Author(s)

Skylar Choi¹, Yongjin Park², Immanuel H. Anaborne³, Jin Sik Song⁴, Ji Woo Han⁵, So Hyun Jeon⁶, Jaewoo Kim⁷, James Kim⁸, Jinkwon Lee⁹, Paul S. Chung^10*

¹Horace Greeley High School, Chappaqua, NY, USA.
²Deerfield Academy, Deerfield, MA, USA.
³Oakton High School, Vienna, VA USA.
⁴School of Arts & Sciences, University of Virginia, Charlottesville, VA, USA.
⁵School of Arts & Sciences, Emory University, Atlanta, GA, USA.
⁶Bachelor of Science, Villanova University, Villanova, PA, USA.
⁷College of Letters & Sciences, University of California Los Angeles, Los Angeles, CA, USA.
⁸School of Arts & Sciences, University of Michigan, Ann Arbor, MI, USA.
⁹Division of Biological Sciences, Revelle College, University of California, San Diego, CA, USA.
¹⁰Fuzbien Technology Institute, Rockville, MD, USA.

Microbial fuel cell (MFC) is one of renewable biofuel production technology that directly converts biomass to electricity. Cellulosic biomass is particularly attractive renewable resources for its low cost and abundance and neutral carbon balance. However, methanogenesis remains as a major factor limiting MFC performance. The current study reports that saponin addition at 0.05% w/v dose to anolyte in MFCs inhibited methanogenesis and improves power generation and cellulose fermentation. Mediator-less two chamber H-type MFCs were prepared using rumen fluid as anode inocula at 20% v/v of anolyte to convert finely ground pine tree (Avicel) at 2%, w/v to electricity. Saponin was added to the anode of MFC at 0.005% or 0.05% v/v dosage for treatment. MFC power and current across an external resistor were measured daily for 10d. On d10, collected gases from anode compartment were measured for total gas volume and analyzed for gas composition on gas chromatography. Supplementation of saponin to MFC at 0.005% did not have any effects on electricity generation or biogas production and composition. Saponin at 0.05% dose reduced 10% of methane production and increased 40% of CO₂ production and 6.4% of total gas production for 10d MFC operation. Voltage across resistor prior to treatment addition (d0) was 164.75 ± 9.07 mV. In control group, voltage across resistor did not change (P = 0.9153) with time course and mean was 167.8 ± 8.20 mV ranged from 157 to 174.5 mV during 10d operation. In 0.05% Saponin group, voltage across resistor increased (P < 0.0001) after d2 and mean was 187.3 ± 4.30 mV ranged between 161.5 and 204.0 mV and the 10d mean of voltage across resistor in 0.05% Saponin was greater (P < 0.0001) than in control group. 0.05% Saponin also had greater voltage across resistor at d5 (P = 0.0030) and d6 (P = 0.0246) than control. End point potential increased (P < 0.0001) in 0.05% Saponin after d2. 0.05% Saponin had greater (P < 0.05) end point potentials than control at d1, d4, d7, d10, and also 10d mean was greater (731.9 vs 606.5 mV; P < 0.0001) in 0.05% Saponin. Power density increased (P < 0.0001) after d2 in 0.05% Saponin. 0.05% Saponin MFCs had greater (P < 0.05) power density than control at d5 and d6, and also a greater (P < 0.0001) overall mean of 10d operation. The current study provides strong background for potential use of saponin and saponin containing natural resources for methanogenesis inhibitor and cellulolysis enhancer in MFC and also cellulolysis reactors.

Microbial Fuel Cells, Saponin, Bioenergy

Choi, S. , Park, Y. , Anaborne, I. , Song, J. , Han, J. , Jeon, S. , Kim, J. , Kim, J. , Lee, J. and Chung, P. (2021) Improvement of Renewable Bioenergy Production in Microbial Fuel Cells with Saponin Supplementation. Journal of Sustainable Bioenergy Systems, 11, 82-93. doi: 10.4236/jsbs.2021.112006.