Abstract
Abstract
A model designed to couple a sludge-wastewater turbulence model (SWTM) with an activated sludge model 2 (ASM2) through a three-dimensional (3D) advection-dispersion equation (ADE) was developed to simulate 3D pollutant concentration fields in a reactor. SWTM is a hydrodynamic model of 3D two-phase turbulent flow. In this model, the sludge settling velocity (SSV) function was modified by the turbulence effect and coupled to a traditional mixture turbulence model to separate sludge movement from mixture. The coupled SWTM-ASM2 model was then integrated into a simplified wastewater treatment plant (WWTP) modeling system based on a real Carrousel-type WWTP located in Fengdu, Chongqing, China, and calibrated using the dynamic effluent data from this plant. Concentration fields of an oxidation ditch simulated using the coupled SWTM-ASM2 model were then validated by comparison of the measured concentrations in the full-scale oxidation ditch of the WWTP evaluated in this study and found to be satisfactory. According to the simulation results and measured dissolved oxygen (DO) concentrations, the ditch was divided into a nitrification, denitrification, and transition zone. Overall, the results of this study indicate that this novel coupled SWTM-ASM2 model could be used to simulate 3D component distributions in a reactor with a complex hydrodynamic structure and to investigate its treatment process through identification of bioreaction zones.