Effects of Electrode Materials on Power Generation of Microbial Fuel Cell

Energy shortage and environmental pollution mainly caused the global energy crisis which led to serious impact on human survival and development. Microbial fuel cells (MFCs) exactly meet the requirements to alleviate the global energy crisis because it has the ability to treat the wastewater and produce electricity concurrently. MFCs are considered as one of the promising technology in the wastewater treatment technology. The power output depends on various factors such as substrate degradation, electrode material, rate of electron transfer from bacteria to the anode, circuit resistance, proton mass transfer in the liquid, external operating conditions and so on. Electrode material is one of the key factors which affect the performance of MFC. Therefore, it is of great significance to select and develop suitable electrode materials to optimize and promote the performance of MFCs. Each electrode material has its own physical and chemical properties such as surface area, electric conductivity and chemical stability. In this research, we have tested two different electrode materials such as; polyacrlyonitrile carbon felt (PACF) and single forward carbon cloth (SFCC) to study the effects of different electrode materials on MFC performance. The results showed that MFC with SFCC using raw POME showed high power density (102.5mW/m2) compared to PACF (45mW/m2). But COD removal efficiency with raw POME of SFCC (43%) and PACF (45%) were not shown much difference. The coulombic efficiency of 1:50 diluted POME reached upto 26% for SFCC whereas for PACF 24% was achieved. SFCC achieved the highest coulombic efficiency and power output than PACF, indicating SFCC facilitate the biofilm formation and improve power generation

Bioelectricity Generation from Palm Oil Mill Effluent in Microbial Fuel Cell Using Polacrylonitrile Carbon Felt as Electrode

Palm oil mill effluent (POME) is an organic waste material produced at the oil palm mills. In its raw form, POME is highly polluting due to its high content of biological and chemical oxygen demand. In the present paper, POME was treated using double chamber microbial fuel cell with simultaneous generation of electricity. Polyacrylonitrile carbon felt (PACF), a new electrode material was used as electrode throughout the MFC experiments. Various dilutions of raw POME were used to analyze the effect of initial chemical oxygen demand (COD) on MFC power generation, COD removal efficiency and coulombic efficiency. Anaerobic sludge was used as inoculum for all the MFC experiments. Since this inoculum originated from POME, it showed higher potential to generate bioenergy from complex POME. Anaerobic sludge enhanced the power production due to better utilization of substrates by various types of microorganisms present in it. Among the raw POME and different concentrations of POME used, the PACF with raw POME showed the maximum power density and volumetric power density of about 45 mW/m2 and 304 mW/m3, respectively, but it showed low coulombic efficiency and low COD removal efficiency of about 0.8 % and 45 %, respectively. The MFC PACF with 1:50 dilution showed higher COD removal efficiency and coulombic efficiency of about 70 % and 24 % but showed low power density and low volumetric power density of about 22 mW/m2 and 149 mW/m3, respectively. The formation of biofilm onto the electrode surface has been confirmed from scanning electron microscopy (SEM) experiments. The results confirm that MFC possesses great potential for the simultaneous treatment of POME and power generation using PACF as electrode and also shows that initial COD has great influence on coulombic efficiency, COD removal efficiency and power generation

The Potentiality of microbial fuel cell anode with enhanced electron transfer

Palm oil mill effluent (POME) is an organic waste material produced at the oil palm mills. In its raw form, POME is highly polluting due to its high content of biological (BOD) and chemical oxygen demand (COD). In this context, treatment of wastewater using MFC (Microbial fuel cell) seems to be promising technology because it reduces operation energy requirement and shows efficient treatment too. In the present work, MFC with POME were used to study the effect of different electrode materials and to harvest high power density (PD) using controlled inoculum. Three different electrode materials such as PACF (Polyacrylonitrile carbon felt), SFCC (Single forward carbon cloth) and GR (Graphite rod) were used as anode and cathode materials for the MFC experiments. Among the raw POME and different concentrations of POME used, the PACF, SFCC with raw POME (60600 mg/L) showed the maximum power density (PD) of about 45mW/m2 and 102.50 mW/m2 respectively but both PACF and SFCC showed low coulombic efficiency (CE) of about 0.8 % and 2.2 % respectively as well as low COD removal efficiency of about 45 % and 54.45 % respectively. The PACF and SFCC MFC with 1:50 dilution (964 mg/L) showed higher COD removal efficiency of about 70 % and 78 % respectively and also CE of about 24% and 51% respectively but showed low PD of about 22 mW/rn2 and 28.48 mW/m2respectively. While, GR with raw POME showed very low PD, CE and COD removal efficiency of about 11.238 MW/M2, 0.2% and 28% respectively. Predominant microbes from anaerobic sludge (AS) were successfully isolated and identified as Pseudomonas aeroginousa, Pseudomonas mendocina, Pseudomonas viridiivida, Acetinobacter schindleri, Actinobacillus capsulatus and Brevibacterium paucivoransusing BIOLOG gene III analysis. Biofilm formation on electrode surface was analyzed using Fourier transformed infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM) analysis. Biofilm was characterized using PCR-DGGE (polymerase chain reaction - denaturing gradient gel electrophoresis) analysis and sequencing and identified the predominant microbes in biofllm which includes Azospiraoryzae, Acetobacterperoxydans and Solimonasvariicoloris.The electrochemical activities have been investigated by electrochemical impedance spectroscopy (EIS). In the final experiment, MFCs inoculated with controlled inoculum (CI) and POME as substrate. The CI was made using the microorganisms which are adapted and grown in palm oil mill effluent. CI was the mixture of fermentative and electrogenic microorganisms. It consists of electrogen (Pseudomonas aeroginousa) from AS and - fermentative microorganisms (Azospiraoryzae, Acetobacterperoxydans, Solimonasvariicoloris) from biofilm since no electrogen found in biofllm. The MFC operated with CI reached the maximum power density of 107.35mW/rn2, which was two times higher as compared to MFC operated with AS as inoculum. The maximum CE of 74 % was achieved from the MFC with CI, which was 50% higher than the CE with AS. But, it showed lower COD removal efficiency of about 32%, which might be due to the absence of required fermentative microorganisms in CI to utilize POME. EIS and the simulated results showed the reduction of charge transfer resistance (Rct) by 19.5% during the operation of the cell with CI. These results demonstrate that the power output of MFCs can be increased using CI

Fast Biofilm Formation and Its Role on Power Generation in Palm Oil Mill Effluent Fed Microbial Fuel Cell

In the present study, fast formation and characterization of biofilm and its role on power generation in the microbial fuel cell (MFC) were investigated and the biofilm formation was also correlated with electrochemical behavior of the MFC. MFC was operated with palm oil mill effluent as substrate and carbon cloth as electrode. A biofilm comprising electrochemically active bacteria on the anode surface showed crucial effect to enhance the performance of the MFC. Infrared spectroscopy and thermogravimetric analysis confirmed the presence of biofilm and scanning electron microscopy examined a biofilm and microbial clumps on electrode surface. The current density was directly dependent on the biofilm growth and increased significantly during the initial growth. Electrochemical impedance spectroscopy was done to monitor the progress of the anode colonization by the microorganisms in the MFC. The findings of this study demonstrated that biofilm formation facilitated electron transport as well as decreased the charge transfer resistance of the anode and thus increased the power generation in the cell

Prolonged Stability of Air-Cathode Microbial Fuel Cell Performance by Inhibiting Aerobic Microbial Growth Using Platinum and Carbon Nanotube (PT-CNT) Nanoparticles as a Cathode Catalyst

The inescapable growth of heterotrophic aerobic bacteria on the surface of air cathodes is an important factor causing oxygen depletion and substrate loss thus reduce the performance stability of air cathode single-chamber microbial fuel cells (MFCs). In this study, the possible use of platinum and carbon nanotube (Pt-CNT) nanoparticles as an antimicrobial agents as well as cathode catalyst for air-cathode MFCs was examined. The biomass content on carbon air-cathodes (CACs) was substantially decreased by 38.2% with Pt-CNT treatment after 26 days of MFCs operation. As a result, the oxygen reduction catalytic performance of the Pt-CNT treated CACs was much stable whereas the fast performance decline of the untreated cathode. Consequently, a quite stable electricity production was obtained for the MFCs with the Pt-CNT treated CACs, alternatively with a 22.5% decrease in maximum power density of the MFCs observed with the untreated cathode. Based on these results, it can be concluded that (1) the growth of oxygenconsuming heterotrophic microbes could be inhibited by Pt-CNT, (2) Pt-CNT could be applied as a cathode catalyst for oxygen reduction, thus (4) the MFC with the Pt-CNT -coated cathode led to the enhenced stable current generation

Evaluation of Electricity Generation and Wastewater Treatment from Palm Oil Mill Effluent Using Single and Dual Chamber Microbial Fuel Cell

Microbial Fuel Cells (MFCs) can be simultaneously used for the treatment of wastewater and generation of electricity. In this study, single chamber air-cathode MFC (sMFC) and double chambered MFC (dMFC) were compared for the palm oil mill effluent (POME) treatment and generation of electricity while Pseudomonas aeruginosa (ATCC – 27,853) was used as inoculum and POME used as substrate. The dMFC was efficient and found to be producing maximum power density of 4.2 W/m3 whereas sMFC produced a maximum power density 1.7 W/m3. Moreover, the dMFC showed higher COD (54%) removal when compared with sMFC (41%). The significant power generation and COD removal efficiency observed in dMFC might be attributed to the microbial catalyzed and reversible electrochemical reactions occurring in the anodic chamber and cathode chamber of dMFC. These results suggest that dMFC is efficient than sMFC in producing electricity as well as in treating wastewater

Treatment of Palm Oil Mill Effluent in Microbial Fuel Cell Using Polyacrylonitrile Carbon Felt as Electrode

Palm oil mill effluent (POME) is an organic waste material produced at the oil palm mills. It is highly polluting due to its high content of biological and chemical oxygen demand. In the present paper, POME was treated using double chamber microbial fuel cell with simultaneous generation of electricity. Polyacrylonitrile carbon felt (PACF) was used as electrode and anaerobic sludge was used as inoculum throughout the MFC experiments. Various dilutions of raw POME were used to analyze the MFC power generation, COD removal efficiency and coulombic efficiency. Among the raw POME and different concentrations of POME used, the PACF with raw POME showed the maximum power density and volumetric power density of about 45mW/m2 and 304mW/m3 respectively but it showed low coulombic efficiency and low COD removal efficiency of about 0.8% and 45% respectively while PACF with 1:50 dilution showed higher COD removal efficiency and coulombic efficiency of about 70% and 24% but showed low power density and low volumetric power density of about 22mW/m2 and 149mW/m3 respectively. The results show that MFC possesses great potential for the simultaneous treatment of POME and power generation using PACF as electrode

Effect of Biofilm Formation on the Performance of Microbial Fuel Cell for the Treatment of Palm Oil Mill Effluent

Anode biofilm is a crucial component in microbial fuel cells (MFCs) for electrogenesis. Better knowledge about the biofilm development process on electrode surface is believed to improve MFC performance. In this study, double-chamber microbial fuel cell was operated with diluted POME (initial COD = 1,000 mg L−1) and polyacrylonitrile carbon felt was used as electrode. The maximum power density, COD removal efficiency and Coulombic efficiency were found as 22 mW m−2, 70 and 24 %, respectively. FTIR and TGA analysis confirmed the formation of biofilm on the electrode surface during MFC operation. The impact of anode biofilm on anodic polarization resistance was investigated using electrochemical impedance spectroscopy (EIS) and microbial community changes during MFC operation using denaturing gradient gel electrophoresis (DGGE). The EIS-simulated results showed the reduction of charge transfer resistance (R ct) by 16.9 % after 14 days of operation of the cell, which confirms that the development of the microbial biofilm on the anode decreases the R ct and therefore improves power generation. DGGE analysis showed the variation in the biofilm composition during the biofilm growth until it forms an initial stable microbial community, thereafter the change in the diversity would be less. The power density showed was directly dependent on the biofilm development and increased significantly during the initial biofilm development period. Furthermore, DGGE patterns obtained from 7th and 14th day suggest the presence of less diversity and probable functional redundancy within the anodic communities possibly responsible for the stable MFC performance in changing environmental conditions

Fast Biofilm Formation and Its Role on Power Generation in Palm Oil Mill Effluent Fed Microbial Fuel Cell

In the present study, fast formation and characterization of biofilm and its role on power generation in the microbial fuel cell (MFC) were investigated and the biofilm formation was also correlated with electrochemical behavior of the MFC. MFC was operated with palm oil mill effluent as substrate and carbon cloth as electrode. A biofilm comprising electrochemically active bacteria on the anode surface showed crucial effect to enhance the performance of the MFC. Infrared spectroscopy and thermogravimetric analysis confirmed the presence of biofilm and scanning electron microscopy examined a biofilm and microbial clumps on electrode surface. The current density was directly dependent on the biofilm growth and increased significantly during the initial growth. Electrochemical impedance spectroscopy was done to monitor the progress of the anode colonization by the microorganisms in the MFC. The findings of this study demonstrated that biofilm formation facilitated electron transport as well as decreased the charge transfer resistance of the anode and thus increased the power generation in the cell

Enhanced Power Generation Using Controlled Inoculum From Palm Oil Mill Effluent Fed Microbial Fuel Cell

Enhancing the anode performance is a critical step for improving the power output of MFCs. This study 38 deals with the dual chamber MFCs to increase the power generation using the controlled inoculum in 39 Palm oil mill effluent (POME). Controlled inoculum (CI) was made using the predominant microorgan- 40 isms such as Pseudomonas aeruginosa, Azospira oryzae, Acetobacter peroxydans and Solimonas variicoloris 41 isolated from palm oil anaerobic sludge (AS) as well as from biofilm of MFC anode operated with AS 42 and identified using BIOLOG gene III analysis, PCR, DGGE and sequencing. Biofilm formation on electrode 43 was investigated by Fourier Transform Infrared spectroscopy (FTIR) and Thermogravimetric analayis 44(TGA). The MFC operated with Polyacrylonitrile carbon felt (PACF) anode and CI reached the maximum 45 power density of 107.35 mW/m 46 2, which was two times higher as compared to MFC operated with usual anaerobic sludge as inoculum. The maximum coulombic efficiency (CE) of 74% was achieved from the 47 MFC with CI, which was 50% higher than the CE with anaerobic sludge. But, it showed lower COD removal 48 efficiency of about 32%, which might be due to the absence of required fermentative microorganisms in CI 49 to utilize POME. The electrochemical activities have been investigated by electrochemical impedance 50 spectroscopy (EIS). EIS and the simulated results showed the significant reduction of charge transfer 51 resistance (Rct) by 40% during the operation of the cell with CI. EIS results provided evidence that there 52 was a substantial improvement in electron transfer between the microorganisms and the anode with CI. 53 These results demonstrate that the power output of MFCs can be increased significantly using CI