Evaluation of the Performance of a Downward Flow Inclined Gravity Settler for Algae Dewatering

91 Pages·2016·0.86 MB·English

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Dustin D. Bowden
Cleveland State University
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Bowden, Dustin D., "Evaluation of the Performance of a Downward Flow Inclined Gravity Settler for Algae
Dewatering" (2015). ETD Archive. 355.
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EVALUATION OF THE PERFORMANCE OF A DOWNWARD FLOW
INCLINED GRAVITY SETTLER FOR ALGAE DEWATERING

DUSTIN D. BOWDEN

Bachelor of Science in Chemical Engineering
Cleveland State University
May, 2013

Submitted in partial fulfillment of requirements for the degree
MASTER OF SCIENCE IN CHEMICAL ENGINEERING
at the
CLEVELAND STATE UNIVERSITY
April, 2015
© COPYRIGHT BY DUSTIN D. BOWDEN 2015

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We hereby approve this thesis for

Dustin D. Bowden

Candidate for the Master of Science in Chemical Engineering degree for the

Department of Chemical and Biomedical Engineering

and the CLEVELAND STATE UNIVERSITY

College of Graduate Studies

_________________________________________________________________

Thesis Chairperson, Dr. Joanne M. Belovich

_____________________________________________
Department & Date

_________________________________________________________________

Thesis Committee Member, Dr. Jorge E. Gatica

_____________________________________________
Department & Date

_________________________________________________________________

Thesis Committee Member, Dr. Moo-Yeal Lee

_____________________________________________
Department & Date

Student’s Date of Defense: (2015-04-22)
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ACKNOWLEDGEMENTS

I would like to thank my parents Valerie DeGiovanni Bowden and Steven
Bowden and my grandmother Elyzabeth DeGiovanni without whose support and
encouragement this thesis would never have been completed.
I would like to thank my advisor Dr. Joanne M. Belovich who gave me this
project and provided advice for the numerous problems I encountered. I am grateful for
all that she has done to assist me.
I would like to thank my committee Dr. Jorge E. Gatica and Dr. Moo-Yeal Lee
for taking their time to review my work.
I would like to thank Becky Laird for all her assistance over the years.
I would like to thank Zhaowei Wang and Jing Hou whose work I have built upon.
I would like to thank Chris Hardulak, Haider Malik, and Bethany Eppig who
trained me. Additionally, I would like to thank all members of the Algae Team. Though
not part of the Algae Team Kurt Ferrel, Andrew Zac, Zak Benmerzouga, Tiesha Mulins
and the others who have taken time to assist me with my work for tasks that I could not
accomplish alone.
I would like to thank Fenn College of Engineering for accepting me and giving
me this opportunity.
Finally I wish to thank all the friends that have encouraged me over the years.

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EVALUATION OF THE PERFORMANCE OF A DOWNWARD FLOW

INCLINED GRAVITY SETTLER FOR ALGAE DEWATERING

DUSTIN D. BOWDEN

ABSTRACT

With recent concerns over the environmental implications of burning fossil fuels
coupled with the depletion of fossil fuel reserves an alternative source of energy is
needed. Algae derived biofuels may be an effective replacement for transportation fuels
as they are carbon neutral and have a high area productivity. Algae is superior to
terrestrial plants as a biofuel source due to its high oil productivity and efficiency along
with the fact that it will not displace food production. Currently the largest obstacle to
the implementation of commercial algae to biofuel processes is algae dewatering. The
separation of algae from water is difficult due to the dilute concentration of the algae
suspension and the extremely low settling velocity of the algae biomass. This work
investigates recent improvements to the downward flow inclined gravity settler which has
the potential to unlock this much needed process. Additionally, an investigation into
algae settling velocity, a field which has received little attention, is also discussed.
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TABLE OF CONTENTS

ABSTRACT ................................................................................................................ v
TABLE OF FIGURES................................................................................................. ix
TABLE OF TABLES.................................................................................................. xi
CHAPTER I INTRODUCTION.................................................................................. 01
1.1 Objectives................................................................................................... 02
1.2 Significance................................................................................................ 03
CHAPTER II BACKGROUND.................................................................................. 06
2.1 Biofuels...................................................................................................... 06
2.1.1 Algae Culture.............................................................................. 08
2.1.1.1 Factors Affecting Algae Growth................................. 08
2.1.1.2 Open Pond Bioreactors................................................ 10
2.1.1.3 Closed System Bioreactors.......................................... 11
2.1.2 Algae Dewatering....................................................................... 13
2.1.3 Lipid Extraction.......................................................................... 16
2.1.4 Lipid Processing.......................................................................... 17
2.2 Gravity Settler Background....................................................................... 18
2.2.1 Downward Flow Settler Studies ................................................ 20
2.3 Settling Velocity........................................................................................ 21
CHAPTER III MATERIALS AND METHODS........................................................ 23
3.1 Algae Cell Line ......................................................................................... 23
3.2 Gravity Settler Design............................................................................... 24
3.2.1 Gravity Settler Inlet.................................................................... 26
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3.2.2 Gravity Settler Flow Chamber.................................................... 27
3.2.3 Gravity Settler Outlet................................................................. 28
3.3 Bioreactor.................................................................................................. 32
3.4 Combined Settler and Bioreactor System................................................. 36
3.5 Definition of Important Parameters in This Study................................... 38
3.6 Algae Sample Collection.......................................................................... 39
3.6.1 Filtering of Collected Data........................................................ 41
3.7 Management of Settler Fouling................................................................ 42
3.8 Settling Velocity Study............................................................................ 44
3.8.1 Settling Velocity Procedure...................................................... 45
3.8.1.1 Calculation of Settling Velocity ................................ 48
3.8.2 Batch Algae Growth for Settling Velocity Study..................... 48
CHAPTER IV RESULTS AND DISCUSSION....................................................... 52
4.1 Gravity Settler Study............................................................................... 52
4.1.1 Notes about Settler Performance.............................................. 52
4.1.1.1 Gravity Settler Governing Equation ......................... 53
4.1.2 General Observations of Gravity Settler Operation................. 54
4.1.3 Algae Recovery........................................................................ 57
4.1.4 Settler Performance.................................................................. 58
4.1.5 Upward Flow Configuration.................................................... 62
4.1.6 Previous Data for Comparison................................................. 64
4.2 Settling Velocity Study........................................................................... 65
4.2.1 Settling Velocity Overview...................................................... 66
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4.2.2 Effect of Culture Growth State on Algae Settling Velocity..... 67
4.2.3 Effect of Saltwater Acclimation on Settling Velocity.............. 67
4.2.4 Algae Clustering....................................................................... 68
4.2.4.1 Distribution of Algae Cell Clusters........................... 69
4.2.4.2 Settling Velocity by Cell Cluster Type..................... 70
4.3 Discussion............................................................................................... 70
CHAPTER V CONCLUSION AND RECOMMENDATIONS…......................... 72
5.1 Conclusion.............................................................................................. 72
5.2 Recommendations.................................................................................. 73
REFERENCES........................................................................................................ 75
APPENDIX....…...................................................................................................... 78
APPENDIX A ......................................................................................................... 79
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TABLE OF FIGURES

FIGURE 1 A ............................................................................................................... 24
FIGURE 1 B ............................................................................................................... 24
FIGURE 2 A ............................................................................................................... 25
FIGURE 2 B ............................................................................................................... 25
FIGURE 3 .................................................................................................................. 25
FIGURE 4 .................................................................................................................. 27
FIGURE 5 .................................................................................................................. 27
FIGURE 6 A .............................................................................................................. 28
FIGURE 6 B .............................................................................................................. 28
FIGURE 7 A .............................................................................................................. 30
FIGURE 7 B .............................................................................................................. 30
FIGURE 7 C .............................................................................................................. 31
FIGURE 8 ................................................................................................................. 33
FIGURE 9 A ............................................................................................................. 34
FIGURE 9 B ............................................................................................................. 34
FIGURE 10 ............................................................................................................... 37
FIGURE 11 A ........................................................................................................... 45
FIGURE 11 B ........................................................................................................... 45
FIGURE 12A ............................................................................................................ 46
FIGURE 12B ............................................................................................................ 46
FIGURE 12C ............................................................................................................ 47
FIGURE 12D ............................................................................................................ 47
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