A brief ver view about microbial fuel cells.

1. MOOC-ACADEMIC WRITING
Microbial fuel cells
by
Hariharan A (120002021@sastra.ac.in)
Student ID:6ae39e8ae92211e98daf7dab33d03ee8
IV year
B .Tech Chemical engineering
SASTRA Deemed University
PAPER ID:SYPA034

2. ANNUAL ENERGY USED FOR WASTE WATER
TREATMENT-15GW(USA).
ORGANIC MATTER IN WATER –17GW(USA).
ENERGY SAVED IS ENERGY CONSERVED.
What's our problem
Energy crisis - It is expected that coal and natural gas
will last until 2060.
Pollution - Water, air, noise, soil, light.
How to react
 Alternative energy source sustainable Identification
and mitigation of pollution.
 The first observation of bacteria generating electrical
potential was reported as early as 1911, but the real
breakthrough occurred in 1999

3. Sources of Waste water
 Sanitary wastes
 Wastewater from the food industry-potato-processing industries (Starch).
 Brewery wastewater(which are rich in organic matter) and also
 Chemical industrial wastewater

4. Galvanic cell: Device which converts
chemical energy into electrical energy.
Electrolytic cell: Device which converts
electrical energy into chemical reaction.
Fuel cell: Are galvanic cell that converts
chemical energy into electrical energy by
means of electrochemical process, fuel is
supplied continuously.
Microbial fuel cells: Chemical reaction is
replaced by microbial reaction, electricity is
produced, load-waste water. Microbes as
catalyst.

5. Mechanism of reaction:
In a microbial fuel cell ,organic matter oxidation is carried out by micro-
organisms while electron resulting from the metabolism are transferred
to anode with simultaneous production of proton which passes through
the membrane.
Direct method- Ability of the microbes to deliver the electron directly to
the electrode.
How to they do it
Cell-bound proteins
Indigenously produced mediators.
Indirect method- Cost accumulation and environmental effects

7. Reactions involved are

8. Examples of
microbes used:

9.  Out of these materials graphite has high surface area per unit volume i.e.,
15000 m^2/m3 and easily manufactured.
Anode materials: Graphite, Pt, Pt black, carbon paper, good
conductivity, non corrosive, high surface area.
Cathode materials: Carbon paper, Pt, graphite.
Separators : Nafion, Ultrex, sulfonated polystyrene
Electrode catalyst: Fe(III),Mno2,Polyaniline,Pt black.

10. Parameters affecting the performance:
 Inter electrode distance
 Electrode material
 pH of treated water.
 Proton exchange membrane used
 Operating condition-Temperatures of anodic and cathodic chamber.
Type of oxidant used-Besides oxygen potassium ferricyanide or
permanganate can be used, costly harmful .

11.  Double chamber MFC'c are complex and
face practical difficulties while scaling up.
 Single-chamber MFC represents a real
alternative- only an anodic chamber, while
the cathode remains exposed to the air
Configurations of MFC’s
• Single Chamber
• Double Chamber
• Flat plate
• Membrane less MFC’s
• UP-flow MFC's.

12. Operating temperatures and perfomance:
 Single chamber configuration with carbon cloth, the maximum values of
COD removal and power density were obtained at 35 °C (94% and 8.1
mW·m−2 cathode for each).

13. Membrane Power density mW/m2
Sulphonated PVDF-co-HFP 290.176±15
Blend of polybenzimidazole (PBI) and
polyvinylpyrrolidone (PVP)
231.38
Nano-alumina+ Sulphonated PVDF-co-
HFP
541.52

14. Electrochemical aspects:
V=IR external
P=VI
V cell = EC - EA - (ή act-ή ohm-ή conc-ή pH difference)
Where µ - over potential or polarization potential
EC - Potential at cathode.(mV)
EA - at anode (mV).
Decrease in power output –
Selective iontransport.
Membrane Impedance .
Voltage losses
Ohmic
Activation
Metabolic
Concentration
Mass transfer

15. • Why Separators
To prevent oxygen reacting with anode.
• To prevent short circuiting of closely spaced electrodes.
Ideal separators
Hydrophilicity for high ion transport
Low oxygen transport
Durable
anti biofilm properties
Low internal resistance
Ion exchange membrane
cationic-Nafion,
Anionic.
Bipolar
 Porous glass electrodes provide a promising result
It has the following advantages;
1. High Coulombic efficiency.
2. Maximum power density
3. Non biodegradability
4. Low cost.
5. Ion transport capability.porous filtration
membranes were
used less CE than the
IEM"s due to
permeability of oxygen
and substrate.

16. Set backs:
Using microbial fuel cells we cannot bring down COD to that extent
so that we can use it or let it out into water streams.
Very low output power.
Experimental results(

17. Advantages of microbial fuel cells
 No reliance on fossil fuels
 Little or no pollutants-cleaner energy
 Energy produced is energy conserved
 No mechanical parts.
 No noise.
Challenges
 Material costs.
 Maintaining stable electrogenic populations.

18. Conclusion
 The recent advancements and studies suggest that MFCs will be of
practical use in the future and will become a preferred option among
sustainable bioenergy processes.
 For their practical implementation, MFCs need to be scaled-up from the
laboratory scale (10−6 to 10−3 m3 ) to a scale suitable for wastewater
treatment (1 to 103 m3 ).
 To date, pilot-scale attempts have proved to be unsatisfactory.
 Look for low cost materials for anode , cathode, membrane preserving the
efficiency.

19. Referrences
 F.J. Hernández-Fernández a , A. Pérez de los Ríos b , M.J. Salar-García a, ⁎,
V.M. Ortiz-Martínez a , L.J. Lozano-Blanco a , C. Godínez a , F. Tomás-
Alonso b , J. Quesada-Medina b, Recent progress and perspectives in
microbial fuel cells for bioenergy generation and wastewater treatment☆
 Guang Chen,†,‡ Bin Wei,‡ Yong Luo,‡ Bruce E. Logan,*,‡ and Michael A.
Hickner*,Polymer Separators for High-Power, High-Efficiency Microbial
Fuel Cells.
 https://www.youtube.com/watch?v=su6PfYeMrsI&t=330s.
 https://nptel.ac.in/courses/103107125/29.
H. Liu, B.E. Logan, Electricity generation using an air-cathode single
chamber microbial fuel cell in the presence and absence of a proton exchange
membrane, Environ. Sci. Technol.
38 (2004) 4040–4046, American Chemical Society.32

20. It’s better to try
and fail rather than
sit & complain
THANK YOU