Biohydrogen production from glucose-containing wastewater in anaerobic sequencing batch reactors: effect of operating conditions

Abstract

Hydrogen is one of the alternative energy resources that is increasingly used instead of fossil fuel to reduce the emission of greenhouse gases. Biohydrogen production is interesting because it can be produced from renewable resources, including wastewaters, under ambient conditions. Hydrogen production from glucose-containing wastewater by dark fermentation process in an anaerobic sequencing batch reactor (ASBR) was evaluated. The anaerobic sludge taken from a brewery wastewater-treating anaerobic unit was pretreated by boiling for 15 min before being added into the ASBR units as the seeding sludge. The ASBR units were operated at different chemical oxygen demand (COD) loading rates from 10 to 50 kg m-3 d-1 under controlled pH at 5.5, 37°C, and 24 h HRT. The results showed that at the optimum COD loading rate of 40 kg m-3 d-1, the produced gas was found to contain 43% H2 and 57% CO2, and no methane in produced gas was detected at all operating conditions. The highest hydrogen yield was 1.46 mol-H2/mol-glucose consumed. Additionally, the main organic components in effluent liquid were butyric and acetic acids. The effect of COD:N ratio was also studied by varying the amount of NH4HCO3 in the feed solution. The optimum N content was achieved at COD:N ratio of 100:2.4 under the system with pH control at 5.5, from which the produced gas mainly contained 44% H2, and the H2 production rate was 1.24 L h-1.