Date of Award


Publication Type

Doctoral Thesis

Degree Name



Civil and Environmental Engineering


Engineering, Civil.


McCorquodale, J. A.,




The use of computer simulation in activated sludge wastewater treatment plant design, operation and control has become more and more popular in current engineering practice. Its application can result in substantial economic savings in the construction, operation and control of sewage treatment. The applicability and reliability of the computer model engaged in the process is the most important factor in effectively applying simulations of activated sludge processes. Clarifier hydrodynamics plays an important role in the activated sludge process. It is perhaps the most sensitive part governing the performance of the activated sludge systems. Attention has long been focused on the modelling of the biological behaviour of the aeration basin in the secondary treatment system. The counterpart of the biological model, i.e. the clarifier model, is usually approached by a one-dimensional flux model known as the thickening function to predict the bottom sludge concentration and profile. This is coupled with a clarification function which is basically an empirical formula to predict the effluent concentration. The importance of clarifier modelling has not been well stressed in the current coupled modelling of activated sludge systems. The research on the hydrodynamic aspects of the processes is currently restricted on clarifiers uncoupled from the system. This approach offers a possibility to completely describe the flow pattern and suspended solids distribution in the clarifier so that its physical performance can be predicted. The effluent solids concentration, which is a most important index reflecting the efficiency of the wastewater treatment, can be simulated based on the numerical solution of the general physical governing equations. The bottom sludge distribution in the radial direction can also be considered to obtain a better prediction of the recycled sludge concentration. The effects due to change of clarifier dimensions can be investigated by this type of model. The coupling of the hydrodynamic model becomes more and more necessary in predicting the system performance influenced by the clarifier configuration and performance. A dynamic model of the activated sludge process is presented in this thesis with a balanced emphasis on the hydrodynamic aspect of the system. The model integrates a biological reaction submodel for the aeration basin and a two-dimensional hydrodynamic and mass transport submodel for the secondary clarifier. The development and verification against a set of field data were carried out. A sensitivity analysis over several parameters led to certain conclusions. The model has been applied to investigate the response and the interdependency of the aerator and the clarifier in the system.Dept. of Civil and Environmental Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1993 .J51. Source: Dissertation Abstracts International, Volume: 56-01, Section: B, page: 0396. Adviser: J. A. McCorquodale. Thesis (Ph.D.)--University of Windsor (Canada), 1993.