CHEMICAL ENGINEERING TRANSACTIONS VOL. 37, 2014 A publication of The Italian Association of Chemical Engineering www.aidic.it/cet Guest Editors: Eliseo Ranzi, Katharina Kohse- Höinghaus Copyright © 2014, AIDIC Servizi S.r.l., I SBN 978-88-95608-28-0; I SSN 2283-9216 Production of Hydrogen from Giant Reed by Dark Fermentation Giuseppe Toscano*, Gaetano Zuccaro, Angelo Ausiello, Luca Micoli, Maria Turco, Domenico Pirozzi Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale, Università degli Studi di Napoli Federico II, P.le Tecchio, 80, 80125 Napoli, Italy giuseppe.toscano@unina.it Arundo donax hydrolysate (ADH), obtained by steam explosion and enzymatic treatment, was exploited as a substrate for anaerobic digestion aimed to the production of hydrogen. Mixed cultures of hydrogen- forming anaerobic bacteria selected from a primary sludge digester were used as inocula. Methanogens were removed from the wild consortium by the use of thermal treatments (autoclaving, freezing and thawing). Either with glucose or ADH as carbon sources, the soluble anaerobic fermentation products were butyric acid, lactic acid, acetic acid, formic acid and ethanol. The collected biogas consisted mainly of hydrogen (86-97%) and carbon dioxide. Hydrogen yield with ADH was lower than that found with glucose fermentation with the same inoculum. Outgrowth of lactic acid bacteria during ADH fermentation was presumably the cause of the low observed yield. Further optimization of ADH pre-treatment and stabilisation of microbial consortium are necessary in order to improve hydrogen yield on ADH. 1. Introduction The diffusion of the hydrogen as a fuel is still limited by the high costs of production and storage (Pant and Gupta, 2009). The biological processes offer a possible approach to obtain a renewable supply of hydrogen (Hallenbeck et al., 2012). The biological production of hydrogen could in principle be based on the direct exploitation of the photosynthetic activity of algae (biophotolysis) or bacteria (photofermentation) (Kapdan and Kargi, 2006). However, the development of these processes toward a practical application will likely require a long term (Hallenbeck et al., 2012). On the other side, dark fermentation (anaerobic digestion without photosynthesis) can be carried out using a technology similar to that of anaerobic digestion with methanogenesis, widely employed at industrial scale and consequently easier to be developed in the short term at industrial level (Chong et al., 2009). Dark fermentation appears to be suitable for the exploitation of agricultural wastes or non-food crops consisting of complex substrates that can be degraded biologically only by microbial consortia (Guo et al., 2010). Many efforts have been directed to the development of efficient technologies to obtain renewable energy from lignocellulosic biomasses, by recycling a large range of agricultural wastes (non-food parts of crops: stems, leaves, husks, etc.) and industry wastes (woodchips, skin and pulp from fruit pressing, etc.). Anaerobic digestion with methanogenesis is a microbial process that has already found wide application for the reduction and stabilization of agricultural wastes (Ward et al., 2008). In the last years, different papers have been concerned at the dark fermentation of lignocellulosic feedstocks (Saratale et al., 2008). The anaerobic food chain begins with the bacterial hydrolysis of complex organic compounds (Figure 1). Insoluble organic polymers, such as carbohydrates and proteins, are broken down to soluble derivatives that become available for other bacteria. Acidogenic bacteria then convert sugars and amino acids into carbon dioxide, hydrogen, ammonia, and organic acids. During acetogenesis, other bacteria convert these resulting organic acids into acetic acid, along with additional ammonia, hydrogen, and carbon dioxide. Finally, methanogens convert these products to methane and carbon dioxide. The adaptation of the DOI: 10.3303/CET1437056 Please cite this article as: Toscano G., Zuccaro G., Ausiello A., Micoli L., Turco M., Pirozzi D., 2014, Production of hydrogen from giant reed by dark fermentation, Chemical Engineering Transactions, 37, 331-336 DOI: 10.3303/CET1437056 331