Modelling the perturbation effects of the chicken litter overloading shocks on long-term semicontinuous anaerobic digesters
Modelling the perturbation effects of the chicken litter overloading shocks on long-term semicontinuous anaerobic digesters
Date
2022-10
Authors
Vera Perez, Gerson Esteban
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad Autónoma Chapingo
Abstract
Chemical composition and mass flow inlet play a vital role in a successful
anaerobic digestion process; if both are kept constant in a continuous
process, methane production can be achieved. Thus, one of the main
concerns in full-scale processes is the overloading shock. That can
unbalance trophic pathways, resulting in the accumulation of volatile fatty
acids (VFA). Depending on the disturbance severity, it can lead to digester
failure. Mathematical modelling applied to biological systems provides
insights and alternatives for overcoming these hurdles. In this context, the
Anaerobic Digestion Model number 1 was implemented in the present work
to simulate organic overloading shocks. The objective was to propose kinetic
parameter values which allow description and understanding of a perturbed
system. Two 10 L mesophilic anaerobic digesters working in a semi continuous mode, A and B, were treated under the same operational
conditions for data collection. The digesters were submitted to two organic
overloading pulses with a long time in between for recovery. VFAs, pH, and
specific methanogenic activity (SMA) were used to monitor the digesters’
performance. A standard differential evolution algorithm (DEA) was used for
calibrating 28 biochemical parameters. Calibration was obtained using just
the data of the first perturbation of digester A. Biochemical parameters
related to the degradation of VFAs showed the most significant changes (i.e.,
Km,c4 from 20 to 4.92; Km,pro from 30 to 2.17; km,ac from 8 to 5.24; km,h2 from 35
to 10.60 kgCOD●m-3
). After calibration, the model outputs showed a better fit
with experimental data regarding modeling efficiency (EF) and the agreement
index (index) than standard biochemical parameters. The result showed that
DEA provides a robust calibration method for simulating the response of
chicken litter overloading shocks in continuous methane production
processes.
Description
Tesis (Maestría en Ciencia y Tecnología Agroalimentaria)