Bio-Electrochemical process for Metal and Sulfur Recovery from Acid Mine Drainage

136 Pages·2017·3.25 MB·English

Bio-Electrochemical process for Metal and Sulfur
Recovery from Acid Mine Drainage

Guillermo Alonso Pozo Zamora

Bachelor of Bioengineering
Master of Science (Microbiology)
Universidad de Concepción, Chile

A thesis submitted for the degree of Doctor of Philosophy at
The University of Queensland in 2017
School of Chemical Engineering
Advanced Water Management Centre
ABSTRACT

Water recycling and resource recovery from acid mine drainage (AMD) are
increasingly being regarded as desirable practices with direct benefits for the environment
and the operational and economic viability of the resources sector.
This thesis proves the concept of a novel bioelectrochemical system (BES) for the
direct electrode-driven resource recovery and practically permanent AMD treatment. The
technology consists of a two-cell bioelectrochemical setup to enable the removal of sulfate
from the ongoing reduction-oxidation sulfur cycle, thereby also reducing salinity, without
external addition of chemicals.
In particular, the goals of this thesis are: (i) to enrich a sulfate reducing bacterial
community capable of directly utilising a carbon based cathode as electron donor for
autotrophic sulfate reduction, or via bioelectrochemically-produced H ; (ii) to elucidate the
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electron flux pathways of autotrophic sulfate reduction and microbial interactions in
cathodic mixed cultures; (iii) to develop a high-rate sulfate reducing bioelectrochemical
reactor based on high surface area electrode materials; (iv) to design and implement a
combined chemical-free bioelectrochemical process that enables the sulfur, metal and
water recovery from AMD.
In order to elucidate whether cathodes can effectively release electrons and act as
the only electron donor to support sulfate reduction process, the effect of cathode potential
and inoculum source were evaluated using electrochemical tools, including the recording
of chronoamperometry and cyclic/linear sweep voltammetry (Chapter 5). Electrochemical
and off-gas analysis coupled to liquid phase sampling was carried out to determine the
electron fluxes from the electrode to the final electron acceptor (sulfate) during autotrophic
sulfate reduction (Chapter 6). Fluorescence in situ hybridization (FISH) and digital image
analysis (DAIME) of the microbial communities in z-stack confirmed the microbial
stratification. After obtaining a well-functioning biocathode for autotrophic sulfate reduction,
its performance was experimentally optimised in terms of high-surface area electrode
materials, like multi-wall carbon nanotubes on reticulated vitreous carbon (MWCNT-RVC)
and carbon granules (CG) (Chapter 7). Finally, a novel BES was tested for AMD treatment
(Chapter 8).
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This thesis reported the effect of inoculum and cathode potential on the successful
enrichment of an autotrophic sulfate-reducing biocathode controlled at -0.9 V vs. standard
hydrogen electrode (SHE). This study proved for the first time that high rates of autotrophic
sulfate reduction (29 ± 3 g SO 2--S m-2 d-1) are mainly driven via hydrogen produced at the
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same cathode, with 95±0.04% Coulombic efficiency towards sulfide production. Moreover,
the relative abundance of the biofilm-forming sulfate-reducing bacteria (SRBs) enriched on
the carbon cloth cathodes (46.1± 3.9%) showed the remarkable ability to consume
hydrogen at a rate of 3.9 ± 0.5 mol H m-2 d-1, outcompeting methanogens and
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homoacetogens for the hydrogen without the need to add chemical inhibitors.
The findings of this thesis show that inexpensive CG can achieve higher current-to-
sulfide efficiencies at lower power consumption than the nano-modified three-dimensional
MWCNT-RVC. Sequencing analysis of the 16S rRNA gene on day 58 revealed that
MWCNT-RVC retained the bacteria and archaea population from the inoculum, while CG
electrode surface was able to select for bacteria over archaea.
The feasibility to integrate a two-stage BES was proven with a lab-scale setup for
AMD treatment. Using AMD, the BES operation enhanced the sulfate reduction rate (SRR)
to 946 ± 18 g SO 2--S m-3 d-1, which corresponds to 189 ± 4 g SO 2--S m-2 d-1. The power
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consumption was 10 kWh kg-1 of S0 recovered with an effective removal of sulfate-S to
less than 550 mg L-1 (85 ± 2% removal).
In addition, the BES operation drove the removal and recovery of the main cations
Al, Fe, Mg, Zn at rates of 151 ± 0 g Al m−3 d−1, 179 ± 1 g Fe m−3 d−1, 172 ± 1 Mg m−3 d−1
and 46 ± 0 g Zn m−3 d−1 into a concentrate stream (containing 263 ± 2 mg Al, 279 ± 2 mg
Fe, 152 ± 0 mg Mg and 90 ± 0 mg Zn per grams of solid precipitated after BES treatment).
The solid metal-sludge was 2 times less voluminous and 9 times more readily settleable
than metal-sludge precipitated using NaOH. The continuous BES treatment also
demonstrated the concomitant precipitation of rare earth elements + yttrium (REY) per
grams of solid, with up to 498 ± 70 µg Y, 166 ± 27 µg Nd, 155 ± 14 µg Gd, among other
high-value metals.
The proven integrated process enhances the potential for mining water recycling
worldwide by achieving sulfur recovery in elemental form and recovery of metals at low
concentrations from mining and mineral processing wastewater.
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DECLARATION BY AUTHOR

This thesis is composed of my original work, and contains no material previously
published or written by another person except where due reference has been made in the
text. I have clearly stated the contribution by others to jointly-authored works that I have
included in my thesis.
I have clearly stated the contribution of others to my thesis as a whole, including
statistical assistance, survey design, data analysis, significant technical procedures,
professional editorial advice, and any other original research work used or reported in my
thesis. The content of my thesis is the result of work I have carried out since the
commencement of my research higher degree candidature and does not include a
substantial part of work that has been submitted to qualify for the award of any other
degree or diploma in any university or other tertiary institution. I have clearly stated which
parts of my thesis, if any, have been submitted to qualify for another award.
I acknowledge that an electronic copy of my thesis must be lodged with the
University Library and, subject to the policy and procedures of The University of
Queensland, the thesis be made available for research and study in accordance with the
Copyright Act 1968 unless a period of embargo has been approved by the Dean of the
Graduate School.
I acknowledge that copyright of all material contained in my thesis resides with the
copyright holder(s) of that material. Where appropriate I have obtained copyright
permission from the copyright holder to reproduce material in this thesis.

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PUBLICATIONS DURING CANDIDATURE

Peer-reviewed paper
1) G. Pozo, L. Jourdin, Y. Lu, P. Ledezma, J. Keller, S. Freguia, Methanobacterium
enables high rate electricity-driven autotrophic sulfate reduction, RSC Adv. 5 (2015).

2) G. Pozo, L. Jourdin, Y. Lu, J. Keller, P. Ledezma, S. Freguia, Cathodic biofilm
activates electrode surface and achieves efficient autotrophic sulfate reduction,
Electrochim. Acta. 213 (2016) 66–74.

3) G. Pozo, Y. Lu, S. Pongy, J. Keller, P. Ledezma, S. Freguia, Selective cathodic
microbial biofilm retention allows a high current-to-sulfide efficiency in sulfate-reducing
microbial electrolysis cells, Bioelectrochemistry. 118 (2017) 62-69.

Conference presentations
4) G. Pozo, P Ledezma, J Keller, S Freguia (2017). Resource recovery from Acid
Mine Drainage without chemical dosing using Microbial Electrochemical Technologies.
The 14th IWA Leading Edge Conference on Water and Wastewater Technologies,
Florianópolis (Brazil), 29 May- 2 June, 2017.

5) P Ledezma, G. Pozo, J Keller, S Freguia (2017). Management of mining
wastewaters in Australia: current practice and future technologies. Water in Industry,
Santiago (Chile), 7-9 June, 2017.

6) G. Pozo, P Ledezma, J Keller, S Freguia (2016). Novel bio-electrochemical
process for water recycling and sulfur/metals recovery from mining wastewater. IWA
World Water Congress and Exhibition, Brisbane (Australia), 9-13 October 2016.

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7) G. Pozo, P Ledezma, J Keller, S Freguia (2016). Two-stage bio-electrochemical
process for treatment of sulfate-rich wastewaters. 3rd European Meeting of the
International Society for Microbial Electrochemistry and Technology (EU-ISMET), Rome
(Italy), 26-28 September 2016.

8) G. Pozo, P Ledezma, J Keller, S Freguia (2016). Elucidating high-rate sulfate
reduction mechanisms in microbial electrochemical systems. 3rd Asian Pacific Conference
of International Society for Microbial Electrochemistry and Technologies (AP-ISMET),
Busan (South Korea), 31 August - 2 September, 2016.

9) G. Pozo, L Jourdin, Y Lu, P Ledezma, J Keller, S Freguia (2016). Real-time
Electron/Mass Balances within Autotrophic Sulfate-Reducing Biocathodes. 67th Annual
International Science of Electrochemistry Meeting (ISE), The Hague, (The Netherlands),
21-26 August 2016.

10) G. Pozo, L Jourdin, Y Lu, P Ledezma, J Keller, S Freguia (2015). The effect of
inoculum and cathode potential on bioelectrochemical autotrophic sulfate reduction
process. The fifth international meeting on microbial electrochemistry and technologies,
Arizona, (USA). 1-4 October, 2015.

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PUBLICATIONS INCLUDED IN THIS THESIS

1) G. Pozo, L. Jourdin, Y. Lu, P. Ledezma, J. Keller, S. Freguia, Methanobacterium
enables high rate electricity-driven autotrophic sulfate reduction, RSC Adv. 5
(2015).89368-89374.

Contributor Statement of contribution
Author Pozo, G (Candidate) Designed experiments (60%)
Conducted experiments (100%)
Wrote the paper (100%)
Author Jourdin, L Designed experiments (5%)
Critically reviewed the paper (25%)
Author Lu, Y Designed experiments (10%)
Critically reviewed the paper (10%)
Author Ledezma, P Designed experiments (5%)
Critically reviewed the paper (25%)
Author Keller, J Designed experiments (10%)
Critically reviewed the paper (10%)
Author Freguia, S Designed experiments (10%)
Critically reviewed the paper (30%)

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2) G. Pozo, L. Jourdin, Y. Lu, J. Keller, P. Ledezma, S. Freguia, Cathodic biofilm
activates electrode surface and achieves efficient autotrophic sulfate reduction,
Electrochim. Acta. 213 (2016) 66–74.

Contributor Statement of contribution
Author Pozo, G (Candidate) Designed experiments (60%)
Conducted experiments (100%)
Wrote the paper (100%)
Author Jourdin, L Designed experiments (10%)
Critically reviewed the paper (25%)
Author Lu, Y Designed experiments (5%)
Critically reviewed the paper (10%)
Author Keller, J Designed experiments (5%)
Critically reviewed the paper (10%)
Author Ledezma, P Designed experiments (10%)
Critically reviewed the paper (25%)
Author Freguia, S Designed experiments (10%)
Critically reviewed the paper (30%)

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3) G. Pozo, Y. Lu, S. Pongy, J. Keller, P. Ledezma, S. Freguia, Selective cathodic
microbial biofilm retention allows a high current-to-sulfide efficiency in sulfate-reducing
microbial electrolysis cells, Bioelectrochemistry. 118 (2017) 62-69.

Contributor Statement of contribution
Author Pozo, G (Candidate) Designed experiments (60%)
Conducted experiments (60%)
Wrote the paper (100%)
Author Lu, Y Designed experiments (10%)
Critically reviewed the paper (25%)
Author Pongy, S Conducted experiments (40%)
Author Keller, J Designed experiments (10%)
Critically reviewed the paper (15%)
Author Ledezma, P Designed experiments (10%)
Critically reviewed the paper (30%)
Author Freguia, S Designed experiments (10%)
Critically reviewed the paper (30%)

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CONTRIBUTIONS BY OTHERS TO THE THESIS

This thesis contains some important contributions made by another researcher, Dr.
B. C. Donose of the University of Queensland, carried out SEM/EDS/Raman imaging of
the electrode samples, which are presented in Chapter 3 and 5 of this thesis.

STATEMENT OF PARTS OF THE THESIS SUBMITTED TO QUALIFY
FOR THE AWARD OF ANOTHER DEGREE

None.

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