Continuous power production and styrene abatement through the addition of silicone oil in a trickling filter-based bioelectrochemical system with an activated sludge tank

Abstract

To increase the power generation capacity of a trickling filter/bioelectrochemical system (TF/BES), this study combines an activated sludge system (AS) with a TF/BES to construct an AS–TF/BES. The efficiency with which the AS system and the TF/BES system treat waste gas that contains styrene is increased by adding silicone oil. The power density of the TF/BES is increased by 1.6 times if an AS system is used, and it is increased by a factor of 3.03 if 10 % silicone oil is added. The increase is caused by an increase in electron loss due to the presence of oxygen in the AS and a more efficient mass transfer of styrene in aqueous solutions and biofilms due to the addition of silicone oil. If silicone oil is added, the ohmic resistance and the charge transfer resistance for the AS–TF/BES are reduced by 16 % and 17 %, respectively, so more power is produced by the AS–TF/BES. The voltage output of an AS–TF/BES increases as silicone oil is added. The power density (361 mW/m3) increases by a factor of 1.9 if 10 % silicone oil is added. In an AS–TF/BES, the ability of the AS to remove oxygen and styrene decreases as the empty bed residence time (EBRT) for the TF/BES decreases, but increases if 10 % silicone oil is added to the AS. The relative abundance of degrading and electrogenic bacteria in the AS and the TF/BES increases 1.22–1.55 times if silicone oil is added to the AS–TF/BES.