REDUCED SULPHUR COMPOUNDS IN AMBIENT AIR AND IN EMISSIONS FROM ...

245 Pages·2007·4.62 MB·English

by  Victor Liang

REDUCED SULPHUR COMPOUNDS IN AMBIENT AIR
AND IN EMISSIONS FROM WASTEWATER CLARIFIERS
AT A KRAFT PULP MILL

by

Chien Chi Victor Liang

A Thesis Submitted in Conformity with the Requirements
for the Degree of Master of Applied Science
Department of Chemical Engineering and Applied Chemistry
University Of Toronto

© Copyright by Chien Chi Victor Liang 2008
Reduced Sulphur Compounds in Ambient Air and in
Emissions from Wastewater Clarifiers at a Kraft Pulp Mill

Master of Applied Science, 2008
Chien Chi Victor Liang
Department of Chemical Engineering and Applied Chemistry
University of Toronto
ABSTRACT
Small quantities of reduced sulphur compounds (RSCs) emitted from Kraft pulp
mills can affect air quality due to low odour thresholds. Chromatographic methods were
developed for individual RSCs at ppt to ppb concentrations. Analyses of ambient air
samples showed that while H S, CH SH, DMS and DMDS were linked to the pulp mill,
2 3
the majority of COS and CS was due to other sources unrelated to the mill. The fluxes
2
of individual RSCs from kraft wastewater clarifiers were quantified for the first time.
DMDS and DMS were the major RSCs emitted from the primary and secondary clarifiers,
respectively. RSC fluxes were one to three orders of magnitude higher at the primary
clarifier than at the secondary one. Clarifier emissions were, however, insignificant
compared to point sources in the mill. Statistically significant correlations were found
between the DMS emission and BOD, COD, as well as TSS in the secondary treatment
system.
ii
ACKNOWLEDGEMENTS
I would like to express my sincere gratitude and appreciation to my supervisors,
Dr. Catalan and Dr. Jia, for their invaluable encouragement, guidance, and advice during
my Master’s studies.
I am grateful to Jenny, Li, Eric, Laura, etc. (in Dr. Jia’s lab), and Linghong,
Andrea, Dongliang, Matt, etc. (in Dr. Catalan’s lab). All of them had helped me in
accomplishing my project.
I am grateful to all my friends in Canada and my childhood friends in Taiwan.
With their love and patience, I was able to reach my goals.
Various employees of Bowater Pulp and Paper Mill, Thunder Bay Ontario must
be thanked for their help in training, sample collection, and provision of information. In
particular, Brent Lindberg, Chris Walton, Tabetha LeBlanc, and Jackie Lorette all need to
be thanked.
Special thanks to members of environmental consortium, Pulp and Paper Center
of University of Toronto, and NSERC for their support in funding of this research.
Finally, I would thank to my mother and my brothers, who had always been there
supporting me. I would also like to dedicate this accomplishment to my beloved father,
who passed away during my study, and I really miss him.

iii
TABLE OF CONTENTS
ABSTRACT ii
ACKNOWLEDGEMENTS iii
TABLE OF CONTENTS iv
LIST OF FIGURES viii
LIST OF TABLES xiii
CHAPTER 1
INTRODUCTION 1
1.1 Background 1
1.2 Objectives 5
CHAPTER 2
LITERATURE REVIEW 7
2.1 Physical and Chemical Properties of Volatile Sulphur Compounds 7
2.2 Biogenic Production of Volatile Sulphur Compounds 9
2.2.1 Hydrogen Sulphide 9
2.2.2 Dimethyl Sulphide 11
2.2.3 Methyl Mercaptan and Dimethyl Disulphide 12
2.2.4 Carbonyl Sulphide 13
2.2.5 Carbon Disulphide 15
2.2.6 Sulphur Dioxide 17
2.3 Formation of Reduced Sulphur Compounds in the Pulping Process in Kraft
Mills 18
2.4 Odour Abatement Strategies for Kraft Mills 19
2.5 Reduced Sulphur Compounds in Wastewater Treatment Facilities at Kraft
Mills 22
2.5.1 Generation of Sulphides by Sulphate Reduction 23
2.5.2 Oxidation of Sulphide 26
2.5.3 Sulphide Precipitation 27
iv
2.5.4 Volatilization of Sulphide 27
2.6 Emission of TRS Compounds at Wastewater Treatment Facilities 28
2.6.1 Wastewater Treatment Facilities at Kraft Pulp Mills 28
2.6.2 Municipal Wastewater Treatment Plants 29
2.7 Health Effects of Reduced Sulphur Compounds from Kraft Mills 30
2.8 Regulations on Volatile Sulphur Compounds 32
2.9 Measurement of Volatile Sulphur Compounds 36
2.10 Odour Impact Assessment 39
CHAPTER 3
REDUCED SULPHUR COMPOUNDS IN AIR EMISSIONS FROM
POINT SOURCES AND WASTEWATER AT BOWATER 41
3.1 TRS Emission Inventory 41
3.2 Kraft Mill Wastewater 43
CHAPTER 4
EXPERIMENTAL METHODS 46
4.1 Sample Collection 46
4.1.1 Ambient Air Sampling 46
4.1.2 Assessment of Degradation of Reduced Sulphur Compounds as a Function of
Time 50
4.1.3 Sampling Emissions from Wastewater Treatment Clarifiers 55
4.2 Sample Analysis 67
4.2.1 Calibration Set-up 67
4.2.2 Configurations of the Gas Chromatographic (GC) System with Pulse Flame
Photometric Detector (GC-PFPD) 71
4.2.3 Calibration Runs 75
4.2.3.1 Runs with Gas Sampling Loop (GSL-GC-PFPD) 76
4.2.3.2 Runs with Cryogenic Trapping (CT-GC-PFPD) 77
4.2.4 Calibration Results 80
4.2.4.1 Calibration Results for GSL-GC-PFPD Analysis 80
4.2.4.1.1 Effect of Column Flow Rate 84
4.2.4.1.2 Variations of Calibration Parameters over Time 88
4.2.4.2 Calibration Results for CT-GC-PFPD Analysis 93
4.2.4.2.1 Effects of Initial column temperature, Split Flow Sequence, and Trap
Loading Time 95
4.2.4.2.2 Variation of Calibration Parameters over Time 101
v
4.2.5 Recommended Instrument Settings 107
4.2.5.1 GSL-GC-PFPD Analysis 107
4.2.5.2 CT-GC-PFPD Analysis 107
4.3 Detection Limits 109
4.3.1 Detection Limits for GSL-GC-PFPD 110
4.3.2 Detection Limits for CT-GC-PFPD 113
CHAPTER 5
RESULTS AND DISCUSSION 115
5.1 Ambient Air Collection 115
5.1.1 Effect of Wind Direction on Measured Concentrations of Volatile Sulphur
Compounds (VSCs) 115
5.1.2 Evolution of VSC Concentrations Versus Time 123
5.1.3 Correlation between Odour Intensity and Concentration of TRS Compounds
128
5.1.4 Frequency Distribution of Reduced Sulphur Compounds 130
5.1.5 Comparison of Changes in Ambient Concentrations with Changes in Plant
Emission Rates of TRS 136
5.1.6 Effect of Temperature, Relative Humidity, and Wind Speed on TRS
Concentrations in Ambient Air 139
5.2 Fugitive VSC Emissions from Clarifiers 142
5.2.1 Primary Clarifier 142
5.2.2 Secondary Clarifier 151
5.2.3 Discussion of Emissions from the Primary and Secondary Clarifiers 160
5.2.3.1 Emission Fluxes 160
5.2.3.2 Emission Rates 162
5.2.4 Comparison of Clarifier Emissions with Other Sources of Emissions at the
Bowater Kraft Mill 167
5.2.5 Correlation of TRS Emissions from the Secondary Clarifier with Wastewater
Quality Parameters 168
CHAPTER 6
SUMMARY AND CONCLUSIONS 183
6.1 Analytical Methods (GSL-GC-PFPD and CT-GC-PFPD) 183
6.2 Measurement of VSCs in Ambient Air around the Bowater Plant 184
6.3 Measurement of VSCs from Wastewater Treatment Clarifiers at the Bowater
Plant 185
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CHAPTER 7
REFERENCES 187
APPENDIX A
Description of Alkaline and Acid Sewers Contributing to the
Effluent Treatment at Bowater Mill A-1
APPENDIX B
Additional Results on the Variations of Calibration Parameters
over Time B-1
B.1 GSL-GC-PFPD Calibration B-1
B.2 CT-GC-PFPD Calibration B-5

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LIST OF FIGURES
Figure 2-1: Schematic of fate of sulphur compounds in the wastewater 23
Figure 2-2: Cyclic pathway proposed to describe the production and transformation of
volatile sulphur compounds and hydrogen sulphide (Higgins et al., 2006) 26
Figure 2-3: PFPD diagram (Varian Analytical Instruments, 2001) 37
Figure 3-1: Summary of main TRS point sources for Bowater facilities (Bowater, 2005)
42
Figure 3-2: Kraft effluent treatment at Bowater before Nov. 2, 2006 43
Figure 3-3: Effluent treatment at Bowater after Nov. 2, 2006 44
Figure 4-1: Aerial photograph of the Bowater mill and sampling locations 47
Figure 4-2: Schematic of the air sampling apparatus 48
Figure 4-3: Ambient air sampling equipment and portable meteorological station set up at
location 2 50
Figure 4-4: Degradation of several reduced sulphur compounds analyzed by GSL-GC-
PFPD as function of time 52
Figure 4-5: Degradation of several reduced sulphur compounds analyzed by CT-GC-
PFPD as function of time 54
Figure 4-6: Flow diagram of Kraft wastewater treatment at Bowater 55
Figure 4-7: Flux sampling train (The flux chamber is partially cut away to show the
sweep air inlet line and the sample line) 58
Figure 4-8: View of the flux chamber (a) top and (b) bottom 58
Figure 4-9: Flux sampling set-up 59
Figure 4-10: Sampling locations for Kraft primary clarifier (Diameter of 21.3 m, exposed
surface area of 358 m2) 62
Figure 4-11: Sampling locations for Kraft secondary clarifier #1 (Diameter of 68.6 m,
exposed surface area of 3696 m2) 66
Figure 4-12: Schematic of the calibration set-up 68
Figure 4-13: Picture of calibration set-up 69
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Figure 4-14: Weight losses (g) in permeation devices versus time. (Secondary y-axis is
for COS data points only). 70
Figure 4-15: Plumbing diagram of the GSL-GC-PFPD 73
Figure 4-16: Plumbing diagram of the CT-GC-PFPD 74
Figure 4-17: PFPD gas flow diagram (Varian Analytical Instruments, 2001) 75
Figure 4-18: Peak area (counts) versus concentration (ppbv) for several volatile sulphur
compounds by GSL-GC-PFPD (column flow = 4.5 ml/min) 83
Figure 4-19: Peak area (counts) versus concentration (ppbv) at column flow rates of 2.0
and 4.5 ml/min for (a) H S, (b) SO , (c) CH SH, (d) DMS, (e) CS and (f)
2 2 3 2
DMDS 87
Figure 4-20: Peak area (counts) vs concentration (ppbv) for (a) H S, (b) COS, (c) SO , (d)
2 2
CH SH, (e) DMS, (f) CS and (g) DMDS over a period of time between Mar.
3 2
14 and Nov. 5, 2006 92
Figure 4-21: Typical calibration curves showing peak area (counts) versus concentration
(ppbv) for several volatile sulphur compounds by CT-GC-PFPD 94
Figure 4-22: A Typical chromatogram (y-axis is mVolts, x-axis is retention time) for CT-
GC-PFPD with an initial column temperature at -15°C, SFR = 0 throughout
the entire run, a trap loading time of 6 min, a trap loading rate of 35 ml/min,
and a column flow rate of 4.5 ml/min 95
Figure 4-23: Peak area (counts) vs concentration (ppbv) at different settings for (a) H S,
2
(b) COS, (c) SO , (d) CH SH, (e) DMS, (f) CS and (g) DMDS 100
2 3 2
Figure 4-24: Peak area (counts) vs concentration (ppbv) for for (a) H S, (b) COS, (c) SO ,
2 2
(d) CH SH, (e) DMS, (f) CS and (g) DMDS over a period of time between
3 2
Jun. 8 to Oct. 22, 2006 (Set #4) 106
Figure 4-25: Peak height (mV) versus concentration (ppbv) for several volatile sulphur
compounds by GSL-GC-PFPD 112
Figure 4-26: Peak height (mV) versus concentration (ppbv) for several volatile sulphur
compounds by CT-GC-PFPD 114
Figure 5-1: Concentration (ppbv) vs. relative wind direction from the Bowater Kraft mill
(°) with qualitative odour assessment for (a) H S, (b) CH SH, (c) DMS, (d)
2 3
DMDS, (e) SO , (f) COS, and (g) CS 122
2 2

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Figure 5-2: Concentrations of COS and CS versus wind direction (An angle of 0º
2
corresponds to wind blowing from North. Angles of +180 º or -180 º
correspond to wind blowing from South. Angles +90 º and -90 º correspond
to wind blowing from East and West, respectively) 123
Figure 5-3: Concentration (ppbv) measured at downwind locations from Apr. 5 to Sept.
14, 2007 with qualitative odour assessment for (a) H S, (b) CH SH, (c) DMS,
2 3
(d) DMDS, (e) COS, and (f) CS 126
2
Figure 5-4: Frequency distributions of (a)H S, (b)CH SH, (c)DMS, (d)DMDS, (e) TRS,
2 3
(f) COS, and (g) CS 136
2
Figure 5-5: TRS concentrations in ambient air (ppbv) vs. temperature (°C) 140
Figure 5-6: TRS concentrations in ambient air (ppbv) vs. relative humidity (%) 141
Figure 5-7: TRS concentrations in ambient air (ppbv) vs. wind speed (km/h) 142
Figure 5-8: Fugitive emission rates (ug/s) from the primary clarifier of the Bowater Kraft
mill for (a) H S, (b) CH SH, (c) DMS, (d) DMDS, (e) COS, (f) CS , and (g)
2 3 2
TRS 145
Figure 5-9: Frequency distribution of emission rates from the primary clarifier for the
period of Sept. 29 to Nov. 2, 2006. (a) H S, (b) CH SH, (c) DMS, (d) DMDS,
2 3
(e) COS, (f) CS , and (g) TRS. 150
2
Figure 5-10: Fugitive emission rates (ug/s) at secondary clarifier #1 of Bowater Kraft mill
for (a) H S, (b) CH SH, (c) DMS, (d) DMDS, (e) COS, (f) CS , and (g) TRS
2 3 2
154
Figure 5-11: Frequency distribution of the emission rates at secondary clarifier # 1 for the
periods of time from Nov. 7 to Nov. 29, 2006 and Apr. 2 to May 24, 2007 for
(a) H S, (b) CH SH, (c) DMS, (d) DMDS, (e) COS, (f) CS , and (g) TRS. 159
2 3 2
Figure 5-12: Fluxes (ug/s⋅m2) of reduced sulphur compounds at the primary clarifier from
Sept. 29 to Nov. 2, 2006 161
Figure 5-13: Fluxes (ug/s⋅m2) of reduced sulphur compounds at the secondary clarifier #1
from Nov. 7, 2006 to May 24, 2007 162
Figure 5-14: Fugitive emission rates (ug/s) of reduced sulphur compounds at primary
clarifier from Sept. 29 to Nov. 2, 2006 163
Figure 5-15: Fugitive emission rates (ug/s) of reduced sulphur compounds at the
secondary clarifier #1 from Nov. 7, 2006 to May 24, 2007 164
Figure 5-16: Comparison of TRS emissions from various sources at the Bowater mill 168
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