The Characterization Of Mixed Culture For Hydrogen Production And Electricity Production In High Temperature MFC And Reverse Electrodialysis

Mixed culture fermentation(MCF) is an important environmental biotechnology to produce hydrogen, acetic acid, butyrate and other chemicals from biodegradable organic wastes. However, the current research mainly focuses on the reactor operating conditions,such as reactor configuration, p H value, hydrogen partial pressure, substrate loading and other factors. While, the microbial community compositions were normally ignored. The microbial community compositions of a chemostat enriched in a thermophilic(55 °C)MCF for hydrogen production under different operational conditions were researched in this work by integrating denaturing gradient gel electrophoresis(DGGE), Illumina Miseq high-throughput sequencing, and 16 S r RNA clone library sequencing. The results showed that the community structure of the enriched cultures was relatively simple. Clones close to the genera of Thermoanaerobacter and Bacillus mainly dominated the bacteria. then homoacetogens and archaea were washed out and not detected even by Illumina Miseq high-throughput sequencing which supported the benefit for hydrogen production. On the other hand, the results revealed that the metabolic shift was clearly associated with the change of dominated bacterial groups. The effects of hydrogen partial pressure(PH2) and p H from 4.0 to 5.5 on the microbial com positions were not notable and Thermoanaerobacter was dominant, thus, the metabolites were also not changed. While Bacillus, Thermoanaerobacter and Propionispora hippei dominated the bacteria communities at neutral p H, or Bacillus and Thermoanaerobacter dominated at high influent glucose concentrations, consequently the main metabolites shifted to acetate,ethanol, propionate, or lactate.At the same time, two other works of thermophilic microbial fuel cell(MFC) and reverse electrodislysis were carried out. In MFC work of mesophilic and thermophilic conditions, microorganisms were inoculated from a local wastewater treatment, acetate was used as the substrate. The results showed that the efficiency of the battery was higher at 35 o C, the substrate was fully utilized, the maximum voltage can reach 600 m V, and the mainly limiting factors of the power production are the mass transfer. At 55 o C, the voltageof the output voltage was not stable, and the output voltage can only reach 130 m V. High internal resistance was a main factor.At last, we also investigated the electrical energy generation in the reverse electrodialysis. Firstly, different types of ion exchange membrane were studied. Then, low concentration region packed with ion exchange resin was proposed to improve the electrical properties with fixing ion exchange membrane. The results showed that:alternately placing anion exchange membrane and cation exchange membrane resulted in the output voltage was higher than putting a single film battery, and material battery voltage reached maximum when the materials were divided bond breaker into three negative membrane and two anode membrane. Thereby, adding ion exchange resin can obviously reduce the internal resistance of the battery and improve the performance of the battery.