• LK Wang, MHS Wang, NK Shammas, and MS Holtorff (2020). Independent physicochemical wastewater treatment system consisting of primary flotation clarification, secondary flotation clarification and tertiary treatment. In: “Environmental Science, Technology, Engineering, and Mathematics (STEM)” , Lawrence K. Wang, Mu-Hao Sung Wang, and Nazih K Shammas (editors). Volume 2020, Number 3, March 2020; 91 pages. Lenox Institute Press, Newtonville, New York 12128-0405, USA. STEM-VOL2020-NUM3-MAR2020.———-ABSTRACT: The first wave of evolutionary development of dissolved air flotation (DAF) is its application for drinking water treatment. Today DAF has been adopted internationally including the world’s largest city, New York, for highly efficient and cost-effective potable water treatment. This book chapter introduces the DAF’s second wave of evolutionary development in wastewater treatment applications, such as primary flotation clarification, secondary flotation clarification, total physicochemical DAF wastewater treatment, multi-stage municipal wastewater treatment, tertiary wastewater treatment, combined municipal and industrial wastewater, DAF process equipment development, DAF process system development, etc. Specific coverage of this publication includes: conceptual development of independent physicochemical wastewater treatment systems (IPCWWTS), process glossary, commercial development process equipment, laboratory process evaluation, chemical optimization, pilot plant installation, BOD removal, TSS removal, nutrient removal, and pilot plant system operation and demonstration using actual screened raw wastewater from Lee Wastewater Treatment Plant, Lee, Massachusetts, USA. The IPCWWTS developed by the authors can be in any shape (circular or rectangular), can use any manufacturers’ products (Supracell, Sandfloat, KAMET, AquaDAF, clair-DAF, etc.), and is for the entire world.