Understanding the impact of flow rate and recycle on the conversion of a complex biorefinery stream using a flow-through microbial electrolysis cell

By Lewis, Alex J.; Borole, Abhijeet P.
Published in Biochemical Engineering Journal NULL 2016

Abstract

Abstract The effect of flow rate and recycle on the conversion of a biomass-derived pyrolysis aqueous phase in a microbial electrolysis cell (MEC) were investigated to demonstrate production of renewable hydrogen in biorefinery. A continuous {MEC} operation was investigated under one-pass and recycle conditions using the complex, biomass-derived, fermentable, mixed substrate feed at a constant concentration of 0.026 g/L, while testing flow rates ranging from 0.19 to 3.6 mL/min. This corresponds to an organic loading rate (OLR) of 0.54-10 g/L-day. Mass transfer issues observed at low flow rates were alleviated using high flow rates. Increasing the flow rate to 3.6 mL/min (3.7 min HRT) during one-pass operation increased the hydrogen productivity 3-fold, but anode conversion efficiency (ACE) decreased from 57.9% to 9.9%. Recycle of the anode liquid helped to alleviate kinetic limitations and the {ACE} increased by 1.8-fold and the hydrogen productivity by 1.2-fold compared to the one-pass condition at the flow rate of 3.6 mL/min (10 g/L-d OLR). High {COD} removal was also achieved under recycle conditions, reaching 74.2

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