Environmental Engineering Reference
In-Depth Information
TABLE 4.2 Hydrogen Production from Conversion of Oil
Palm Shell and Physic Nut Waste
Type Biomass/Temperature
Gas Production (vol%)
Oil palm shell
773 K
973 K
1173 K
Physic nut
773 K 8.22
973 K 9.29
1173 K 11.63
Source : Reproduced with permission from Sricharoenchaikul et al. [9].
metabolism is an exciting new area of technology development that offers
the potential production of usable hydrogen from a variety of renewable
sources [12]. There are three types of microorganisms of biohydrogen gen-
eration: cyano-bacteria, anaerobic bacteria, and fermentative bacteria. A
promising method is the biological production of hydrogen by fermentation.
The production of hydrogen from biomass by fermentation is one of the
routes that can contribute to a future sustainable hydrogen economy. The
amount of hydrogen produced from glucose is affected by fermentation
pathways and liquid end products [13]. Butyric acid and acetic acid consti-
tute more than 80% of total end products [14]. Theoretically, 4 mol of H 2
can be produced from 1 mol of glucose in acetate-type fermentation, however
only 2  mol of H 2 are produced when butyrate is the main fermentation
product. To date, many studies have been done on fermentative hydrogen
production from pure sugars and from feedstock, such as byproducts from
the agricultural and food industry, municipal waste, or wastewaters [15].
Anaerobic digestion of solid organic waste, including municipal and agricul-
tural wastes and wastewater sludge, is one such renewable source for H 2
production. However, continual H 2 production using this process has limita-
tions, one of which is the low yields of hydrogen currently produced from
the fermentation of even the simplest sugars [16]. A combination of dark and
photofermentation in a two-stage hybrid system has been found to improve
the overall yield of hydrogen [17]. Anaerobic bacteria decompose glucose
or starch via acetate fermentative metabolism as the first step, and photosyn-
thetic bacteria convert the resultant acetate to hydrogen in another reactor as
the second stage. The hydrogen yield is increased by twofolds in comparison
to that using only dark fermentation [18].
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