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)