Graphene-Coated Hollow Fiber Membrane as the Cathode in Anaerobic Electrochemical Membrane Bioreactors – Effect of Configuration and Applied Voltage on Performance and Membrane Fouling

Werner, Craig M.; Katuri, Krishna P.; Hari, Ananda Rao; Chen, Wei; Lai, Zhiping; Logan, Bruce E.; Amy, Gary L.; Saikaly, Pascal E.

doi:10.1021/acs.est.5b02833

Cited by 104 publications

(53 citation statements)

References 40 publications

(78 reference statements)

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“…For example, accumulation of propionate (>20 mM) at high organic loading rates is detrimental to methanogenic systems (Pullammanappallil et al, 2001; Gallert and Winter, 2008; Ma et al, 2009). Thus, propionate removal is necessary for the stable operation of AD; and (2) integrating MECs to membrane bioreactors (MBRs), in what is referred to as anaerobic electrochemical MBR, for recovering energy and water from low strength wastewaters such as municipal wastewater (Katuri et al, 2014, 2016; Werner et al, 2016). In municipal wastewater, acetate and propionate represent the main VFAs, and their concentrations fluctuate resulting in a diverse and temporally fluctuating microbial communities.…”

Section: Introductionmentioning

confidence: 99%

Temporal Microbial Community Dynamics in Microbial Electrolysis Cells – Influence of Acetate and Propionate Concentration

et al. 2017

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Microbial electrolysis cells (MECs) are widely considered as a next generation wastewater treatment system. However, fundamental insight on the temporal dynamics of microbial communities associated with MEC performance under different organic types with varied loading concentrations is still unknown, nevertheless this knowledge is essential for optimizing this technology for real-scale applications. Here, the temporal dynamics of anodic microbial communities associated with MEC performance was examined at low (0.5 g COD/L) and high (4 g COD/L) concentrations of acetate or propionate, which are important intermediates of fermentation of municipal wastewaters and sludge. The results showed that acetate-fed reactors exhibited higher performance in terms of maximum current density (I: 4.25 ± 0.23 A/m2), coulombic efficiency (CE: 95 ± 8%), and substrate degradation rate (98.8 ± 1.2%) than propionate-fed reactors (I: 2.7 ± 0.28 A/m2; CE: 68 ± 9.5%; substrate degradation rate: 84 ± 13%) irrespective of the concentrations tested. Despite of the repeated sampling of the anodic biofilm over time, the high-concentration reactors demonstrated lower and stable performance in terms of current density (I: 1.1 ± 0.14 to 4.2 ± 0.21 A/m2), coulombic efficiency (CE: 44 ± 4.1 to 103 ± 7.2%) and substrate degradation rate (64.9 ± 6.3 to 99.7 ± 0.5%), while the low-concentration reactors produced higher and dynamic performance (I: 1.1 ± 0.12 to 4.6 ± 0.1 A/m2; CE: 52 ± 2.5 to 105 ± 2.7%; substrate degradation rate: 87.2 ± 0.2 to 99.9 ± 0.06%) with the different substrates tested. Correlating reactor’s performance with temporal dynamics of microbial communities showed that relatively similar anodic microbial community composition but with varying relative abundances was observed in all the reactors despite differences in the substrate and concentrations tested. Particularly, Geobacter was the predominant bacteria on the anode biofilm of all MECs over time suggesting its possible role in maintaining functional stability of MECs fed with low and high concentrations of acetate and propionate. Taken together, these results provide new insights on the microbial community dynamics and its correlation to performance in MECs fed with different concentrations of acetate and propionate, which are important volatile fatty acids in wastewater.

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Section: Introductionmentioning

confidence: 99%

Temporal Microbial Community Dynamics in Microbial Electrolysis Cells – Influence of Acetate and Propionate Concentration

et al. 2017

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“…The bioreactor with the catalytic membrane yielded a positive net energy and produced an effluent with low organic content. Graphene layer was later directly synthesized on the Ni hollow‐fiber membrane to further improve the effluent quality . The catalytic membrane was proven durable with low transmembrane pressure after long‐term operation.…”

Section: Discussionmentioning

confidence: 99%

Platinum Group Metal–free Catalysts for Hydrogen Evolution Reaction in Microbial Electrolysis Cells

Yuan

2017

The Chemical Record

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Hydrogen gas is a green energy carrier with great environmental benefits. Microbial electrolysis cells (MECs) can convert low-grade organic matter to hydrogen gas with low energy consumption and have gained a growing interest in the past decade. Cathode catalysts for the hydrogen evolution reaction (HER) present a major challenge for the development and future applications of MECs. An ideal cathode catalyst should be catalytically active, simple to synthesize, durable in a complex environment, and cost-effective. A variety of noble-metal free catalysts have been developed and investigated for HER in MECs, including Nickel and its alloys, MoS , carbon-based catalysts and biocatalysts. MECs in turn can serve as a research platform to study the durability of the HER catalysts. This personal account has reviewed, analyzed, and discussed those catalysts with an emphasis on synthesis and modification, system performance and potential for practical applications. It is expected to provide insights into the development of HER catalysts towards MEC applications.

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“…Such graphenes are rarely applied (nor are they probably useful) for fuel cell applications. CVD graphene has, however, been reported to be beneficial for Anaerobic Electrochemical Membrane BioReactors (AnEMBRs) [34]. The general principle of the process is the same as a fuel cell, so the device has been discussed.…”

Section: Pristine Graphenementioning

confidence: 99%

“…The biofilm therefore acts as a resistive layer between the cathode and the electrolyte over a period of time, and is the major contributor to device failure. The rectangular system forms a biofilm that is ten times less thick than the tubular system (0.4 μm) [34], meaning that the hydrogen evolving from the reaction can act as a scrubber to replenish the electrode surface. The graphene layer in this case provides the platform for microbes to anchor upon and transduce electrical current into the evolution of hydrogen through microbial interactions.…”

Section: Pristine Graphenementioning

confidence: 99%

Incorporating Graphene into Fuel Cell Design

Randviir

Banks

2016

NanoScience and Technology

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Since the fabrication and subsequent physical characterisation of graphene in 2004 and 2005, a host of potential uses have been suggested and researched. To date, some have had some success, while others are significantly lacking in critical research due to unforeseen problems with the electrochemical properties of graphene. Of the many applications, fuel cells were predicted to gain benefit from graphene; the focus of this book chapter is to assess whether graphene has a place in fuel cells, and disseminate the current state of research across the globe for this purpose. It is evident that the applicability of graphene as a fuel cell anode, cathode, or proton exchange membrane, is dramatically dependent upon the type of graphene used in the fuel cell design. Pristine graphenes lack the necessary active sites for low energy electrochemical reactions required in fuel cells, and therefore their use as anodes or cathodes is seemingly limited. However pristine graphene may permit protons across atomic scale defects in its lattice and prove to be a good material for a proton exchange membrane when coupled with its tensile strength. Laser-induced graphene is a relatively new technique for the fabrication of graphene but offers a potential route towards manufacture of 3D graphene architectures that could be useful for cathodic reactions such as oxygen reduction. Reduced graphene oxides in their many guises could also be useful, provided that a replicable standard can be formulated for fuel cell anode and cathodes. Graphene oxides also have potential for proton exchange membranes but may suffer from longevity issues as a result of the decreased hydrophobicity allowing swelling of the material when in an aqueous environment. Nitrogen-doped graphenes are also potential candidates for the future of fuel cell research for both anodic and cathodic reactions. The future of graphene as a fuel cell material is predicted to be several years away because the research in this area has not solved issues of longevity, reproducibility, and temperature tolerance, while maintaining a good cell voltage and current density.

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Graphene-Coated Hollow Fiber Membrane as the Cathode in Anaerobic Electrochemical Membrane Bioreactors – Effect of Configuration and Applied Voltage on Performance and Membrane Fouling

Abstract: suspension. These results show that the new rectangular reactor design, which had increased rates of hydrogen production, successfully delayed the onset of cathode biofouling and improved reactor performance.

Cited by 104 publications

References 40 publications

Temporal Microbial Community Dynamics in Microbial Electrolysis Cells – Influence of Acetate and Propionate Concentration

Temporal Microbial Community Dynamics in Microbial Electrolysis Cells – Influence of Acetate and Propionate Concentration

Platinum Group Metal–free Catalysts for Hydrogen Evolution Reaction in Microbial Electrolysis Cells

Incorporating Graphene into Fuel Cell Design

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