Cogeneration of hydrogen and methane from pretreated fat by anaerobic fermentation

Abstract

Cogeneration of hydrogen and methane from pretreated fat by anaerobic fermentation was investigated to improve energy conversion efficiency in hydrogen production from fat,In the hydrogen producing phase,more fat hydrolyzes after the treatment of lipase and alkali,so the cumulative hydrogen production increases. Domesticated bacteria accommodate quickly in the substrate,which results in the curtailment of lag-phase time and the increase of the specific hydrogen production. The optimum sodium ion concentration is no more than 0.2 mol/L when using NaOH for hydrolyzation,otherwise hydrogen producing bacteria would be inhibited by high concentration of sodium ion. Methane is produced from the residue of hydrogen production to increase the energy conversion efficiency and the feedstock utilization ratio. The maximum specific hydrogen yield from fat is 32.6 mL/g in the first stage and the methane yield is 24.88 mL/g in the second stage. The cogeneration of hydrogen and methane from fat by two-phase anaerobic fermentation can increase the energy conversion efficiency from 0.85% (only hydrogen production) to 2.99%.