Increasing in gasoline prices and depletion of fossil fuels in 80’s decade resulted in research and commercialization activities directed toward production of renewable fuels such as ethanol and butanol. Renewable resources such as rice straw, has been promoted as potential feedstock for production of fuels. In this project, production of Acetone, Butanol and Ethanol (ABE) from rice straw as substrate by biological method was investigated. Rice straw is a lignocellusic material, which should convert to fermentable sugers. At the first step, the ability of bacterial fermentation on glucose synthetic medium with P2 stock solutions (Buffer phosphate, Vitamins, and Minerals) or PGY-P2 solution and PGY (medium without P2 stock solutions) was investigated. After this stage and proof of ability of bacterial fermentationon on synthetic medium, rice straw pretreated by three different pretreatment methods and then hydrolyzed to sugers by enzymatic hydrolysis. Three different methods were used, including dilute sulfuric acid pretreatment, concentrated phosphoric acid pretreatment at modest reaction conditions (50 °C), and alkaline pretreatment by NaOH. Then the pretreated rice straw was hydrolyzed by enzymes. These prepared hydrolyzates were fermented by clostridium acetobutylicum bacteria. In the fermentation step, maximum theoretical solvent yield was achieved 38.60% (maximum yield) on substrate drived from alkaline pretreatment-enzymatic hydrolysis and 37.99% for substrate drived from phosphoric acid pretreatment-enzymatic hydrolysis. This amount for dilute acid pretreatment-enzymatic hydrolysis substrate was very low (only 3.44%). The above results showed if appropriate pretreatment methods used for rice straw, This lignocellulosic material would be a suitable substrate for this fermentation process. Keywords: Acetone-Butanol-Ethanol (ABE), Rice straw, C.acetobutylicum ,Pretreatment, Enzymatic hydrolysis, Fermentation
