Design and Analysis of Chemical Coagulation Systems to Enhance the Performance of Waste Stabilization Lagoons

The purpose of this thesis is to elucidate the concept of chemical coagulation and its application in enhancing the performance of waste stabilization lagoons. The design and analysis of a pre-pond chemical precipitation system and an in-pond chemical precipitation system are presented, compared, and contrasted to an aerated lagoon system; the design of each system includes liquid and sludge treatment. The design and analysis of the chemically enhanced lagoon systems are for the city of Tatui, Sao Paulo, Brasil. The current lagoon treatment system is overloaded, and thus will be upgraded or replaced. The designs, presented in this thesis, are based on jar tests conducted at the present facility. The analysis includes an analysis of the jar test data, the field study, and the design of all each alternative. It was found that the aerated lagoon system is under-designed from the standpoint of mixing requirements and is the least cost-effective. The pre-pond precipitation lagoon system yields a high removal efficiency of BOD 5 and is moderately cost-efficient. The in-pond precipitation lagoon system yields a high BOD 5 removal efficiency and is also the most cost-effective design.