Simulation of a full-scale wastewater treatment plant performance at various temperatures using Extended Activated Sludge Model No.1

Abstract

In this paper, a simulation model was adapted for the 6th of October wastewater treatment plant (WWTP) located in Cairo, Egypt. The study aims to investigate the effect of variable temperature on treated effluent wastewater with regards to various operational parameters. The temperature in the arid region where the plant is located varies significantly between summer and winter. The simulation model was created using the Runge–Kutta 4th order numerical technique in the MATLAB platform and applies Extended Activated Sludge Model No. 1 (ASM1) equations for WWTP modeling. This model reflected the equations of ASM1 with modified Monod kinetics for the dissociation of soluble biodegradable organic substrates into unionized organic substrates to be utilized by aerobic heterotrophs and autotrophs. Wastewater characterization was determined with a detailed sampling campaign for the WWTP influent, primary settled, and effluent discharges. Model calibration and sensitivity analyses of kinetic parameters were conducted for model validation. A comprehensive study was performed to examine the effect of various operating parameters on the removal of chemical oxygen demand (COD) at different temperatures using the calibrated model. The operational conditions studied are dissolved oxygen (DO), hydraulic retention time (HRT), and mixed liquor volatile suspended solids (MLVSS). The modified model indicates that COD removal efficiency reaches about 65% for MLVSS of 2,500 mg/L at 15°C, whereas the COD removal efficiency is increased by about 15% as the measured temperature increases from 15°C to 35°C at a DO value of 2 mg/L and HRT of 6 h. Furthermore, the simulation results imply that COD removal can be significantly enhanced by increasing both MLVSS and DO to 4,000 and 3 mg/L, respectively.