Enhanced electron recovery by optimizing sandwich structure agricultural waste corncob filled anode in microbial electrochemical system to facilitate wastewater denitrification.

[Display omitted] • Sandwich structure anode was designed by help of COMSOL simulation. • 3D printing current collector was first used in microbial electrochemical system. • Corncob was used as sole carbon source for efficient denitrification. • Optimizing anode structure enhanced electrons generation and collection. • Sandwich structure anode improved autotrophic denitrification efficiency. Microbial electrochemical system autotrophic denitrification has attracted much attention due to its cost-efficiency and clean advantages. The autotrophic denitrification rate highly depends on the input electrons to the cathode. In this study, agricultural waste corncob was filled into sandwich structure anode as low-cost carbon source for electron production. The COMSOL software was used to guide the construction of sandwich structure anode to control carbon source release and enhance electron collection, including suitable pore size (4 mm) and current collector arrangement (five branches). Optimized sandwich structure anode system with the help of 3D printing obtained a higher denitrification efficiency (21.79 ± 0.22 gNO 3 --N/m3d) than anodic systems without pore and current collector. Statistical analysis showed that enhanced autotrophic denitrification efficiency was the responsible for enhanced denitrification performance of the optimized anode system. This study provides a strategy to improve the autotrophic denitrification performance of the microbial electrochemical system by optimizing the anode structure. [ABSTRACT FROM AUTHOR]