Simultaneous Production of Ethanol and Hydrogen from Agricultural Waste and Forest Residues Available in North-East India

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Hydrogen and ethanol derived from lignocellulosic biomass are promising biofuels and of great potential to become alternatives to fossil fuels.The present researchfocuses on the carbohydrate platform for simultaneous production of ethanol and hydrogen in fluidized bed and stirred tank bioreactor. Areca nut (Arecacatecheu) husk, Moj (Albizialucida), and Bon bogori (Ziziphusrugosus) available in North-East India are chosen as the lignocellulosic biomass feed stocks for biofuel production. The cellulose concentration in Areca nut husk, Moj and Bonbogori was determined as 44.46%, 53.46% and 51.56%, respectively. The lignin concentration lies within the range 11-23%. Maximumcrystalinity was observed in Areca nut husk fiber (63.84%) followed by Moj (46.43%) and Bon bogori (42.46%). The calorific values of all the biomasses were found within the range of 17 MJKg-1to 22MJ Kg-1. To facilitatesaccharification process two types of pretreatment process were conducted viz. dilute acid pretreatment and ultrasound assisted lime pretreatment for allthe biomass samples. The Taguchi method of optimization was applied to optimize both the pretreatment processes.The ultrasound assisted lime pretreatment process was found better than dilute acid pretreatment process and it removed 68%, 65% and 64% of the lignin present in the naive lignocellulosic fibers of Bonbogori, Arecanut husk and Moj, respectively.The saccharification process was conducted at 50ओC, 150 RPM for 96 hoursand the saccharification efficiency (ultrasound assisted lime pretreated) was highest in Bonbogori (82.5%) followed by Moj (80.1%) and Arecanut husk (79.5%).Among all the three biomass used in this study Bon bogori have showed the maximum saccharification efficiency therefore,Bonbogori was used for the fermentative production of both ethanol and hydrogen.Immobilizedwastewater sludge was used for simultaneous bio-ethanol and hydrogen production from the enzymatic hydrolysate of Bonbogori.The optimal factor combination for both ethanol and hydrogen production was achieved at 40ओC temperature and 5.5 pH.Fluidized bed bioreactor performed better than the stirred tank reactor for production of both ethanol (0.21 औ.04 mol) and hydrogen (30.8औ 0.5 mmol).
Supervisor: Kaustubha Mohanty