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. 2019 Dec 24;8(1):41.
doi: 10.3390/microorganisms8010041.

Recovery of Metals from Acid Mine Drainage by Bioelectrochemical System Inoculated with a Novel Exoelectrogen, Pseudomonas sp. E8

Chenbing Ai  1   2   3 , Shanshan Hou  2   4 , Zhang Yan  2   4   5 , Xiaoya Zheng  2   4 , Charles Amanze  2   4 , Liyuan Chai  1   3 , Guanzhou Qiu  2   4 , Weimin Zeng  2   4
Affiliations

Recovery of Metals from Acid Mine Drainage by Bioelectrochemical System Inoculated with a Novel Exoelectrogen, Pseudomonas sp. E8

Chenbing Ai et al. Microorganisms. .

Abstract

Acid mine drainage (AMD) is a typical source of environmental pollution ascribing to its characteristics of high acidity and heavy metal content. Currently, most strategies for AMD treatment merely focus on metal removal rather than metal recovery. However, bioelectrochemical system (BES) is a promising technology to simultaneously remove and recover metal ions from AMD. In this study, both cupric ion and cadmium ion in simulated AMD were effectively recovered by BES inoculated with a novel exoelectrogen, Pseudomonas sp. E8, that was first isolated from the anodic electroactive biofilm of a microbial fuel cell (MFC) in this study. Pseudomonas sp. E8 is a facultative anaerobic bacterium with a rod shape, 0.43-0.47 μm wide, and 1.10-1.30 μm long. Pseudomonas sp. E8 can agglomerate on the anode surface to form a biofilm in the single-chamber MFC using diluted Luria-Bertani (LB) medium as an energy substrate. A single-chamber MFC containing the electroactive Pseudomonas sp. E8 biofilms has a maximum output voltage of 191 mV and a maximum power density of 70.40 mW/m2, which is much higher than those obtained by most other exoelectrogenic strains in the genus of Pseudomonas. Almost all the Cu2+ (99.95% ± 0.09%) and Cd2+ (99.86% ± 0.04%) in simulated AMD were selectively recovered by a microbial fuel cell (MFC) and a microbial electrolysis cell (MEC). After the treatment with BES, the high concentrations of Cu2+(184.78 mg/L), Cd2+(132.25 mg/L), and total iron (49.87 mg/L) in simulated AMD were decreased to 0.02, 0.19, and 0 mg/L, respectively. Scanning electron micrograph (SEM), energy dispersive X-ray spectrometry (EDXS) and X-ray diffraction (XRD) analysis indicate that the Cu2+ and Cd2+ in simulated AMD were selectively recovered by microbial electrochemical reduction as Cu0 (together with trace amounts of Cu2O) or Cd0 on the cathode surface. Collectively, data suggest that Pseudomonas sp. E8 has great potential for AMD treatment and metal recovery.

Keywords: acid mine drainage; exoelectrogen; metal recovery; microbial electrolysis cell; microbial fuel cell.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Phylogenetic tree of Pseudomonas sp. E8 with the related taxa.
Figure 2
Figure 2
Scanning electron micrographs (SEM) of Pseudomonas sp. E8.
Figure 3
Figure 3
Growth curves of Pseudomonas sp. E8 with Luria-Bertani (LB) as substrate under aerobic or anaerobic condition.
Figure 4
Figure 4
The output voltage (A), power density (B), and polarization curves (C) of a microbial fuel cell (MFC) inoculated with Pseudomonas sp. E8.
Figure 5
Figure 5
Electrochemical impedance spectroscopy (EIS) analysis of MFC inoculated with Pseudomonas sp. E8.
Figure 6
Figure 6
Attachment of Pseudomonas sp. E8 on the anode (A): abiotic control; (B): Pseudomonas sp. E8.
Figure 7
Figure 7
Cu 2+ (A), Cd2+ (B) removal rate, pH value (C), and iron concentration (D) change curve in MFC-microbial electrolysis cell (MEC) cathode chamber.
Figure 8
Figure 8
Color change of cathode carbon cloth in different treatment stages (1: before treatment; 2: abiotic; 3: MFC processes; 4: MEC processes).
Figure 9
Figure 9
SEM morphology and element composition of the cathode. (A,B): before treatment; (C,D): abiotic; (E,F): MFC; (G,H): MEC. (The element compositions of regions in red frame were analyzed by EDXS).
Figure 10
Figure 10
XRD analysis of cathode carbon cloth in different treatment stages.
See this image and copyright information in PMC

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