Enhanced methane potential of rice straw with microwave assisted pretreatment and its kinetic analysis.

Biogas has become an alternative clean source of energy. Agricultural residues being renewable and abundant resources could be efficiently used as a feed for methane production. The recalcitrant behaviour of rice straw marks pretreatment an important step to facilitate the transformation into renewable (methane) energy source. Microwave pretreatment has been considered as one of the most effective method, as it can directly (thermal and nonthermal effects) react with the feedstock and destroy its complex matrix. The present study considered the different temperature and exposure time (i.e., 130-230 °C, 2-5 min). Biochemical methane potential was assessed corresponding to the maximum solubilization rate; specific methane yield was obtained as 325.76 mL/g/VS. The total net energy gain of 3288.576 J/g/VS was obtained. The performance parameters were calculated by using different kinetic models. It followed the trend as modified Gompertz > transference function > logistic function models. Field Emission Scanning Electron Microscopy (FESEM) and Fourier Transform Infrared (FTIR) analysis confirmed the breakdown of lignocellulose structure resulting from the rupture of cuticular surface.