DESIGN OPTIMIZATION OF LAGOON SYSTEM FOR WASTEWATER TREATMENT

Abstract

Lagoons have been found to be an effective and relatively inexpensive means of treating domestic sewage. Economic considerations and space limitations tend to make this method of treatment attractive to small urban areas. The goal in wastewater treatment plant design is to provide systems to meet specified requirements at minimal cost. Optimization models have been used over the years in the preliminary design of wastewater treatment systems to obtain a least cost design. However, with a view to obtain the optimum design other information such as cost and performance data of the treatment processes need to be considered together. The thesis deals with the development of a mathematical model incorporating the performance relationships and cost functions for the component units of a lagoon system (viz aerated lagoon followed by a waste stabilization pond) for sewage treatment. A grid search algorithm has been used for functional and minimal cost design i.e.,optimal design of the system. The normal and optimal cost comparisons were made and percentage saving due to optimal design was reported. Optimum pond depths on the basis of bacterial removal efficiency were formulated and optimum depth reported. Based upon the findings, conclusions have been drawn regarding the optimum design of lagoon system for sewage treatment.