Kinetic Modeling of Volatile Fatty Acids Production Using Cassava Wastewater as Low-Cost Substrate

The production of volatile fatty acids (VFAs) through the acidogenic fermentation of wastewater has garnered significant attention in recent years. This study examines the kinetics of VFA production in batch reactors using cassava wastewater as a substrate under previously identified conditions (initial pH of 5.7, S/M ratio of 4 gCOD/gVS, and temperature of 34 ± 1 °C). Additionally, this study identifies the best-fit models for estimating kinetic parameters related to the consumption of soluble organic matter and VFA production. VFA production yields ranged from 0.15 to 0.44 gCODVFA/gCOD over the 12-day fermentation period, with the highest yield observed on day 9. The acids produced consisted of 29.7% acetic acid, 43.3% propionic acid, and 27.0% butyric acid. The modified Gompertz and first-order with residual models effectively described the consumption of soluble organic matter, while the first-order and BPK models accurately represented the VFA production. These models showed the highest R2 values and the lowest RMSE and AIC values. Cassava wastewater is a low-cost substrate with potential for VFA recovery. Its kinetic modeling provides valuable insights for the design, control, and scale-up of acidogenic reactors.