3D printed cathodes for microbial electrolysis cell-assisted anaerobic digester: Evaluation of performance, resilience, and fluid dynamics
Tae Hyun Chung, A. S. Abd Rahman, Anindya Amal Chakrabarty, Basem S. Zakaria, Mohammad Abu Hasan Khondoker, Bipro Ranjan Dhar
Abstract
This study comprehensively evaluated the performance of 3D printed electrodes with different lattice structures (Cubic, Diamond, Schwartz, and SplitP) in microbial electrolysis cell-assisted anaerobic digestion (MEC-AD) systems under various power supply conditions (24 h ON, 18 h ON, 12 h ON, and 6 h ON). The shortest startup time (2 days) and the highest biomethane production (534.8 ± 30 L/m 3 ) under continuous power supply mode (24 h ON) was achieved by SplitP-MEC-AD, which possessed the largest surface area, but it achieved the lowest current density generation and biomethane production under intermittent power supply modes (18 h–6 h ON). The computational fluid dynamics analysis revealed that SplitP-MEC-AD experienced significantly high turbulence (turbulent kinetic energy = 0.86141 m 2 /s 2 , max fluid velocity = 2.95 m/s), which may have hindered the cathode biofilm combined with unfavorable intermittent power supply conditions. The highest current densities were always achieved by Cubic-MEC-AD, which had the lowest resistance. Diamond-MEC-AD (larger surface area and lower resistance) achieved the highest biomethane generation (411.4 ± 53.7 L/m 3 ) during the intermittent power supply. Cathodic microbial communities differed significantly among MEC-ADs, possibly due to varying geometries. Our research indicates that both Cubic and Diamond electrodes are suitable cathode choices for MEC-AD systems with further modifications.