Mechanisms for Aerobic Degradation of Commercial Naphthenic Acids

95 Pages·2017·1.2 MB·English

by  Samuel Louis Muller

Clemson University
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All Theses Theses
8-2016
Mechanisms for Aerobic Degradation of
Commercial Naphthenic Acids
Samuel Louis Muller
Clemson University, [email protected]
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Muller, Samuel Louis, "Mechanisms for Aerobic Degradation of Commercial Naphthenic Acids" (2016).All Theses. 2450.
https://tigerprints.clemson.edu/all_theses/2450
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MECHANISMS FOR AEROBIC DEGRADATION OF COMMERCIAL
NAPHTHENIC ACIDS
A Thesis
Presented to
the Graduate School of
Clemson University
In Partial Fulfillment
of the Requirements for the Degree
Master of Science
Hydrogeology
by
Samuel Louis Muller
August 2016
Accepted by:
James Castle, Committee Chair
John H. Rodgers, Jr.
Monique Haakensen
ABSTRACT
Naphthenic acids (NAs) are a class of thousands of carboxylic acids associated
with petroleum degradation. They become dissolved in oil sands process waters (OSPW)
during the bitumen extraction process, and the resulting process waters can elicit toxicity
to aquatic organisms. NAs are weakly biodegradable, but have half-lives of months to
years, making it difficult to treat NAs with bioremediation. Two methods for promoting
aerobic degradation (cometabolism and mycoremediation) were investigated as proof of
concept for effectiveness in degrading commercial NAs. A reciprocating reactor
inoculated with a white rot fungus, Pleurotus pulmonaris, was built and compared to an
uninoculated reactor to determine the effects of this fungus on NA degradation.
Inoculated reactors were more effective than uninoculated reactors in removing
NAs, with zero-order half lives of 32 and 39 hours, respectively. This demonstrated the
usefulness of both P. pulmonaris and a reciprocating reactor in promoting aerobic NA
degradation. Cometabolic NA degradation using different substrates and substrate
concentrations was investigated at bench scale. This study confirmed that cometabolic
substrate addition increases NA removal rate in comparison to unamended degradation. It
also showed that the concentration ratio of substrate to NAs affects the removal rate of
NAs. This has important implications to the design of a constructed wetland treatment
system for ecological risk mitigation of OSPW, where wetland detritus may serve as a
cometabolic substrate to promote NA degradation.
ii
DEDICATION
This thesis is dedicated to the Chattooga River. Completion of this thesis would
not have been possible if not for the restorative touch of its waters. May it ever flow
freely.
iii
ACKNOWLEDGMENTS
I would like to thank my advisor, Dr. James Castle for encouraging me to follow
my interests throughout my research. His guidance helped shape me as a scientist. I also
thank my committee members, Dr. John Rodgers Jr. and Dr. Monique Haakensen for
providing insight into other disciplines and pushing me to strive for excellence.
Additionally, I would like to thank the fellow members of the OSPW group for their
assistance and feedback throughout the completion of this research.
Outside of the university, I received love and encouragement throughout the
completion of this thesis. My girlfriend, Megan Chase, supported me through my
graduate studies unfailingly. To my parents and twin sister, thank you for all of your love.
iv
TABLE OF CONTENTS
Page
TITLE PAGE .................................................................................................................... i
ABSTRACT ..................................................................................................................... ii
DEDICATION ................................................................................................................ iii
ACKNOWLEDGMENTS .............................................................................................. iv
LIST OF TABLES .......................................................................................................... vi
LIST OF FIGURES ...................................................................................................... viii
CHAPTER
I. INTRODUCTION ......................................................................................... 1
II. EFFECTS OF COMETABOLIC SUBSTRATES
ON COMMERCIAL (FLUKA) NAPHTHENIC ACID
DEGRADATION .................................................................................... 8
III. MYCOREMEDIATION OF COMMERCIAL (FLUKA)
NAPHTHENIC ACIDS USING A RECIPROCATING
REACTOR ............................................................................................. 40
IV. CONCLUSIONS .......................................................................................... 69
APPENDICES ............................................................................................................... 72
A: STANDARD OPERATING PROCEDURES ............................................ 73
B: CHAPTER 2 EXPLANATORY PARAMETER TABLES ....................... 80
v
LIST OF TABLES
Table Page
2.1 Physical and chemical properties of Sigma-Aldrich
(Fluka) naphthenic acids ........................................................................ 27
2.2 Macronutrient characteristics for tested cometabolic
substrates ................................................................................................ 28
2.3 Methods for measuring explanatory parameters .......................................... 29
2.4 Explanatory parameters measured in experimental vessels
for cometabolic substrates and untreated control ................................... 30
2.5 Summary of 96-h acute toxicity tests for comparison of
cometabolic substrates. .......................................................................... 31
2.6 Summary of 96-h acute toxicity tests for comparison of
cometabolic substrate concentrations .................................................... 32
3.1 Physical and chemical properties of Sigma-Aldrich
(Fluka) naphthenic acids ........................................................................ 58
3.2 Methods for measuring explanatory parameters .......................................... 59
3.3 Explanatory parameters, initial conditions and range
throughout experiments ......................................................................... 60
3.4 Comparison of initial and final pH and alkalinity for
inoculated and uninoculated reactors ..................................................... 61
3.5 Mean removal rate coefficients and extents for inoculated
reactors, uninoculated reactors, and sterile sorption .............................. 62
vi
List of Tables (continued)
Table Page
3.6 Summary of mean NA concentrations and 96-h survival
for inoculated reactors, uninoculated reactors, and sorption ................. 63
vii
LIST OF FIGURES
Figure Page
2.1 Conceptual model for investigating cometabolic remediation
of commercial NAs ................................................................................ 33
2.2 Measured NA concentrations for cometabolic degradation ......................... 34
2.3 Measured NA concentrations when substrates were added
to water in the absence of NAs .............................................................. 35
2.4 Subtraction of substrate-associated fatty acids from total
measured NA concentrations for cometabolic degradation
of NAs .................................................................................................... 36
2.5 Results of sterile sorption tests for solid substrates ..................................... 37
2.6 Changes in acute toxicity to P. promelas due to cometabolism
of NAs .................................................................................................... 38
2.7 Efficacy of different biofermentation product treatment
concentrations for altering acute toxicity to P. promelas ..................... 39
3.1 Schematic of reciprocating reactor design ................................................... 64
3.2 Photograph of reciprocating reactors ........................................................... 65
3.3 Change in NA concentrations for inoculated reactors,
uninoculated reactors, and sterile sorption ............................................. 66
3.4 Mean ORP potential throughout a reactor cycle .......................................... 67
3.5 Change in acute toxicity to P. promelas for reactors
and sterile sorption ................................................................................. 68
viii
CHAPTER ONE
INTRODUCTION
With global oil demand rising, non-conventional oil reserves are being relied
upon increasingly to fulfill the world’s need for petroleum (International Energy Agency
2014). The Athabasca Basin in northeastern Alberta, Canada contains the largest deposit
of oil sands in the world, with proven reserves of approximately 169 billion barrels
(Alberta Energy 2014). Oil sands are a biodegraded energy deposit containing bitumen, a
highly viscous petroleum form that cannot be extracted with conventional oil production
techniques (Alberta Government 2014). Currently, production is from shallow deposits
that are surface mined, and an area of approximately 767 km2 has been disturbed by oil
sands production to date (Alberta Government 2014). Bitumen is traditionally extracted
from the oil sands through a caustic hot water extraction using sodium hydroxide (Allen
2008). The resulting process water, which is acutely toxic to aquatic organisms, contains
salts, trace metals, and organic compounds (Allen 2008). Oil producers in the Athabasca
region operate under a zero-discharge policy, so the volume of accumulated process
water continues to increase.
OSPW
Oil sands production requires a large volume of water to extract the bitumen from
sands of the McMurray deposit. On average, 3 barrels of water are used to process one
barrel of oil (Allen 2008, Quagraine et al. 2005). 2007 estimates place the volume of
stored process water in the Athabasca region to be approximately 700 million m3
(Dominski 2007). The water that accumulates on oil sands leases is known as oil sands
1