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Publication

Understanding the Impact of Flow Rate and Recycle on the Conversion of a Complex Biorefinery Stream Using a Flow-through Microbial Electrolysis Cell

by Alex J Lewis, Abhijeet P Borole
Publication Type
Journal
Journal Name
Biochemical Engineering Journal
Publication Date
Page Numbers
95 to 104
Volume
116
Issue
Dec 15

tThe effect of flow rate and recycle on the conversion of a biomass-derived pyrolysis aqueous phase in amicrobial electrolysis cell (MEC) were investigated to demonstrate production of renewable hydrogen inbiorefinery. A continuous MEC operation was investigated under one-pass and recycle conditions usingthe 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 hydrogenproductivity 3-fold, but anode conversion efficiency (ACE) decreased from 57.9% to 9.9%. Recycle of theanode liquid helped to alleviate kinetic limitations and the ACE increased by 1.8-fold and the hydrogenproductivity by 1.2-fold compared to the one-pass condition at the flow rate of 3.6 mL/min (10 g/L-dOLR). High COD removal was also achieved under recycle conditions, reaching 74.2 ± 1.1%, with hydrogenproduction rate of 2.92 ± 0.51 L/L-day. This study demonstrates the advantages of combining faster flowrates with a recycle process to improve rate of hydrogen production from a switchgrass-derived streamin the biorefinery.