Potential to produce biohydrogen from various wastewaters Bruna Soares Fernandes, Guilherme Peixoto, Fernanda Rui Albrecht, Nora Katia Saavedra del Aguila, Marcelo Zaiat ⁎ Laboratório de Processos Biológicos (LPB), Departamento de Hidráulica e Saneamento, Escola de Engenharia de São Carlos (EESC), Universidade de São Paulo (USP), Engenharia Ambiental, Bloco 4-F, Av. João Dagnone, 1100, Santa Angelina, 13.563-120, São Carlos, SP, Brazil abstract article info Article history: Received 22 June 2009 Revised 24 March 2010 Accepted 25 March 2010 Keywords: Bioreactor Hydrogen Wastewater This research evaluates the potential for producing hydrogen in anaerobic reactors using wastewater from various sources (domestic sewage, vinasse from ethanol production, and glycerin from biodiesel production). The assays were performed in batch reactors with a volume of 2 l, and sucrose was used as a control substrate. The inoculum was taken from a packed-bed reactor used to produce hydrogen from a sucrose-based synthetic substrate. Hydrogen was produced from all of the wastewaters assayed (200 ml H 2 / g COD for domestic sewage; 579 ml H 2 /g COD for vinasse; 200 ml H 2 /g COD for glycerin; and 270 ml H 2 /g COD for sucrose). Vinasse showed the highest potential for hydrogen production, as seen from its higher hydrogen yield (25 mmol H 2 /g COD) and maximum hydrogen production rate (3.08 mmol H 2 /g VSS h). © 2010 International Energy Initiative. Published by Elsevier Inc. All rights reserved. Introduction The bioproduction of hydrogen is an interesting option because organic waste can be used as a feedstock for the process. The fermentative process is an alternative due to hydrogen production's low energy usage when compared to electrolysis and methane steam reforming. The generation of hydrogen by electrolysis consumes 4.5 to 5 kW h/m 3 H 2 in high-efficiency industrial electrolyzers (Stojić et al., 2003), and high amounts of energy are required to produce temperatures from 970 to 1100 K and pressures above 3.5 MPa for the steam reforming of methane (Kothari et al., 2008). Hydrogen generation using the fermentation process is possible with various types of wastewater using either mixed or pure cultures (Hallenbeck, 2004). The use of various effluents, mainly wastewater containing cellulose, pentose, and xylose (Rogers and Gottschalk, 1993; Taguchi et al., 1995), glycerol, residues from biodiesel production (Ito et al., 2005), effluent from cheese processing (Yang et al., 2007), dairy wastewater (Mohan et al., 2008), by-products of wheat flour processing (Hawkes et al., 2008), molasses (Li et al., 2007), solid food wastes (Han and Shin, 2004), effluent from paper production (Vazquez et al., 2005) and domestic sewage (van Ginkel et al., 2005), among others, has been reported. Wastewater, both from domestic sewage and industrial effluents, is a potential energy source readily found in any community. Thus, hydrogen generation from wastewater costs less and can be carried out using local feedstock. The wastewater evaluated in this work was chosen due to the focus of Brazilian industrial expansion on the production of renewable fuels, such biodiesel and ethanol, and the need to find an environmentally safe destination for waste generated by these processes. Thus, the choice of wastewater was strategic: glycerol or glycerin, the main residues from the processing of biodiesel, vinasse, the main residue generated from the production of ethanol, and domestic sewage, which, despite its low organic load, is continuously generated in large and small communities. Current glycerol generation in Brazil is about 17.6 million liters per year considering the study realized by Silva et al. (2009), which estimates that biodiesel production generates 10% (w/w) glycerol. Vinasse generation is usually 14 times the volume of ethanol produced. Data from UNICA (Sugarcane Agroindustry Union of São Paulo State) show that it has produced 15 million cubic meters of ethanol in the 2004–2005 harvest, thus resulting in a 210 million cubic meter generation of vinasse. According to the national census on domestic wastewater realized in 2000 by IBGE (Brazilian Institute for Geography and Statistic), metropolitan regions like Campinas, SP, Porto Alegre, RS, and Curitiba, PR generate about 95,001 to 276,900 m 3 /day of sewage. Thus, in 1 year, a city like Curitiba, PR (Brazil) can generate approximately 101 million cubic meters of domestic sewage. This paper reports on experiments carried out to evaluate the potential for hydrogen generation from different types of wastewater through simple assays in bench-scale batch reactors with sucrose as the control substrate. Materials and methods Batch reactors The reactors were composed of 2-l glass flasks (Duran ® flasks), consisting of 1 l of liquid volume and 1 l of headspace. Energy for Sustainable Development 14 (2010) 143–148 ⁎ Corresponding author. Fax: +55 16 3373 9550. E-mail address: zaiat@sc.usp.br (M. Zaiat). 0973-0826/$ – see front matter © 2010 International Energy Initiative. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.esd.2010.03.004 Contents lists available at ScienceDirect Energy for Sustainable Development