MATHEMATICAL-MODELING FOR SUPPORTING SCALE-UP OF AN ANAEROBIC WASTE-WATER TREATMENT IN A FLUIDIZED-BED REACTOR

The paper deals with a mathematical model for anaerobic treatment of w aste water from sugar industry which has been developed for supporting the scale-up of a fluidized bed reactor. The dynamic model is based o n material balance equations for substrates and products in gas and li quid phase. The effects taken into account are the biological degradat ion steps including chemical equilibria and mass transport between gas and liquid phase as well as convection and dispersion. Axial gradient s of pH-values are calculated from a charge balance, Simulation result s show reasonable agreement with measured gradients of substrates and pH in a 10 m(3) fluidized bed reactor. For a new 500 m(3) fluidized be d reactor simulations are performed to study the effects of increased hydrostatic pressure and increased ratio of feed to recirculation rate on the pH-values at the bottom of the reactor. The results indicate t hat for high GOD-loading rates stationary pH-gradients may have signif icant influence upon the outcome of the process. Copyright (C) 1996 IA WQ.