Microbial fuel cell (MFC): A potential system to harness bioelectricity from wastewater treatment S Veer Raghavulu Raghavulu
Introduction World wide researching for carbon free power generation and neutral/positive waste water treatment MFC is a biochemical-catalyzed system which generates electrical energy through the oxidation of biodegradable organic matter in the presence fermentative bacteria. It is a renewable energy source and is an attractive source. Advantages Environmentally clean, renew ability, liberates large amount of energy and easily converted to electricity by fuel cells, only waste product being water. Dual benefits- generating a clean fuel and reducing waste. Direct generating of fuel has potential advantages- does not require the separation and purification of the gas. Currently, research on MFC is growing.
Introduction World wide researching for carbon free power generation and neutral/positive waste water treatment MFC is a biochemical-catalyzed system which generates electrical energy through the oxidation of biodegradable organic matter in the presence fermentative bacteria. It is a renewable energy source and is an attractive source. Advantages Environmentally clean, renew ability, liberates large amount of energy and easily converted to electricity by fuel cells, only waste product being water. Dual benefits- generating a clean fuel and reducing waste. Direct generating of fuel has potential advantages- does not require the separation and purification of the gas. Currently, research on MFC is growing.
Introduction Research is going on world wide for carbon free power generation and neutral/positive waste water treatment
Present Scenario Increasing energy Needs
Possible solution Sustainable & Efficient technology for production and utilization of energy
Depleting fossil reserves Increasing pollution load
Renewable energy sources Nonpolluting energy
Microbial Electricity Generation
Components proposed to be involved in the electron transport from cells to the anode in MFC
MFC consists of two electrodes sandwiched around an electrolyte. Oxygen acts as a final electron accepter generating electricity, water and heat
Some Microbes are be able to produce their own electron mediators enhancing electron transfer
Anodic reactions : CH3COO- + 2OH- → 2CO2 + 5H+ + 8eCathodic reaction : O2 + 4e− + 4H+→ 2H2O
MFC is a complex system Electrochemical activity of microorganisms Fuel cell- configuration Biofilm on the anode Fuel for anode bacteria Anodic biocatalyst Cathode/anode reaction Proton Exchange Membrane It is important to study all these aspects to make make MFC MFC
SCOPE AND OBJECTIVES To investigate the feasibility of bioelectricity generation eukaryotic and prokaryotic microorganisms as anodic biocatalysts. To optimize physical, chemical and biological parameters. To investigate the influence of various types of proton exchange membranes (PEM) on the performance of MFC To evaluate the potential of MFC as bio-electrochemical treatment system To study microbial diversity of anodic chamber in MFC To study the effect of bioaugmentation strategy on the process performance of MFC
Scope and Objectives Generation of carbon neutral bioelectricity as an alternative energy fuel for
the sustainable environment using wastewater as substrate ………Green and renewable energy
Different organic wastewaters (ranging from domestic to industrial) as
renewable energy resources …… sustainable development
Simultaneous wastewater treatment … dual benefit Developing an economically feasible design using low cost materials
(electrodes, PEM, substrate, etc.)
Non-catalyzed electrodes and mediator-less reactors … Economic viability Mixed anaerobic consortia as the biocatalyst …. Practical application Optimization and understanding process parameters during MFC operation Investigation of the anodic redox conditions optimum for electron transfer Analysis of microbial diversity by PCR-DGGE
Schematic overview of work
Acronyms MFC
Microbial fuel cell
PEM
Proton exchange membrane
OCV
Open circuit voltage
AC
Aerated catholyte
FC
Ferricynide catholyte
ED
Electron discharge
CV
Cyclic voltammetry
TDS
Total dissolve solvents
DSW
Designed synthetic wastewater
CW
Chemical wastewater
OLR
Organic loading rate
PDB
Partially developed biofilm
FDB
Fully developed biofilm
Anodic Biocatalysts
Characteristics of the wastewaters used as feed
Types of MFC designed and operated
Dual chambered MFCs
Single chambered MFCs
Bioelectrochemical behavior of by Prokaryotic and Eukaryotic
Evaluation of yeast biofuel cell by CV at different feed pH and OLR
Evaluation of prokaryotic biofuel cell by CV
Cyclic voltammetry profiles generated during stabilized phase of biofuel cell operation at variable experimental conditions (0th – black; 16th – blue; 24th – green; 36th – megentha; 54th
Bioelectricity generation by Prokaryotic and Eukaryotic
Open circuit voltage during the operation of MFC with the function of time (Mixed culture (MFCM); Pseudomonas aeruginosa (MFCP); Escherichia coli (MFCE) Shewanella putrefaciens Aeromonas hydrophila (MFCA)
(MFCS)
and
Voltage (open circuit) and (b) current generated during the operation of MFC at different feeding pH values and organic loading rates (OLR I, 0.91 kg COD/m3-day; OLR II, 1.43 Kg COD/ m3-day) with the function of time
Evaluation MFC configuration with mixed culture and wastewater Three types of catholytes Ferricyanide (Double chamber) Aerated (Double chamber) Open-air cathode (Single chamber)
Among these ferricyanide having higher efficiency with respect to power…. But not eco-friendly. Double chamber configuration requires higher reactor reactor volume. volume. Even though less power generation in in single single chamber chamber compared to double chamber….. Economically more feasible Similar substrate degradation Advantages in up scaling the technology
Open circuit voltage and current variation during MFC operation using ferricyanide and aerated catholytes
Influence of anodic pH on MFC performance
Dual chamber operation
Polarization curve
Acidophilic pH operation documented highest current output (5.18 mA (100 Ω); 0.632 V; 3.27 mW) with MFCFC ,(4.26 mA; 0.578 V; 2.46 mW) with MFC AC and 339 mV, 1.66 mA with open air cathode. Single chamber operation
Alternative material to PEM
Function of various types of proton exchange membranes studied
The experiments depict replacing Nafion117 with glass wool and cellulose material as proton exchange membrane which is cost effective and utilizing wastewater as substrate for in situ power power generation
Treatment of Cellulosic material MFC with 0.75M H2SO4 treated cellulose membrane (CM) as PEM showed maximum OCV (334 mV) and current (1.37 mA at 100 Ω) Plant based cellulosic material prepared and used as a PEM in MFC
Biofilm growth on anode influencing MFC performance Influences the direct electron transfer Age of the biofilm Biofilm growth Environment Electron discharge and power generation
SEM images of the biofilm developed on anode
a
b
The biofilm formed on the anode was subjected to scanning electron microscopy (SEM). a) PDB and b) FDB on graphite anode
Electrochemical influence of bio-augmentation on MFC Aeromonas Pseudomonas
auriginosa
E.coli
hydrophila
Shewanella putrifiecience
CV of anode generated from MFC P, MFCM and MFCE fuel cell operations using Ag/AgCl as reference electrode(Block- 0 th h ,Pink - 12th ,Cyan - 24th , Blue -36th and Brown - 48th ) Before augmentation equal electron discharge (ED) (1.04± 0.16 mA). Higher ED (11.73 mA) was observed with S. Putrificiens augmented system followed by P. aeruginosa e (8.42 mA), A
Performance of fuel cell with bio-augmentation
Open circuit voltage during the operation of MFC P. aeruginosa augmented system yielded higher power output (OCV, 418 418 mV; mV; 3.87 3.87 mA at 100 Ω) followed by S. putrifiencs (OCV, 378 mV; 2.73 mA at 100 Ω) and A. hydrophila (OCV, 296 mV; 2.26 mA at 100 Ω). E.coli augmented system registered lower power generation (OCV, 216 mV; 1.76 mA at 100 Ω).
Bioaugmented strains traced by fluorescent molecular probing
Survival of augmented strains was traced by FISH technique using cy3 labeled fluorescent probes which was important prerequisite for success of bioaugmentation
Microbial Diversity analysis DGGE was performed by the PCR amplified product of 16S rDNA at variable V3 region using universal primers (341F, 517R) for both dual and single chamber MFC. Phylogenetic sequence affiliation and similarity to the closet relative of amplified 16 rDNA sequence excised from DGGE gels observed dual and single chamber MFCs
Phylogenetic tree Sequences were submitted to the Nucleotide Sequence Database to the GeneBank public database under the accession numbers from FR670602 to FR670610. The phylogenetic distribution showed significant diversity in microbial community.
Neighbor-joining trees constructed using Mega 4.0 from MFCDC to closely related
Neighbor-joining trees constructed using Mega 4.0 from MFCSC to closely related
MFC function as Bio-electrochemical treatment system apart from power generation
Performance of MFC as BET
Conclusions • MFC operated with mixed culture was more effective in power generation, wastewater treatment and industrial applicability
• Performance of MFC influenced by – Reactor configuration (Double and
Single chamber) – Operating conditions (pH, Organic loading rate, waste composition)
• Bio-electrochemical treatment was achieved in MFC due to in situ biopotential of MFC
• Anodic biofilm development and bioaugmentation strategies were used to enhance the electron transfer from bacterial cell to electrode
• The study evaluate the different operational parameters required for optimizing towards scaling up of bioelectricity by MFC
Publications from the reported work 1. Veer Raghavulu S., Suresh Babu P., Kannaiah Goud R., Srikanth S., Venkata Mohan S. Bioaugmentation of electrochemically active strain to enhance the electron discharge of mixed culture: Process evaluation through electrokinetic analysis.
Journal of RSC Advances , 2012, 2, 677-688
2. Veer Raghavulu, S., Sarma, PN., Venkata Mohan, S.,
Bioelectrochemical behavior of Pseudomonas
aeruginosa and Escherichia coli with the function of anaerobic consortia during biofuel cell operation.
Journal of Applied
Microbiology, 2011. 110, 666–674
3. Venkata Mohan, S., Veer Raghavulu, S., Goud, RK., Sarma, PN. Microbial diversity analysis of long term operated biofilm configured anaerobic reactor producing hydrogen from wastewater under diverse conditions. International Journal of Hydrogen Energy, 2010. 35, 12208-12215 4. Veer Raghavulu, S., Venkata Mohan, S., Goud, RK., Sarma, PN.
Saccharomyces cerviceae as anodic
biocatalyst in non-catalyzed aerated biofuel cell: influence of redox condition andsubstrate load on power generation.
Bioresource
Technology, 2011. 102, 2751-2757 5. Veer Raghavulu, S., Venkata Mohan, S., Reddy, MV., Sarma, PN.
Behavior of single chambered mediatorless microbial fuel cell (MFC) at acidophilic, neutral and alkaline microenvironments during chemical wastewater treatment.
International Journal of Hydrogen Energy. 2009. 34, 7547-7554
Publications from the reported work 6. Veer Raghavulu, S., Venkata Mohan, S., Goud, RK., Sarma, PN .
Anodic pH microenvironment
influence on microbial fuel cell (MFC) performance in concurrence with aerated and ferricyanide catholytes.
Electrochemical
Communications. 2009. 11, 371-375
7. Venkata Mohan, S., Veer Raghavulu, S., Dinakar, P., Sarma, PN.
Integrated function of microbial fuel cell (MFC) as bio-electrochemical treatment system associated with bioelectricity generation under higher substrate load.
Biosensors and Bioelectronics. 2009. 24, 2021-2027
8. Venkata Mohan, S., Veer Raghavulu, S., Sarma, PN. Influence of anodic biofilm growth on bioelectricity production in single chambered mediatorless microbial fuel cell using mixed anaerobic consortia . Biosensors and Bioelectronics. 2009 24, 41-47 9. Venkata Mohan, S., Srikanth, S., Veer Raghavulu, S., Mohanakrishna, G., Kiran Kumar, A., Sarma, PN. Evaluation of the potential of various aquatic eco-systems in harnessing bioelectricity through benthic fuel cell: Effect of electrode assembly and water characteristics. Bioresource Technology. 2009. 100, 2240–2246
Publications from the reported work 10. Venkata Mohan, S., Veer Raghavulu, S.,Sarma, PN. Biochemical evaluation of bioelectricity production process from anaerobic wastewater treatment in a single chambered microbial fuel cell (MFC) employing glass wool membrane . Biosensors and Bioelectronics. 2008 23, 1326-32. 11. Venkata Mohan, S., Sarvanan, R., Veer Raghavulu, S., Mohankrishna, G., Sarma PN. Bioelectricity production from wastewater treatment in dual chambered microbial fuel cell (MFC) using selectively enriched mixed microflora: Effect of catholyte.
Bioresource Technology.2008. 99(3), 596-603
12. Venkata Mohan, S., Veer Raghavulu, S., Srikanth, S., Sarma, PN. Bioelectricity production by meditorless microbial fuel cell (MFC) under acidophilic condition using wastewater as substrate: influence of substrate loading rate.
Current Science. 2007. 92(12), 1720-1726
Other Publications 1. Min-Kyu Ji, Veer Raghavulu S , Hyun-Shik Y,Reda A.I, Jaeyoung C, Wontae Le, Thomas C. Timmes, Inamuddin, Byong-Hun Jeon. Simultaneous nutrient removal and lipid production from pretreated piggery wastewater by Chlorella vulgaris YSW-04 Applied Microbiology and Biotechnology 2012 (Accepted) 2. Venkata Mohan, S., Veer Raghavulu, S., Mohanakrishna, G., Srikanth, S., Sarma, PN. Optimization and evaluation of fermentative hydrogen production and wastewater treatment processes using data enveloping analysis (DEA) and Taguchi design of experimental (DOE) methodology. International Journal of Hydrogen Energy . 2009. 34, 216-226 3. Reddy, BS., Reddy, BP., Veer Raghavulu, S., Ramakrishna, S., Venkateswarlu, Y., Diwan, PV. Evaluation of antioxidant and antimicrobial properties of Soymida febrifuga leaf extracts. Phytotherapy Research . 2008 22 (7), 943-947 4. Venkata Mohan, S., Mohanakrishna, G., Veer Raghavulu, S ., Sarma, PN. Enhancing biohydrogen production from chemical wastewater treatment in anaerobic sequencing batchbiofilm reactor (AnSBBR) by bioaugmenting with selectively enriched kanamycin resistant anaerobic mixed consortia.
International Journal of Hydrogen Energy . 2007. 32, 3284–3292
