| Currently, the world-wide energy crisis and increasing environmental pollution are inspiring people to research renewable, environment-friendly and new technologies. Recovery of useful energy from industrial wastewater has become an important issue in the field of environmental chemistry. Microbial fuel cell (MFC) that uses microorganism as biocatalyst produces clean, non-polluting electrical energy from chemical energy of industrial wastewater through microbial metabolism. MFC as an interdisciplinary subject is at experiment level and has not been practical application, which involves biological, environmental, electrochemical, etc. In this work, a double-chambers MFC was used to vaccinate sludge of anaerobic tank from coking wastewater and the experiment applied online tame method to study the electricity-generation performance and the experiment determinated degradation rate of phenol which is a toxic substance.(1) In the process of the addition of organic substrate glucose into the anode liquid, the amount of glucose reduced gradually, and the bacteria adapted the electrical system of MFC fed with coking wastewater after the battary has run for 5 periods. The bacteria shapes of biofilm domesticated maturely were bacillus, coccus, and coccus was in the majority. The system with glucose concentration 0.25 g/L had the maximum output power density of battery 55.65 mW/m2, with current density of 525 mA/m2. The redox peak emerged in the cycle volt-ampere curve, meaning that electronic intermediaries were generated in the system. The redox peak removed in the first three cycles, pointing out that more than one kind of electrochemical activity bacteria participated in the electrochemical reaction of the mixed bacteria system. In the forth and fifth period, a remarkable and symmetrical redox peak appeared respectively, and the locations of the peaks were approximately the same. This phenomenon demonstrated that the biofilm have been domesticated maturely, and the electrochemical activity was more stable. Compared with other anode impedance, the charge transfer resistance Rct occupied the absolute share in the entire process, implying that the electric catalytic reaction in the positive pole was charge transfer control style.(2) The addition of glucose and phenol into the anode liquid would form the co-substrate system. The initial mass concentrations of glucose and phenol are 1 g/L and 0.2 g/L repectively, then the concentrations of glucose was reduced gradually, and only phenol substrate was added into the system after five cycles, with its concentrations were 0.2 g/L,0.4 g/L, and 0.6 g/L, respectively. The electrochemical activity and poison resistance of the bacteria was enhanced in this domestication process. In the impedance measurement, the concentration of phenol in single substrate MFC were 0.2 g/L,0.6 g/L, and the internal resistances Rs of the anode liquid were 2.142 Ω 2 and 3.541 Ω, respectively. Compared with other anode impedance, the charge transfer resistance Rct occupied the absolute share, and the electric catalytic reaction in the positive pole was charge transfer control style. There was no redox peak appearing in the cycle volt-ampere curve, indicating that there were no redox intermediaries produced in the system, and the electrons were transmitted to the anode through the bacteria or the nano-wire. When the biofilms domesticated maturely dealed with the singe phenol substrate with its initial mass concentrations 0.2 g/L, it had the maximum output power density of battery 42.9 mW/m2, with current density 300 mA/m2. The degradation rate of phenol was more quickly in the first 48 hours, then decreased gradually, and the degradation was mainly completed in 96 hours. The COD removal rate of the battary in the 48th,96th,144th,192th hour were 20.6%、28.6%、35.8%、40.9%, and coulomb efficiencies were 11.8 %,13.6%,16.2%,18.5%, respectively. |
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