Environmental Engineering Reference
In-Depth Information
9 Concluding Remarks
To establish an environmentally sustainable biohydrogen technology, multidis-
ciplinary research approach is vital. Process engineering and optimization of
operational factors govern the performance of any biological system and also have
considerable influence on fermentative H
2
production. The persistence of an acidic
microenvironment due to production of soluble acid metabolites as end-products
inhibits the process leading to low substrate conversion efficiency to H
2
. Apart
from lower conversion efficiency, one of the important aspects to be paid signifi-
cant attention is the non-utilized organic fraction that usually remains as a soluble
fermentation product from acidogenic process. Various routes to utilize residual
organic fraction of acidogenic process as substrate can be explored. Integration of
multiple processes possible for additional revenue generation in the form of addition
energy (H
2
, bioelectricity, methane, etc.) and wastewater treatment utilizing acido-
genic effluents are depicted in Fig 7. Application of genetic engineering aspects to
stimulate conversion process efficiency is one potentially promising research area.
Solid Waste
(Food based, cellulosic, sludge,
agricultural waste, etc.)
Wastewater
Pretreatment
H
2
Acidogenic process
Volatile fatty acid rich
waste
H
2
H
2
H
2
CH
4
PHA
Bioelectricity
Photo
Fermentation
process
Acidogenic
process
Microbial
Electrolysis
Anoxic
Operation
Microbial fuel
cells
Methanogenic
Process
Fig. 7
Some of the possible process integration routes which can be used for generating renewable
energy from waste and wastewater
Design and development of bioreactor systems for H
2
production is one of the
areas where considerable focus is required. Scaling up of the process to pilot or large
scale to generate baseline engineering data will sustain the technology with respect
to commercialization. Interaction between the research community and industry
from time to time to understand the requirements and design the technology accord-
ingly holds the key to the successful commercialization of this process. Moreover,
the process to convert existing/operating anaerobic reactors producing methane to
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