Conversion of Wastes
into Bioelectricity
Trent Benefield
Ryan Risinger
http://www.ecofriend.com/eco-tech-energy-producingmicrobes-generate-electricity-from-mud.html
http://shanghaiist.com/2012/06/13/progressiveresidential-electricity-tariffs.php
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Summary
Why is this important?
MET's (Microbial Electrochemical technologies)
Prior Work
Electricity Generation
Chemical Production in MEC's (Microbial
Electrolysis Cells)
Compare with conventional technologies
Improvements
Conclusions
References
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Why is this important?
Treating wastewater takes 15 GW power in U.S.
Domestic, industrial, and animal wastewater has
considerable potential energy (~1.5x10^11
kWh)
~17 GW power equivalent
Additional 600 GW power annually from
agriculture biomass
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http://www.ecofriend.com/generating-electricity-from-waste-water.html
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MET's
Microbial Electrochemical Technologies
Use microorganisms to generate electricity and
produce chemicals
Process able to use wide variety of wastes
Acetates, protein, lignocellulose, etc.
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http://www.sfi.mtu.edu/FutureFuelfromForest/LignocellulosicBioma
ss.htm
http://www.terradaily.com/reports/New_Processing_Steps_Promise_More_Economical_Etha
nol_Production.html
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Prior Work
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Basic technology has been around since the
early 19th century.
In 1931 a series of microbial fuel cells was
created that produced 31 volts, but the
current was only 2 milliamps.
Recently in Australia, Foster's Brewing Co.
has produced a large scale bioreactor (660
gallons) that uses the brewing process
wastewater as a fuel source. It produces
clean water and 2 kilowatts of electrical
power.
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Electricity Generation
Exoelectrogenic
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Use of "electron shuttles"
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example: Geobacter, Shewanella
Flavin, and phenazine
 Electron transport chain
Anode: Bacteria release electrons/protons
Cathode: Oxygen is oxidizer
http://chemed.chem.wisc.edu/chempaths/GenChem-Textbook/Electrochemical-Cells-695.html
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Wide variety of wastes in process
Need variety of microbes
More power=more specialized wastes
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o
Acetates, Lactate
More complex wastes=more interactions
needed to break down molecules
o
Syntrophic interactions, similar to anaerobic digestion
http://wishart.biology.ualberta.ca/BacMap/cgi/getSpeciesCard.cgi?acc
ession=NC_003552&ref=index_12.html
http://www.methanedivers.com/
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Chemical Production in MEC's
Microbial Electrolysis Cells
Applying power can produce variety of chemicals
biofuels, by producing hydrogen
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o
o
Produced at the cathode
More thermodynamically efficient than water splitting
 -.13 V minimum addition, -1.2 V for water splitting
Voltage required for Hydrogen production: -.41 V
Voltage at anode: -.28 V
-.41 V minus -.28 V = -.13 V
B. E. Logan et al., Microbial electrolysis cells for high yield hydrogen gas production from organic matter. Environ. Sci. Technol.42,
8630 (2008).
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http://en.wikipedia.org/wiki/File:Microbial_electrolysis_cell.png
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Organic chemicals produced at cathode
Apply voltage
Methane is most common in MEC's
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NaOH
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produced by H2 evolved at cathode
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Cation exchange membrane separator
Produced due to pH gradients between chambers
Anode: proton build up
Cathode: proton deficiency
Hydrogen Peroxide
o
H2O normally produced at cathode
O2 + 2H2O + 2e- -> H2O2 + 2OH11
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Compare with conventional technologies
Current wastewater processing technologies
Developing since over a century
Requires -0.3 kWh/m^3 electricity
Carnot Cycle limitations
Membrane bioreactors
Requires 1-2 kWh/m^3 electricity
Economical with very large digesters only
Needs concentrated waste streams
Warmer temperatures
Low energy recovery
Decreasing need for sludge handling
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S. Hays, F. Zhang, B. E. Logan, Performance of two different types of anodes in membrane electrode assembly
microbial fuel cells for power generation from domestic wastewater. J. Power Sources196, 8293 (2011).
P. L. McCarty, J. Bae, J. Kim, Domestic wastewater treatment as a net energy producer—can this be achieved?
Environ. Sci. Technol.45, 7100 (2011). 21749111
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Examples of Types of Possible Feed
Waste Type
Heat of Combustion kcal/kg
Charcoal
7213
Animal Fats
9450
Wood Chips
4785
Coffee Waste
4371
Acetic Acid
3446
Sunflower Stalk
4300
Tobacco Waste
2910
http://lehrafuel.com/briquetts-calorificvalue.html
http://www.balboapacific.com/WasteToEnergy/BTU_Values.pdf
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Improvements
Increase power output in microbes
Addition of Enterococcus faecium increase
power output by 30-70%
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o
Little power produced on its own
More research required
Pretreat incoming biomass Increases
digestibility
Lime (calcium hydroxide) pretreatment
Breaks down lignin in lignocellulose
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http://www.sfi.mtu.edu/FutureFuelfromForest/Lignocellulosic
Biomass.htm
http://en.wikipedia.org/wiki/File:Cellulose-2D-skeletal.png
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Conclusion
Technology is has lots of potential for energy
generation.
Current research still can't achieve large
electricity generation.
Many different feeds with varying potential
energies
Improvements are still possible (varying
microbial cultures, pretreatmment)
One of the greatest advantages is to recycle
wastewater with drastically less electricity
input.
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References
1.
P. L. McCarty, J. Bae, J. Kim, Domestic wastewater treatment as a net energy producer—can this
be achieved? Environ. Sci. Technol.45, 7100 (2011). 21749111
2.
B. E. Logan, Extracting hydrogen and electricity from renewable resources. Environ. Sci. Technol.
38, 160A (2004).
3.
R. D. Perlack et al., “Biomass as feedstock for a bioenergy and bioproducts industry: The technical
feasibility of a billion-ton annual supply,” vol. ORNL/TM-2005/66, report no. DOE/GO-102995-2135
(Oak Ridge National Laboratory, Oak Ridge, TN, 2005).
4.
B. E. Logan, Exoelectrogenic bacteria that power microbial fuel cells. Nat. Rev. Microbiol. 7, 375
(2009).
5.
E. Marsili et al., Shewanella secretes flavins that mediate extracellular electron transfer. Proc. Natl.
Acad. Sci. U.S.A.105, 3968 (2008).
6.
H. von Canstein, J. Ogawa, S. Shimizu, J. R. Lloyd, Secretion of flavins by Shewanella species and
their role in extracellular electron transfer. Appl. Environ. Microbiol. 74, 615 (2008).
10.1128/AEM.01387
7.
T. H. Pham et al., Metabolites produced by Pseudomonas sp. enable a Gram-positive bacterium to
achieve extracellular electron transfer. Appl. Microbiol. Biotechnol. 77, 1119 (2008).
10.1007/s00253-007-1248
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8.
Logan, Bruce E. and Korneel Rabaey. "Conversion of Wastes into Bioelectricity and Chemicals by
Using Microbial Electrochemical Technologies." Science 337 (2012): 686-689. Print.
9.
"Microbial Fuel Cell" Wikipedia. n.p., n.d. Web. September 10, 2012.
10. P. D. Kiely, J. M. Regan, B. E. Logan, The electric picnic: Synergistic requirements for
exoelectrogenic microbial communities. Curr. Opin. Biotechnol. 22, 378 (2011).
11. D. F. Call, B. E. Logan, Lactate oxidation coupled to iron or electrode reduction by Geobacter
sulfurreducens PCA. Appl. Environ. Microbiol. 77, 8791 (2011). 10.1128/AEM.06434
12. A. M. Speers, G. Reguera, Electron donors supporting growth and electroactivity of Geobacter
sulfurreducens anode biofilms. Appl. Environ. Microbiol. 78, 437 (2012). 10.1128/AEM.06782
13. B. E. Logan et al., Microbial electrolysis cells for high yield hydrogen gas production from organic
matter. Environ. Sci. Technol.42, 8630 (2008).
14. P. Clauwaert et al., Combining biocatalyzed electrolysis with anaerobic digestion. Water Sci.
Technol.57, 575 (2008).
15. P. Parameswaran, H. Zhang, C. I. Torres, B. E. Rittmann, R. Krajmalnik-Brown, Microbial
community structure in a biofilm anode fed with a fermentable substrate: the significance of
hydrogen scavengers. Biotechnol. Bioeng.105, 69 (2010).
16. R. A. Rozendal, H. V. V. Hamelers, C. J. N. Buisman, Effects of membrane cation transport on pH
and microbial fuel cell performance. Environ. Sci. Technol.40, 5206 (2006).
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17. K. Rabaey, S. Bützer, S. Brown, J. Keller, R. A. Rozendal, High current generation coupled to
caustic production using a lamellar bioelectrochemical system. Environ. Sci. Technol.44, 4315
(2010).
18. S. T. Read, P. Dutta, P. L. Bond, J. Keller, K. Rabaey, Initial development and structure of biofilms
on microbial fuel cell anodes. BMC Microbiol.10, 98 (2010). 10.1186/1471-2180-10
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