Studies On The Microbial Fuel Cell Using Up-flow Anaerobic Sludge Bed As Anode Chamber

In this study we combined the technologies of microbial fuel cells (MFCs) and up-flow anaerobic sludge bed (UASB) to treat the high concentration of organic wastewater efficiently while using microorganisms for power generation. Currently UASB process has been a very mature technique, but the MFCs technology is still in the initial stage, and it is not very in-depth studied. In this dissertation, we did the preliminary study on the technology of sequencing batch microbial fuel cells firstly, analyzed the influencing factors of MFCs performance, optimized the sequencing batch MFCs operating conditions, and then on this basis built the microbial fuel cells using up-flow anaerobic sludge bed as anode chamber which combined the technologies of UASB and MFCs. In this way we achieved a satisfactory result.The dissertation is divided into two sections:In the first section, we constructed a microbial fuel cell with glucose as the fuel. Factors affecting the performance of microbial fuel cells, i.e., the type of ion exchange material (and the absence of this material), electrode materials, electrode spacing and solution ionic strength (and potassium hexacyanoferrate) were investigated and optimized in this study. It was found that optimal performance for microbial fuel cells could be obtained by employing the homogeneous cation exchange membrane and plain high-purity graphite plate as electrodes with an electrode spacing of 0.5cm. Sodium chloride and potassium hexacyanoferrate solutions added could enhance the power generation. We got more power than other MFCs without plated platinum electrode.In the second section, we constructed the microbial fuel cells using up-flow anaerobic sludge bed as the anode chamber. A stable electric output could be attained with continuous feeding of wastewater and by taking the advantage of high removal efficiency of COD with UASB. The effects of hydraulic residence time and feeding mode were investigated. The results showed that when added the sodium chloride and potassium hexacyanoferrate solutions, a power output of 145 mW/m2 and an open voltage of 0.78V could be achieved with a maximum current of 321 mA/m2 using high-purity graphite plates as electrodes, homogeneous ion exchange membrane and continuous feeding mode with an hydraulic residence time of 6h. The stability of the energy output of microbial fuel cells in our experiments provides the experimental basis for its practical applications, which is the ultimate goal of our experiments.