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Microbial processes and their implications in tailings management
Tariq SiddiqueDepartment of Renewable Resources
Outline
General overview of oil sands development and tailings production
Environmental issues associated with oil sands tailings• Greenhouse gas emissions• Slow dewatering and consolidation of tailings• Constituents of concern (organic and inorganic substances)
Tailings management under End Pit Lake scenario Tailings management under dry reclamation scenario
Oil sands development in Alberta, CanadaPeace River
ColdLake
Alberta
Edmonton
Athabasca
Bitumen production Current production: 3.4 million barrels day-1 (2021) Projected production: 4.0 million barrels day-1 (2029)
Current tailings production: 1.3 million m3 day-1
Total volume of fluid fine tailings = ~ 1.24 billion m3
Total area under tailings ponds = 259 km2
Total liquid surface area of ponds = 101 km2
Oil sands tailings production (2017)
Oil sands deposits Oil sands deposits: 1.7-2.5 trillion barrels Proven reserves: ~ 165 billion barrels
https://www.alberta.ca/oil-sands-facts-and-statistics.aspxhttp://osip.alberta.ca/map/
Syncrude
CNRL
CNUL
Suncor
Suncor
Imperial
Bitumen Separation
Upgrader / Refinery
Hydro-transport
Tailings pond
Hot waterFr
oth
(bitu
men
)
Tailings slurry
Diluent
www.nationalpost.com
Diluent = <1%
End-pit lake
http://www.macleans.ca/economy/business/what-lies-beneath-albertas-man-made-lakes/
MFT
: Wet
recl
amat
ion
Process waterAqueous slurry of sand, silt, clay, residual bitumen (~5%), unrecovered naphtha (~1%)
Construction of uplands
TT: D
ry re
clam
atio
n
Surface mining and bitumen extraction process
5Photo courtesy Geotechnical Engineering, UAlberta
Environmental issues associated with tailings
Mildred Lake Settling Basin
• Greenhouse gas emissions• Slow dewatering and consolidation of
tailings• Constituents of concern
– petroleum hydrocarbons– naphthenic acids– trace metals
6
• Source and GHG emissions and model prediction from tailings ponds/ end-pit lakes
• Consolidation and dewatering of tailings
Siddique et al., 2006. Environ. Sci. Technol. 40: 5459-64Siddique et al., 2007. Environ. Sci. Technol. 41: 2350-56Siddique et al. 2008. Chemosphere. 72: 1573-1580Siddique et al. 2011. Environ. Sci. Technol. 45: 5892-5899Siddique et al. 2012. Environ. Sci. Technol. 46: 9802-9810Siddique et al. 2014a. Front. Microbiol. 5:106 Siddique et al. 2014b. Front. Microbiol. 5:107Siddique et al. 2015. Environ. Sci. Technol. 49: 14732-14739Arkel et al. 2015. J. Environ. Qual. 44: 145-153M. Shahimin et al. 2016. Sci. Total Environ. 553: 250-257M. Shahimin & Siddique 2017. Environ. Pollut. 221: 398-406M. Shahimin & Siddique 2017. Sci. Total Environ. 583: 115-122Foght et al. 2017. FEMS. 93: fix034Siddique et al. 2018. Handbook of Hydrocarbon MicrobiologyKong et al. 2019. Sci. Total Environ. 694: 133645Siddique and Kuznetsova. 2020. Can. J. Soil Sci. 100: 537-545Siddique et al. 2020. Environ. Pollut. 258: 113768 Cárdenas-Manríquez et al. 2020. Nova Scientia 12: 1-30Young et al. 2020. Bioresour. Technol. Rep. 11: 100547Kuznetsova et al. 2021. J. Environ. Chem. Eng. 9: 104715
7
Where does the GHG (CH4) come from?
• Different extraction processes• Different tailings management• Different ages
Syncrude vs CNUL vs CNRL (tailings ponds)
Fugitive hydrocarbons
ē
Oxic
Suboxic
Anoxic
Microbes in sediments
Microcosm
• Naphtha (n-, iso-, cyclo-alkanes and monoaromaticsprimarily in C6-C10 range); Syncrude, Suncor, CNRL
• Paraffinic solvent (n- and iso-alkanes in C5-C6 range); CNUL, Imperial Oil
Mature fine tailings spiked with following hydrocarbons:
n-Alkanesn- C5
n- C6
n- C7
n- C8
n- C9
n- C10
n- C14
n- C16
n- C18
iso-Alkanes2-Methyl-C5
3-Methyl-C6
2-Methyl-C7
4-Methyl-C7
2-Methyl-C8
3-Methyl-C8
4-Methyl-C8
2-Methyl-C9
Cycloalkanes
Ethylcyclo-pentane
Methylcyclo-hexane
Ethylcyclo-hexane
Petroleum hydrocarbons biodegraded to CH4
Mono-aromatics
Toluene o-Xylene m-Xylene
p-Xylene
Biodegradation of paraffinic solvent components by CNUL MFT
0 500 1000 1500 2000 2500
0
1
2
3
4
5
6
CH
4 (m
mol
)
Day
Control n-Alk 1 n-Alk 2 n-Alk 3 iso-Alk 1 iso-Alk 2 iso-Alk 3
0 500 1000 1500 2000 2500
0
100
200
300
400
500
600
Con
cent
ratio
n (m
g L-1
)
Day
nC5 (n-Alk 1) nC6 (n-Alk 1) nC5 (n-Alk 2) nC6 (n-Alk 2) nC5 (n-Alk 3) nC6 (n-Alk 3)
0 500 1000 1500 2000 2500
0
100
200
300
400
500
600
Con
cent
ratio
n (m
g L-1
)
Day
2-MC4 (iso-Alk 1) 2-MC5 (iso-Alk 1) 3-MC5 (iso-Alk 1) 2-MC4 (iso-Alk 2) 2-MC5 (iso-Alk 2) 3-MC5 (iso-Alk 2) 2-MC4 (iso-Alk 3) 2-MC5 (iso-Alk 3) 3-MC5 (iso-Alk 3)
Siddique et al. 2015. Environ. Sci. Technol. 49: 14732-14739
Long lag phases and incubations were observed for methanogenic hydrocarbon biodegradation
~ 7 years
0 400 800 1200 16000
20
40
60
80
100
Met
hane
(%)
Day
C6-C10
C14-C18
MC6-C8
0 400 800 1200 16000
20
40
60
80
100
120
140
Hyd
roca
rbon
s (%
)
Day
C6 C7 C8 C10 C14 C16
C18 3-MC6 2-MC7 4-MC7 2-MC8
Sequential biodegradation of hydrocarbonsn-Alkanes > iso-Alkanes
Siddique and Kuznetsova. 2020. Can. J. Soil Sci. 100: 537-545
11
0 100 200 300 400 500 6000
1
2
3
4
5
CH
4 (m
mol
)
Day
Unamended control Abiotic control 2-Alkanes 4-Alkanes
0 100 200 300 400 500 6000
1
2
3
4
5
CH
4 (m
mol
)
Day
Unamended control Abiotic control 2-Alkanes 4-Alkanes
CNUL FFT CNRL FFT
Mohamad Shahimin et al. 2016. Sci. Total Environ. 553: 250-257
C5 C6 C8 C10 C5 C6 C8 C10Abiotic Control 4-alkane
0
100
200
300
400
500
600
Con
cent
ratio
n (m
g L-1
)
Day 0 Day 283 Day 392 Day 521
C5 C6 C8 C10 C5 C6 C8 C10Abiotic Control 4-alkane
0
100
200
300
400
500
600
Con
cent
ratio
n (m
g L-1
)
Day 0 Day 294 Day 403 Day 532
Preferential biodegradation of hydrocarbons
12
CNUL FFT CNRL FFT
0 20 40 60 80 100D
ay 0
Day
308
Alb
ian
2-al
kane
s
0 20 40 60 80 100
Day
0D
ay 3
08
Alb
ian
4-al
kane
s (A
)
0 20 40 60 80 100
Day
0D
ay 5
32
CN
RL
2-al
kane
s
0 20 40 60 80 100
Day
0D
ay 3
19D
ay 5
32
CN
RL
4-al
kane
s
0.00
Day 0Day 308
Alb
ian
2-al
kan
es
CoriobacteriaceaeAnaerolineaceaePeptococcaceaeNitrospiraceaeHydrogenophilaceaeRhodocyclaceaeDesulfobacteraceaeSyntrophaceaeChromatiaceaeOthers <5%
Bacterial community structure during preferential degradation
13
Biodegradation pathway in oil sands tailings
Siddique et al. 2011. Environ. Sci. Technol. 45: 5892-5899Siddique et al. 2012. Environ. Sci. Technol. 46: 9802-9810Siddique et al. 2015. Environ. Sci. Technol. 49: 14732-14739M. Shahimin et al. 2016. Sci. Total Environ. 553: 250-257M. Shahimin & Siddique 2017. Environ. Pollut. 221: 398-406M. Shahimin & Siddique 2017. Sci. Total Environ. 583: 115-122Siddique et al. 2020. Environ. Pollut. 258: 113768
dtSFdt
dCt
iii
i )(CH0
4
CH4 formationDegradationLag phase
Bacteria and Archaea
Recovered Water
Mature Fine Tailings containing hydrocarbons
CH4 & CO2
Second-generation stoichiometric model to predict GHG emissions
Siddique et al. 2008. Chemosphere. 72: 1573-1580Kong et al. 2019. Sci. Total Environ. 694: 133645
0 500 1000 1500time (days)
0
0.5
1
1.5
2
2.5
CH
4 (mm
ole)
CNUL
0 500 1000 1500time (days)
0
0.5
1
1.5
2
CH
4 (mm
ole)
0 200 400 600 800time (days)
0
0.5
1
CH
4 (mm
ol)
CNRL
Syncrude
Syncrude MSLB CNRL Horizon CNUL MRMLabile hydrocarbon % of
diluent amass (t) 2016 b
mass (t) 2017 b
% of diluent a
mass (t) 2016 b
mass (t) 2017 b
% of diluent a
mass (t) 2016 b
mass (t) 2017 b
Toluene 6.11 2452 1840 0 0m-, p-Xylene 4.64 1862 1398 0 0o-Xylene 1.78 714 536 0 0n-C5 0 0 0 0 24.00 4112 4679n-C6 0.60 241 181 3.85 666 951 11.26 1929 2195n-C7 4.50 1806 1356 9.35 1618 2310 0n-C8 6.05 2428 1822 4.65 805 1149 0n-C9 1.99 799 599 1.70 294 420 0n-C10 0.31 126 94 1.65 286 408 02-MC5 0 0 0 1.25 216 309 23.50 4027 45822-MC6 1.30 522 392 5.30 917 1309 03-MC6 1.51 607 456 5.05 874 1248 02-MC7 4.92 1976 1483 3.85 666 951 04-MC7 1.86 747 561 1.25 216 309 02-MC8 1.16 465 349 1.00 173 247 03-MC8 1.55 623 467 0.55 95 136 02-MC9 0.31 124 93 2.90 502 717 0Proportion of diluent considered labile (%)
39 42 59
Total labile hydrocarbon mass entering OSTP (t) a
15492 11627 7329 10463 10068 11456
Mass of individual hydrocarbons in diluents
Contribution of diluent hydrocarbons to total CH4emissions from ponds ranges between 50-95%
Kong et al. 2019. Sci. Total Environ. 694: 133645
FeIII, NV& SVI?
Oxic zone
Suboxic zone
Anoxic zone
OSPW
FFT
Aerobic oxidation of CH4 and PHC
PHC and CH4 oxidation under nitrate- reducing conditions
PHC and CH4 oxidation under iron- and sulfate- reducing conditions
CH4
CO2+H2O
N2 NO2-
NO3-
FeII
FeIII SO42-
H2S PHC & CH4
CO2+H2O
PHC & CH4
CO2+H2O
OSPW
Residual PHC
Methano-genesis
FeIII & SVI?
Conceptual model of redox processes and GHG mitigation strategies in pond/EPL
NSERC CRD Project in progress
Microbial consolidation and dewatering of tailings
GT GT
GC
P1
PR
P2
P3
U1
U2
U3
P1
P2
P3
A1
A2
A3
Unamended Amended
Assembly: sealed under N2 GT= Gas trapGC= Gas ChromatographA1-3= Sampling portsU1-3= Sampling portsP1-3= Pressure transducer portsPR= Pressure reading unit
Column experiment (50 L; > 200 days)
AmendmentHydrolyzed canola meal: 0.4 g C L-1
Parameters studied• Gas production• Consolidation• Porewater recovery and
chemistry• Mineral transformation• Microbial communities
CO2 + 2H2OMicrobes in sediment
HCO3- + H3O+
Organic substrate biodegradation
CH4 (Methanogenesis): ebullition channels
(Ca,Mg)CO3
H+
Clay particlesdominated by Na+
Ionic strength, DDL & CEC
Flocculated clay particles
CaHCO3+
Pathway I
Na+Na+
Na+Na+
Na+Na+
Mg2+
Ca2+
Fe2+
Ca2+
Ca2+Ca2+
Na+
Na+
Ca2+Mg2+
Fe2+
Fe2+
Na+
Na+
HCO3-
Ca2+
Mg2+
Fe2+
Sr2+
Ba2+
FeOOH
Microbial FeIII
reduction
Clay entrapment by Fe minerals
FeII as sulfides (FeS), siderite (FeCO3), vivianite Fe3(PO4)2.8H2O
Pathway IIAPathway IIB
Pathway II
mixed-valence amorphous FeII-FeIII minerals
Tailings consolidation pathway
Consolidation of tailings using small-scale bioreactor
0 30 60 90 120
0
15
30
45
60W
ater
reco
very
(%)
Day
U0 A0 W1 W2 W3 W4 W5 W8
0 30 60 90 120
Con
solid
atio
n (%
)
Day
U0 A0 W1 W2 W3 W4 W5 W8
0
15
30
45
60
20
Wet reclamation of tailings – creation of end-pit lakes
Kuznetsov et al. 2021. In preparationSamadi et al. 2021. In preparation
Amended Amended
Un-amended
Columns• Sampling ports: 5 (P1-P5)• FFT added: 50L• Cap water: 20L• Column establishment:
March-June, 2015• Incubation: 10, 20, 30oC Source of materials• FFT: Base Mine Lake (BML)• Cap water: BML plus Beaver
creek reservoir
Amendment• n-Alkanes: C8 and C10• Aromatics: Toluene and o-xylene• iso-Alkanes: 2-methylpentane and
3-methylhexane
Column experiment(140-L columns; > 3 year)
0 300 600 900 1200 15000
1000
2000
3000
4000 C11 A C12 A
0 300 600 900 1200 15000
1000
2000
3000
4000 C7 A C8 A
0 300 600 900 1200 15000
1000
2000
3000
4000 C3 A C4 A
0 300 600 900 1200 15000
100
200
300
400
500
600
700 NTU
0 300 600 900 1200 15000
100
200
300
400
500
600
700 NTU
0 300 600 900 1200 15000
100
200
300
400
500
600
700 NTU
20oC 30oC
Turbidity associated with methane production
P3
P4
P5
P1P2
10oC
P3
P4
P5
P1P2
Amended
Turbidity (NTU)
Day
Amended
CH4 (mmol)
Methane production effect on bitumen release from FFT
Un-amended column
Amended column
Amended column
Un-amended column
Bitumen layer
Microbial activity produces chemical flux by inducing geochemical changes in FFT
Cap water
FFT
Hydrocarbons
FeIII FeII
CH4 + CO2Microbes
Fe minerals’ transformationDissolution of carbonate minerals
Low pH
HCO3-, Ca2+, Mg2+,
K+,Sr2+, Ba2+,
Flux due to ebullition
Bitumen transported from FFT via bubbles
Turbidity associated with bubbling
Biogenic gas bubbles
Bitumen coated bubbles
GHG emissions
Mudline
FFT consolidation
Methanogenesis and associated biogeochemical changes
25
Tailings management under dry reclamation scenario
Kuznetsov et al. 2015. Science of the Total Environment. 505: 1-10.Kuznetsova et al. 2016. Sci. Total Environ. 571: 699-710
Thickened tailings management under upland Scenario (oxic environment)
TT1 TT2
Two TTs from field trial: TT1 without polymer; TT2 with polymer addition Irrigate: 750 mL weekly with dH2O (pH 7) or artificial rainwater (pH 5.5); based on
meterological data for Athabasca Oil Sands Region Aerate: air flow during incubation in laboratory fume hood Measure: leachate chemistry weekly; solids chemistry at longer intervals
Acid rock drainage (ARD)
-250
-200
-150
-100
-50
0TT2
t CaC
O3 e
quiv
. 100
0 t-1
Standard ABA Modified ABA
TT1-5
TT1 TT20
4
8
12
16
wt %
Pyrite Carbonates
0 100 200 300 400 5001
2
3
4
5
6
7
8
9
Leac
hate
pH
Day
TT1 Tray 1 TT1 Tray 2 TT2 Tray 3 TT2 Tray 4
TT1 TT2
0 100 200 300 400 5000.00
0.03
0.06
0.09
0.12
0.15Pb
(mg
L-1 )
Day
Tray 1 Tray 2
0 100 200 300 400 5000.0
0.1
0.2
0.3
0.4
Cr (
mg
L-1 )
Day
Tray 1 Tray 2
0 100 200 300 400 5000.0
0.5
1.0
1.5
2.0
Ni (
mg
L-1 )
Day
Tray 1 Tray 2
0 100 200 300 400 5000.00
0.02
0.04
0.06
Pb (m
g L-
1 )
Day
Tray 3 Tray 4
0 100 200 300 400 5000.0
0.3
0.6
0.9
1.2
Cr (
mg
L-1 )
Day
Tray 3 Tray 4
0 100 200 300 400 5000
2
4
6
8
10N
i (m
g L-
1 )
Day
Tray 3 Tray 4
Trace metals in leachate
0 20 40 60 80 100
TT1 initial
TT1 Tray1; Day 0
TT1 Tray1; Day 305
TT1 Tray1; Day 367
TT1 Tray2; Day 0
TT1 Tray2; Day 305
TT1 Tray2; Day 367
TT2 initial
TT2 Tray3; Day 276
TT2 Tray4; Day 276
ActinomycetalesArthrobacterTerrabacterMicrococcineaeIntrasporangiaceaeNocardioidesPseudonocardiaRhizobialesMethylobacteriumBradyrhizobiumAcidiphiliumBetaproteobacteriaBurkholderialesHerbaspirillumGallionellaHerminiimonasSorangiumPseudomonasAcidithiobacillusSulfobacillusDesulfosporosinus
(Acti
nomy
cetal
es)
(Rhiz
obial
es)
-Pr
oteob
acter
ia
-Proteobacteria
-Pro
teo-
bacte
riaCl
ostri-
diales
-P
roteo
bacte
riaAc
tinob
acter
ia
Microbial community structure during ARD
Conclusions• Indigenous microbes cause methane emissions during hydrocarbon
metabolism• Stoichiometric model can predict extent and longevity of emissions
• Methanogenesis alters porewater and solid phase chemistry; increases turbidity, flux of some metals, porewater recovery and consolidation of tailings; and releases bitumen affecting cap water quality in end pit lake
• Thickened tailings produced from froth treatment tailings can produce acid rock drainage if reclaimed under aerobic conditions
• Methanogenesis accelerates consolidation and dewatering of tailings and can be strategized for tailings management
31
Acknowledgements Government and industry sponsorshipResearchers
1. Dr. Julia Foght (Biosciences)2. Dr. Phillip Fedorak (Biosciences)3. Dr. Ania Ulrich (CEE)4. Dr. Rajender Gupta (CE)5. Dr. Mark Lewis (Math & Stat)6. Dr. Hao Wang (Math & Stat)7. Dr. Alsu Kuznetsova (RENR)8. Dr. Petr Kuznetsov (RENR)9. Tara Penner (Syncrude)10. Nicholas Arkell (RENR)11. Carmen Li (Biosciences)12. Rozlyn Young (Biosciences)13. Kathleen Semple (Biosciences)14. Dr. M. Faidz Shahimin (RENR)15. Saima Zamir (RENR)16. Kai Wei (Chemical Engineering)
Technical discussion1. Dr. Zvonko Burkus (Alberta
Environment & Parks)2. Carla Wytrykush (Syncrude)3. Dallas Heisler (Syncrude)