Optimization of growth medium in microbial fuel cell for electricity production by paenibacillus
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This document summarizes research into optimizing the growth medium in a microbial fuel cell to maximize electricity production using Paenibacillus bacteria. Experiments tested different concentrations of glucose as the carbon source and found that 5g/L generated the highest voltage of 910mV. Testing over time found voltage increased with time, reaching a maximum of 750mV after 7 hours. Increasing the carbohydrate concentration initially increased voltage, but higher concentrations beyond 5g/L resulted in lower voltages. The research aims to utilize waste water from bread production as the substrate to generate electricity through bacterial conversion of sugars to protons, electrons, and carbon dioxide.
![International Journal of Science and Research (IJSR), India Online ISSN: 2319‐7064
Volume 1 Issue 3, December 2012
www.ijsr.net
Optimization of Growth Medium in Microbial Fuel
Cell for Electricity Production by Paenibacillus
Shikhi Shrivastava1
1
Takshshila Institute of Engineering & Technology
Jabalpur (MP)
shikhi.shrivastava@gmail.com
Rani Ayachi2
2
Takshshila Institute of Engineering & Technology
Jabalpur (MP)
raniayachi@takshshila.org
Abstract: Microbial fuel cell ( MFC ) represents a new method for electricity generation and waste water treatment. Microbial fuel
cells are devices that can use bacterial metabolism to produce an electrical current from a wide range organic substrates. This research
explores the application of MFC in generating electricity using waste water from Popular bread factory Jabalpur. In order to obtain the
aim of this research, a system of MFC with microbe Paenibacillus has been used. As parameter, it was evaluated the electricity produced
during MFC operation on variation at different concentration of organic substances.
Keywords: Electricity, Electrodes, MFC, Paenibacillus, Waste water
1. Introduction
Recent rise in energy costs, rapidly dwindling crude oil
supplies and concern over the negative effects of carbon
emissions have reignited both public and private interest
in finding cheap alternative renewable energy sources.
Many “green” energy generating process rely on the
metabolic activity of microbes to turn human waste
products into useable energy. MFC is considered to be a
promising sustainable technology to meet increasing
energy needs, especially using wastewaters as substrates,
which can generate electricity and accomplish wastewater
treatment simultaneously, thus may offset the operational
costs of wastewater treatment plant [1].
MFC can be best defined as a fuel cell where microbes act
as catalyst in degrading the organic content to produce
electricity. It is a device that straight away converts
microbial metabolic or enzyme catalytic energy into
electricity by using usual electrochemical technology [2].
Various types of the microbial fuel cell exists, differing
majorly on the source of substrates, microbes used and
mechanism of electron transfer to the anode. Based on
mechanism of electron transfer to the anode, there are two
types of microbial fuel cell which are the mediator
microbial fuel cell and the mediator-less microbial fuel
cell.
Mediator-microbial fuel cells are microbial fuel cells
which use a mediator to transfer electrons produced from
the microbial metabolism of small chain carbohydrates to
the anode [3]. This is necessary because most bacteria
cannot transfer electrons directly to the anode [4].
Mediators like thionine, methyl blue, methyl viologen and
humic acid tap into the electron transport chain and
abstract electrons (becoming reduced in the process) and
carry these electrons through the lipid membrane and the
outer cell membrane [5][6].
Mediator-less microbial fuel cells, on the other hand, use
special microbes which possess the ability to donate
electrons to the anode provided oxygen (a stronger
electrophilic agent) is absent [4][7]. There are variants of
the mediatorless microbial fuel cell which differ with
respect to the sources of nutrient and type of inoculum
used.
In direct electron transfer, there are several
microorganisms Eg. Shewanella putrefaciens, Geobacter
sulferreducens, G. metallireducens and Rhodoferax
ferrireducens, that transfer electrons from inside the cell to
extracellular acceptors via c-type cytochromes, biofilms
and highly conductive pili (nanowires) [8]. These
microorganisms have high Coulombic efficiency and can
form biofilms on the anode surface that act as electron
acceptors and transfer electrons directly to the anode
resulting in the production of more energy [9][10].
Electron transfer by own /artificial mediators: In indirect
electron transfer, electrons from microbial carriers are
transported onto the electrode surface either by a
microorganism’s (Shewanella oneidensis, Geothrix
fermentans) own mediator which in turn facilitate
extracellular electron transfer or by added mediators. The
MFCs that use mediators as electron shuttles are called
mediator MFCs. Mediators provide a platform for the
microorganisms to generate electrochemically active
reduced products. The reduced form of the mediator is cell
permeable, accept electrons from the electron carrier and
transfer them onto the electrode surface [11]. Usually
neutral red, thionine, methylene blue, anthraquinone-2, 6-
disulfonate, phenazines and iron chelates are added to the
reactor as redox mediators [12].
74](https://image.slidesharecdn.com/optimizationofgrowthmediuminmicrobialfuelcellforelectricityproductionbypaenibacillus-181002080749/85/Optimization-of-growth-medium-in-microbial-fuel-cell-for-electricity-production-by-paenibacillus-1-320.jpg)
![International Journal of Science and Research (IJSR), India Online ISSN: 2319‐7064
Volume 1 Issue 3, December 2012
www.ijsr.net
Figure 2: Graph showing voltage generated by
Paenibacillus at different glucose concentrations
Note:
Pbf: Glucose present in water sample of popular bread
factory.
pbf + conc: Glucose present in water sample of popular
bread factory and of extra glucose added for maximum
voltage generation by bacteria.
Voltage generated by Paenibacillus at different time
interval: The MFC was run up to 12 hrs and the voltage
was recorded at every 1 hr interval in presence of
mediator. There was a definite increase in the voltage with
the increase in time as we can see from Table - 2. It was
found that maximum voltage was generated 750mV after
7 hours.
Table 2: Voltage generated by Paenibacillus when
methylene blue mediator was used
Time ( in hrs ) Voltage
generated(mV)
At zero hour 130
At 2 hours 370
At 4 hours 480
At 7 hours 750
Figure 3: Graph showing voltage generated by
Paenibacillus at different time interval
4. Discussion
Microbial fuel cell is based upon the basic principle in
which biochemical energy is converted into electrical
energy. Consumption of organic substrate (e.g. glucose)
by microorganism in aerobic condition produces CO2 and
H2O
C6H12O6 + 6H2O + 6O2 → 6CO2 + 12H2O
If the terminal electron acceptor oxygen is replaced by
mediator then the electrons will be trapped by mediator,
which will get reduced and transport to electrons to the
electrode at anodic chamber .However when oxygen is not
present (anaerobic condition) they produce carbon
dioxide, protons and electrons as described below [13].
C6H12O6 + 6H2O → 6CO2 + 24H+ + 24e-
Based on the result, it was found that maximum voltage
(910 mV) was generated when glucose was added in
concentration of 5g/ l. The MFC was run up to 12 hrs and
the voltage was recorded at every 1 hr interval in presence
of mediator. It was found that maximum voltage was
generated 750mV after 7 hours.
5. Conclusion
Microorganisms that can combine the oxidation of organic
biomass to electron transfer to electrodes put forward the
self-sufficient systems that can successfully convert waste
organic matter and reusable biomass into electricity.
Oxidation of these newly rigid sources of organic carbon
does not supply net carbon dioxide to the environment and
unlike hydrogen fuel cells; there is no requirement for
wide pre-handing out of the fuel or for costly catalysts.
With the suitable optimization, microbial fuel cells might
be able to power an extensive collection of broadly used
procedure. Technology of Microbial Fuel Cell is one
alternative of energy production using renewable resource.
References
[1] Rakesh Reddy N, Nirmal Raman K, Ajay Babu OK
and Muralidharan A (2007). Potential stage in
wastewater treatment for generation of bioelectricity
76](https://image.slidesharecdn.com/optimizationofgrowthmediuminmicrobialfuelcellforelectricityproductionbypaenibacillus-181002080749/85/Optimization-of-growth-medium-in-microbial-fuel-cell-for-electricity-production-by-paenibacillus-3-320.jpg)
![International Journal of Science and Research (IJSR), India Online ISSN: 2319‐7064
Volume 1 Issue 3, December 2012
www.ijsr.net
using MFC, Current Research Topics in Applied
Microbiology and Microbial Biotechnology 1 322-
326.
[2] Allen R.M., Bennetto H.P. (1993). Microbial fuel
cells: electricity production from carbohydrates.
Appl Biochem Biotechnol, 39-40:27-40.
[3] Logan, B.E, Hamelers, P., Rozendal, R., Schroder,
U., Keller, I., Freuguia, S., Alterman, P., Verstraete,
W. and Rabaey, K. (2006). Microbial Fuel Cells:
Methodology and Technology. Environmental
Science and Technology, Vol. 40: 5181 – 5192.
[4] Scholz, F., Mario, J., Chaudhuri, S.K. (2003).
Bacterial Batteries. Nature Biotechnology. Vol.
21(10) pp 1151-1152.
[5] DiBucci, J. and Boland, T. (2011). Turning waste
into wealth, the future of microbial fuel cells. Paper
#1065, Conference Session #C5, Eleventh Annual
Conference, Swanson School of Engineering,
University of Pittsburgh.
[6] Kim, J., Han, S., Oh, S. and Park, K. (2011). A Non-
Pt Catalyst for Improved Oxygen Reduction
Reaction in Microbial Fuel Cells. Journal of the
Korean Electrochemical Society. Vol. 14 (2): 71 –
76.
[7] Mohan, V., Roghavalu, S., Srikanth, G. and Sarma,
P. (2007). Bioelectricity production by mediatorless
microbial fuel cells under acidophilic conditions
using wastewater as substrate loading rate. Current
Science. Vol. 92 (12) pp 1720 – 1726.
[8] Derek,R L. (2008). The microbe electric: conversion
of organic matter into electricity. Current opinion in
Biotechnology 19,564-571.
[9] Chaudhuri, S.K., and Lovley, D.R. (2003).
Electricity generation by direct oxidation of glucose
in mediatorless microbial fuel cells, Nature
biotechnology 21, 1229-1232.
[10] Kim, H.J., Park, H.S., Hyun, M.S., Chang, I.S., Kim,
M., and Kim, B.H. (2002). A mediator-less microbial
fuel cell using a metal reducing bacterium,
Shewanella putrefaciens. Enzyme and Microbial
Technology 30, 145-152.
[11] Lovley, D.R. (2006). Bug juice: harvesting
electricity with microorganisms. Nat Rev Micro 4,
497-508.
[12] Du, Z., Li, H., and Gu, T. (2007). A state of the art
review on microbial fuel cells: A Promising
technology for wastewater treatment and bioenergy.
Biotechnology Advances 25, 464-482.
[13]Scott, K. and Murano, C. (2007). Microbial fuel cells
utilizing carbohydrates. Journal of Chemical
Technology and Biotechnology. Vol. 82 pp 92 – 100.
77](https://image.slidesharecdn.com/optimizationofgrowthmediuminmicrobialfuelcellforelectricityproductionbypaenibacillus-181002080749/85/Optimization-of-growth-medium-in-microbial-fuel-cell-for-electricity-production-by-paenibacillus-4-320.jpg)
Optimization of growth medium in microbial fuel cell for electricity production by paenibacillus
- 1. International Journal of Science and Research (IJSR), India Online ISSN: 2319‐7064 Volume 1 Issue 3, December 2012 www.ijsr.net Optimization of Growth Medium in Microbial Fuel Cell for Electricity Production by Paenibacillus Shikhi Shrivastava1 1 Takshshila Institute of Engineering & Technology Jabalpur (MP) [email protected] Rani Ayachi2 2 Takshshila Institute of Engineering & Technology Jabalpur (MP) [email protected] Abstract: Microbial fuel cell ( MFC ) represents a new method for electricity generation and waste water treatment. Microbial fuel cells are devices that can use bacterial metabolism to produce an electrical current from a wide range organic substrates. This research explores the application of MFC in generating electricity using waste water from Popular bread factory Jabalpur. In order to obtain the aim of this research, a system of MFC with microbe Paenibacillus has been used. As parameter, it was evaluated the electricity produced during MFC operation on variation at different concentration of organic substances. Keywords: Electricity, Electrodes, MFC, Paenibacillus, Waste water 1. Introduction Recent rise in energy costs, rapidly dwindling crude oil supplies and concern over the negative effects of carbon emissions have reignited both public and private interest in finding cheap alternative renewable energy sources. Many “green” energy generating process rely on the metabolic activity of microbes to turn human waste products into useable energy. MFC is considered to be a promising sustainable technology to meet increasing energy needs, especially using wastewaters as substrates, which can generate electricity and accomplish wastewater treatment simultaneously, thus may offset the operational costs of wastewater treatment plant [1]. MFC can be best defined as a fuel cell where microbes act as catalyst in degrading the organic content to produce electricity. It is a device that straight away converts microbial metabolic or enzyme catalytic energy into electricity by using usual electrochemical technology [2]. Various types of the microbial fuel cell exists, differing majorly on the source of substrates, microbes used and mechanism of electron transfer to the anode. Based on mechanism of electron transfer to the anode, there are two types of microbial fuel cell which are the mediator microbial fuel cell and the mediator-less microbial fuel cell. Mediator-microbial fuel cells are microbial fuel cells which use a mediator to transfer electrons produced from the microbial metabolism of small chain carbohydrates to the anode [3]. This is necessary because most bacteria cannot transfer electrons directly to the anode [4]. Mediators like thionine, methyl blue, methyl viologen and humic acid tap into the electron transport chain and abstract electrons (becoming reduced in the process) and carry these electrons through the lipid membrane and the outer cell membrane [5][6]. Mediator-less microbial fuel cells, on the other hand, use special microbes which possess the ability to donate electrons to the anode provided oxygen (a stronger electrophilic agent) is absent [4][7]. There are variants of the mediatorless microbial fuel cell which differ with respect to the sources of nutrient and type of inoculum used. In direct electron transfer, there are several microorganisms Eg. Shewanella putrefaciens, Geobacter sulferreducens, G. metallireducens and Rhodoferax ferrireducens, that transfer electrons from inside the cell to extracellular acceptors via c-type cytochromes, biofilms and highly conductive pili (nanowires) [8]. These microorganisms have high Coulombic efficiency and can form biofilms on the anode surface that act as electron acceptors and transfer electrons directly to the anode resulting in the production of more energy [9][10]. Electron transfer by own /artificial mediators: In indirect electron transfer, electrons from microbial carriers are transported onto the electrode surface either by a microorganism’s (Shewanella oneidensis, Geothrix fermentans) own mediator which in turn facilitate extracellular electron transfer or by added mediators. The MFCs that use mediators as electron shuttles are called mediator MFCs. Mediators provide a platform for the microorganisms to generate electrochemically active reduced products. The reduced form of the mediator is cell permeable, accept electrons from the electron carrier and transfer them onto the electrode surface [11]. Usually neutral red, thionine, methylene blue, anthraquinone-2, 6- disulfonate, phenazines and iron chelates are added to the reactor as redox mediators [12]. 74
- 2. International Journal of Science and Research (IJSR), India Online ISSN: 2319‐7064 Volume 1 Issue 3, December 2012 www.ijsr.net 2. Material and method MFC construction Electrode: Carbon electrode (Graphite) were used at both the ends of cathode and anode and tightly fixed with containers containing medium, culture and buffer. Cathodic chamber: The cathode chamber of the MFC was made up of 1.2 liters plastic bottle filled with aerated phosphate buffer (50 mM K2HPO4; pH 7.5) as catholyte. Anodic Chamber: the 1.2 liters sterilized plastic bottle is used for this purpose. The bottle is surface sterilized by washing with 70% ethyl alcohol and 1% HgCl2 solution followed by UV exposure for 15 minutes. Then the autoclaved minimal medium broth was filled in it. Methylene blue and syringe filter sterilized dextrose solution was added to it and the caps containing electrodes were tightly fixed to it. Then 20 ml of previously enriched culture of bacteria was added. Salt bridge: The salt bridge was prepared by dissolving 3% agar in 1M NaCl. The mixture was boiled for 2 minutes and casted in the PVC pipe (12cm X 2cm). The salt bridge was properly sealed and kept in refrigerator for proper settling. Sugar Stock (Carbon Source): Waste water from popular bread factory Jabalpur has been used. It contains organic matter like starch, glucose, and sucrose which is used by bacteria for growth. Bacteria: Paenibaccilus was used as micro organism (biocatalyst). It is starch digestive bacteria and it is able to convert starch into glucose. This bacterium is not harmful for living organisms as well as environment. Mediator: Methylene blue is a redox indicators act as electron shuttles that are reduced by microorganisms and oxidized by the MFC electrodes thereby transporting the electrons produced via biological metabolism to the electrodes in a fuel cell. Circuit Assembly: Two chambers were internally connected by salt bridge and externally the circuit was connected with copper wires which were joined to the two electrodes at its two ends and to the multi meter by another two ends. The potential difference generated by the Fuel Cell was measured by using multi meter. Figure 1: Schematic diagram of MFC MFC Operation: This research intends to utilize the waste water generated from popular bread factory Jabalpur to generate electricity in Microbial Fuel Cell (MFC) system. The Paenibaccilus was used as micro organism (biocatalyst). The bacteria will convert sugar components in the waste water into Carbon dioxide, where in the intermediate process will be released electron generating electricity in MFC system. All the components of MFC are connected i.e. via salt bridge internally and with externally with wires to the multi meter. The substrate (waste water) was added in the anodic chamber. The anodic chamber was completely sealed to maintain anaerobic condition. The voltage generation was recorded at the interval of 1 hour up to 12 hours for bacterial isolate in presence of mediator. The MFC set up was kept at static conditions. The carbohydrate concentration was tested along with Bacterial isolate for their ability to generate potential difference. 3. Results Effect of increasing carbohydrate concentration: The carbohydrate source used was glucose. Different concentrations of carbohydrate solutions were made and filter sterilized by syringe filter method. The amount of glucose is already present in popular bread factory waste water is 3g/l and voltage generated by this concentration is 510mV. The concentrations used were 3g/l, 4g /l, 5g/l, 6g/l , 7g/l, and 8g /l (Table-1). It was found that maximum voltage (910mV) was generated when glucose was added in concentration of 5g/ l. Table 1: Voltage generated by Paenibacillus at different carbohydrate concentrations. Concentration of glucose solution used in g /l Maximum voltage generated in mV 3 510 4 720 5 910 6 895 7 870 8 830 75
- 3. International Journal of Science and Research (IJSR), India Online ISSN: 2319‐7064 Volume 1 Issue 3, December 2012 www.ijsr.net Figure 2: Graph showing voltage generated by Paenibacillus at different glucose concentrations Note: Pbf: Glucose present in water sample of popular bread factory. pbf + conc: Glucose present in water sample of popular bread factory and of extra glucose added for maximum voltage generation by bacteria. Voltage generated by Paenibacillus at different time interval: The MFC was run up to 12 hrs and the voltage was recorded at every 1 hr interval in presence of mediator. There was a definite increase in the voltage with the increase in time as we can see from Table - 2. It was found that maximum voltage was generated 750mV after 7 hours. Table 2: Voltage generated by Paenibacillus when methylene blue mediator was used Time ( in hrs ) Voltage generated(mV) At zero hour 130 At 2 hours 370 At 4 hours 480 At 7 hours 750 Figure 3: Graph showing voltage generated by Paenibacillus at different time interval 4. Discussion Microbial fuel cell is based upon the basic principle in which biochemical energy is converted into electrical energy. Consumption of organic substrate (e.g. glucose) by microorganism in aerobic condition produces CO2 and H2O C6H12O6 + 6H2O + 6O2 → 6CO2 + 12H2O If the terminal electron acceptor oxygen is replaced by mediator then the electrons will be trapped by mediator, which will get reduced and transport to electrons to the electrode at anodic chamber .However when oxygen is not present (anaerobic condition) they produce carbon dioxide, protons and electrons as described below [13]. C6H12O6 + 6H2O → 6CO2 + 24H+ + 24e- Based on the result, it was found that maximum voltage (910 mV) was generated when glucose was added in concentration of 5g/ l. The MFC was run up to 12 hrs and the voltage was recorded at every 1 hr interval in presence of mediator. It was found that maximum voltage was generated 750mV after 7 hours. 5. Conclusion Microorganisms that can combine the oxidation of organic biomass to electron transfer to electrodes put forward the self-sufficient systems that can successfully convert waste organic matter and reusable biomass into electricity. Oxidation of these newly rigid sources of organic carbon does not supply net carbon dioxide to the environment and unlike hydrogen fuel cells; there is no requirement for wide pre-handing out of the fuel or for costly catalysts. With the suitable optimization, microbial fuel cells might be able to power an extensive collection of broadly used procedure. Technology of Microbial Fuel Cell is one alternative of energy production using renewable resource. References [1] Rakesh Reddy N, Nirmal Raman K, Ajay Babu OK and Muralidharan A (2007). Potential stage in wastewater treatment for generation of bioelectricity 76
- 4. International Journal of Science and Research (IJSR), India Online ISSN: 2319‐7064 Volume 1 Issue 3, December 2012 www.ijsr.net using MFC, Current Research Topics in Applied Microbiology and Microbial Biotechnology 1 322- 326. [2] Allen R.M., Bennetto H.P. (1993). Microbial fuel cells: electricity production from carbohydrates. Appl Biochem Biotechnol, 39-40:27-40. [3] Logan, B.E, Hamelers, P., Rozendal, R., Schroder, U., Keller, I., Freuguia, S., Alterman, P., Verstraete, W. and Rabaey, K. (2006). Microbial Fuel Cells: Methodology and Technology. Environmental Science and Technology, Vol. 40: 5181 – 5192. [4] Scholz, F., Mario, J., Chaudhuri, S.K. (2003). Bacterial Batteries. Nature Biotechnology. Vol. 21(10) pp 1151-1152. [5] DiBucci, J. and Boland, T. (2011). Turning waste into wealth, the future of microbial fuel cells. Paper #1065, Conference Session #C5, Eleventh Annual Conference, Swanson School of Engineering, University of Pittsburgh. [6] Kim, J., Han, S., Oh, S. and Park, K. (2011). A Non- Pt Catalyst for Improved Oxygen Reduction Reaction in Microbial Fuel Cells. Journal of the Korean Electrochemical Society. Vol. 14 (2): 71 – 76. [7] Mohan, V., Roghavalu, S., Srikanth, G. and Sarma, P. (2007). Bioelectricity production by mediatorless microbial fuel cells under acidophilic conditions using wastewater as substrate loading rate. Current Science. Vol. 92 (12) pp 1720 – 1726. [8] Derek,R L. (2008). The microbe electric: conversion of organic matter into electricity. Current opinion in Biotechnology 19,564-571. [9] Chaudhuri, S.K., and Lovley, D.R. (2003). Electricity generation by direct oxidation of glucose in mediatorless microbial fuel cells, Nature biotechnology 21, 1229-1232. [10] Kim, H.J., Park, H.S., Hyun, M.S., Chang, I.S., Kim, M., and Kim, B.H. (2002). A mediator-less microbial fuel cell using a metal reducing bacterium, Shewanella putrefaciens. Enzyme and Microbial Technology 30, 145-152. [11] Lovley, D.R. (2006). Bug juice: harvesting electricity with microorganisms. Nat Rev Micro 4, 497-508. [12] Du, Z., Li, H., and Gu, T. (2007). A state of the art review on microbial fuel cells: A Promising technology for wastewater treatment and bioenergy. Biotechnology Advances 25, 464-482. [13]Scott, K. and Murano, C. (2007). Microbial fuel cells utilizing carbohydrates. Journal of Chemical Technology and Biotechnology. Vol. 82 pp 92 – 100. 77