Electrode-Based Approach for Monitoring In Situ Microbial Activity During Subsurface Bioremediation

Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Environmental Science and Technology (Impact Factor: 5.33). 11/2009; 44(1):47-54. DOI: 10.1021/es9017464
Source: PubMed


Current production by microorganisms colonizing subsurface electrodes and its relationship to substrate availability and microbial activity was evaluated in an aquifer undergoing bioremediation. Borehole graphite anodes were installed downgradient from a region of acetate injection designed to stimulate bioreduction of U(VI); cathodes consisted of graphite electrodes embedded at the ground surface. Significant increases in current density (< or =50 mA/m2) tracked delivery of acetate to the electrodes, dropping rapidly when acetate inputs were discontinued. An upgradient control electrode not exposed to acetate produced low, steady currents (< or =0.2 mA/m2). Elevated current was strongly correlated with uranium removal but minimal correlation existed with elevated Fe(II). Confocal laser scanning microscopy of electrodes revealed firmly attached biofilms, and analysis of 16S rRNA gene sequences indicated the electrode surfaces were dominated (67-80%) by Geobacter species. This is the first demonstration that electrodes can produce readily detectable currents despite long-range (6 m) separation of anode and cathode, and these results suggest that oxidation of acetate coupled to electron transfer to electrodes by Geobacter species was the primary source of current. Thus it is expected that current production may serve as an effective proxy for monitoring in situ microbial activity in a variety of subsurface anoxic environments.

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    • "In terms of other applications, SMFC can also act as a bio-monitor to evaluate microbial activities during bioremediation in anoxic aquifers (Williams et al., 2009). Zhang et al. (2011a) powered a wireless temperature sensor based on the output of SMFC while Thomas et al. (2013) used SMFC to power a wireless telecommunication system. "
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    ABSTRACT: Microbial fuel cell (MFC) technology offers the dual advantages of wastewater treatment and electricity generation. Research efforts have been made to improve its power output. However, MFC seems limited at pilot scale and power outputs appear to have plateaued. As such, some integrated technologies have emerged based on MFC. These hybrid technologies have the larger potential for scaling up and practical application compared with the pure MFC. Therefore, in their review the authors present these emerged technologies and discuss the development tendency and the challenges. The review can hopefully provide a framework to identify priorities for further research on this area.
    Critical Reviews in Environmental Science and Technology 06/2015; · 3.47 Impact Factor
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    • "Microbial activity monitoring has also been proposed as another application of an MFC-based sensor (Patchett et al., 1988; Tront et al., 2008a,b; Williams et al., 2010b). The idea is based on the response of current generation to different substrate (BOD) concentrations based on the activity of the biofilm colonized on the anode. "
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    ABSTRACT: Abstract A Microbial Fuel Cell is a bioelectrochemical device that exploits metabolic activities of living microorganisms for generation of electric current. The usefulness and unique and exclusive architecture of this device has received wide attention recently of engineers and researchers of various disciplines such as microbiologists, chemical engineers, biotechnologists, environment engineers and mechanical engineers, and the subject of MFCs has thereby progressed as a well-developed technology. Sustained innovations and continuous development efforts have established the usefulness of MFCs towards many specialized and value-added applications beyond electricity generation, such as wastewater treatment and implantable body devices. This review is an attempt to provide an update on this rapidly growing technology.
    Critical Reviews in Microbiology 06/2014; DOI:10.3109/1040841X.2014.905513 · 6.02 Impact Factor
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    • "In order to scale-up this strategy for successful in situ application, extensive testings based on subsurface characteristics and site-specific design needs to be studied. Williams and colleagues (2010) for the first time demonstrated the in situ applicability of graphite electrodes in the subsurface serving as electron acceptors for microbial stimulation during uranium bioremediation at Rifle site in Colorado. A similar approach may be employed for the remediation of chlorinated solvents. "
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    ABSTRACT: Microbial electric systems (MESs) hold significant promise for the sustainable remediation of chlorinated solvents such as tetrachlorethene (perchloroethylene, PCE). Although the bio-electrochemical potential of some specific bacterial species such as Dehalcoccoides and Geobacteraceae have been exploited, this ability in other undefined microorganisms has not been extensively assessed. Hence, the focus of this study was to investigate indigenous and potentially bio-electrochemically active microorganisms in PCE-contaminated groundwater. Lab-scale MESs were fed with acetate and carbon electrode/PCE as electron donors and acceptors, respectively, under biostimulation (BS) and BS-bioaugmentation (BS-BA) regimes. Molecular analysis of the indigenous groundwater community identified mainly Spirochaetes, Firmicutes, Bacteroidetes, and γ and δ-Proteobacteria. Environmental scanning electron photomicrographs of the anode surfaces showed extensive indigenous microbial colonization under both regimes. This colonization and BS resulted in 100% dechlorination in both treatments with complete dechlorination occurring 4 weeks earlier in BS-BA samples and up to 11.5 μA of current being generated. The indigenous non-Dehalococcoides community was found to contribute significantly to electron transfer with ∼61% of the current generated due to their activities. This study therefore shows the potential of the indigenous non-Dehalococcoides bacterial community in bio-electrochemically reducing PCE that could prove to be a cost-effective and sustainable bioremediation practice.
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