Page 279 - Refining Biomass Residues for Sustainable Energy and Bioproducts

Agroresidue-based biorefineries 247

Amiri et al. (2014) reported a strategy for an efficient production of butanol from
organosolvent pretreated rice straw. Pretreatment was carried out with organosol-

vent containing ethanol and dilute sulfuric acid for 60 min at 150 C. The hydroly-
zate obtained after enzymatic saccharification of the pretreated biomass was used
for ABE fermentation using Clostridium acetobutylicum. Upon ABE fermentation
the strain produced 80.3, 21.1, and 22.5 g of butanol, acetone, and ethanol,
respectively.
Potential of nonpretreated rice straw hydrolyzate for biobutanol production under
nonsterile environmental conditions was evaluated by Chen et al. (2013). The study
revealed that biobutanol production under nonsterile conditions is feasible with a
high cell density of Clostridium saccharoperbutylacetonicum N1-4. Cost of main-
taining sterile conditions is one of the limitations for cost-effective butanol produc-
tion. Media engineering for biobutanol production by C. acetobutylicum MTCC
481 using rice straw hydrolyzate was reported by Ranjan et al. (2013b).Various
physical and cultural parameters were optimized by an orthogonal array of
design experiments. Optimum conditions were temperature of 37 C, pH of 4.0,

inoculum size of 5% (v/v), inoculum age of 18 h, and agitation of 150 rpm.
Scaled up at 2 and 5 L, bioreactors produced 12.17 and 12.22 g/L of butanol,
respectively.
Gottumukkala et al. (2013) produced biobutanol from rice straw hydrolyzate
using a nonacetone producing Clostridium sporogenes BE01. Fermentation inhibitors
were removed using anionic resin Seralite SRA 400. A total of 5.52 g/L of butanol
was produced, and it is the highest reported butanol production by C. sporogenes.
The feasibility of rice straw as a substrate for biobutanol production was reported
by Ranjan et al. (2013a). Anaerobic fermentation of rice straw hydrolyzate was car-
ried out with C. acetobutylicum NCIM 2337. Under optimized conditions, 13.5 g/L
of butanol was produced. The study revealed the potential of rice straw as an eco-
nomically feasible substrate for the production of biobutanol.
Butanol production from corncob residue using Clostridium beijerinckii NCIMB
8052 was evaluated by Zhang et al. (2012). ABE fermentation was carried out with
both detoxified and nondetoxified corncob hydrolyzates. The studies revealed that
detoxification with calcium hydroxide gave better product yield. Fermentation with
nondetoxified hydrolyzate yielded 3.8 g/L of ABE, while with calcium hydroxide
detoxified hydrolyzate yielded 16 g/L of ABE. The study revealed the potential of
corncob as a suitable substrate for ABE fermentation. Qureshi et al. (2007) devel-
oped a strategy for biobutanol production from nondetoxified wheat straw hydroly-
zate using C. beijerinckii. The study revealed that wheat straw hydrolyzate
supplemented with glucose produced 47.6 g/L ABE.

11.2.1.3 Biohydrogen
Biohydrogen is a clean and carbon-free fuel. It is chemically produced by the com-
bustion of water. It finds a wide range of applications from transportation to genera-
tion of electricity. Hydrogen production from fossil fuels requires higher energy as
well as liberation of CO 2 that is the main gas that causes greenhouse effect. In this