the effect of anaerobic treatment of pulp mill effluents on reactor performance and granular sludge

226 Pages·2015·3.9 MB·English

THE EFFECT OF ANAEROBIC TREATMENT OF PULP
MILL EFFLUENTS ON REACTOR PERFORMANCE AND
GRANULAR SLUDGE
by
MINQING IVY YANG
A thesis submitted in conformity with the requirements
for the degree of Doctor of Philosophy
Department of Chemical Engineering and Applied Chemistry
University of Toronto
© Copyright by Minqing Ivy Yang 2015
The Effect of Anaerobic Treatment of Pulp Mill Effluents on
Reactor Performance and Granular Sludge
Minqing Ivy Yang
Doctor of Philosophy
Department of Chemical Engineering and Applied Chemistry
University of Toronto
2015

ABSTRACT
Pulp mill wastewaters contain high concentrations of organic compounds that can be
partially converted into methane. Granulation of sludge is the key to successful treatment of
pulp mill effluents in high rate anaerobic reactors. This research focused on the anaerobic
treatment of a high strength pulp mill alkaline effluent from sulphite pulping (AE) of softwood
chips, which was characterized by rich COD content and relatively high concentrations of resin
acids and long-chain fatty acids (RFAs) known to be compounds inhibitory to methanogens.
Two continuous reactor experiments were conducted to study the treatment of this softwood AE.
In the first experiment, different concentrations of AE were treated for one month in four
reactors. In the second experiment, increasing loadings of AE were added to the test reactor over
a nine-month period.
The negative impact of the addition of AE on reactor performance and granulation was
confirmed, shown as poorer organic removals, lower biogas production, and smaller and weaker
granules in the AE sludge. Larger amounts of RFAs (>50mg RFAs / g TSS sludge) were found
to associate with the sludge solids receiving a high AE loading, with palmitic acid being the
most dominant RFA. RFA loadings were found to be significantly negatively correlated to the
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biogas production. Therefore, RFAs were proposed to play an important role in the negative
impact of AE. Microbial community analysis using pyrotag sequencing of amplified 16S rRNA
genes from various samples collected from the two studies revealed that the communities of the
sludge treating AE were very different than those of the AE-free sludge. In terms of the
organisms affected by the addition of AE, Oscillospira was significantly positively correlated to
AE loadings. The sludge treating AE also contained significantly lower percentages of
methanogens. Furthermore, no clear sign of sludge acclimating to AE with enhanced biogas
production was found. It is recommended that AE should be pretreated to reduce its toxic effect
and to achieve greater COD removals toward higher biogas production.
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ACKNOWLEDGEMENTS
I am using this opportunity to express my gratitude to everyone who supported me
throughout the course of this Ph.D. project. I would like to express my special appreciation and
thanks to:
• Professor D. Grant Allen and Professor Elizabeth A. Edwards, my tremendous mentors,
for their supervision, advice, guidance, encouragement and patience.
• Professor Bradley A. Saville and Professor Emma Master, my committee members, for
their helpful advice and suggestions
• Professor Ramin Farnood for offering being my additional faculty member in my
departmental oral examination
• Endang Susilawati, Weijun Gao, Christina Heidorn, Joan Chen, Mary Butera, Leticia
Gutierrez, Pauline Martini, Julie Mendonca, Phil Milczarek, Gorette Silva, Arlene Smith,
Kathleen Weishar and Daniel Tomchyshyn, the staffs in the Department and in Biozone, for
their administrative and technical help
• My research partner, Torsten Meyer, for helping me to run the UofT continuous study
and giving me suggestions
• the past and current colleagues Yi, Nalina, Elena, June, Scott, Sofia, Peter, Sam, Tim,
Ariel, Cheryl, Laura, Shuiquan, Fei, Olivia, Sarah, Luz, Line, Mel, Nigel and other members in
Edlab and Allen lab for their training, help and solidarity
• Weijun Wang, Jon Obnamia, Kayla Nemr and Andrei Starostine for their technical
support and advice
• My previous thesis students and summer students Liqun Zheng, Jennifer Leung and
Angie Tse for their help in experiments and sample analysis
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• Tembec Temiscaming Mill and FPInnovations personnel for sample collection and
sharing of analysis data
• The Environmental Consortium members of the Pulp and Paper Centre at the University
of Toronto, Genome Canada, the Ontario Genomics Institute, Ontario Government Scholarship
program (OGS) and The Natural Sciences and Engineering Research Council of Canada for
funding my research
• My parents, brother, grandparents, parents in-law and sister in-law for their endless love,
support and encouragement

I would like give my deepest appreciation and thanks to my husband Zhicheng Ryan Liang, for
his unconditional understanding, support and love in the past 17 years. There have been ups and
downs during my Master and Ph.D. studies. When I was upset and stressful, Ryan gave me
advice and courage to overcome the challenges.

Last but not least, I would like to thank my daughter Hayley Liang. Hayley is everything that
keeps me motivated and inspired.

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This thesis is dedicated to the bright memory of my grandfather,
Jutian Lei (1928-2014).

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TABLE OF CONTENTS
ABSTRACT ................................................................................................................................................ ii
ACKNOWLEDGEMENTS ....................................................................................................................... iv
LIST OF FIGURES.................................................................................................................................... xi
LIST OF TABLES ................................................................................................................................... xiv
LIST OF APPENDICES ............................................................................................................................ xv
NOMENCLATURE ................................................................................................................................. xvi
CHAPTER1. INTRODUCTION ................................................................................................................. 1
1.1 Anaerobic Treatment of Pulp Mill Effluents and Anaerobic Granulation ......................................... 1
1.2 Problem Definition ............................................................................................................................. 2
1.3 Objectives ........................................................................................................................................... 3
1.4 Hypotheses ......................................................................................................................................... 3
1.5 Research Approach ............................................................................................................................ 4
1.6 Thesis Outline .................................................................................................................................... 5
1.7 Authorships and Contributors to this Research .................................................................................. 5
1.8 Publications and Academic Achievements ........................................................................................ 6
CHAPTER 2. LITERATURE REVIEW ..................................................................................................... 8
2.1 Anaerobic Degradation and Treatment .............................................................................................. 8
2.1.1 Pathway and Microorganisms ..................................................................................................... 8
2.1.2 High Rate Anaerobic Reactors .................................................................................................. 10
2.2 Anaerobic Granulation ..................................................................................................................... 11
2.2.1 Different Models of Granulation ............................................................................................... 11
2.2.2 Granule Disintegration and Floatation, and Agents to Enhance Granulation ........................... 12
2.3 Anaerobic Treatment of Pulp Mill Effluents .................................................................................... 13
2.3.1 Anaerobic Treatability and Toxicity of Pulp Mill Effluents and Constituents ......................... 14
2.3.2 Studies of Granular Sludge Treating Pulp Mill Effluents and Constituents.............................. 15
2.4 Resin Acids and Long-Chain Fatty Acids (RFAs) ........................................................................... 16
2.4.1 General Introduction to RFAs ................................................................................................... 17
2.4.2 RFAs in Anaerobic Treatment .................................................................................................. 18
2.5 Methods to Characterize Anaerobic Granules.................................................................................. 22
2.5.1 Physical Examinations of Anaerobic Granules ......................................................................... 23
2.5.2 Microbial Examinations of Anaerobic Sludge .......................................................................... 25
2.6 Concluding Remarks ........................................................................................................................ 31
CHAPTER 3. CHARACTERISTICS OF PULP MILL EFFLUENTS...................................................... 33
3.1 Introduction ...................................................................................................................................... 33
3.2 Process Overview, Effluent Sources and Various Grades of Sulphite Pulp ..................................... 34
3.2.1 BCTMP and Sulphite Pulping Processes .................................................................................. 34
3.2.2 Wood Species Used to Produce Various Types of Sulphite Pulp ............................................. 37
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3.2.3 General Operation of the Full Scale Internal Circulation (IC) Reactors in the Mill ................. 38
3.3 Data Sources, Analytical Methods and Stream Samples ................................................................. 38
3.4 Results of the Characteristics of BCTMP Effluent .......................................................................... 40
3.5 Results of the Characteristics of Acid Condensate (AC) ................................................................. 41
3.6 Results of the Characteristics of Pulp Washer Effluent (AE) .......................................................... 44
3.6.1 Comparison of Various Types of AE ........................................................................................ 44
3.6.2 Results of the HPLC Analysis of SW1 AE ............................................................................... 47
3.6.3 Total Carbohydrates and Total Proteins in SW1 and SW2 AEs ............................................... 49
3.6.4 Summary of the AE Characteristics .......................................................................................... 50
3.7 Summary of the Characteristics of BCTMP Effluent, AC and AE .................................................. 50
CHAPTER 4. DEVELOPMENT OF METHODS TO STUDY THE PHYSICAL PROPERTIES AND
THE MICROBIAL COMMUNITIES OF GRANULAR SLUDGE ......................................................... 53
4.1 Introduction ...................................................................................................................................... 53
4.2 Development of Methods to Test Particle Size Distribution ............................................................ 53
4.2.1 Sludge Samples and Methods ................................................................................................... 53
4.2.2 Results of the Method Development for Particle Size Distribution Analysis ........................... 55
4.3 Development of Granule Weakness Test ......................................................................................... 58
4.3.1 Sludge Samples and Methods ................................................................................................... 58
4.3.2 Results of Method Development of the Granule Weakness Test .............................................. 60
4.4 Evaluations of Various Molecular Methods of Microbial Community Analysis ............................. 62
4.4.1 Sludge Samples and Methods ................................................................................................... 62
4.4.2 Results: Evaluation of Different Molecular Methods of Microbial Community Analysis ....... 66
4.5. Summary of Method Development ................................................................................................. 72
CHAPTER 5. THE FP CONCENTRATION STUDY: THE EFFECT OF DIFFERENT
CONCENTRATIONS OF AE ................................................................................................................... 74
5.1 Introduction ...................................................................................................................................... 74
5.2 Materials and Methods ..................................................................................................................... 75
5.2.1 Reactor Setup and Seed Sludge ................................................................................................. 75
5.2.2 Feeds: Pulp Mill Effluents and Additional Nutrients ................................................................ 76
5.2.3 Analysis of Feeds and Effluents ................................................................................................ 78
5.2.4 Sampling, Storage, and Physical and Chemical Analyses of Sludge ........................................ 79
5.2.5 Microbial Examinations of the FP Sludge ................................................................................ 80
5.3 Effect of the Addition of AE on Reactor Performance .................................................................... 83
5.3.1 Removal of Total Suspended Solids (TSS) ............................................................................... 83
5.3.2 Removal of Soluble COD (sCOD) ............................................................................................ 84
5.3.3 Biogas Production ..................................................................................................................... 86
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5.3.4 Specific Biogas Yields .............................................................................................................. 87
5.3.5 Summary of Reactor Performance ............................................................................................ 88
5.4 The Effect of the Addition of AE on Granulation of Sludge ........................................................... 88
5.4.1 TSS and VSS Contained in Particles Larger than 200µm (%TSS and %VSS ) ........ 88
>200µm >200µm
5.4.2 Particle Size Distribution for Granules (>200µm) .................................................................... 90
5.4.3 Weakness of Granular Sludge ................................................................................................... 91
5.4.4 Summary of the Physical Properties of Sludge ......................................................................... 92
5.5 Effect of the Addition of AE on the Microbial Communities of Anaerobic Sludge ........................ 92
5.5.1Reproducibility of Sampling and Sequencing ............................................................................ 93
5.5.2 Microbial Diversity ................................................................................................................... 94
5.5.3 Microbial Composition ............................................................................................................. 94
5.5.4 Similarity and Variations among Different Sludge Samples .................................................... 96
5.5.5 Identification of Microorganisms Affected by Operational Parameters ................................... 97
5.6 RFAs in Anaerobic Treatment of Pulp Mill Effluents ................................................................... 100
5.6.1 RFAs in Reactor Feeds and Effluents ..................................................................................... 101
5.6.2 RFA Concentrations in Sludge Samples ................................................................................. 103
5.6.3 Summary of the RFA Analysis ............................................................................................... 104
5.7 Summary of the FP Concentration Study ....................................................................................... 104
CHAPTER 6. THE UOFT LONG-TERM STUDY: THE EFFECT OF CONTINUOUS TREATMENT
OF AE ...................................................................................................................................................... 107
6.1 Introduction .................................................................................................................................... 107
6.2 Materials and Methods ................................................................................................................... 108
6.2.1 Reactor Setup .......................................................................................................................... 108
6.2.2 Synthetic Feed, AE and Additional Nutrients ......................................................................... 109
6.2.3 Organic Loading Rates and Feeding Schedule ........................................................................ 111
6.2.4 Sample Collection and Routine Measurements....................................................................... 112
6.2.5 Batch Assay Setup ................................................................................................................... 113
6.3 Effect of the Addition of AE on Reactor Performance. ................................................................. 115
6.3.1 %sCOD Removal .................................................................................................................... 115
6.3.2 Daily Biogas Production ......................................................................................................... 116
6.3.3 TSS in Reactor Effluents ......................................................................................................... 117
6.4 Effect of the Addition of AE on the Physical Properties of Granular Sludge ................................ 118
6.4.1 Percentage of Total Suspended Solids Contained in Sludge > 200µm (%TSS ) ............. 119
>200µm
6.4.2 Particle Size Distribution of Sludge Based on Image Analysis .............................................. 119
6.4.3 Granule Weakness ................................................................................................................... 121
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6.5 Microbial Communities of Sludge in the Anaerobic Treatment of AE.......................................... 121
6.5.1 Clustering of Samples, and Microbial Diversity of Sludge ..................................................... 122
6.5.2 Microbial Compositions and Dynamics of the Sludge Samples ............................................. 124
6.5.3 Organisms Affected by the Addition of AE ............................................................................ 129
6.5.4 Summary of the Microbial Studies .......................................................................................... 132
6.6 The Fate of Resin Acids and Long-Chain Fatty Acids (RFAs) ..................................................... 133
6.7 Batch Assays to Evaluate Acclimation towards Better Treatment of AE ...................................... 134
6.8 Summary of the Chapter ................................................................................................................ 137
CHAPTER 7. OVERALL DISCUSSION OF THE ANAEROBIC TREATMENT OF PULP MILL
EFFLUENTS............................................................................................................................................ 139
7.1 Summary of Characteristics of Pulp Mill Effluents and Synthetic Feed........................................ 140
7.2 Effect of the Addition of AE on Reactor Performance and Granulation ....................................... 142
7.3 Microbial Communities of Sludge in the Anaerobic Treatment of Pulp Mill Effluents ................ 147
7.3.1 Predominance of Microbial Groups in Sludge ........................................................................ 147
7.3.2 Microbial Groups Responding to AE ...................................................................................... 152
7.3.3 Dynamics of the Microbial Communities ............................................................................... 154
7.3.4 Granulation of Anaerobic Sludge in the Treatment of Pulp Mill Effluents: the Microbial
Perspectives ...................................................................................................................................... 155
7.3.5 Summary of the Microbial Studies .......................................................................................... 157
7.4 Investigation of Possible Sludge Acclimation on AE and Feasible Strategies of Blending AE to the
Reactor Feed......................................................................................................................................... 159
7.5 Discussion on the Developed Methods for Physical and Microbial Examinations ........................ 161
CHAPTER 8. CONCLUSIONS, SIGNIFICANCE AND RECOMMENDATIONS .............................. 164
8.1. Overall Conclusions of this Research ........................................................................................... 164
8.2 Engineering and Scientific Significance ........................................................................................ 167
8.3 Recommendations for Future Studies ............................................................................................ 168
References ................................................................................................................................................ 170
References for Chapter 2 ...................................................................................................................... 170
References for Chapter 3 ...................................................................................................................... 176
References for Chapter 4 ...................................................................................................................... 177
References for Chapter 5 ...................................................................................................................... 178
References for Chapter 6 ...................................................................................................................... 180
References for Chapter 7 ...................................................................................................................... 181

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