Hydrodynamic Mixing Characteristics Of EGSB Reactor

In this study, a lab-scale EGSB reactor was established and ran with certain organic loading rate, while experiments on the characteristics of expanded granular sludge bed and residence time distribution (RTD) were conducted under different superficial liquid upfiow velocities (vup) conditions. Two flow models with multiple parameters (GDMWB and CPDE) were established and simulated based on the analysis of the simulation results and deviations of two single-parameter flow models (DPF and TIS).Through these work, some conclusions can be drawn:1) The optimal range of liquid upfiow velocity (vup) is 2-4 m/h for the biomass retention and stable COD removal rate of the EGSB reactor.2) Dead zone exists in the EGSB reactor, whose volume can be reduced by increasing theVup.3) The varity of axial dispersion coefficient (Dz/uL) and tank-in-series number (N) with the vup increased only has the relative meaning which imply the mixing intensity of the whole system decreased first and then increased in time domain. However, it can not interpret the mixing characteristics of the reactor in space domain.4) It is reasonable for developing the combined models by defining the reactor is composed of sludge bed and settling section in series. Moreover, model CPDE interpret the long tail of RTD curves perfectly.5) Model GDMWB is fit for simulation under high vup condition and model CPDE for low.