Bio Electricity Production by Mediator Less MFC (Microbial Fuel

8/7/2019 Bio Electricity Production by Mediator Less MFC (Microbial Fuel

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Research By: S. Venkata Mohan, S. Veer Raghavulu, S. Srikanth and P. N.Sarma*Bioengineering and Environmental Engineering Centre, Indian Institute of Chemical

Technology, Hyderabad 500 007, India

Presented By: Arunjyoti BanikM.Tech (BT) 1st Yr 2nd Sem



Present statistics



........ Contd



Materials Usedy Anaerobic Wastewater further enriched with glucose, 3 g/l; NH4Cl, 0.5

g/l; H2PO4, 0.20 g/l; K2HPO4, 0.20 g/l; MgCl2, 0.25 g/l; CoCl2, 20 mg/l;ZnCl2, 10 mg/l; CuCl2, 10 mg/l; CaCl2, 4 mg/l; MnCl2, 10 mg/l.

y Dual Chambered MFC .

Nafion 117

5cm X 5cm X 1cm



Schematic diagram of the MFC

Glucose

CO2

AeratedPo4 Buffer

Mechanism of CurrentGeneration

50�



Operationy

Air was continuously sparged maintaining dissolved oxygen (DO) concentration between4 and 5 mg/l.

y The anaerobic mixed microflora was adapted to aseptic anaerobic microenvironmentafter sampling the inoculum.

y Anolyte (synthetic feed and mixed microflora) was recirculated continuously at a rate 100ml/min using a peristaltic pump in order to provide effective contact between the

substrate and mixed consortia.

y Constant removal of chemical oxygen demand (COD) and voltage output wereconsidered as indicators for satisfactory formation of the biofilm and stable operatingconditions.

y Before changing the feed, the inoculum was allowed to settle down (30 min) andexhausted feed(650 ml) was pumped out under anaerobic conditions.

y The settled mixed inoculum (50 ml by volume) was used for subsequent experiments tosustain microflora.

y Fresh synthetic feed (650 ml) was loaded once the voltage started decreasing. After every feeding event, the anode chamber was sparged with N2 for 2 min to maintain anaerobicmicroenvironment.



Results:

A steady increase in potential difference

was observed with every additional feed

and this might be attributed to adaptation,

phenomenon and development of biofilm

on the graphite surface of the anode.



For all methanogenic bacteria (MB) specific pH optimum for growth is near pH 7.0,

while acetogenic bacteria (AB) had lower pH optimum around 6.0.

AB are notably less sensitive to pH variations. This made us choose AB as inoculum.

The designed synthetic feed prior to feeding was adjusted to pH 5.5, which facilitated

growth of AB and at the same time inhibit the functioning of MB.

This susceptible environment created, facilitates the generation of molecular H2.

VF A formation and persistent acidogenic metabolism encountered in the anode

chamber presumably indicated a micro-environment congenial to the proliferation of H2-

producing AB rather than H2

-consuming species.

Contd.....



OLR: Organic Loading Rate;

SDR: Substrate Degradation Rate; VF A: Volatile Fatty Acid;

+ indicates VF A generation;

- indicates VF A consumption;

OLR = {[COD0 X feed rate]/reactor volume}.

SDR = {[(COD0 ± CODT ) X feed rate]/reactor volume}



Conclusion This study documented the feasibility of bioelectricity generation showing that the

method is environmentally sound and sustainable as substrate was wastewater .

Experimental data revealed the effectiveness of acidophilic conditions maintained

forpower generation within a short period of adaptation time.

The OLR (1/Voltage);OLR (1/Current);OLR CODR % andOLR SDR; However

the last proportionality is valid in all 4 cycles.

The mixed consortia employed do not require soluble mediators, but can donate

electrons directly to the electrode surface by attachment.

They not only produced power in association with COD reduction, but also

facilitated transfer of electrons to the anode without an exogenous mediator.

COD removal efficiency observed enumerated the functioning of

MFCas alternativewastewater treatment unit in addition to renewable energy generation.



The Ultimate Conclusions

The dual activity could significantly reduce the cost

associated with the current wastewater treatmentmethods.

This process could be effectively integrated to

wastewater treatment plant,wherein renewable energy could be generated alongwith wastewater treatment.



References:http://www.microbialfuelcell.org

http://www.scienceinschool.org/Issue14

http://www.ias.ac.in/crrsci/jun252007/1720.pdf

http://www.nature.com/nbt/journal/v21/n10/full/nbt8

67.htmlhttp://pubs.rsc.org/en/Content/ArticleLanding/2006/

CC/b600876c

http://www.rshanthini.com/tmp/CP307/MFCWWTre

atment.pdf http://web.mit.edu/pweigele/www/Towards%20a%20

Personal%20Bioreactor/Readings_files/MFC%20revie w-%20Lovely.pdf

en.wikipedia.org/wiki/Microbial_fuel_cell

Bio Electricity Production by Mediator Less MFC (Microbial Fuel

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