An accelerated approach of biogas production through a two-stage BioH2/CH4 continuous anaerobic digestion system from Napier grass

Napier grass found to be greatest potential for gaseous bioenergy production. The biohydrogen and biomethane productions from untreated Napier grass in single and two-stage continuous bioreactors was evaluated using anaerobic digestion technology. The bioreactors were fed Napier grass with organic loading rate (OLR) of 0.5, 1.0 and 2.0 kg VS/m(3)-d, respectively. The hydrogen, methane, and energy yields were evaluated. The methane yield of single-stage system was 282.08 CH4/g vS with OLR of 0.5 kg VS/m(3)-d. For two-stage system, the biohydrogen and biomethane yields were 90.06 mL H-2/g vS and 367.00 mL CH4/g vS with OLRs of 1.0 and 0.5 kg VS/m(3)-d, respectively. The energy yields of single and two-stage systems were 13.14 and 10.10 kJ/g vS respectively. The peak OLR of Napier grass was 0.5 kg VS/m(3)-d for the two-stage system whereas the total energy recovery was 30 % higher than the single-stage system.