E. Palmqvist et al., DESIGN AND OPERATION OF A BENCH-SCALE PROCESS-DEVELOPMENT UNIT FOR THE PRODUCTION OF ETHANOL FROM LIGNOCELLULOSICS, Bioresource technology, 58(2), 1996, pp. 171-179
Citations number
22
Categorie Soggetti
Energy & Fuels","Biothechnology & Applied Migrobiology",Agriculture
A bench-scale unit for the development of an enzymatic process for the
bioconversion of lignocellulosics to ethanol has been used to study t
he recycling of waste-water streams to minimize fresh-water requiremen
ts and reduce effluent streams. Willow, after impregnation with sulphu
r dioxide, was steam-pretreated, enzymatically hydrolysed, and the sug
ars produced were fermented using S. cerevisiae. The fermentation brot
h was distilled and the stillage was fractionated by evaporation into
six separate condensate fractions and a residue. The overall yield of
ethanol from willow was 65% of the theoretical yield based on total fe
rmentable sugars. The inhibitory effect of the evaporation condensates
was assessed by fermentation using S. cerevisiae. The non-volatile re
sidue of the stillage was found to be inhibitory to fermentation. The
ethanol yield decreased from 0.37 g/g in a pure sugar reference to 0.3
1 g/g in the residue and the average ethanol fermentation rate decreas
ed fi om 6.3 g/(l h) to 2.7 g/(l h), respectively. The evaporation con
densates, containing the volatile components, showed no negative effec
ts on fermentation. The intermediate evaporation condensate fractions,
fractions 4 and 5, had the lowest chemical oxygen demand (GOD), 1560
and 1120 mg/l, compared with 33 300 mg/l for the stillage. Therefore,
these fractions can be released directly into the effluent without fur
ther treatment. Copyright (C) 1997 Elsevier Science Ltd.