Modeling of anaerobic bioreactors oriented to optimization. Solutions for IPDAE systems

MAUREN FUENTES; MIGUEL C. MUSSATI; NICOLÁS SCENNA; PÍO AGUIRRE

Lyon

Congreso; 18th European Symposium on Computer Aided Process Engineering (ESCAPE-18; 2008

IFP Institute Francais de Petrole

A global model of an anaerobic fluidized bed reactor (Fuentes et al., 2007d) is used to optimize different loading strategies and investigate some aspects on process control to drive the system towards optimal performance under disturbance scenarios. The gOPT tool of gPROMS (Process System Enterprise Ltd.) was used to perform the dynamic optimization calculations. Some aspects on DAE and IPDAE systems formulations for optimization purposes are exposed. Most of the computational work deals with piecewise constant functions. A case study related to a multispecies biofilm reactor for wastewater treatment is analyzed. Results are based on different dynamic optimization formulations such as maximization of biomass concentration inside the bioreactor and biogas production.  Operating disturbances such as increased organic loading rate (feed flow rate) during the start-up period, and changes in the cations concentration, result in strong numerical discontinuities that were included in the simulation schedules. Optimization of bioreactor performance in multispecies biofilm requires formulating path constraints for system pH in order to achieve high contaminant removal efficiencies.