Optimization of hybrid anaerobic-aerobic SBR- based systems

摘要

This work deals with optimization of biological hybrid systems based on both anaerobic and aerobic sequential batch reactors (SBRs). The global model can address the differences between aerated and anaerobic systems by assigning adequate parameter values related to the presence of oxygen in the medium, aeration and sedimentation times, and selecting the kinetics model to represent the digestion stage. An existing set of experimental data is used for model validation. Fluctuating operation conditions during cycles such as disturbances in the organic loading rate, feed and recycle flow rates and changes in the hydrodynamic regime result in strong numerical discontinuities that are included in the simulation schedules. Optimization results are based on minimizing the reaction time/total cycle time ratio subjected to (pH, DO and nitrite) path constraints and interior- and end-point constraints related to the (COD and nitrogen) pollutant removal efficiency and settling conditions. A decrease of 29% in the total cycle time, i.e. an increase in the organic loading rate from 443 to 611 mg dm~(-3) d~(-1) is reached without modifying the quality of effluent. gOPT tool of gPROMS was used to perform the dynamic optimization.