Comparison of vacuum and high pressure evaporated wood hydrolyzate for ethanol production by repeated fed-batch using flocculating Saccharomyces cerevisiae

• Comparison of vacuum and high pressure evaporated wood hydrolyzate for ethanol production by repeated fed-batch using flocculating Saccharomyces cerevisiae

• With the aim of increasing the sugars concentration in dilute-acid lignocellulosic hydrolyzate to more than 100 g/l for industrial applications, the hydrolyzate from spruce was concentrated about threefold by high-pressure or vacuum evaporations. It was then fermented by repeated fed-batch cultivation using flocculating Saccharomyces cerevisiae with no prior detoxification. The sugars and inhibitors concentrations in the hydrolyzates were compared after the evaporations and also fermentation. The evaporations were carried out either under vacuum (VEH) at 0.5 bar and 80 degrees C or with 1.3 bar pressure (HPEH) at 107.5 degrees C, which resulted in 153.3 and 164.6 g/l total sugars, respectively. No sugar decomposition occurred during either of the evaporations, while more than 96% of furfural and to a lesser extent formic and acetic acids disappeared from the hydrolyzates. However, HMF and levulinic acid remained in the hydrolyzates and were concentrated proportionally. The concentrated hydrolyzates were then fermented in a 4 l bioreactor with 12-22 g/l yeast and 0.14-0.22 h(-1) initial dilute rates (ID). More than 84% of the fermentable sugars present in the VEH were fermented by fed-batch cultivation using 12 g/l yeast and initial dilution rate (ID) of 0.22 h(-1), and resulted in 0.40+/-0.01 g/g ethanol from the fermentable sugars in one cycle of fermentation. Fermentation of HPEH was as successful as VEH and resulted in more than 86% of the sugar consumption under the corresponding conditions. By lowering the initial dilution rate to 0.14 h(-1), more than 97% of the total fermentable sugars were consumed, and ethanol yield was 0.44+/-0.01 g/g in one cycle of fermentation. The yeast was able to convert or assimilate HMF, levulinic, acetic, and formic acids by 96, 30, 43, and 74%, respectively.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Industriell bioteknik -- Annan industriell bioteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Industrial Biotechnology -- Other Industrial Biotechnology (hsv//eng)

Nyckelord

chitin

glucosamine

ethanol

biomass

biogas

lignocelluloses

baker's yeast

saccharomyces

cerevisiae

encapsulation

flocculation

superabsorbents

chitosan

zygomycetes

mucor

rhizopus

rhizomucor

MTBE

biopolymers

furfural

acetic acid

HMF

fed-batch

continuous cultivation

immobilization

denitrification

activated sludge

bread

orange peels

citrus

waste

keratin

methyl tertiary butyl ether

Energi och material

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)