Environmental Engineering Reference
In-Depth Information
Table 3.1
(
Continued
)
Pretreatment methods
Major process conditions
Major effects
Advantages
Disadvantages
Chemical processes
Acid hydrolysis
Dilute acids;
HCl/H
2
SO
4
/HPO
3
;
<4% acid; <160°C;
concentrated acid;
HCl/H
2
SO
4
/TFA;
>40% for concentrated acid;
160-220°C; treatment period
for hours or less
Dilute acid; hemicellulose
removal; concentrated acid;
cellulose and hemicellulose
hydrolyzed
Low cost; effective for wide
range of biomass
Formation of
fermentation
inhibitors;
corrosive
Alkaline hydrolysis
NaOH/KOH/CaOH
2
of
1-10%;
treatment time of hours- days
at ambient temperature
Lignin and hemicellulose removal
Low cost; low energy
requirement; low level of
inhibitors; low energy
requirement
Only suitable for
biomass with low
lignin content;
incorporation of
high amount of
salts
Ozonolysis
2-3% (w/w) ozone with flow
rate of 60 L hr
-1
; treatment
time for 1-2 hr at ambient
temperature and pressure
Lignin removal; partial
hemicellulose removal
Expensive
Biological processes
Fungal digestion
Fermentation temperature at
20-30°C; treatment period
from weeks to months;
initial biomass moisture
content of 60-85%
Lignin removal
Very low cost; no harsh
chemicals; environmentally
friendly
Very time
consuming