Biomedical Engineering Reference
In-Depth Information
Straw
Filtrate
Bacterial
cellulose
fermentation
Preparation
desertified land
improved
materials
with an
appropriate mix
Steam explosion
pretreatment
Solid state
fermentation with
composite strains
Residue of
steam-explded
straw
Fig. 4.3
Process route for preparation of improved straw materials of desertification land
higher than 15 %; the total number of effective viable microorganisms was higher
than 300 million per gram; and the nitrogen, phosphorus, and potassium content was
higher than 5 %.
(4) Bionic feed
Bionic feed is also called artificial rumen feed. The principle is to mimic the envi-
ronment of cattle and sheep rumen to use an artificial method to degrade cellulose
and increase the amount of crude protein by beneficial microbial fermentation.
The nutrients of crop stalks through bionic treatment can be improved greatly. The
texture becomes soft and sticky, and the feed has a sour flavor; thus, animals like to
eat it. For fermented straw, 15-20 % (up to 35 %) of crude fiber is broken down,
true protein is increased by 50 % or more, and it contains 18 amino acids. Crude fat
is increased more than 60 %, and volatile fatty acids are also significantly increased.
The straw bionic feed for cattle, pigs, chickens, ducks, and fish can replace 50-
80 % of concentrated feed, and the feeding effects are not lower than normal
feeding levels [
76
]. At present, there are mechanized and semimechanized large-
scale fermentation facilities in domestic use. They can prepare 1,500 kg bionic feed
at once. Stirring, feed control, and feed mixing in the fermentation process are all
controlled by the machinery [
77
].
(5) Bio-based chemicals
In 2004, the U.S. Department of Energy ranked polyols such as glycerol and
sorbitol as one of the most important 12 kinds of “building block” molecules in the
development process of biomass. Traditional bio-based polyols are first to hydrolyze
cellulose to glucose by chemical or biological methods, further converting it into
energy or organic chemicals. At present, research on lignocellulosic feedstocks
converted to the polyol substances has mainly been based on cellulose as a raw
material. Chemical catalytic hydrogenation of straw can create a targeted product
containing hydroxyl, which is the process with high atom economy, and has been
given attention by international and domestic research in recent years. However,
because straw has low carbon content, low energy density, and heterogeneity, the
process of the straw conversion to polyol is much more complex than that of
