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Theoretical Investigation of Coupled Microbial Electrochemical Cells in Micro-Sized Systems and Assessment of Biohydrogen Generation

Arab Yarmohammadi, Fatemeh | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54597 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Yaghmaei, Soheila; Mardanpour, Mohammad Mahdi
  7. Abstract:
  8. Due to the importance of hydrogen production for its applications in therapy, this research reports the fabrication of a coupled microfluidic microbial electrochemical cell, including microfluidic microbial fuel cells (MFCs) and a microfluidic microbial electrolysis cell (MEC) series in order to perform it as a selfpowered bioenergy generator to produce biohydrogen with no need for an external power source. The designed went goes through a validation process that relied on experimental results of a coupled system in glucose degradation. By determining the governing equations of the system and simulating its behavior in various conditions, the effect of operational factors on the system performance was determined. Different variables such as substrate distribution in biofilm and anolite, distribution of attached and suspended microorganisms, biofilm thickness, etc. were calculated. The effect of number of MFCs, substrate concentration, external resistance and the depth of microchannel as well as the change in microbial concentration and biofilm distribuition on the performance of the system were investigated. The model prediction showed that by increasing the number of MFCs from 1 to 3 cells, the concentration of attached bacteria increases by 38%. Moreover, with decreasing external resistance from 300 to 5 kΩ, the concentration of attached bacteria increased by 89.7%. Increasing the number of MFCs in the system increases the power density and applied potential to the MEC, as a result, the rate of biohydrogen generation will increase. The results indicated that enhancing the required potential difference would increase biohydrogen production rate, because of an increase in the chemical potential of protons for the reduction process in cathode. For an optimum glucose concentration of 200 mg l-1, the biohydrogen production rate was 17% greater for the coupled system equipped with five microfluidic MFCs in comparison with three MFCs. In conclusion, results indicate the applicability of the proposed model in modeling of coupled systems and prove their ability to extract energy without using an external power source as an important step for future commercial applications
  9. Keywords:
  10. Coupled System ; Modeling ; Electrochemical Cells ; Biohydrogen Production ; Microbial Electrolysis Cell

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