Mechanisms Of Voltage Resersal In Microb Ial Fuel Cell Stacks And Novel Systems Coupled With Biohydrogen Reactors

With the global economic rapid development,water pollution has been one of the most serious issues threating human society. The traditional sewage treatment methods need to consume a lot of energy in wastewater treatment. Compared with the traditional wastewater treatment methods, microbial fuel cell(MFC) is one promising technology, which can simultaneously treat wastewater and produce electricity.However, the voltage of one single MFC is very small, largely hindering the application of MFCs. The open circuit voltage of one single MFC was 0.8V, and the working voltage is only 0.5V when one 100 ohm load is connected into the circuit. This paper focuses on the research of MFC voltage reversal under the starting conditions of using small resistance, experimental results show that the reverse phenomenon exists generally in the MFC stack We also constructed the MFCs-MEC coupled system, and investigated the relationship between the performance of MFC stack and the hydrogen production performance of MEC. Finally, based on the p H regulation characteristics of single chamber MFCs, we constructed coupled systems of sequencing batch photosynthetic hydrogen production reactor with air cathode single chamber MFC stack. The main conclusions of this study are as follow:1) The research of MFCs driver MFC cathode potential reverse and hydrogen productionIn this study, we started up the MFCs under the starting conditions of using small resistance, and investigated the performance of MFCs. We removed the MFC that the potential were reversed, and then we investigated the performance of the MFCs stack that is composed of the rest cells. The results showed that the potential of MFCs started with small resistance reversed under high current density. The reason is mainly because of the limitation of H+ diffusion rate for the anode biofilm. The MFC stacks that removed the MFC of voltage reverse will also occur voltage reverse.2) The research of the coupled system of MFCs and MECWe constructed a coupled system of MFCs and MEC, and investigated the performance of hydrogen production. The results showed that the hydrogen production rate, hydrogen recovery rate and substrate utilization rate of the system of 4MFCs-MEC is the highest,which were 23.1 ml/L/day,54.35 m L H2/g substrate, and 0.28 g/L, respectively.3) The research of coupleed system of photosynthetic biohydrogen reactors(PBR) and MFCsWe constructed a coupled system of sequencing batch photosynthetic biohydrogen reactors with single chamber MFCs. The results showed that the single-chamber MFC could alleviate the substrate acidification problem of PBR in the coupled system. The MFC of coupled system is conducive to the maintenance of the high p H value to ease the substrate acidification problem of PBR. The MFC of coupled system could degrade the organic acid from photosynthetic hydrogen production reactor. In addition, the performance of hydrogen production and glucose degradation rate decreased with the increase of MFC number in coupled system. The hydrogen production performance of PBR-3MFCs system was the best, of which the hydrogen production of single batch cycle is 2.8mmol, 75% higher than that of PBR system.