Construction And Performance Characteristics Of The Carbon Tubular Microbial Fuel Cell Stack

Energy crisis and environment issues have weigh heavily against the development of human society. Exploring of clean energy and sewage treatment technology hold a great promise in sustainability of human development. Microbial fuel cells(MFCs), as a “green” sustainable energy technology capable of treating wastewater and producing electricity simultaneously, have attracted intensive attention recent years.However, the real utilization of MFCs still is limited by its low power performance, voltage output and high fabrication cost. To achieve the practical application of MFC, a membrane-free air cathode MFCs were fabricated and connected in series or parallel, aiming to improve the performance. Considering these issues, the paper presented two kinds of air-cathode MFC: an activated carbon air-cathode MFC(AC-MFC) and a bamboo charcoal tube air-cathode MFC(BC-MFC). The study investigated the performance of two kinds of MFC. Experiment results demonstrated that BC-MFC not only possessed a better performance compared with the AC-MFC, but also presented a more optimal structure allowing for serially or parallelly connection through a simple water distribution system. In this paper, four different kinds of BC-MFC stacks, connecting with different water distribution system and circuits, were constructed to evaluate their performance. Meanwhile, considering the fact that the performance of MFC stack was mainly dominated by cathode performance of BC-MFC, several improvements were proposed. The main research results were as follows:1 The AC-MFC and BC-MFC performance. The maximum power density and open circuit voltage of BC-MFC is 7.8 W/m3 and 472 m V, which is 1.4 times(5.5 W/m3)and 1.2 times(380 m V) higher than that of AC-MFC, respectively. The results showed that BC-MFC has a better performance compared with AC-MFC.2 Research on performance degradation and improvement. The results showed that the cathode of BC-MFC is mainly responsible for the deterioration of MFC stack performance. This could be explained by the fact that the biofilm attached to the cathode surface hinder the diffusion of proton from electrolyte to cathode, leading to the decrease of cathode performance. Therefore, measures were taken to inhibit the growth of cathode biofilm and improve the performance of BC-MFC stack by using a low concentration medium(200 mg/L COD).3 Performance of BC-MFC stacks with different water distribution system and electrical circuit connections. Four different kinds of MFC stacks were constructed: 1) Water distribution & Electrical circuit were in parallel connection; 2) Water distribution was in series connection & Electrical circuit was in parallel connection; 3) Water distribution was in parallel connection & Electrical circuit was in series connection; 4) Water distribution & Electrical circuit were in series connection. It was found that MFC stacks electrically connected in parallel obtained a higher power generation than that of MFC stacks in series connection with a lower open circuit voltage.