Dynamical Analysis of a wastewater treatment process for biogas production

This paper deals with a dynamical analysis of a lab scale anaerobic reactor, which is used for biogas production from wastewater treatment. The reaction volume inside the reactor is 5 L in a continuous operation with a flow rate of 0.5 L h-1. Using a pole-zero analysis, the step response and phase portrait analysis, two hydrodynamic behaviors of anaerobic bacteria are studied: dilution rate and biomass filter; this analysis is done via numerical simulations. The main objective is to determine the effect of bacteria immobilization and operating condition variations on the process properties: stability, substrate degradation, biogas production and operating regions. The obtained results show that bacteria immobilization improves the process performances since the attraction region to the treatment point is enlarged and the washout point is hard to be reached. This situation implies that a larger biomethane production can be obtained and larger input disturbances can be rejected.