Enhanced gaseous ethyl acetate degradation and power generation by a bioelectrochemical system

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This work develops a novel hollow air-cathode biotrickling filter (BTF) microbial fuel cell (MFC) to treat ethyl acetate (EA) in a waste air stream. A BTF was combined with an MFC to form a BTF-MFC, which was effective in controlling volatile organic compounds (VOCs) emission and generating power. The BTF-MFC has an air cathode in its center, increasing the absorption and retention of water by the proton exchange membrane (PEM) to improve its ability to receive protons and oxygen and thereby accelerating the reduction reaction in the cathode. The EA removal efficiency was 17% higher under the close-circuit condition than the open-circuit condition, revealing the potential of the BTF-MFC for VOC control. Under optimum condition, a removal efficiency, maximum power density (PD), and maximum current density (CD) of 92.1%, 146.8 mW/m2, and 500.6 mA/m2, respectively, were obtained. The PD and CD were approximately five times, and the closed-circuit voltage (CCV) was 1.3 times, those obtained in the literature. Furthermore, MFC exhibited a linear increase in elimination capacity (EC) from 35.5 g/m3/h to 66.3 g/m3/h as the EA concentration under organic loading was increased from 36 to 72 g/m3/h under the critical load of about 70 g/m3/h and the maximum EC of 81 g/m3/h. This work establishes the feasibility of using both the improved PEM and a hollow air cathode to increase substantially the generation of electricity by an MFC and to remove EA with a relatively high efficiency.