Chapter 23

Process Design for Biological Conversion of Cattails to Ethanol (pp. 423-434)
Authors:  (Bo Zhang, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Hubei, China, and others)
Abstract:
The effects of different pretreatment technologies, including sulfuric acid, hot-water,
NaOH and MgCl2 pretreatments, on the fermentation of xylose and glucose released
from cattails to ethanol by Saccharomyces cerevisiae ATCC 24858 and Escherichia coli
KO11 were investigated. Glucose from cattail cellulose was able to be fermented to
ethanol using S. cerevisiae, resulting in 85-91% of the theoretical ethanol yield. Glucose
and xylose released from cattail cellulose and hemicellulose were able to be fermented to
ethanol using E. coli KO11, resulting in approximately 85% of the theoretical ethanol
yield. Among four pretreatment methods, the dilute acid pretreatment was found to be
superior, and approximately 85% of original sugars in the cattails were converted to
ethanol.
The effects of different biomass species (cattail harvested in different seasons and
corn stover) and their chemical composition on the overall process efficiency and
economic performance considering feedstock availability and feedstock costs to
manufacture ethanol from lignocellulose was studied. Cattails harvested in fall have the
highest cellulose and xylan content, leading to the lowest Minimum Ethanol Selling Price
(MESP) of $2.28, and the highest ethanol production of 57.2 MM gal/yr from processing
773,000 dry U.S. ton feedstock.
Carbon dioxide emission from processing cattails is in the range of 2450-2650
Kmol/hr, which is higher than the CO2 emission from corn stove (~2110 Kmol/hr).
Because of high lignin content in cattails, it‘s very important to explore emerging
technologies such as pyrolysis and gasification to produce multi-products and obtain
higher values from cattail lignin. The potential environmental impacts including CO,
SO2, NOx emission from the biorefinery process and waste water treatment were also
discussed.