Trickling filter in a biocathode microbial fuel cell for efficient wastewater treatment and energy production

Aiming to reduce the energy input, oxygen supply by trickling filter was employed in a biocathode microbial fuel cell（MFC） to examine its performance of electricity production and sewage treatment. During batch operation, trickling MFC（TMFC） could start and aerate effectively（DO>3.60 mg/L）. During continuous operation, TMFC produced a maximum current density of 71.8 A/m3 and maximum power density of 26.2 W/m3 under the hydraulic retention time（HRT） of 10 h. By increasing the HRT to 15 h, 90.6% of COD and 99.0% of ammonia in simulated domestic sewage were efficiently removed and the maximum power density was 19.4 W/m3. Continuous purification of real municipal wastewater achieved 85.9% of COD removal rate and 91.6%of ammonia removal rate. Sequencing result of biocathodic microorganisms indicated that it consisted of four major classes and the dominant class was γ-proteobacteria, which accounted for up to 84.38%. The dominant genus was Acinetobacter, which accounted for 57.81%. The phylogenetic tree showed different relationships among the 19 species of biocathode microorganisms and the predominant species was Acinetobacter calcoaceticus.