ICChE 2017, ChE 400, Thesis [B.Sc.] Toriqul Islam, Abdullah Al Moinee Supervisor: Dr. Nahid Sanzida ChE, BUET

1. Effect of electrodes, aeration,
salt bridges and source of microbes in a
mediator-free double chambered
microbial fuel cell
Department of Chemical Engineering
Bangladesh University of Engineering & Technology
International Conference of Chemical Engineering
Bangladesh University of Engineering & Technology
December 22, 2017
Paper ID: 122

2. Synopsis
❑ The potential of generating bioelectricity in a mediator-free double
chambered microbial fuel cell is a dependant variable of the
independent parameters stipulated in the cell construction
mechanism.
❑ The effect of these stipulated independent variables as source of
microbial colony, material of construction of electrodes and salt
bridges, presence and absence of aeration was evaluated in the cell
to have the best efficacy.
❑ The efficiency of the fuel cell was studied on the basis of the
electricity generated via treatment of waste water and manure used
as biowaste.

3. Objectives
The fact that bacteria can directly supply electrons or oxidize the
substrates to produce electricity makes MFCs an ideal media for
wastewater treatment and electricity production simultaneously.
1. Production of electricity and study the variables to make it feasible
and sustainable
2. Treatment of waste water in an environment friendly way utilizing
the potential of microorganisms

4. Motivation
SOURCES of ENERGY [1]
❑ Fossil fuels & Nuclear sources
Pollutions
 Emissions
 Global Warming
❑ Renewable Sources
Fuel Cells
✓ Plethora advantages in comparison
❖No Emissions & No existing mobile part
❖Microbial Fuel Cell (MFC)
1 Rahimnejad, M. (2015). Microbial Fuel Cell as new technology for bioelectricity generation. A review. Alexandria Engineering Journal, 56(3), 745-756.

5. Applications
❑ Generation of electricity
❑ Purification of waste water
❑ Prototype rover at space by bacteria (due to more electron density
than Li-battery)[2]
❑ Pure hydrogen production[3]
❑ Heavy Metal Recovery[4]
❑ Biosensors in medical sector
2. Bond, D. R. and Lovely, D. R. (2003). Electricity Production by Geobacter sulfurreducens Attached to Electrodes. Applied and Environmental Microbiology, 69(3), 1548-1555
3. Logan, B.E., Hamelers, B., Rozendal, R., Schröder, U., Keller, J., Freguia, S., Aelterman, P., Verstraete W. and Rabaey, K. (2006). Microbial Fuel Cells: Methodology
and Technology. Environmental Science Technology, 40(17), 5181-5192.
4. Mathuriya, A.S. and Yakhmi, J.V. (2015). Microbial fuel cell to recover heavy metals. Environmental Chemistry Letter, 12(4), 483-494.

6. Background of Motivation
❑ Inventions and research to increase the amount of efficient energy
❑ Limited feasible results till 1911 (observed by Potter)
❑ Ascending appeal & research issue from 1990
❑ Research domain turned vaster from 1999 once it was discovered
that mediator is not compulsory (cost effective and avoid toxicity)

7. Microbial Fuel Cell (MFC)
MFC is a bio-electrochemical device that can harness the
microbial cell respiration to generate energy by supplying
electrons in the cell by their physiochemical activities.

8. Mechanism in MFC
Figure 1 : General principle of a MFC [5]
5. Kuman, R., Singh, L. and Zularisam, A.W. (2016). Exoelectrogens: Recent advances in molecular drivers involve in extracellular electron transfer and strategies used to improve it for
microbial fuel cell applications. Renewable and Sustainable Energy Reviews, 56, 1322-1336 .

9. Types of MFC based on working mechanism
MFC can be classified into two major categories –
❑ Mediated MFCs
❑ Mediator free MFCs
Mediated MFCs- If the microbes are electrically inert to transmit
electron, mediators (e.g. humic acid) are used. They are toxic and
expensive.
Mediator free MFCs – When the microbes are electrically active
(exoelectrogens with pili as nanowire e.g. Geobacter sp.[6],[7])
mediators are not required.
6. Shi, L., Dong, H., Reguera, G., Beyenal, H., Lu, A., Liu, J., Yu, H.Q., and Fredrickson, J. K., 2016,“Extracellular electron transfer mechanisms between microorganisms and minerals,”
Nature Reviews: Microbiology, 14(10), pp. 651-662.
7. Bond, D. R., Lovely, and D. R., 2003,“Electricity production by geobacter sulfurreducensattached to electrodes,”Applied and Environmental Microbiology, 69(3), pp. 1548-1555.

10. Types of MFC based on Structure
❑ Single chamber MFC – Both the anode and cathode are
in a single chamber separated by a membrane .
❑ Double chamber MFC – Anode and cathode
compartments are in separated chamber connected with an
ion exchange membrane or salt bridge .
❑ Stacked MFC – Several single chamber MFCs are
connected in series or parallel connection to achieve
greater current flow.

11. Experimental Set Up for MFC
Figure 2: Full Experimental of Microbial Fuel Cell for an experimental run with waste
water sample from Pran Industiral Park, Bangladesh.

12. Construction of Double Chamber MFC
❑ An anode chamber– 500ml plastic chamber containing waste
water (Source: Pran Industrial Park, Narsingdi, Bangladesh) or
manure (Source: Plant Nursery, Agargaon, Dhaka)
❑ A cathode chamber– identical as anode chamber with cathodic
solution
❑ Salt bridge– saturated NaCl salt bridge or agar (china grass)
paste
❑ Aquarium pump– for aeration
❑ A multi-meter– for measurement of current and voltage

13. Experimental Procedure
❑ Preparation of salt bridge and connection between anode and cathode
❑ Take potable water for cathodic chamber and waste water or manure for anodic
❑ Connection among multimeter, anode and cathode
❑ Connection of aquarium pump at cathode for aeration
❑ Run time for every experiment was 12 hours for waste water and 6 hours for
manure while data of current and voltage was collected perpetually
❑ Measurement of COD by means of HACH machine for raw and treated water to
get the percentage COD removal.
Figure 4: Photograph of the HACH machine to measure percentage of COD removal

14. Schematic Diagram of the MFC
Figure 3: Schematic Diagram of the Microbial Fuel Cell

15. Figure 5: Graphite electrodes
used in experiments of this
MFC projects
Figure 6: Aluminum foil
electrodes used in experiments
of this MFC projects
Effect of Electrodes
❑ Graphite Electrode (anode and cathode)
& Aluminium foil (anode)
❑ Aluminium can react with water but
aluminium foil has protective coating
on it and hence it doesn’t react with
water.
❑ This foil has been used as anode for its
high conductivity as well as availability
in comparison with the conductivity of
carbon or graphite electrode.
❑ Anodic solution – industrial waste water
or nursery manure
❑ Cathodic solution – tap water, very
diluted KOH solution

16. Effect of Aeration
Figure 7: Aeration Pump
❑ Anodic solution must be air tight. If there exits external
oxygen, the organic substances will produce CO2 instead of
electron. Moreover aeration in anodic chamber hinders the
formation of biofilm [8].
❑ Aeration is important for the cathodic chamber[9]. Proper
aeration supplies oxygen that combines with the proton and
electron to produce water to maintain the pH of the solution.
❑ The preferable pH range for bacteria is 6.8 to 8. If aeration
isn’t proper or absent, the solution will become acidic
gradually which isn’t preferable condition for bacteria and
voltage drops quickly.
❑ As comparisons in the experiments runs it has been clear that
aeration generates more current than the absence of aeration.
8. Ren, L., 2014, “Examination Of Bioelectrochemical Systems With Different Configurations For Wastewater Treatment,” Ph.D. thesis, The Pennsylvania State
University, USA.
9. Quan, X.C., Quan, Y. P. & Tao, K., 2012,“Effect of anode aeration on the performance and microbial community of an air cathode microbial fuel cell,” Chemical
Engineering Journal, 210(2012), pp. 150-156. DOI: 10.1016/j.cej.2012.09.009.

17. Effect of Salt Bridges
Figure 8: Salt bridges – Materials to construction
❑ Impact of Salt Bridge – NaCl solution or Agar paste.
❑ Liquid phase saturated sodium chloride solution aids better than
the semi solid agar paste.
❑ As the comparison shown earlier that agar salt bridge is less
conductive for proton than NaCl salt bridge because of its ion
exchange efficiency with the better conductivity than the semi
solid agar paste.

18. Effect of the source of microbes
Figure 9: Waste water & Manure – Source of microbe
❑ Anolyte: Waste water and Manure
❑ Waste water as liquid media has given more current and COD removal than solid or diluted
manure in the same set-up because of the conductivity of the media and mobility of the
microorganisms.
❑ Microorganisms in a solid or semi solid zone are less mobile than in the liquid medium as in
manure with respect to waste water . Electron transfer mechanism may involve conductive pili,
direct contact through a conductive biofilm, and/or shuttling via excreted mediator enzymes.
❑ So in manure the current generation is less than waste water due to their immobility as they usually
live there by being a colony. Current generation is increased by dilution due to water added to
increase the mobility[10] .
10. Floury, S.J.J. , Gagnaire, V. , Lortal, S. & Thierry, A. (2015). Bacterial Colonies in Solid Media and Foods: A Review on Their Growth and Interactions
with the Micro-Environment. Frontiers in Microbiology, 6, p.1284.

19. Effect of Electrodes & Aeartion:
Figures of current and voltage obtained on
waster water treatment
Figure 10: Current(μA) vs Time(hr) Figure 11: Voltage(mV) vs Time(hr)

20. Figure 12: Current(μA) vs Time(hr) Figure 13: Voltage(mV) vs Time(hr)
Effect of Salt bridges, Electrodes, & Aeartion:
Figures of current and voltage obtained on
waster water treatment

21. Effect of Nutrients
❑ Impacts of Nutrient– 15 g glucose/ 500 ml waste water[11]
❑ The more the sustainability of microorganisms in their stationary phase, higher is the
removal of COD. To visualize the impact of nutrients, we can compare experiment 3
and 11 in case of wastewater treatment.
❑ Both of them are identical in setup except the presence and absence of nutrient. In
addition of nutrient the electricity generation along with the percentage of COD
removal have been increased.
11. Shuler, M.L and Kargi, F (2002). The Basic of Biology: An Engineer’s Perspective Bioprocesss Engineeirng Basic Concepts, New Jersey, USA, Pearson
Education Inc. table 2.10, p.52.

22. Figure 14 : Current(μA) vs Time(hr) Figure 15 : Voltage(mV) vs Time(hr)
Effect of Nutrients, Salt bridges, Electrodes, & Aeartion:
Figures of current and voltage obtained on
waster water treatment

23. Graphical comparison among the best 3 combination in
waste water treatment
Figure 16: Current(μA) vs Time(hr) Figure 17: Voltage(mV) vs Time(hr)

24. Percentage of COD removal for experiments in
waste water treatment
1 2 3 4 5 6 7 8 9 10 11 12
0
10
20
30
40
50
60
Experiment No.
CODremoval(%)
COD removal (%) vs Experiment No.
Figure 18: COD removal (%) for waste water treatment

25. Best 3 COD removal (%) among12 Experiments in
waste water treatment
3 7 11
0
10
20
30
40
50
60
Experiment No.
CODremoval(%)
COD removal (%) vs Experiment No.
Exp no Combination
3 Al Foil + Electrode + NaCl salt Bridge + Aeration (COD
Removal : 45%)
7 Al Foil + Electrode+ Agar (China Grass) Bridge + Aeration
(COD Removal : 30%)
11 Al Foil +Electrode + NaCl salt Bridge + Aeration + Nutrient
(COD Removal : 53%
Figure 19: COD removal (%) comparison for the best 3
combination in waste water treatment
Table 1: Comparison of Combinations
among the best three results

26. Experiment number Maximum current μA Maximum voltage mV Removal of COD
01 19.5 95.3 16%
02 17.8 92.5 12%
03 168.6 643.2 45%
04 165.3 651.7 42%
05 14.6 72.1 13%
06 17.8 89.7 10%
07 112.2 496.5 30%
08 90.1 601.8 27%
09 25.1 118.6 19%
10 23.5 115.6 15%
11 185.8 757.4 53%
12 181.6 743.8 49%
Table 2 : Results of Waste Sample (Waste Water)

27. Table 3: Results of Waste Sample (Manure)
Experiment number Maximum current μA Maximum voltage Removal of COD
01 1.80 19.0 2.5%
02 2.20 30.20 4%
03 9.1 32.60 6%
04 11.5 64.75 9%
05 13.4 73.60 15%
06 28.9 64.10 19%

28. Figures of current and voltage obtained
on manure tests
0 1 2 3 4 5 6
0
5
10
15
20
25
30
Time(hr)
Current(uA)
Current(uA) vs Time(hr)
Dry Manure + Agar (China Grass) Salt Bridge+ No Aeration
Dry Manure + Agar (China Grass) Salt Bridge+Aeration
25% Diluted Manure + Agar (China Grass) Salt Bridge+Aeration
55% Diluted Manure + Agar (China Grass) Salt Bridge+Aeration
60% Diluted Manure + NaCl Salt Bridge+Aeration
60% Diluted Manure + NaCl Salt Bridge+Aeration+Nutrient
0 1 2 3 4 5 6
0
10
20
30
40
50
60
70
80
Time(hr)
Voltage(mV)
Voltage(mV) vs Time(hr)
Dry Manure + Agar (China Grass) Salt Bridge+No Aeration
Dry Manure + Agar (China Grass) Salt Bridge+ Aeration
25% Diluted Manure + Agar (China Grass) Salt Bridge+Aeration
55% Diluted Manure + Agar (China Grass) Salt Bridge+Aeration
60% Diluted Manure + NaCl Salt Bridge+Aeration
60% Diluted Manure + NaCl Salt Bridge+Aeration+Nutrient
Figure 20: Current(μA) vs Time(hr) Figure 21: Voltage(mV) vs Time(hr)

29. Percentage of COD removal for the experiments
using manure as the waste
1 2 3 4 5 6
0
2
4
6
8
10
12
14
16
18
20
Experiment No.
CODRemoval(%)
COD Removal (%) vs Experiment No.
Figure 22: COD removal (%) for manure

30. Effect of the source of mircobes:
Comparison of bioelectricity generation between waste
water and Manure in MFC
0 1 2 3 4 5 6
0
20
40
60
80
100
120
140
160
180
200
Time(hr)
Current(uA)
Current(uA) vs Time(hr)
Manure
Waste Water
Figure 23: Comparison of bioelectricity generation between waste water and Manure in
MFC

31. Conclusions
❑ Limitaions:
➢ High Cost and High Mass Generation
➢ Low power density on limited current generation
❑ Future Steps:
➢ Dependence on mediator and understanding of electron transport system for versatile strains
of bacteria
➢ Parameters in experiments varied and modified in efficient ways to surpass the obstacles
❑ Best combination of experimental results
➢ 185.8 micro ampere with 53% COD removal
➢ Graphite Cathode + Aluminium Foil Anode + Aeration + Salt bridge of Sodium Chloride Solution
+ Nutrients
❑ Thus, MFC makes us optimist to open a greener threshold for the earth in the years to
come.

32. Acknowledgement
❑ PRAN Foods Ltd., PRAN-RFL Group, PIP, Dhaka, Bangladesh.
❑ Department of Chemical Engineering, BUET, Dhaka – 1000, Bangladesh.

33. THANK YOU
Paper ID: 122
International Conference of Chemical Engineering
Bangladesh University of Engineering & Technology
December 22, 2017
Department of Chemical Engineering
Bangladesh University of Engineering & Technology