Kinetic evaluation of sonicated food waste in continuously stirred tank reactor

This work aimed to evaluate the process performance and stability of the anaerobic digestion of sonicated food waste (SFW) by determining the kinetic parameters using Monod, Contois, Modified Stover-Kincannon, and Grau second-order multicomponent substrate removal kinetic models. The anaerobic digestion was conducted on the sonicated food waste (SFW) in a 13 L continuously stirred tank reactor (CSTR) with a stepwise organic loading rate (OLR) ranging from 1.5 to 3.5 gCOD/L.day. The experimental works were carried out in two stages (start-up then followed by semi-continuous). The ultrasonic pretreatment was performed by sonicating the food waste slurry for 10 minutes at a 20 kHz frequency and specific energy input of 25,997 kJ/kg TS. The process performance, as well as acceptable stability in the SFW digester, provided satisfactory predictions with Monod, Modified Stover-Kincannon, Grau second-order multicomponent substrate removal, and Contois kinetic models. A significant relationship was seen between the predicted and experimental data with correlation coefficients (R²) ranging from 0.893 to 0.996. In this study, the Monod model with R² = 0.996 indicates the most suitable model for understanding the kinetic parameters of the anaerobic system in the CSTR which digests the sonicated food waste (SFW) slurry.