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16 Bioreactors for the Production of Industrial Chemicals and Bioenergy Recovery from Waste

rates. Allowing for sensible feature, anaerobic membrane bioreactors (AnMBRs)

for biological hydrogen manufacturing is highlighted.

Among the miscellaneous biofuel choices, biohydrogen is a major future energy

carrier due to its greater efficacy of transformation into utilizable power, high

energy density, and lower pollutants generation [10, 11]. In recent times, diversity

of technologies for hydrogen making from selected resources has been comprehen-

sively investigated. Among these, hydrogen production from biomass considered as

extremely smart choice as a less energy extensive and cheaper process. Biohydrogen

can be produced by numerous biological paths like photofermentation of organic

compounds and organic waste using photosynthetic bacteria, biophotolysis of

water with the help of algae and cyanobacteria [12]. Some fermentative bacteria

can produce hydrogen gas continuously without any light source in anaerobic

wastewater treatment. Besides hydrogen, these bacteria generate other products

to gratify their metabolic requirements and additional growth. These products

comprise organic acids, alcohol, acetone, biodegradable plastics, and fibers [13].

Traditionally, continuous stirred tank reactors (CSTRs) have been extensively used

for biohydrogen production by fermentative bacteria. The CSTRs have simple

structure, ease of function, and efficient uniform mixing and operate under various

circumstances of the substrate, pH, and HRT. Among bioreactor designs, merged

hydrogen fermenters with AnMBR is one of the most capable solutions. Membranes

in AnMBR, compared with CSTR, can put off biomass loss from the reactor,

consequently allowing the long solid retention time (SRT) necessary for effectual

treatment while allowing relatively short HRT. Moreover, AnMBR produces excel-

lent quality effluent and reduces plant footstep [14, 15]. Nevertheless, membrane

fouling is at a standstill the major hindrance in AnMBR applications [15].

16.2

Basic Biohydrogen-Manufacturing Technologies

and their Deficiency

Biohydrogen can be generated by numerous biological paths and divided

into two main categories: light-dependent and dark fermentation processes.

Light-independent process is dark fermentation, whereas light-dependent pro-

cesses include photofermentation and photolysis. All biohydrogen making

pathways depend on either nitrogenase or hydrogenase for hydrogen evolution.

These pathways gain energy either straight from light energy or via consuming

photosynthetically derived carbon compounds. Among these, dark fermentation

receives high scientific consideration and pilot plants have been also recognized [16].

16.2.1

Direct Biophotolysis

In this practice, biohydrogen production can be influenced by the photosynthetic

ability of an organism, for example, a green algae or cyanobacterium, which

captures solar energy to execute water-splitting procedure (producing O2) and

diminish ferredoxin, an electron carrier in the chloroplasts. Subsequently, electrons