A novel of biohythane gaseous fuel production from pineapple peel waste juice in two-stage of continuously stirred anaerobic bioreactors

Abstract

This study integrated two continuous stirred anaerobic bioreactors (CSABR) for two-stage biohytane gaseous fuel (a mixture of hydrogen and methane) production at mesophilic condition. The first stage of biohydrogen production reactor (CSABRH) was fed by the pineapple peel waste juice with substrate concentration of 64.56 g COD/L. The hydrogenogenic effluent from CSABRH was directly fed to second stage of methane production reactor (CSABRC). The working volumes of CSABRH and CSABRC bioreactors were 1.2 and 5 L, respectively. Optimization of Hydraulic Retention Time (HRT) for two-stage hydrogen and methane production after an integration were examined. A maximum hydrogen production rate of 599.0 ± 77.8 mL/LR-d and methane production rate of 174.6 ± 9.4 mL/LR-d were achieved at optimal HRT of 4 h in the CSABRH and 3 d in the CSABRC with the substrate concentration of 66.15 ± 2 and 37.7 ± 1.9 g COD/L in the first and second stage, respectively. The two-stage reactors performed well in producing hydrogen and methane over 140 and 50 days with a total chemical oxygen demand (COD) removal efficiency of 85.0%. Total biogas and heating value production rates in total 6.2 L working volume were 2495.1 mL/d and 13.1 kcal/d, respectively. These results indicate that the pineapple peel waste could be efficiently used for biohythane (H2 + CH4) production and the two-stage process can operate successfully under high feeding flow rate conditions.