| Currently, the global energy crisis caused by large amount of energy consumption and the environmental issues caused by the energy consumption both are inspiring people to find and explore renewable energy technologies which are environment friendly. Recycling the large amount of valuable energy in the domestic wastewater has become an important topic in the field of environmental chemistry. Microbial fuel cell (MFC) is an electrochemical reaction device which can invert chemical energy into electricity energy. MFC belongs to interdisciplines, which involve multiple disciplines, such as biology, electrochemistry, environtology and other fields. MFC can use microbes as catalyst to produce electricity, converting the substance’s chemical energy into electrical energy. It has many advantages such as green, safe operation, easy to control, extensive source of raw materials, and so on. Application of MFC in the domestic wastewater treatment, can combine wastewater treatment with electricity generation together, and this is expected to change the situation of the existing high-cost treatment of domestic wastewater. It has a broad application prospect, but also faces great challenges. Nowadays, MFC is still in experimental research stage, and there are many technical problems to be solved and many theoretical studies need further improvement.In this paper, a double-chamber MFC reaction device was constructed and anaerobic sludge from wastewater treatment by AAO process was vaccinated. Then the MFC was tamed by online mode, and electrochemical properties of the microbial fuel cell were investigated by electrochemical testing methods including AC impedance, cyclic voltammetry.(1) The concentration of glucose in the MFC anode was1.00g/L,0.33g/L,0.25g/L,0.17g/L,0.10g/L, respectively, by adding glucose to the anode solution. The MFC was running for five cycles, with each concentration as a cycle, to investigate the effect of glucose concentration on the electrical characteristics of the MFC. In a certain range, improving glucose concentration could contribute to microbial growth and reproduction, and could accelerate the formation of the mature biofilm and help to improve the electrochemical activity and electricity-generating capacity. But if the concentration is too high, there will appear saturation effect and there is no benefit to improve the efficiency of electricity production. The suitable concentration of glucose for microbial growth and reproduction can obviously improve the electrochemical activity and the capacity to generate electricity of the MFC. High activity to product electricity is conducive to conduct the electronics and decrease the anodic overpotential. At the same overpotential, when the concentration of glucose is0.33g/L, the MFC has the maximum current density. And when the concentration of glucose is0.33g/L, the battery has the maximum power density of26.70mW/m2. When the concentrations of glucose are1g/L,0.33g/L,0.25g/L,0.17g/L,0.10g/L, the ratios the charge transfer impedance in the anodic internal resistance are96.9%,95.6%,97.7%,99.3%,99.7%, respectively, illustrating that the control process of electrochemical reaction is load transfer process.(2) Investigating the effect on the electricity-generating capacity of MFC when the temperature changing. Through operating MFC at five different temperatures as five cycles, the effect of temperature on the electricity-generating properties of MFC was studied. The temperature of the five cycles were18℃,25℃,32℃,39℃,46℃, respectively. The research found that, in a certain temperature range, improving the temperature is conducive to bacterial growth and reproduction, and is helpful to the domestication of mature biofilm accelerate the bacterial metabolism, these all can effectively improve bacterial electrochemical activity and electricity-producing capacity. At the same time, the temperature can affect the conductivity of the electrolyte, the migration rate of ions and proton transfer rate in the solution.When the temperature rises, the migration rate of ion increases, and the electrolyte conductivity enhances, and the mass transfer resistance and the electrolytic solution resistance both decrease, the charge transfer rate in the cathode also accelerates. If the temperature is too low, the activity of enzymes of bacteria is also very low, and the metabolism is slow. If the temperature is too high, the enzyme may inactivate, and bacteria may die, then the power output of the MFC diminishes. Under the combined effect of these factors, the research showed that, when the system temperature is32℃, the biofilm has the best electrochemical activity, bacteria have high electricity-producing activity, what s more, this is conducive to electronic conduction. At the same current density, when the temperature of the MFC is32℃, the anode overpotential is the minimum. And at this temperature, the MFC has the maximum power density of156.2mW/m. When the temperatures maintained at18℃,25℃,32℃,39℃and46℃, the corresponding exchange current density is1.67×10-6mA/m2,1.68×10-5mA/m2,8.02×10-5mA/m2,3.01×10-5mA/m2,2.20×10-6mA/m2, respectively. When the MFC is at32℃the exchange current density is the biggest. |
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