Optimization of biogas production during start-up with electrode-assisted anaerobic digestion

Abstract

To better understand anaerobic digestion (AD) conditions during start-up, a series of batch and bench-scale studies were conducted to investigate conditions affecting the performance of the anaerobic reactors, including pH fluctuations, ammonia inhibition, and bioaugmentation. Capacitive soil moisture sensors were placed inside the AD reactors to provide near real-time microbial monitoring under experimental batch conditions and to create a microbial electrolysis cell (MEC) environment. After an eight-day digestion process at 40 °C, the capacitive soil moisture sensors performed as a rudimentary microbial activity tracking device. However, the electrodes had a statistically significant impact on biogas production with a small potential 0.8 V having a stabilizing effect on AD at 40 °C during start-up. Furthermore, electrode-assisted AD noted a biogas output 63.7% higher than the conventional AD without electrodes. Conversely, the bioaugmented electrode-assisted AD showed a 7% increase in biogas volume when compared to the non-bioaugmented batch.

Keywords: Anaerobic digestion; BES; Biogas; Electrode-assisted; MEC; Sensors; Start-up.