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

Abstract

We investigated the effect of flow rate and recycle on the conversion of a biomass-derived pyrolysis aqueous phase in amicrobial electrolysis cell (MEC) to demonstrate production of renewable hydrogen in biorefinery. 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 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 1.1%, with hydrogen production rate of 2.92 ± 0.51 L/L-day. This study demonstrates the advantages of combining faster flow rates with a recycle process to improve rate of hydrogen production from a switchgrass-derived stream inmore » the biorefinery.« less

Authors:
 [1]; ORCiD logo [2]
  1. Univ. of Tennessee, Knoxville, TN (United States)
  2. Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1263843
Grant/Contract Number:
AC05-00OR22725; DEAC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Biochemical Engineering Journal
Additional Journal Information:
Journal Name: Biochemical Engineering Journal; Journal ID: ISSN 1369-703X
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; 08 HYDROGEN; switchgrass; bio-oil aqueous phase; pyrolysis; Integrated hydrogen production; organic loading rate; hydraulic retention time

Citation Formats

Lewis, Alex J., and Borole, Abhijeet P. Understanding the impact of flow rate and recycle on the conversion of a complex biorefinery stream using a flow-through microbial electrolysis cell. United States: N. p., 2016. Web. doi:10.1016/j.bej.2016.06.008.
Lewis, Alex J., & Borole, Abhijeet P. Understanding the impact of flow rate and recycle on the conversion of a complex biorefinery stream using a flow-through microbial electrolysis cell. United States. doi:10.1016/j.bej.2016.06.008.
Lewis, Alex J., and Borole, Abhijeet P. 2016. "Understanding the impact of flow rate and recycle on the conversion of a complex biorefinery stream using a flow-through microbial electrolysis cell". United States. doi:10.1016/j.bej.2016.06.008. https://www.osti.gov/servlets/purl/1263843.
@article{osti_1263843,
title = {Understanding the impact of flow rate and recycle on the conversion of a complex biorefinery stream using a flow-through microbial electrolysis cell},
author = {Lewis, Alex J. and Borole, Abhijeet P.},
abstractNote = {We investigated the effect of flow rate and recycle on the conversion of a biomass-derived pyrolysis aqueous phase in amicrobial electrolysis cell (MEC) to demonstrate production of renewable hydrogen in biorefinery. 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 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 1.1%, with hydrogen production rate of 2.92 ± 0.51 L/L-day. This study demonstrates the advantages of combining faster flow rates with a recycle process to improve rate of hydrogen production from a switchgrass-derived stream in the biorefinery.},
doi = {10.1016/j.bej.2016.06.008},
journal = {Biochemical Engineering Journal},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 6
}

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  • A biorefinery process typically uses about 4-10 times as much water as the amount of biofuel generated. The wastewater produced in a biorefinery process contains residual sugars, 5-furfural, phenolics, and other pretreatment and fermentation byproducts. Treatment of the wastewater can reduce the need for fresh water and potentially add to the environmental benefits of the process. Use of microbial fuel cells (MFCs) for conversion of the various organics present in a post-fermentation biorefinery stream is reported here. The organic loading was varied over a wide range to assess removal efficiency, coulombic efficiency and power production. A coulombic efficiency of 40%more » was observed for a low loading of 1% (0.66 g/L) and decreased to 1.8% for the undiluted process stream (66.4 g/L organic loading). A maximum power density of 1180 mW/m2 was observed at a loading of 8%. Excessive loading was found to result in poor electrogenic performance. The results indicate that operation of an MFC at an intermediate loading using dilution and recirculation of the process stream can enable effective treatment with bioenergy recovery.« less
  • Background Microbial fuel cells (MFC) and microbial electrolysis cells are electrical devices that treat water using microorganisms and convert soluble organic matter into electricity and hydrogen, respectively. Emerging cellulosic biorefineries are expected to use large amounts of water during production of ethanol. Pretreatment of cellulosic biomass results in production of fermentation inhibitors which accumulate in process water and make the water recycle process difficult. Use of MFCs to remove the inhibitory sugar and lignin degradation products from recycle water is investigated in this study. Results Use of an MFC to reduce the levels of furfural, 5-hydroxymethylfurfural, vanillic acid, 4- hydroxybenzaldehydemore » and 4-hydroxyacetophenone while simultaneously producing electricity is demonstrated here. An integrated MFC design approach was used which resulted in high power densities for the MFC, reaching up to 3700mW/m2 (356W/m3 net anode volume) and a coulombic efficiency of 69%. The exoelectrogenic microbial consortium enriched in the anode was characterized using a 16S rRNA clone library method. A unique exoelectrogenic microbial consortium dominated by -Proteobacteria (50%), along with -Proteobacteria (28%), -Proteobacteria (14%), -Proteobacteria (6%) and others was identified. The consortium demonstrated broad substrate specificity, ability to handle high inhibitor concentrations (5 to 20mM) with near complete removal, while maintaining long-term stability with respect to power production. Conclusions Use of MFCs for removing fermentation inhibitors has implications for: 1) enabling higher ethanol yields at high biomass loading in cellulosic ethanol biorefineries, 2) improved water recycle and 3) electricity production up to 25% of total biorefinery power needs.« less
  • Impedance changes of the anode, cathode and solution were examined for a microbial fuel cell (MFC) under varying conditions in order to improve its performance. An MFC inoculated with a pre-enriched microbial culture resulted in a startup time of ten days. Over this period, the anode impedance decreased below the cathode impedance, suggesting a cathode limited power output. Decreasing the anode flow rate did not impact the anode impedance significantly, while it increased the cathode impedance by 65% . Reducing the anode-medium ionic strength from 100% to 10% increased the cathode impedance by 48%.