Hydrogen production from rotten dates by sequential three stages fermentation

Abstract This study was devoted for H2 production from rotten fruits of date palm (Phoenix dactylifera L.) by three fermentation stages. A facultative anaerobe, Escherichia coli EGY was used in first stage to consume O2 and maintain strict anaerobic conditions for a second stage dark fermentative H2 production by the strictly anaerobic Clostridium acetobutylicum ATCC 824. Subsequently, a third stage photofermentation using Rhodobacter capsulatus DSM 1710 has been conducted for the H2 production. The maximum total H2 yield of the three stages (7.8 mol H2 mol−1 sucrose) was obtained when 5 g L−1 of sucrose was supplemented to fermentor as rotten date fruits. A maximum estimated cumulative H2 yield of the three stages (162 LH2 kg−1 fresh rotten dates) was estimated at the (5 g L−1) sucrose concentration. These results suggest that rotten dates can be efficiently used for commercial H2 production. The described protocol did not require addition of a reducing agent or flashing with argon which both are expensive.