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

16.5

Techniques to Improve Biohydrogen Production

In recent times, biological hydrogen manufacturing has enhanced scientific delib-

eration due to its possibility for infinite, low cost, and renewable source of clean

energy. Among all hydrogen-manufacturing technologies, anaerobic hydrogen fer-

mentation appeared to be most favorable since hydrogen can be generated at higher

rates. In addition, a variety of wastewaters and organic wastes supplemented with

carbohydrates can be treated in this process, consequently capable to generate sus-

tainable low-cost biohydrogen with simultaneous waste minimization.

16.5.1

Reactor Design and Configuration

Biohydrogen generation could be probably enhanced through particular reactor

design and configurations. Reactor design should be appropriate and should be

stable for long duration of action time. Lee et al. reported that AnMBR appar-

ently achieve comparatively enhanced volumetric hydrogen generation rates

[27]. However, some studies recognized that overall hydrogen generation perfor-

mance of AnMBR under steady-state operation fairly exceeds that of the CSTR.

Recently, Noblecourt et al. observed usual and highest productivities of 0.75 and

2.46 l-H2/l⋅hour in AnMBR, which were 44% and 51% higher, respectively, in associa-

tion with control system without membrane. Latest study gave insight into blending

of a stable hydrogen fermenter with incorporated membrane system [15]. The

grades established that hydrogen-manufacturing rates in the rectangular AnMBR

were higher (reached 0.21 ± 0.05 m³H2/m³ day at 0.7 V and 0.41 ± 0.08 m³H2/m³ day

at 0.9 V) than that of tubular one (0.01 ± 0.01 m³H2/m³ day).

16.5.2

Microbial Consortia

The use of microbial consortia as a substitute of pure culture could improve

biohydrogen removal as they are prone to restrain a suite of the compulsory

hydrolytic actions and are probably more vigorous against procedural differences

and ecological circumstances (such as pH, temperature, growth, and nutrients).

Optimized environment will increase biohydrogen yields. Microbial consortia

will facilitate an economic viability because it can offer synergistic association

between microorganisms and this process can utilize diverse substrates [28]. But,

hydrogen-utilizing microorganisms, such as hydrogenotrophs, methanogens, and

sulfur consuming ones, will also present in mixed culture. The pretreatment

method is used to enrich the composition of biohydrogen producers in mixed

bacterial communities and to inhibit the biohydrogen-consuming microorganisms

such as homoacetogens and methanogens, which are prevalent in mixed microbial

communities [29].