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diethanolamine, aminoethoxyethanol (DGA), etc. Amine scrubbing generally consists of
an absorber and a stripper unit. The process provides efficient removal of H 2 S and CO 2 .
In membrane separation, permeable membranes are used that enrich concentration of
methane by trapping the other impure gases.
In fermentation, distillation is the most common technique used for liquid biofuels upgra-
dation. It works on the principle of volatile nature of substances. The separation of more
volatile compounds occurs primarily from less volatile heavy compounds. The various
types of distillation, conventional distillation, azeotrpic distillation, extractive distillation,
and molecular distillation are used for products upgradation. Other purification technolo-
gies include absorption, adsorption, super critical fluid extraction, and liquid liquid
extraction. Currently, adsorption with molecular sieve for bioethanol purification is gain-
ing attention because the process requires less energy input than distillation process.
Biobutanol and bioethanol are also purified by membrane technology (pervaporation) and
gas stripping method (Pulyalin et al., 2015).

The upgraded end products from the abovementioned processes have utility in
various fields and can become an effective substitute for the available energy
resources.

15.7 Conclusion

India generates enormous amount of agricultural wastes every year and it affects its
economical growth if these wastes are not utilized in a proper way. In appropriate
collection, open dumping of these affects the environmental condition and also the
human health. Several problems associated with the biomass include high moisture,
low calorific value, large particle size, different composition, etc. Effective pretreat-
ment can solve these basic problems but there is a need to think for waste to bioe-
nergy approach for effective utilization of agricultural wastes. Various techniques
(pyrolysis, gasification, AD, etc.) are available for the bioenergy generation.
Research in the field of upgradation of products to high-energy feedstock and its
successful utilization will lessen the load on the fossil fuels. However, awareness
among the people about these processes is very less and they pay little attention in
utilizing renewable energy sources. Therefore there is a need of promoting R&D
activities on utilizing the agricultural wastes that will not only reduce the amount of
these wastes but it will also open the doors for bioenergy generation which decrease
the gap between demand and supply of energy. MNRE has installed various bio-
mass power generation plants along with many gasification plants in various states
of India for effective utilization of local available biomass wastes.

Acknowledgment

The authors acknowledge the necessary facilities provided by the Department of Chemical
Engineering and Technology, Indian Institute of Technology (BHU), Varanasi, for undertak-
ing this work.