Feasibility of rice straw as alternate substrate for biobutanol production

• Published in: Applied energy 2013-03, Vol.103, p.32-38
• Main Authors: Ranjan, Amrita, Khanna, Swati, Moholkar, V.S.
• Format: Article
• Language: English
• Subjects: acetone; acid hydrolysis; Alcohols: methanol, ethanol, etc; Alternative fuels. Production and utilization; Anaerobic fermentation; Applied sciences; Biobutanol; biofuels; Biomass; Bioreactor; butanol; Clostridium acetobutylicum; Diesel; Energy; ethanol; Ethyl alcohol; Exact sciences and technology; feedstocks; Fermentation; Fuels; gasoline; Glucose; hydrolysates; Hydrolyzate; Lignocelluloses; Natural energy; Oryza sativa; reducing sugars; Rice; rice straw; solvents; Straw; Stresses; Sugars
• ISSN: 0306-2619; 1872-9118
• DOI: 10.1016/j.apenergy.2012.10.035

► Utilization of rice straw for the production of alcoholic biofuel. ► Release of 3.9% (w/v) total sugar with 2.3% w/v of glucose by stress assisted acid hydrolysis of rice straw. ► Production of ABE through clostridial fermentation of RSH. ► Production of 6.24gL−1, 13.5gL−1 and 0.82gL−1 of ABE using RSH as a feedstock. Biobutanol has recently emerged as a potential alternate liquid fuel for gasoline and diesel. In this work, we have studied clostridial fermentation of stress assisted-acid hydrolyzed rice straw that exhibited a typical trend of acidogenesis followed by solventogenesis. Acid hydrolysis of 5% (w/v) mixture of rice straw in water with simultaneous application of shearing stress resulted in release of 3.9% (w/v) total sugar out of which 3.1% (w/v) was reducing sugar. Glucose formed major fraction (75%) of the reducing sugar (or 2.3% w/v total sugar). Thus, essentially, 5% (w/v) of rice straw solution released nearly 46% (w/w) (i.e. 23gL−1 glucose for 50gL−1 rice straw solution) glucose. Anaerobic fermentation of rice straw hydrolyzate using Clostridium acetobutylicum NCIM 2337 resulted in production of 6.24gL−1 of acetone, 13.5gL−1 of butanol and only 0.82gL−1 of ethanol. The net consumption of substrates was as follows: glucose 12.86gL−1 (i.e. ∼55%), total reducing sugar 18.32gL−1 (∼57%) and total sugar 24.5gL−1 (∼61%). Thus, higher solvents yield and significant sugar utilization makes rice straw a potential feedstock for biofuels production.