Zero-valent iron for the in situ remediation of Antarctic contaminated sites

266 Pages·2015·11.81 MB·English

Zero-valent iron for the in situ remediation of
Antarctic contaminated sites

Tom M. Statham

Submitted in total fulfilment of the requirements of the degree of
Doctor of Philosophy

Supervisors:
Kathryn Mumford
Ian Snape
Geoff Stevens

March, 2015

Department of Chemical and Biomolecular Engineering
The University of Melbourne

Abstract
To successfully remediate contaminated areas in Antarctica and other cold
regions there is a requirement to develop suitable heavy metal containment and
treatment technologies.

Potential contaminant technologies for the remediation of Antarctic contaminated
sites were assessed and the results indicate that a granular zero-valent iron (ZVI)
permeable reactive barrier (PRB) is appropriate for the treatment of heavy metal
contamination. This containment and ground/surface water treatment approach
could complement either dig-and-haul or stabilisation/fixation remediation
methods.

A mass transport model was developed that accounts for (i) aqueous-phase
dispersion processes, (ii) film diffusion of contaminant ions to the reacting
surface and (iii) the reactive mechanism itself. Regression of a series of dynamic
flow-kinetic experiments suggest that the removal of Cu2+ and Zn2+ ions would
be controlled by mass transfer to a small reacting proportion of the iron
oxyhydroxide surface area.

Designing water treatment systems with contamination removal based on ZVI
requires an understanding of the formation of a series of iron oxyhydroxides
produced during corrosion of the thermodynamically unstable ZVI core. X-ray
diffractometry (XRD) and geochemical modelling were used to investigate the
mechanisms of copper and zinc removal and the formation of iron oxyhydroxides
in batch experiments at 4 and 25 °C over 349 days. Copper removal was
predominantly associated with a mineral product, which was unstable in an
aerobic environment. Zinc and some copper were sequestered into the iron
oxyhydroxide structure and did not redissolve when the pH was reduced.

When located in a cold region exposed to freeze-thaw cycling, solution-media
interactions may be detrimental to PRB performance. A laboratory based
simulation of PRB performance was conducted within Darcy Boxes under freeze-
thaw conditions. The reactive contaminants, Cu2+ and Zn2+ ions, were removed
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from the pore water during solution flow and freeze-thaw cycling. The retention
time within the reactive media, assessed by a conservative tracer, decreased by
15–18% during the set first freeze-thaw cycling and remained constant then on
during the set second freeze-thaw cycling. Agglomeration of particles was
observed during an experimental freeze-thaw ZVI PRB simulation. However,
there was no significant change in the hydraulic conductivity. The < 212 µm
particles produced during the flow of solution and freeze-thaw cycling did not
contain concentrated levels of the treated contaminant metals.

Based on the laboratory results, a media sequence for the treatment of both
hydrocarbon and heavy metal contamination was installed within an existing PRB
at Casey Station, Antarctica. Results from two seasons of monitoring indicate
that the media achieved a greater chemical phosphorus removal capacity when
compared to previous Antarctic PRB designs. However, non-idea flow was
observed during the second season.

Geophysical studies and an excavator based subsurface site assessment were
conducted to continue the development of a conceptual site model for the Wilkes
Tip Site, a contaminated site in Antarctica. The potential remediation directions
of this site were also discussed.
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Declaration

This is to certify that:

i. the thesis comprises only my original work except where indicated in the
Preface;

ii. due acknowledgement has been made in the text to all other material used;

iii. the thesis is less than 100,000 words in length, exclusive of tables, maps,
bibliographies and appendices.

Tom M. Statham

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Acknowledgements
When entering Geoff Stevens’ office in 2010 to inquire about research in
Antarctic remediation I had little idea about the path I was undertaking. Aspects
of this thesis were and still are well out of my knowledge on certain topics and
could not have been completed without a lot of help and support from people
who will be friends long after thesis submission.

Firstly, I would like to thank my supervisors Kathryn Mumford, Geoff Stevens
and Ian Snape for their balance of support and freedom, advice, and humour.

Lachlan Mason’s assistance is woven throughout this thesis, including turning
ideas into functional MATLAB code, laboratory monitoring and field work.
Additional field work at Casey Station would not have been completed without
the support of many expeditioners especially Danielle Camenzuli, Ben Freidman,
Johan Mets, Greg Hince, Dan Wilkins, Lauren Wise, Rebecca McWatters, Dan
Jones and Tim Spedding. Laboratory work, support or interpretation presented in
this thesis has been conducted by numerous people including Scott Stark, Damian
Gore, John Rayner, Roger Curtain, Alita Aguiar, Carolina Tallon, Laura Gordon,
Andrew Lee and Kezia. All things administration were completed by Tabitha
Cesnak and Michelle de Silva. My sincerest thanks and appreciation to all these
patient souls.

While conducting this work I received financial support from an Australian
Postgraduate Award scholarship. Additional funding and support was provided
by the Particulate Fluids Processing Centre (PFPC), Department of Chemical and
Biomolecular Engineering, The University of Melbourne School of Engineering,
Australian Antarctic Division Terrestrial and Near Shore Ecosystems and
Australian Antarctic Science Grant 4029.

Lastly, I would like to acknowledge my parents and family for the upbringing
and support to allow me to spend nine years as a student at university; and also
my friends, especially Ed Yencken, for their encouragement during this time.

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Publications arising from this thesis
Journal articles
Chapter 3
Statham, T., Mumford, K., Stevens, G., Removal of copper and zinc from ground water by
granular zero-valent iron: a study of kinetics, accepted Separation Science and Technology

Chapter 4
Statham, T., Mason, L., Mumford, K., Stevens, G., The specific reactive surface area of metal
contaminant removal by granular zero-valent iron, in review Water Research

Chapter 5
Statham, T., Mumford, K., Stark, S., Gore, D., Stevens, G., Removal of copper and zinc from
ground water by granular zero-valent iron: a mechanistic study, in review Separation Science
and Technology

Chapter 6
Statham, T., Mumford, K., Rayner, J., Stevens, G. (2015), Removal of copper and zinc from
ground water by granular zero-valent iron: a dynamic freeze-thaw permeable reactive barrier
laboratory experiment, Cold Regions Science and Technology, 110, 120-128

Chapter 7
Statham, T., Mumford, K., Stark, S., Snape, I., Stevens, G., A permeable reactive media
sequence for the remediation of heavy metal and hydrocarbon contaminated water: a field
assessment at Casey Station, Antarctica, in final preparation

Consulting reports
Chapters 1 and 2
Statham, T., Mumford, K., Stevens, G., Gore, D., Snape, S., Stark, S., (2012) “Assessment and
development of Antarctic remediation technologies for the Wilkes and Davis tip sites” Prepared
for the Australian Antarctic Division

Conference abstracts
Statham, T., Mumford, K., Snape, I., Stevens, G. (2014) “In situ remediation and management
of contaminated sites in Antarctica” NORDROCS 2014 5th Nordic Joint Meeting on
Remediation of Contaminated Sites, Stockholm, Sweden, September 15–18

Statham, T., Mumford, K., Stevens, G. (2013) “Development of permeable reactive barriers for
the in situ treatment and management of Antarctic contaminated sites” AOTULE Postgraduate
Conference, Bangkok, Thailand, October 17–19

Statham, T., Mumford, K., Rayner, J., Stark, S., Hince, G., Snape, I., Gore, D. (2013), “The use
of permeable reactive barriers to treat and manage contaminated sites in Antarctica” CleanUp
2013, the 5th International Contaminated Site Remediation Conference, Melbourne, Australia,
September 15–18 (poster)

Statham, T. (2013) “The use of permeable reactive barriers to treat contaminated sites in
Antarctica” Strategic Antarctic Science, Hobart, Australia, June 24–28

Statham, T., Mumford, K., Snape, I., Stevens, G. (2012) “Development of containment metal
treatment systems suitable for cold regions” The 8th International Conference – Contaminants in
Freezing Ground, Obergurgl, Austria, April 22–26
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Table of contents
Abstract i
Declaration iii
Acknowledgements iv
Publications arising from this thesis v
Table of contents vi
List of figures viii
List of tables xi
1. Introduction 1
1.1 Metal contaminated sites in the Australian Antarctic Territory 1
1.2 Contaminated site treatment methods 12
1.3 Research objectives 15
2. Background information and material selection 16
2.1 PRB development background 16
2.2 Required direction 21
2.3 Solution speciation 24
2.4 Zero-valent iron background 26
2.5 Metal removal mechanisms 34
2.6 Iron performance constraints 40
2.7 Required research 42
3. Short time scale batch studies 44
3.1 Introduction 44
3.2 Kinetic theory 45
3.3 Experimental methods 47
3.4 Results and discussion 49
3.5 Conclusion 60
4. Kinetic column studies 61
4.1 Introduction 61
4.2 Experimental methods 63
4.3 Kinetic modelling 65
4.4 Results and discussion 71
4.5 Implications for PRB design 84
4.6 Conclusion 85
5. Granular iron mechanistic studies 86
5.1 Introduction 86
5.2 Experimental methods 88
5.3 Results and discussion 90
5.4 Implications for PRB design 100
5.5 Conclusion 101
6. Freeze-thaw assessment 103
6.1 Introduction 103
6.2 Theory and background 103
6.3 Experimental method 113
6.4 Results and discussion 117
6.5 Implications for PRB design 128
6.6 Conclusion 129
7. Field assessment of a PRB for multi-contaminant sites 131
7.1 Background 131
7.2 Design 132
7.3 Tracer theory 139
7.4 Field and analysis methods 141
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7.5 Results and discussion 144
7.6 Implications for PRB design 153
7.7 Conclusion 154
8. Knowledge gained at Wilkes and recommendations 156
8.1 Recent assessments conducted at Wilkes 156
8.2 Assessment results 157
8.3 Suggested Wilkes remediation direction 163
8.4 Conclusion 166
9. Concluding remarks and direction 167
9.1 Thesis summary 167
9.2 Generalised final remarks 169
9.3 Future Antarctic in situ remediation research 169
Nomenclature 171
Acronyms 171
Minerals 172
Mathematical symbols 173
References 175
Appendices 195
Appendix 2A: Material screening test details 195
Appendix 2B: PheePlot predominance diagrams 196
Appendix 2C: PheePlot speciation diagrams 197
Appendix 3A: Column comparison of ZVI sources 198
Appendix 4A: Fixed inlet contaminant concentration results 200
Appendix 5A: XRD analysis 209
Appendix 5B: Experimental data 216
Appendix 5C: PhreePlot code 228
Appendix 6A: Solution contaminant concentrations and modelling 229
Appendix 6B: SEM and EDS results 233
Appendix 6C: Aqua regia digestion 237
Appendix 6D: Comparison Cu and Zn concentration in fines and bulk material 238
Appendix 6E: XRD analysis 239
Appendix 7A: Tracer test raw data 243
Appendix 7B: Sampling probe data 245
Appendix 8A: OhmMapper survey 247
Appendix 8B: Ice profile laboratory results 250

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List of figures
Figure 1.1: The location of Wilkes Station and Tip .................................................................. 3
Figure 1.2: An aerial photograph of the capped Davis Tip and surrounding features ................. 8
Figure 1.3: The Davis Tip showing surveyed perimeter, shot point locations of seismic line
with MASW section superimposed on seismic line ........................................................ 10
Figure 1.4: MASW section through the abandoned Davis Tip ................................................. 10
Figure 1.5: A comparison of the trade offs of different remediation methods .......................... 13
Figure 2.1: Phosphate concentrations within Casey PRB during the first and second seasons of
operation ..................................................................................................................... 19
Figure 2.2: A potential in situ treatment strategy to treat hydrocarbon and heavy metal
contaminated sites ........................................................................................................ 21
Figure 2.3: 24 hour removal of metal on a medium bulk volume basis .................................... 23
Figure 2.4: Predominance diagrams for: left copper, middle zinc and right iron ...................... 25
Figure 2.5: Speciation diagrams for: left copper, middle zinc and right iron ........................... 25
Figure 2.6: The proportion of various products and the ageing temperature of ferrihydrite a:
lepidocrocite, b: goethite, c: hematite ........................................................................... 31
Figure 2.7: Cross sectional SEM–BSE image of cemented iron filings showing iron
oxyhydroxide formation adjacent to the iron filing surface ............................................ 34
Figure 2.8: Potential elements removed by ZVI ..................................................................... 41
Figure 3.1: Sieve determined particle size distributions of the ZVI sources ............................ 50
Figure 3.2: Evaluation of single contaminant copper removal experimental first order kinetics
for the ZVI sources ...................................................................................................... 52
Figure 3.3: Single contaminant observed first order rate constant varying Chem-Supply iron
concentration ............................................................................................................... 53
Figure 3.4: Iron dissolution at an initial contaminant concentration of 0 or 50 µM .................. 54
Figure 3.5: Comparison of iron dissolution at varying ZVI for copper and zinc removal ......... 54
Figure 3.6: Comparison of pH in multiple copper pulse addition runs ..................................... 55
Figure 3.7: Comparison of observed first order rates varying shaker velocity for Peerless iron at
4 and 25 °C .................................................................................................................. 57
Figure 3.8: Metal concentrations for a multiple copper addition experiment for a Chem-Supply
iron ............................................................................................................................. 58
Figure 3.9: Comparison of the copper first order plot for each run in a multiple copper addition
experiment ................................................................................................................... 59
Figure 3.10: Mastersizer determined particle size distribution of iron oxyhydroxides formed
during metal removal ................................................................................................... 60
Figure 4.1: Dynamic column experiment schematic ............................................................... 64
Figure 4.2: Column modelling discretisation of the x-domain; model uses N = 100 ................. 70
Figure 4.3: Regressed linear model for the determination of column axial dispersion parameters
................................................................................................................................... 72
Figure 4.4: Example contaminant concentrations across a column while increasing and
decreasing the column residence time ........................................................................... 73
Figure 4.5: Equilibrium PHREEQC pH dependence of copper and zinc hydroxide formation and
sample experimental copper data .................................................................................. 74
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