ABSTRACT

Wastewater Treatment System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1156 27.1.3 Application of Secondary Flotation Clari cation as an

Engineering Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1156 27.1.4 Objectives of the Engineering Research and Documentations . . . . . . . . . . . . 1157

27.2 DAF and DAFF Clari ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1159 27.2.1 Commercially Available DAF and DAFF

Clari ers for Biological Wastewater Treatment Systems . . . . . . . . . . . . . . . . 1159 27.2.2 General Operational Description of DAF and DAFF Clari ers . . . . . . . . . . . 1161

27.3 Improved Biological Treatment System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1166 27.3.1 General Principles and Process Description . . . . . . . . . . . . . . . . . . . . . . . . . . 1166 27.3.2 General Kinetics of Activated Sludge Wastewater

Treatment System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1168 27.3.3 Process-Speci c Kinetics of Conventional Activated

Sludge Process Systems with Sludge Recycle . . . . . . . . . . . . . . . . . . . . . . . . . 1168 27.3.4 Speci c Kinetics of the Improved Activated

Sludge Process Using Secondary Flotation . . . . . . . . . . . . . . . . . . . . . . . . . . 1171 27.4 Case History: A Petrochemical Corporation in Texas . . . . . . . . . . . . . . . . . . . . . . . . . 1175 27.5 Case History: A Municipal Ef uent Treatment Plant in Haltern, Germany . . . . . . . . . 1177 27.6 Case History: A Paper Company in Houston, Texas . . . . . . . . . . . . . . . . . . . . . . . . . . 1178 27.7 Discussions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1183 27.8 Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1185 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1186 Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1186 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1186 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1187

A description is given of a unique solution for the problems of overloaded conventional activated sludge systems. A high-rate dissolved air otation (DAF) clari er is applied in series between the

microorganisms before secondary sedimentation. This results in the following improvements in the existing wastewater treatment system:

a. Solids and hydraulic loadings on an overloaded secondary sedimentation are reduced for preventing sludge rising, increasing clari cation ef ciency, and saving construction cost on expansion of secondary sedimentation facilities.