Conversion of waste biomass (pea-shells) into hydrogen and methane through anaerobic digestion

Waste pea-shells were digested under batch anaerobic conditions. Digestion of pea-shell slurries (PSS) at 1–5% total solids (TS) concentration, with H2-producting organisms yielded 99–362l biogas-H/kg organic solids reduced (biogas-H: mixture of H2, CO2 and H2S). Hydrogen constituted 33–46% of the total biogas-H. Methanogenesis of PSS (1–5% TS) was most effective at 1% TS level. During 25 days of incubation, 507 l biogas/kg was generated (biogas: mixture of CH4, CO2 and H2S). Methane accounted for 43% of the total biogas yield. Biogas yield of 1% TS PSS without the fibrous sheath was only 16•5% of that of 1% TS PSS with the fibrous sheath. However, 3% TS PSS without the fibrous sheath showed improved results, which could be employed for continuous-culture digestions.