Simultaneous Optimization of Structure and Operation for Coking Wastewater Biological Treatment Process

In this paper, the simultaneous optimization of process structure and operation conditions for the coking wastewater biological treatment process is carried out based on a superstructure-based model. The superstructure proposed covers current widely used biological treatment processes in a coking wastewater treatment plant. The activated sludge model no. 3 calibrated for coking wastewater and thickening factors is chosen to describe the biological processes and the secondary clarifier, respectively. The optimization problem is formulated as a mixed integer nonlinear programming model (MINLP), which is implemented and solved using the general algebraic modeling system (GAMS). For given influent coking wastewater flow rate and composition as input, the O/A/O process and A/O/O process are selected for the influent with COD concentration of 2000 and 3000 g/m3respectively. The results provide the valuable information for the development and operation of activated sludge processes for coking wastewater biological treatment and useful insights for policy makers as well.