Combining membrane bioreactors with microbial fuel cells for … › ... › 16_A3-Poster.pdf ·...
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First results Half-cell experiments with flat membranes show that filtration and current production at the same time are possible. Therefore sintered stainless steel filters with average pore sizes of 0.5μm and 1μm were tested as filtration active anodes. Geobacter sulfurreducens was used as exo- electrogenic organism together with a growth medium containing acetate. With the 1μm membrane a high permeate flow of 3500 lm -2 h -1 at 3 bars can be reached (Fig. 2A), while the current densities are 11Am - ² at 0 V vs. NHE (Fig. 2B). The 0.5μm membrane yields lower permeate flows of 1700 lm -2 h -1 but higher current densities of up to 16 Am - ² at 0 V vs. NHE. L Conclusions It has been demonstrated, that membrane filtration and microbial fuel cells can be combined by simultaneously using the anode of a MFC as filter in a membrane bioreactor. Further work will be focused on the characterization of complete fuel cells operating on real waste waters. L Acknowledgements We gratefully acknowledge financial support from the Baden- Württemberg Stiftung L References [1] Janicek, A.(2014): Biofuels n. 1, 5, pp. 79–92 Summary Microbial fuel cells (MFC) are a promising new technology to directly convert wastewater’s chemically stored energy into electrical energy. Our work shows that a conductive membrane filter can simultaneously be used as anode of a MFC so that part of the needed energy for the filtration unit of a membrane bioreactor (MBR) can be supplied by the MFC. L Motivation MFCs are promising, but are not yet economically feasible due to little power outputs (0.002 - 2 Wm - ²) in real systems [1]. At the same time membrane bioreactors are increasingly used all over the world but still have a high energy demand. Combining those two systems in one structure promises to reduce the energy demand of a membrane bioreactor without significantly increasing the investment costs. In our concept (Fig. 1) for the first time the anode of a microbial fuel cell is used simultaneously as membrane filter. This has several advantages: • Active proton transport from anode to cathode, which prevents the formation of a detrimental pH gradient between the electrodes • Compact design which leads to smaller internal resistances • Negatively charged membrane which may help to reduce fouling Combining membrane bioreactors with microbial fuel cells for energy efficient wastewater treatment Laboratory for MEMS Applications, Department of Microsystems Engineering - IMTEK, University of Freiburg, Germany J. Danzer, A. Götze, S. Kerzenmacher Figure 2: (A) Filtration and (B) bioelectrochemical performance of stainless steel membranes of the pore sizes 1μm and 0.5μm. Solid symbols ( ) show data while increasing the TMP, open symbols ( ) while decreasing TMP. Current densities are shown at 0 V vs. NHE (Normal Hydrogen Electrode). Figure 1: Concept of a membrane filter used as microbial fuel cell B A
Transcript of Combining membrane bioreactors with microbial fuel cells for … › ... › 16_A3-Poster.pdf ·...
First resultsHalf-cell experiments with flat membranes show that filtrationand current production at the same time are possible.Therefore sintered stainless steel filters with average poresizes of 0.5μm and 1μm were tested as filtration activeanodes. Geobacter sulfurreducens was used as exo-electrogenic organism together with a growth mediumcontaining acetate.With the 1μm membrane a high permeate flow of 3500 lm-2h-1
at 3 bars can be reached (Fig. 2A), while the current densitiesare 11Am-² at 0 V vs. NHE (Fig. 2B). The 0.5μm membraneyields lower permeate flows of 1700 lm-2h-1 but higher currentdensities of up to 16 Am-² at 0 V vs. NHE.
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ConclusionsIt has been demonstrated, that membrane filtration andmicrobial fuel cells can be combined by simultaneously usingthe anode of a MFC as filter in a membrane bioreactor.Further work will be focused on the characterization ofcomplete fuel cells operating on real waste waters.
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AcknowledgementsWe gratefully acknowledge financial support from the Baden-Württemberg Stiftung
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References[1] Janicek, A.(2014): Biofuels n. 1, 5, pp. 79–92
Summary Microbial fuel cells (MFC) are a promising new technology todirectly convert wastewater’s chemically stored energy intoelectrical energy. Our work shows that a conductivemembrane filter can simultaneously be used as anode of aMFC so that part of the needed energy for the filtration unit ofa membrane bioreactor (MBR) can be supplied by the MFC.
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MotivationMFCs are promising, but are not yet economically feasibledue to little power outputs (0.002 - 2 Wm-²) in real systems[1]. At the same time membrane bioreactors are increasinglyused all over the world but still have a high energy demand.Combining those two systems in one structure promises toreduce the energy demand of a membrane bioreactor withoutsignificantly increasing the investment costs.In our concept (Fig. 1) for the first time the anode of amicrobial fuel cell is used simultaneously as membrane filter.This has several advantages:
• Active proton transport from anode to cathode, whichprevents the formation of a detrimental pH gradientbetween the electrodes
• Compact design which leads to smaller internalresistances
• Negatively charged membrane which may help toreduce fouling
Combining membrane bioreactors with microbial fuel cells for energy efficient wastewater treatment
Laboratory for MEMS Applications, Department of Microsystems Engineering - IMTEK, University of Freiburg, Germany
J. Danzer, A. Götze, S. Kerzenmacher
Figure 2: (A) Filtration and (B) bioelectrochemical performance of stainless steelmembranes of the pore sizes 1μm and 0.5μm. Solid symbols ( ) showdata while increasing the TMP, open symbols ( ) while decreasing TMP.Current densities are shown at 0 V vs. NHE (Normal Hydrogen Electrode).
Figure 1: Concept of a membrane filter used as microbial fuel cell
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