Studies Of Substrate Microbial Fuel Cells (MFCs) Performance Factors And Phenol

With the development of society and the rapid increase in population, more and more energy is demanded by human each passing day, which brings resource depletion and environmental pollution problems. For low carbon life and the road of sustainable development, then human pay more and more attention to waste, Microbial fuel cells (MFCs) are the one in line with the concept of this preface technology. MFCs are novel environmental friendly energy device which converts chemical energy contained in organic compounds to electrical energy by using microorganism as a biocatalyst. For now, MFCs are still in the experimental research stage, many bottlenecks will be needed to overcome before they are used in catual. This paper mainly studies the three aspects:the factors affecting the performance of MFCs, the regulation of pH anode solution, the degradation of difficult substance-phenol. And the specific contents as follows:Part one:Study on the influencing factors of MFCs performanceThe concentration of the substrate, the level of discharge, the area of the anode and ion exchange membrane were investigated to impact on MFCs performance during the experiment. Increasing substrate concentration of MFCs could prolong the discharge time, increase production capacity, but it was not conducive to the substrate to improve the efficiency of coulomb efficiency. Improving the discharge level of MFCs could short the discharge time, increase production capacity, improve the efficiency of substrate in coulomb efficiency, but the premise was the superior performance of bio-film MFCs, allowed high current through. And the electrode area was huge, polarization phenomenon was not serious; the smaller internal resistance, the larger output power. Increased anode area and ion exchange membrane area were good for decreasing resistance, increasing production of electricity, producing substrate coulomb efficiency.Part two:MFCs anode solution pH change research and managementComparison of MFCs pH changed in the open and closed state of the anode solution, found that current changes and circuit of pH were closely related to the current, and the greater current, the faster decline rate of pH. Combination of the anode solution titration curve calculation the quantity of anode produce hydrogen ions in the solution, with the electrons in the external circuit, found that the ratio reaching0.84. This shows that the microbial catalysis substrates to produce less than20%of the hydrogen ions only by ion exchange membrane to the cathode, and complete the rest of the charge transfer were other cations in the solution.The lower pH of anode solution had seriously affected the catalytic activity of microorganisms, so to improve the efficiency of MFCs substrate removal rate and coulomb, we need to control the change of the pH value of the solution. Calcium carbonate anode solid, sodium bicarbonate, sodium hydroxide solution and increasing the concentration of buffer system were added to the experiments, which had effectively improved the MFCs performance. To compair the comprehensive evaluation, we found that hydroxide solution method in sodium was the most practical.Part three:Phenol and sodium acetate as the mixed substrate of MFCs’performance researchPhenol was often contained in industrial wastewater and could be used as MFCs’substrate, during the experiment different proportions easy decomposition of sodium acetate was mixed as the substrate, too. We investigaed the ralatingship between the mixed substrate and the electrical, the influence of the phenol and the COD removal rate. Experimental results showed that when the microorganisms on the degradation of the substrate had a selective, simple structure of the small molecular compound sodium acetate was easy decomposed, show the asynchronism of phenol and the COD removal rate. At the same time, the addition of sodium acetate could significantly increase the output power of MFCs. When using phenol as a single substrate, MFCs in the closed state of phenol removal effect were good.PCR-DGGE bands of clustering analysis showed that different substrates of MFCs system, through the long time running, greated changes would happen in the anode system’s microbial community structure.