Hydrogen production from glucose-containing wastewater using an anaerobic sequencing batch reactor: Effects of COD loading rate, nitrogen content, and organic acid composition

In this work, the process performance of an anaerobic sequencing batch reactor (ASBR) for the hydrogen production from glucose-containing wastewater was studied. The anaerobic sludge taken from a brewery wastewater-treating anaerobic unit was pretreated by boiling for 15 min before being added into the ASBR unit as the seeding sludge. The ASBR unit was operated at a temperature of 37 °C, a hydraulic reaction time (HRT) of 24 h, and different chemical oxygen demand (COD) loading rates from 10 to 50 kg m−3 d−1 without and with pH control at 5.5. The results showed that at the optimum COD loading rate of 40 kg m−3 d−1 and pH 5.5, the produced gas was found to contain 44% H2 and 56% CO2, and no methane in the produced gas was detected at all operating conditions. At these optimum conditions, the highest hydrogen yield was 1.46 mol H2/mol glucose consumed. Additionally, the main organic components in the liquid effluent were acetic and butyric acids. Under the optimum COD-to-nitrogen (COD:N) ratio of 100:2.4, the system with pH controlled at 5.5 gave the highest specific H2 production rate of 7.44 l H2 l−1 d−1, corresponding to the highest butyric acid to acetic acid ratio.