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Evaluation of agricultural wastes for the use in ethanol production by Candida shehatae TISTR 5843

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Chaiyawat Nopphakao, Prawphan Yuvadetkun, Nobpharat Keawlor,hanapron Thanasrirangkul, Yotaka Poobudcha and Mallika Boonmee

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This study aimed to evaluate four agricultural wastes: rice straw, oil palm empty fruit bunch (oil palm EFB), sugarcane bagasse and corncob, for their potential when used as feedstocks in ethanol production. The waste materials were subjected to acid pretreatment by autoclaving at 121 oC followed by enzyme (Accellerase 1500?) hydrolysis prior to ethanol fermentation. By varying the times in acid pretreatment, 10 minutes was shown to be sufficient based on the test of susceptibility to cellulose hydrolysis. The enzyme dosage study resulted in the use of 60 FPU/g dry solid (DS) for all acid-treated materials except for oil palm EFB which required the dosage of 110 FPU/g DS. Different forms of substrates used in enzyme hydrolysis (the acid-treated solids versus the acid-treated slurries) did not affect the amount of ethanol produced from resulting oil palm EFB and sugarcane bagasse hydrolysates, but they did affect in the case of rice straw and corncob hydrolysates. The fermentation of rice straw, oil palm EFB, sugarcane bagasse and corncob hydrolysates by Candida shehatae TISTR 5843 resulted in 9.8, 9.3, 7.9 and 10.9 g/l of ethanol respectively.

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ethanol, Candida shehatae, agricultural wastes, acid pretreatment, enzyme hydrolysis