Biohydrogen production from sugarcane bagasse hydrolysate by elephant dung: Effects of initial pH and substrate concentration Arunsri Fangkum a , Alissara Reungsang a,b, * a Department of Biotechnology, Faculty of Technology, Khon Kaen University, A. Muang, Khon Kaen 40002, Thailand b Fermentation Research Center for Value Added of Agricultural Products, Faculty of Technology, Khon Kaen University, A. Muang, Khon Kaen 40002, Thailand article info Article history: Received 16 March 2010 Received in revised form 9 May 2010 Accepted 24 May 2010 Available online 4 July 2010 Keywords: Bio-hydrogen Sugarcane bagasse hydrolysate Elephant dung abstract Pre-heated elephant dung was used as inoculum to produce hydrogen from sugarcane bagasse (SCB) hydrolysate. SCB was hydrolyzed by H 2 SO 4 or NaOH at various concentra- tions (0.25e5% volume) and reaction time of 60 min at 121  C, 1.5 kg/cm 2 in the autoclave. The optimal condition for the pretreatment was obtained when SCB was hydrolyzed by H 2 SO 4 at 1% volume which yielded 11.28 g/L of total sugar (1.46 g glucose/L; 9.10 g xylose/L; 0.72 g arabinose/L). The maximum hydrogen yield of 0.84 mol H 2 /mol total sugar and the hydrogen production rate of 109.55 mL H 2 /L day were obtained at the initial pH 6.5 and initial total sugar concentration 10 g/L. Hydrogen-producing bacterium (Clostridium pas- teurianum) and non hydrogen-producing bacterium (Flavobacterium sp.) were dominating species in the elephant dung and in hydrogen fermentation broth. Sporolactobacillus sp. was found to be responsible for a low hydrogen yield obtained. Copyright ª 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. 1. Introduction Hydrogen is an alternative energy source to replace conven- tional fossil fuels [1]. People believe that hydrogen based economy may contribute to meet the growth in the world energy demand [2]. Hydrogen is a clean fuel with no CO 2 emissions and can easily be used in fuel cells for generation of electricity. Besides, hydrogen has a high energy yield of 122 kJ/ g, which is 2.75 times greater than fuel from hydrocarbon [3]. Generation of hydrogen can be achieved by a variety of tech- nologies, among which biological hydrogen production is considered a promising route for producing hydrogen [4]. Biological hydrogen production via dark fermentation has gained considerable interest in recent years due to its high rate of hydrogen production, technical simplicity, no light needed and the ability to utilize various kinds of substrates [5,6]. Sugarcane bagasse (SCB) is a lignocellulosic material con- taining sugars polymerized to cellulose and hemicellulose that can be liberated by hydrolysis and subsequently fer- mented by microorganisms to form different chemicals [7]. Dilute acid hydrolysis catalyze hemicellulose to its constitu- ents is a well known and effective method. The composition and concentration of the hydrolysis product depend on the type of material used and the operational conditions employed. The amount of sugar recovered from the raw material is dependent on the reaction time, temperature and concentration of acid [8]. After SCB hydrolysis, sugars are the * Corresponding author at: Department of Biotechnology, Faculty of Technology, Khon Kaen University, A. Muang, Khon Kaen 40002, Thailand. Tel./fax: þ66 43 362 121. E-mail address: alissara@kku.ac.th (A. Reungsang). Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 36 (2011) 8687 e8696 0360-3199/$ e see front matter Copyright ª 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2010.05.119