Modelling a fluidized bed for water treatment via GAMS Package

The pellet reactor model for phosphorus recovery from waste water is identified as a combination of elementary systems imbedded in a superstructure. Potential solutions are determined using GAMS environment,(2004), and are compared to those obtained in a previous works (Montastruc et al., 2004) by using a combined stochastic/NLP approach. The problem is solved for two values of fluidization velocity (50L/h and 90L/h), which represent two experimental behaviours, and with two GAMS tools (DICOPT and SBB). For the two flowrates considered separately, the solutions of Montastruc and SBB are quite equivalent. However, when both flowrates are considered together, SBB easily reaches an optimal solution with a minimum number of elementary units. Due to crisp constraints, the Montastruc’s method and DICOPT need “good” initializations for giving only worse solutions than SBB. From this study, it appears that the SBB procedure is more efficient than the DICOPT one and the hybrid method of Montastruc for modelling a fluidized bed through a superstructure