Sometimes combined pretreatment is also helpful in conversion of more biomass
to biogas. It requires high temperature treatment (at 130
C) and then final
pretreatment at 170
C with 8 bar pressure and in 80 min for thermal hydrolysis of
algal biomass for better results. This results in better hydrolysis of biomass with high
yield of biogas formation as compared to gas obtained at low temperature
pretreatment or with ultrasonication technique. Another very good mechanical
pretreatment adapted is production of biogas in continuous reactor to improve the
overall methane yield.
With combined ultrasonic or microwave pretreatment, there is report of enhanced
methane production in continuous bioreactor. Another very successful method is the
combined application of enzymatic and thermal pretreatment where protease can be
used for digestion of microalgae such as Chlorella vulgaris for methane production
and the yield was 26% more in continuous reactor. It has been also reported that
thermochemical pretreatment combined with alkaline pretreatment can improve the
biogas production in the reactors. Cocktail of enzymes also results in improved
biogas production. The enzymes which can be mixed are cellulose, glucohydrolase,
xylanase, and hemicellulose for intended use. Because of synergistic action of these
enzymes, a better digestion of biomass results which could improve biogas
production.
Since microalgae alone and directly cannot be used for production of biogas,
therefore most of the microalgae which is rich in oil can be first used for extraction of
biodiesel and then residual biomass can be used for production of biogas. This
process microalgae residue can be mixed with other biowastes for anaerobic digestion which results in improved biogas production up to 74%.
Another technique developed in order to improve the biogas from algae was
nutrient starvation during cultivation of microalgae, for example, phosphorus limitation results in improved biogas production so in conclusion, We can say that
energy and electricity production can be improved with biomass after adopting
suitable pretreatment technique.
Acknowledgements I would like to express my gratitude to my esteemed mentor in Biofuel
research Professor Dr. Pradeep Mishra (HOD, Dept. of Chemical Engineering, IT B.H.U.) and
Dr. Neha Srivastava for inviting me to write an article on this hot topic, which is need of the hour.
I acknowledge the support of AMRITSAR GROUP OF COLLEGES authorities, Director
Finance Madam Ragini (ACET, College), my staff of Agriculture Department for having directly
or indirectly supporting me during the writing of this article, especially Dr. Ravindra (GNDU), my
wife Dr. Suchi Rai Bhatt (Principal), my son (Master Anshuman Bhatt), and my daughter
(Tejaswini Bhatt).
References
Abdeshahian P, Lim JS, Ho WS et al (2016) Potential of biogas production from farm animal waste
in Malaysia. Renew Sust Energ Rev 60:714–723
Agrahari R, Tiwari GN (2013) The production of biogas using kitchen waste. Int J Energy Sci 3
(6):48. https://doi.org/10.14355/ijes.2013.0306.05
136
S. M. Bhatt and S. Bhat
to biogas. It requires high temperature treatment (at 130
C) and then final
pretreatment at 170
C with 8 bar pressure and in 80 min for thermal hydrolysis of
algal biomass for better results. This results in better hydrolysis of biomass with high
yield of biogas formation as compared to gas obtained at low temperature
pretreatment or with ultrasonication technique. Another very good mechanical
pretreatment adapted is production of biogas in continuous reactor to improve the
overall methane yield.
With combined ultrasonic or microwave pretreatment, there is report of enhanced
methane production in continuous bioreactor. Another very successful method is the
combined application of enzymatic and thermal pretreatment where protease can be
used for digestion of microalgae such as Chlorella vulgaris for methane production
and the yield was 26% more in continuous reactor. It has been also reported that
thermochemical pretreatment combined with alkaline pretreatment can improve the
biogas production in the reactors. Cocktail of enzymes also results in improved
biogas production. The enzymes which can be mixed are cellulose, glucohydrolase,
xylanase, and hemicellulose for intended use. Because of synergistic action of these
enzymes, a better digestion of biomass results which could improve biogas
production.
Since microalgae alone and directly cannot be used for production of biogas,
therefore most of the microalgae which is rich in oil can be first used for extraction of
biodiesel and then residual biomass can be used for production of biogas. This
process microalgae residue can be mixed with other biowastes for anaerobic digestion which results in improved biogas production up to 74%.
Another technique developed in order to improve the biogas from algae was
nutrient starvation during cultivation of microalgae, for example, phosphorus limitation results in improved biogas production so in conclusion, We can say that
energy and electricity production can be improved with biomass after adopting
suitable pretreatment technique.
Acknowledgements I would like to express my gratitude to my esteemed mentor in Biofuel
research Professor Dr. Pradeep Mishra (HOD, Dept. of Chemical Engineering, IT B.H.U.) and
Dr. Neha Srivastava for inviting me to write an article on this hot topic, which is need of the hour.
I acknowledge the support of AMRITSAR GROUP OF COLLEGES authorities, Director
Finance Madam Ragini (ACET, College), my staff of Agriculture Department for having directly
or indirectly supporting me during the writing of this article, especially Dr. Ravindra (GNDU), my
wife Dr. Suchi Rai Bhatt (Principal), my son (Master Anshuman Bhatt), and my daughter
(Tejaswini Bhatt).
References
Abdeshahian P, Lim JS, Ho WS et al (2016) Potential of biogas production from farm animal waste
in Malaysia. Renew Sust Energ Rev 60:714–723
Agrahari R, Tiwari GN (2013) The production of biogas using kitchen waste. Int J Energy Sci 3
(6):48. https://doi.org/10.14355/ijes.2013.0306.05
136
S. M. Bhatt and S. Bhat