Optimization of process parameters for accelerated methane yield from anaerobic co-digestion of rice straw and food waste

Abstract

Biogas production from agricultural residue by anaerobic digestion is the most favourable option for providing sustainable energy and reducing the environmental pollution. The experimental methane potential of co-digested rice straw and food waste were measured for different carbon to nitrogen (C/N) ratios in 1 L anaerobic reactor. Co-digesting rice straw with food waste for C/N 25, 30 and 35 almost showed the similar methane yield 294.17 ± 3.78 mL/g-VSadded, with an increase of 134.53 mL/g-VSadded (71.09%) than mono-digestion. After optimizing the C/N ratio for co-digestion, interactive effect of initial pH and food/microorganism (F/M) ratio were also explored in this study using central composite design – response surface methodology (CCD-RSM). Results from the optimization study showed significant interaction, and validation experiment for optimum condition (C/N 30, pH 7.32, F/M 1.87) showed a methane yield of 323.78 mL/g-VSadded (94.41%), 166.54 mL/g-VSadded higher than the mono-digestion (control).