Continuous operation and hydrogen production characteristics of a novel hydrogen production reactor

A novel external-circulation granular sludge bed (ECGSB) reactor seeded with anaerobic activated sludge was developed for high-rate fermentative hydrogen production using molasses wastewater. The ECGSB system produced hydrogen efficiently even at very high volume loading rate (VFA). The maximum hydrogen production rate of 7.43 L/L·d was obtained at the VLR 70-80 kg/(m³·d). The average hydrogen production rate was 6.44 L/L·d with the hydrogen content of 50%-56% in the biogas. Formation of self-flocculated granular sludge was observed during the operation of high VLR. An average biomass concentration of up to 24.1 gVSS/d was achieved even at very high VLR. The granular sludge was thought to be responsible for the high efficient reactor operation and hydrogen production, because it led to more efficient biomass retention and make the reactor more stable in response to the shock load. The results showed an outstanding operation stability and hydrogen production potential of the ECGSB hydrogen-producing reactor. The development of the new type reactor would accelerate the industrial-scale fermentative hydrogen production pace.