EU-27. The average residence time of SO2 in the atmosphere is about 5–6 weeks. That pollutant is largelygenerated at electric power plants. Its concentration in combustion gases will depend on the amount ofsulphur present in the original fuel, which usually does not exceed 3–4% by weight but may occasionallyreach 10%. Oil does, in most cases, contain higher amounts of sulphur than coal, while sulphur content isbasically negligible in natural gas. Part of that sulphur may be removed from the fuel to reduce emissionsduring combustion.

In terms of environmental impact, SO2 can react with moisture in the air to form H2SO4, leading toacid precipitation commonly known as acid rain . In terms of health effects, SO2 can cause respiratorydisorder and lung diseases.

A small amount of the SO2 formed during combustion may be further oxidized to SO3, usually notmore than 5%. Its concentration will increase at higher temperature and in the presence of excess oxygen.SO3 has a much higher corrosion potential than SO2. It is important to prevent its condensation in theplants. Sulphur trioxide may react with water vapour to produce H2SO4. Besides, SO3 has been reportedto be 10 times more toxic than SO2, mainly for the respiratory system [3].

1.2.4 Nitrogen oxides

Among the different oxides of nitrogen (nitric oxide (NO), nitrogen dioxide (NO2), nitrate (NO3), nitrousoxide (N2O), dinitrogen trioxide (N2O3), dinitrogen tetroxide (N2O4) and dinitrogen pentoxide (N2O5)), thesymbol NOx refers to the sum of NO and NO2 which are considered to be the major relevant contaminantsof that group in the atmosphere. NO and NO2 have average residence times in the air close to one day.Other oxides of nitrogen generally appear only at very low concentrations in NOx-polluted environments.On reaction with atmospheric moisture, NOx form small particles. The environmental impact of N2O hasalso been discussed, although, for historical reasons, that compound is not included in the group of NOx as

8 Air Pollution Prevention and Control

such. N2O is a major greenhouse gas, similarly to methane and CO2, but with a global warming potentialalmost 300 times higher than that of CO2. The global warming potential of a pollutant is an estimation ofits ability to trap heat or infrared radiation reflected by the Earth’s surface. Agriculture is a major source ofanthropogenic N2O emissions to the atmosphere, through nitrification of ammonium-containing fertilizersand animal waste or denitrification of NO3 in soils. Contrary to NOx, N2O is not directly a product offuel combustion.

NOx react with hydrocarbons and oxygen in the presence of ultraviolet (UV) radiation to producephotochemical smog, mainly in urban areas. They can cause eye and skin irritation and have adverseeffects on the respiratory system and on plants. In the atmosphere, NO generated during combustion willeventually be converted to NO2. Besides, NO2 reacts with the hydroxyl radical from water to form HNO3.It is then eliminated from the atmosphere by either dry deposition or wet deposition, resulting in the lattercase in acid rain , as summarized in the following reactions:

NO2 + OH• → HNO3 (1.5)

As shown in the reactions in Equations (1.6), (1.7) and (1.8), NO2 leads to the formation of unwantedground-level ozone, in the presence of UV light and volatile organic compounds, in the lower atmosphere.The reactions are temperature dependent, and more ozone is detected in the air at higher temperature (i.e.during the day and in the summer period).

NO2 + hν → NO + O• (1.6)

O• + O2 → O3 (1.7)

O3 + NO → NO2 + O2 (1.8)

Part of the ozone formed from NO2 is removed through a reaction of O3 with NO. This suggests that othermechanisms or compounds must be involved in ozone accumulation in the atmosphere. It will be shown,in Section 1.2.5, that VOCs also play a key role in the overall process.

As much as about 90% of NOx are emitted into the atmosphere during combustion processes, fromeither mobile sources or stationary sources. Nitrogen oxides are formed from both nitrogen naturallypresent in combustion air (in which case it is called thermal NOx ) and nitrogen compounds found in thefuels. The reaction between nitrogen and oxygen is significant only at high temperatures. The influenceof temperature on the rate of NOx formation is, however, highly variable and depends on the source ofnitrogen. Its formation may also sometimes depend on the involvement of hydrocarbons in the reaction.Depending on its origin, fuel oil generally does not contain more than 0.5% nitrogen by weight. Conversely,coal may contain up to 2–3% nitrogen by weight, where it is mainly combined with carbon in the form ofpolycyclic aromatic rings. Those C—N bonds are more stable than C—C bonds and need high temperaturesto be converted to NOx. It was mentioned in this chapter that natural gas contains hardly any sulphur.The same is true for nitrogen. Natural gas is thus a quite clean fuel in terms of NOx and SOx emissions.Besides, natural gas emits virtually no particulate matter compared to coal and oil. The products of itscombustion are mainly water vapour and CO2, if complete oxidation takes place. It is estimated that theworld would run out of coal in about 200–300 years based on current consumption estimations, while thesources of oil and natural gas would presumably get exhausted before the end of this century. It is worthmentioning that the use of hydrogen as a source of energy would theoretically not produce any NOx,according to the following reaction:

H2 + O2 → H2O (1.9)

However, this is generally not totally true in practice. In the presence of air, hydrogen may even producemore NOx than during natural gas combustion, as a result of the reaction involving nitrogen and oxygennaturally present in air.