Direct current assisted bio-hydrogen production from acid hydrolyzed waste paper

One of the most important problems in dark fermentative hydrogen production is the need for the regulation of the ambient pH due to the formation of volatile fatty acids. For this purpose, alkaline chemicals are usually used; however, alkaline addition to the media increases salt formation, which negatively affects microbial activity. In this study, pH adjustment was performed by providing direct current as an alternative to alkali addition. Experiments were carried out batchwise and electricity was only applied to neutralize the acidic pH value. The waste paper hydrolysate was used as a substrate and the effects of applied voltage (0.25-3 V), substrate concentration (4.8-41.2 g/L at 1 V) and electrode distance (0.3-1.3 cm at 1 V) on hydrogen production performance was investigated. Voltages less than 1 V required too much time to keep the pH convenient and voltages more than 1.5 V adversely affected hydrogen production performance. Providing direct current to the fermentation media significantly reduced the adaptation phase. Conditions for optimal pH adjustment and hydrogen production were obtained at 1 V, 20 g glucose/L and 0.5 cm electrode distance. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.