Revista Mexicana de Ingeniería Química, Vol. 22, No. 3 (2023), IA23168

Modelling the perturbation effects of the chicken litter overloading shocks on long-term semicontinuous anaerobic digesters

G.E. Vera-Perez, R. Domínguez-Puerto, A. Pérez-López, E. Fitz-Rodríguez, T. Espinosa-Solares



Overloading shock is one of the main concerns in anaerobic digestion full-scale processes. It can lead up to digester failure. Mathematical modelling applied to biological systems allows to provide insights to the process and in that manner to propose alternatives for the overloading events. In this context, the Anaerobic Digestion Model Number 1 was implemented to simulate the digester performance during organic overloading shocks. The objective was to propose kinetic parameter values for the description and understanding of a perturbed system in order to offer alternatives for perturbed digesters. For data collection, two 10 L mesophilic anaerobic digesters were used, named A and B, working in a continuous mode and under the same operational conditions. The substrate was a 3.0 % chicken litter solution, the inoculum that came from a digester specialized in chicken litter degradation; the hydraulic retention time was 30 d. The digesters were subjected to two organic overloading pulses having a long period of time in between for digester performance recovery. Volatile fatty acids, pH, and specific methanogenic activity were used to monitor digester performance. A standard differential evolution algorithm was used for calibration; which was performed using the data of the first perturbation of digester A. Biochemical parameters related to the degradation of volatile fatty acids showed significant changes (i.e., Km,c4 from 20.0 to 4.92 d-1; Km,pro from 30.0 to 2.17 d-1; km,ac from 8.0 to 5.24 d-1; km,h2 from 35 to 10.60 d-1). After calibration, the model outputs, for digesters A and B, showed a satisfactory fit to experimental data. The result shows that differential evolution algorithm provide a robust calibration method for simulating the response of chicken litter overloading shocks in continuous methane production processes.

Keywords: disturbance, OLR, ADM1, volatile fatty acids, VFA accumulation, biogas.