Utilization of solid and liquid waste generated during ethanol fermentation process for production of gaseous fuel through anaerobic digestion – A zero waste approach

•Feasibility study on biogas production from solid and liquid waste.•Comparative performance at thermophilic and mesophilic temperatures.•Solid residues from TR1 andTR2 yielded more biogas than MR1 and MR2.•The waste generated during ethanol fermentation were amenable for biomethanation.

Preliminary investigations were performed in the laboratory using batch reactors at 10% solid concentration for the assessment of the biogas production at thermophilic and mesophilic temperatures using solid residues generated during ethanol fermentation process. One kg of solid residues (left after enzyme extraction and enzymatic hydrolysis) from thermophilic reactors (TR1 and TR2) produced around 131 and 84 L of biogas, respectively, whereas biogas production from mesophilic reactors (MR1 and MR2) was 86 and 62 L, respectively. After 20 and 35 days of retention time, the TS and VS reductions from TR1, TR2 and MR1, MR2 were found to be 39.2% and 35.0%, 67.3% and 61.0%, 21.0% and 18.0%, 34.7% and 27.8%, respectively. Whereas the liquid waste was treated using four laboratory anaerobic hybrid reactors (AHRs) with two different natural and synthetic packing media at 15–3 days HRTs. AHRs packed with natural media showed better COD removal efficiency and methane yield.