Experimental investigation of biohydrogen production using a novel vacuum‑assisted anaerobic digestion system

This study investigates biohydrogen production through vacuum assisted anaerobic digestion of a cow manure-based solution containing 5 g/L glucose, 90 mg/L urea, and 10% hydrogen peroxide at pH 9.5. The system was operated under three different vacuum pressures: 5, 10, and 15 bar. Hydrogen production was monitored for over 12 hours, with measurements every 15 minutes during the first 3 hours. The highest hydrogen yield (24.6 mL/g) was obtained at 10 bar, while lower and higher pressures resulted in reduced yields (12.4 mL/g at 5 bar and 17.9 mL/g at 15 bar). The enhanced performance at 10 bar is attributed to improved gas transfer, microbial activity, and the synergistic effects of urea and hydrogen peroxide. The results highlight the potential of combining vacuum application with chemical enhancement to optimize hydrogen production in anaerobic systems.