Electricity-Generating Microbial Communities in Biotrickling Filter-Microbial Fuel Cells for Gaseous Ethyl Acetate Treatment

Chi-Wen Lin^*,Chih-Hung Wu, Jing-Chen Shih

Department of Safety, Health and Environmental Engineering, National Yunlin University of Science and Technology, 123 University Rd., Sec. 3, Douliou, Yunlin 64002, Taiwan, ROC

Abstract

This study developed an integrated one-stage biofiltration system treating gaseous contaminants using biotrickling filter (BF) coupled with microbial fuel cell (MFC) by taking advantages from the MFC systems and biofiltration technologies. A unique anode design allowing fully contact between coke and graphite anode forming a three-dimensional electrode in the anode region of the biotrickling filter-microbial fuel cell (BF-MFC) system was developed to amplify anode area. Moreover, a new membrane design providing effective delivery of the proton released from microorganisms biodegrading ethyl acetate (EA), from anode to the cathode was developed by using a polyvinyl alcohol-membrane electrode assembly which separating anode from cathode in the BF-MFC. In addition, we tested for the first time the feasibility of using coke as the anode material to form a three-dimensional electrode for amplifying electricity production in MFC. The innovative BF-MFC system was then applied to investigate the performance under various inlet loads, the electricity generation, and microbial changes toward gaseous EA biodegradation. The effect of EA levels on microbial community structures was also assessed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis. The results show that an EA elimination capacity of 83.80 g/m³·h and the maximum power density of 49.1 mW/m² were observed. Microbial community analysis revealed that two distinct groups of exoelectrogenic microbes and EA-degraders were existed. The former dominated in coke media, whereas the latter was present in the interior surface of the BF-MFC and in suspension in the recirculating tank. These results exhibited that the developed BF-MFC provided an alternative for the environmentally friendly removal of gaseous EA in combination with electricity production.

Keyword: biotrickling filter-microbial fuel cell (BF-MFC), denaturing gradient gel electrophoresis (DGGE) analysis, polyvinyl alcohol-membrane electrode assembly (PVA-MEA), generation electricity