Co-digestion of Food Waste and Switchgrass for Biogas Potential: Effects of Process Parameters

Abstract

Anaerobic digestion is the technology aimed at organic substrates conversion to biomethane potential. The co-digestibility performance of food waste and switchgrass at different mix ratio and the temperature is evaluated in the present study. To address this performance evaluation, the response of volatile acid groups’ viz. acetic, propionic, butyric and valeric acids, pH related to the biomethane potential. The highest methane yield observed with 1:1 FW: SG is 267 ml/g VSadded at mesophilic and 234 ml/g VSadded at thermophilic condition respectively. Methane yield has a positive response on co-digestion is confirmed by digestion performance index (DPI). Also, process parameters viz acetic and butyric acid concentrations were in the range 15–70% and 18–70% for the loadings at 35 °C and 55 °C respectively. SG showed the highest butyric acid concentration, and in contrast, the utmost acetic acid produced from both FW and SG respectively. Even though at higher acid concentrations, less significant inhibition on biomethane yields is observed during performance evaluation. Result revealed that co-digestion at 1:1 ratio yields the improved performance with FW and SG at mesophilic as well as in thermophilic condition. Food waste is predominant and achieves the second highest methane yield compared to switchgrass in single substrate digestion. This study confirms the presence of slow and fast biodegradable organic matters have an equal contribution to the biomethane yield.