Simulation and optimization of a full-scale Carrousel oxidation ditch plant for municipal wastewater treatment

Abstract

A full-scale Carrousel oxidation ditch wastewater treatment plant (WWTP) was simulated and optimized through integrating the activated sludge model 2d (ASM2d), support vector regression (SVR) and accelerating genetic algorithm (AGA). The ASM2d model after calibration and validation with the operating data was used to simulate the process. Operating parameters, including hydraulic retention times (HRTs) of anaerobic, anoxic and aerobic tanks, solids retention time (SRT) and internal recirculation ratio were subjected to optimization using SVR and AGA. The simulation results were normalized and SVR was employed to correlate the operating factors and the effluent quality. Then, the AGA approach was used to obtain the optimal operating conditions. The multiple-objective optimization with different weights indexes was adopted to achieve simultaneous nutrient removal. Compared with the present operating conditions, the HRT of the anoxic tank, the internal recirculation ratio and the SRT should be reduced, while the HRT of the aerobic tank should be prolonged to achieve better effluent quality. Such an integrated approach in this study offers an effective and useful tool to optimize the oxidation ditch process of WWTPs.