Usage of advanced biological kinetic models in sizing wastewater biological treatment reactors

Nowadays, an activated sludge process is the most commonly used biological wastewater treatment process. In addition to its cost-effective properties in removing the organic material form wastewater, it is flexible, reliable, and has the capability of producing high quality effluent. Advanced models simulating the complex biochemical reactions taking place in activated sludge reactors have been progressively applied in many process fields. Examples of these models are the International Water Association Models (ASM) No.1, ASM No.2, and ASM No.3. A mathematical framework is developed for use in the optimal sizing of a wastewater treatment system comprising an activated sludge system preceded by a primary clarifier. Recent mathematical models including the ASM3 model are employed to predict the performance of the considered unit processes. Cost information functions, including capital and operational costs of different system units, are also modeled. An optimization problem is formulated with the objective of producing optimal sizes of different units with least cost while meeting the effluent requirements. The problem is a nonlinear programming problem that is solved using the General Algebraic Modeling Systems software "GAMS". The optimization model is applied to an illustrative problem producing valuable results that help in explaining the influence of various involved parameters and the inputs upon the system performance.