International Journal of Hydrogen Energy 30 (2005) 1535 – 1542 www.elsevier.com/locate/ijhydene Biohydrogen gas production from food processing and domestic wastewaters Steven W. Van Ginkel a, b, ∗ , Sang-Eun Oh a , Bruce E. Logan a, b a Department of Civil and Environmental Engineering, The Pennsylvania State University, 212 Sackett Building, University Park, PA 16802, USA b Penn State Hydrogen Energy (H 2 E) Center, 212 Sackett Building, The Pennsylvania State University, University Park, PA 16802, USA Accepted 16 September 2004 Available online 10 November 2004 Abstract The food processing industry produces highly concentrated, carbohydrate-rich wastewaters, but their potential for biological hydrogen production has not been extensively studied.Wastewaters were obtained from four different food-processing industries that had chemical oxygen demands of 9 g/L (apple processing), 21 g/L (potato processing), and 0.6 and 20 g/L (confectioners A and B). Biogas produced from all four food processing wastewaters consistently contained 60% hydrogen, with the balance as carbon dioxide. Chemical oxygen demand (COD) removals as a result of hydrogen gas production were generally in the range of 5–11%. Overall hydrogen gas conversions were 0.7–0.9 L-H 2 /L-wastewater for the apple wastewater, 0.1L/L for Confectioner-A, 0.4–2.0 L/L for Confectioner B, and 2.1–2.8 L/L for the potato wastewater. When nutrients were added to samples, there was a good correlation between hydrogen production and COD removal, with an average of 0.10 ±0.01 L-H 2 /g- COD. However, hydrogen production could not be correlated to COD removal in the absence of nutrients or in more extensive in-plant tests at the potato processing facility. Gas produced by a domestic wastewater sample (concentrated 25×) contained only 23±8% hydrogen, resulting in an estimated maximum production of only 0.01 L/L for the original, non-diluted wastewater. Based on an observed hydrogen production yield from the effluent of the potato processing plant of 1.0 L-H 2 /L, and annual flows at the potato processing plant, it was estimated that if hydrogen gas was produced at this site it could be worth as much as $65,000/year.  2004 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved. Keywords: Hydrogen production; Food processing wastewater 1. Introduction Hydrogen gas shows great promise as a non-polluting fuel, but to reduce carbon dioxide releases hydrogen gas will need to be produced from renewable sources. Most ∗ Corresponding author. Department of Civil and Environmen- tal Engineering, The Pennsylvania State University, 212 Sackett Building, University Park, PA 16802, USA. Tel.: +1 814 865 4851; fax: +1 814 863 7304. E-mail address: steppen@psu.edu (S.W. Van Ginkel). 0360-3199/$30.00  2004 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2004.09.017 hydrogen gas produced in the United States is obtained from thermocatalytic and gasification processes using natu- ral gas (50%), petroleum-derived napthenes and distillates (30%), and coal (18%), with the remainder from electricity (2%). Biological hydrogen production from the fermenta- tion of renewable substrates is one promising alternative although the use of commercially produced food products, such as corn and sugar, is not yet economical [1]. Wastew- aters show great potential for economical production of hydrogen because producing a product from a waste could reduce waste treatment and disposal costs [2]. Hydrogen has