Process Design and Economics of On-Site Cellulase Production on Various Carbon Sources in a Softwood-Based Ethanol Plant

Table 1

Features of enzyme and ethanol productions. Both CEF and SSF are carried out in batch operation. Carbon source A: pretreated liquid fraction, B: pretreated liquid fraction and molasses, and C: pretreated liquid fraction and pressed pretreated slurry with a total WIS content of 1%, 2%, and 3%; +: 1.5-fold specific activity.

	Reference	A	A+	B	B+	C1	C2	C3
Components into CEF, tonne/year
Hexosans	—	430	368	298	236	776	1374	1861
Pentosans	—	7	6	5	4	13	23	32
Hexoses	—	5133	3352	6242	4120	4812	4256	3805
Pentoses	—	1487	971	622	413	1394	1233	1102
WIS^a	—	806	690	558	442	1453	2575	3486
C5 ratio in CEF^b, %	—	21	21	9	9	20	18	16
WIS content in CEF, %	—	0.5	0.7	0.8	0.9	1.0	2.0	3.0
Productivity of CEF^c, FPU/(L·h)	—	70	107	154	230	75	84	93
Components into SSF, tonne/year
Hexosans	62980	62550	62612	62683	62745	62205	61606	61120
Hexoses	32634	27521	29304	30499	31228	27841	28397	28848
Yeast	3168	3160	3160	3160	3168	3144	3128	3112
Enzyme protein	1816^e	1656	1104	1682	1121	1651	1642	1635
Mycelium	—	1727	1152	1754	1170	1722	1713	1705
WIS^a, ktonne/year	117.98	117.55	117.61	117.68	117.74	117.19	116.59	116.09
Overall EtOH yield^d, L/dry tonne	270	254	260	263	266	254	254	254

^aIncludes hexosans and pentosans.
^b(pentosansinME+pentoses)/total sugar in ME.
^cCorresponds to an enzyme fermentation time of 108 h.
^dIncludes yeast and enzyme productions and ethanol losses in the process.
^eThe purchased enzyme preparation was assumed to contain 10% protein.