Zeolite addition to improve biohydrogen production from dark fermentation of organic wastes

Abstract Background Hydrogen is a clean and renewable energy source that can be produced by biological processes, such as dark fermentation. However, hydrogen production yields are usually low.Results In this work, biohydrogen production from a mixture (1:1) of glucose and arabinose (4.4 g L -1 , in COD) was improved about 1.3 times in batch reactors, and increased 3 times in a continuous reactor (from 143 mL H2 L -1 d -1 to 430 mL H2 L -1 d -1 ), when zeolite type-13X was added. The presence of zeolite led to the stimulation of different metabolic pathways and to changes in the microbial community composition, which seems to be linked to hydrogen production improvement. The zeolite effect in dark fermentation was also verified for more complex substrates. Hydrogen production yield from Sargassum sp., was improved 1.4 times by the presence of zeolite (94.8 L H 2 Kg -1 Sargassum sp . Volatile Solids (VS)).Conclusions The results show that zeolite is suitable to improve biohydrogen production by dark fermentation.