Agric & Bioresources Engineering

Permanent URI for this collectionhttp://197.211.34.35:4000/handle/123456789/144

Agric & Bioresources Engineering

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Start date: 2020

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Now showing 1 - 8 of 8
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    Comparative study of BQ2557 and LTC3108 as efficient ultra-low bioelectricity harvesters from soil microbes using microbial fuel cells.
    (IEC, 2023-03-23) Simeon, Meshack Imologie; Mohammed, A. S; Freitag, R.
    Microbial fuel cells (MFCs) are attractive bio-electrochemical transducers that can convert waste and organic substrates into usable energy through the metabolic activity of electroactive microbes. However, the power generated by MFCs is relatively low compared to other types of fuel cells. This poses a serious problem for the practical application of MFCs. Commercially available voltage boosters are not suitable for use with MFCs due to the low current capacity of the MFCs. Therefore, special amplifiers are needed to boost the power of MFCs. In this study, two ultra-low harvesters (BQ25570 and LTC 3108) were configured and tested for their efficiency in extracting usable energy from soil MFCs. The result showed that the BQ could harvest bioelectricity from three MFCs connected in series to charge a 0.22 F supercapacitor up to 3.5 volts, which in turn was used to power a light-emitting diode (LED). The LTC, on the other hand, boosted the voltage of a single MFC from 0.72 V to 3.3 V. The increased voltage was used directly to supply a white LED operating at a constant voltage of 2.5 V. The voltage at the LED remained constant even when the MFC voltage dropped to 20 mV. These results demonstrated the potential of soil microbes to generate free energy that can be harvested, amplified and used for practical applications. Compared to the BQ, the LTC performed better with the soil MFC, boosting the voltage of a single MFC unit to a usable level without the need for a battery or supercapacitor.
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    Influence of Electrodes Spacing on the Maximum Power of a Soil Microbial Fuel Cell Based on Stainless-Steel-Nanocarbon Composite Electrodes.
    (ISMET, 2021-10-09) Simeon, Meshack Imologie; Freitag, Ruth
    The electrical output of microbial fuel cells (MFCs) is unstable due to the natural activities of the electroactive bacteria involved. To sustain the maximum performance of MFCs, an optimization of the architectural aspect is necessary with special consideration of electrode materials, electrode spacing, and substrate availability. This study was conducted with three single-chamber soil MFCs having different electrode spacings (2, 5 and 8 cm) and electrodes made of stainless-steel mesh with activated carbon catalyst layers to investigate the influence of the electrode spacings on the sustainability of the Maximum Power Point (MPP) of a soil MFC with synthetic urine medium (SUM) as substrate. The MFCs using mud from active soil were polarized every three days until the MPP was reached and then refueled with SUM every 6 days during a 90-day operating period. During the initial treatments, the maximum power was inversely proportional to the anode-cathode distance. However, this trend could not be maintained during continuous treatments, as the optimum performance was achieved with an electrode spacing of 5 cm. At 2 cm, 5 cm, and 8 cm electrode spacing, the maximum power and the open-circuit voltage were 695.67 + 36.0041 µW and 779.71 ±13.698 mV for 18 days, 517.66 ± 30.4 µW and 804.8 ±12.01 mV for 66 days, and 474.9 ± 45.3 µW and 757.49 ±11.488 mV for 54 days, respectively. During continuous treatment, the internal resistances of the MFCs decreased by 34.30, 28.2, and 41.87 %, respectively, due to an increase in electrolyte conductivity. Electrochemical impedance spectroscopy of the MFCs showed that the treatment had a more significant effect on electrolyte resistance than charge transfer resistance. These results showed that optimal cathode-anode spacing ensures substrate availability at the electrodes to maintain bacterial metabolism, resulting in stable performance of an MFC over a reasonably long period.
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    Evaluation of the Electrical Performance of a Soil-Type Microbial Fuel Cell Treated with a Substrate at Different Electrode Spacings
    (Proceedings of ICEESEN2020, 2020-11-21) Simeon, Meshack Imologie; Imoize, Agbotiname L.; Freitag, Ruth
    The effect of electrode spacing on the performance of a microbial fuel cell (MFC) under batch treatment with a substrate was investigated with three single-chamber MFCs built with biologically active soil. The electrodes consisted of a stainless-steel mesh with layers of activated carbon catalyst. The MFCs were fed with artificial urine after reaching a stationary phase. After the initial treatment, the cell with the smallest electrode gap produced the maximum peak power under polarization. At 2 cm, 5 cm and 8 cm electrode spacing, the maximum power was 726.2 µW, 547 µW, and 520.3, respectively; while the average power of the MFCs from the first point of treatment with substrate to the last point was 297 + 259.2, 505.43+ 42.5, and 433.81+ 64, respectively. A significant decrease in internal resistance of the MFCs was observed during batch treatment. The impedance analysis of the MFCs showed that the reduction in internal resistance was largely due to a significant decrease in ohmic resistance compared to the charge transfer resistance.
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    Comparative evaluation of the performance of a capacitive and a non-capacitive microbial fuel cell
    (IEEE, 2021-03-25) Simeon, Meshack Imologie; A. L. Imoize; Freitag, Ruth
    Electrode materials play a critical role in the performance of microbial fuel cells. This study investigates the contribution of capacitive bio-electrodes to sustainable power production in a single-chamber microbial fuel cell (MFC). The capacitive electrodes consisted of a stainless-steel wire mesh with an activated carbon layer, while the non-capacitive control electrodes were made of graphite felt with a wound current collector. The MFCs were constructed using a glass vessel with the anode completely buried in biologically active soil and the cathode placed above the soil to form a single-chamber configuration. The performance of the MFCs was investigated using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The results showed that the performance of the capacitive MFC was three times better than that of the non-capacitive MFC. While there was no significant difference in the Ohmic resistances of the MFCs, there was a significant difference in charge transfer resistance and capacitance of the MFCs. The capacitive MFC had a double layer capacitance of 8.282 µF in addition to the diffuse layer capacitance at the layer/metal interface of 2.012 F, while the non-capacitive MFC had a double layer capacitance of 5.034 µF with no diffuse layer capacitance. The results show that the capacitive characteristics of both cathode and anode improve the performance of a single-chamber MFC.
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    Optimization of soil microbial fuel cell: influence of feeding duration, electrode factors and diversity factor of uncontrolled mixed microbial communities
    (international Society for microbial Electrochemistry amd Technology-ISMET8, 2022-09-19) Simeon, Meshack Imologie; Freitag, Ruth
    The electrochemical performance of the microbial fuel cell (MFC) depends not only on the operational and design parameters, but also on biological factors (Gadkari et al., 2019). Therefore, optimization studies that incorporate the interactive effects of the main influencing factors and the contributions of the biological factor would improve the understanding of the improvement strategies needed to advance the application of MFCs in the real world. While single-factor experiments are simple and less expensive to conduct, the reproducibility of the results of such experiments cannot be established with a high degree of confidence, especially in a complex system such as MFC. In this study, the feeding duration (4, 6 and 8 days), electrode material (carbon felt (CF) and modified stainless steel mesh (SM)), and electrode spacing (2, 4 and 8 cm) were integrated into a single design to optimize the performance of Soil MFC for stable and useful bioelectricity. The binder component of the SM was further optimized with four polymeric binders (epoxy, PVA, PVDF, and PTFE) and a new method - pasting and reinforcement (Simeon et al., 2022). PCR amplification and sequencing of 16S rDNA fragments were performed on the genomic DNA extracted from the MFCs, and bioinformatics analysis was performed using the QIIME2 microbiome analysis package. The results showed that the SM with a surface modified by conductive carbon black and epoxy binder exhibited superior performance in all experimental phases and achieved a maximum power three times higher than the CF at an electrode spacing of 4 cm and a feeding duration of 8 days. PVDF produced the highest current under real-time external loading, while epoxy produced the highest and most sustained power of 487.15 + 9.5 mW/m2 under linear polarization. Bioinformatic analysis revealed a wide bacterial diversity, with the most abundant phyla belonging to Proteobacteria (30-35%), Acidobacteriota (10-13%), Actinobacteriota (4-14%), Chloroflexi (6-9 %), Bacteroidota (3-9%), firmicutes (3-6%). Complex diversity in composition and abundance was observed mainly between the anode and cathode and between sampling time points, but no statistically significant difference was observed between the two electrode materials. This study indicates that the electrode material has the greatest influence on the sustainability and extent of bioelectricity capacity of a soil microbial fuel cell. Therefore, an increased focus on improving the electrode material would be a step in the right direction to position SMFCs as viable energy systems that can compete with the other established bio-electrochemical systems
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    Influence of electrode spacing and fed-batch operation on the maximum performance trend of a soil microbial fuel cell
    (International journal o f hydrogen energy-Elsevier, 2021-12-04) Simeon, Meshack Imologie; Freitag, Ruth
    The effect of electrode spacing on a soil microbial fuel cell (MFC) performance under fed-batch treatment with synthetic urine medium (SUM) was investigated at 2, 5, and 8 cm electrode spacing. The electrodes consisted of stainless-steel mesh with coarse layers of carbon-black. The MFCs were fed with SUM when the natural substrate of the medium was exhausted. Initial feeding resulted in 79.6, 108.7, and 103.1% increase in OCV with a proportional percentage increase in power at 2, 5, and 8 cm electrode spacing. Six days after the first feeding, the power was 189.9, 150.7, and 108. 5 mW/m2 in ascending order of electrode spacing. With more extended treatment, the overall maximum power was obtained at 8 cm spacing. In ascending order of electrode spacing, the highest power (207.92, 263.38, and 271.1 mW/m2) was obtained on days 39, 42, and 93, respectively. The study shows that a larger anode-to-cathode distance requires a longer time for the soil MFC to achieve stable and maximum performance in fed-batch operation.
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    Performance evaluation and impedance spectroscopy of carbon-felt and reinforced stainless-steel mesh electrodes in terrestrial microbial fuel cells for biopower generation
    (Measurement: Energy-Elsevier, 2025-01-19) Simeon, Meshack Imologie; Amarachi C. Alaka; Peter Daniel; Olalekan David Adeniyi
    Terrestrial Microbial Fuel Cells (TMFCs) offer promising potential for renewable energy by harnessing microbial metabolism to generate electricity from soil-based organic matter. Electrode materials are key to TMFC performance, facilitating electron transfer between microbes and the circuit. However, the effect of electrode impedance on TMFC efficiency is not well understood. This study fills that gap by comparing surface-modified stainless-steel mesh (SMS) and carbon felt (CF) electrodes, focusing on performance metrics and impedance spectroscopy to optimize electrode design for improved power generation from TMFCs. The SMS electrode fabricated using the pasting and reinforcement process demonstrated superior performance with a maximum power of 859 μW compared to the 234 μW power of the CF electrode. This better performance of the SMS electrode was attributed to its pseudocapacitive behavior, enhancing internal charge storage capacity and overall MFC efficiency. Electrochemical impedance spectroscopy revealed a substantially higher charge transfer resistance in the CF electrode, resulting in a 190.8 % difference between the two electrodes. Conversely, the SMS electrode exhibited lower resistance and improved diffusion characteristics, facilitating efficient electron transfer and mass transport. These findings underscore the significance of tailored electrode materials in optimizing MFC performance and emphasize the utility of electrochemical impedance spectroscopy in elucidating complex electrochemical processes within MFC systems, thus guiding future advancements in sustainable power production in terrestrial MFCs.