Enhancing biomethane yield from food waste through surfactant-assisted mechanical pretreatment: An optimization approach

In the present investigation, the response surface methodology-based central composite design (RSM-CCD) was used to model the potential of improving the solubilization of food waste through surfactant-assisted homogenization pretreatment (SAHP). RSM-CCD models were investigated based on homogenization speed and time for HP, surfactant dosage, and homogenization time at optimized homogenization speed by HP for SAHP input parameters and chemical oxygen demand (COD) solubilization (CODsol) as response parameters. HP optimum condition was 7020 rpm, 9.9 min to attain 11.6% solubilization with 292.8 kJ/kg total solid (TS) specific energy consumption (ESp). On the other hand, 19.9% CODsol was obtained in the SAHP under optimum conditions of 6.3 μl and 3.7 min, with ESp of 116.2 kJ/kg TS, respectively. The CODsol increment and ESp decrease by 176.2 kJ/kg TS indicate the significance of combined pretreatment and synergistic action of surfactant. Eventually, the maximum biomethane generation was found in SAHP as 67 ml/gCOD, higher than that of HP (40 ml/gCOD) and without pretreatment samples (17 ml/gCOD), respectively.