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Biotransformation of Furanic and Phenolic Compounds with Hydrogen Gas Production in a Microbial Electrolysis Cell
journal contribution
posted on 2015-11-17, 00:00 authored by Xiaofei Zeng, Abhijeet
P. Borole, Spyros G. PavlostathisFuranic
and phenolic compounds are problematic byproducts resulting
from the breakdown of lignocellulosic biomass during biofuel production.
The capacity of a microbial electrolysis cell (MEC) to produce hydrogen
gas (H2) using a mixture of two furanic (furfural, FF;
5-hydroxymethyl furfural, HMF) and three phenolic (syringic acid,
SA; vanillic acid, VA; and 4-hydroxybenzoic acid, HBA) compounds as
the substrate in the bioanode was assessed. The rate and extent of
biotransformation of the five compounds and efficiency of H2 production, as well as the structure of the anode microbial community,
were investigated. The five compounds were completely transformed
within 7-day batch runs and their biotransformation rate increased
with increasing initial concentration. At an initial concentration
of 1200 mg/L (8.7 mM) of the mixture of the five compounds, their
biotransformation rate ranged from 0.85 to 2.34 mM/d. The anode Coulombic
efficiency was 44–69%, which is comparable to that of wastewater-fed
MECs. The H2 yield varied from 0.26 to 0.42 g H2–COD/g COD removed in the anode, and the bioanode volume-normalized
H2 production rate was 0.07–0.1 L/L-d. The biotransformation
of the five compounds took place via fermentation followed by exoelectrogenesis.
The major identified fermentation products that did not transform
further were catechol and phenol. Acetate was the direct substrate
for exoelectrogenesis. Current and H2 production were inhibited
at an initial substrate concentration of 1200 mg/L, resulting in acetate
accumulation at a much higher level than that measured in other batch
runs conducted with a lower initial concentration of the five compounds.
The anode microbial community consisted of exoelectrogens, putative
degraders of the five compounds, and syntrophic partners of exoelectrogens.
The MEC H2 production demonstrated in this study is an
alternative to the currently used process of reforming natural gas
to supply H2 needed to upgrade bio-oils to stable hydrocarbon
fuels.