20 research outputs found
A novel hybrid organosolv: steam explosion method for the efficient fractionation and pretreatment of birch biomass
Background:
The main role of pretreatment is to reduce the natural biomass recalcitrance and thus enhance sac-
charification yield. A further prerequisite for efficient utilization of all biomass components is their efficient fractiona-
tion into well-defined process streams. Currently available pretreatment methods only partially fulfill these criteria.
Steam explosion, for example, excels as a pretreatment method but has limited potential for fractionation, whereas
organosolv is excellent for delignification but offers poor biomass deconstruction.
Results:
In this article, a hybrid method combining the cooking and fractionation of conventional organosolv pre
-
treatment with the implementation of an explosive discharge of the cooking mixture at the end of pretreatment was
developed. The effects of various pretreatment parameters (ethanol content, duration, and addition of sulfuric acid)
were evaluated. Pretreatment of birch at 200
°C with 60%
v/v ethanol and 1%
w/w
biomass
H
2
SO
4
was proven to be the
most efficient pretreatment condition yielding pretreated solids with 77.9%
w/w cellulose, 8.9%
w/w hemicellulose,
and 7.0
w/w lignin content. Under these conditions, high delignification of 86.2% was demonstrated. The recovered
lignin was of high purity, with cellulose and hemicellulose contents not exceeding 0.31 and 3.25%
w/w, respectively,
and ash to be <
0.17%
w/w in all cases, making it suitable for various applications. The pretreated solids presented
high saccharification yields, reaching 68% at low enzyme load (6
FPU/g) and complete saccharification at high
enzyme load (22.5
FPU/g). Finally, simultaneous saccharification and fermentation (SSF) at 20%
w/w solids yielded an
ethanol titer of 80
g/L after 192
h, corresponding to 90% of the theoretical maximum.
Conclusions:
The novel hybrid method developed in this study allowed for the efficient fractionation of birch
biomass and production of pretreated solids with high cellulose and low lignin contents. Moreover, the explosive dis-
charge at the end of pretreatment had a positive effect on enzymatic saccharification, resulting in high hydrolyzability
of the
pretreated solids and elevated ethanol titers in the
following high-gravity SSF. To the best of our knowledge,
the ethanol concentration obtained with this method is the highest so far for birch biomass