Lawrence K. Wang, Mu-Hao Sung Wang, Thomas Suozzo, Rebecca A. Dixon, and Terry L. Wright (2023) . Chemical and Biochemical Technologies for Environmental Infrastructure Sustainability, In: “Evolutionary Progress in Science, Technology, Engineering, Arts, and Mathematics (STEAM)”, Lawrence K. Wang and Hung-ping Tsao (editors). Volume 5, Number 10A, October 2023; 5(10A), 58 pages. Lenox Institute Press, MA, USA. https://doi.org/10.17613/z30s-gj22 ….. ABSTRACT: Various highly efficient flotation processes and systems are introduced for water and wastewater infrastructure sustainability. This publication covers the following subjects: (a) Flotation types , theories, principles, and “zero velocity concept”; (b) Unit processes of mixing, coagulation, precipitation, flocculation, clarification (flotation or sedimentation), filtration, disinfection, sludge thickening and sludge dewatering; (c) Flotation rising rate, surface loading rate, and detention time; (d) Dissolved air flotation (DAF), DAF-filtration (DAFF) and sedimentation comparison; (e) Various municipal and industrial applications of DAF and DAFF; (f) Full scale rectangular and circular DAF and DAFF installations for potable water treatment and industrial effluent treatment when land space and budget are limited; (g) upgrading an existing sedimentation to a DAF-sedimentation clarifier; (h) DAF sludge thickening and screwpress sludge dewatering (Float Press); (i) Oxyozosynthesis system (oxygenation, ozonation, sludge wet oxidation, and Float Press sludge dewatering); (j) Biological or physicochemical sequencing batch reactor (SBR); (k) Recent advances in and case histories of dissolved gas flotation (DGF), primary flotation, secondary flotation, tertiary flotation, nitrification, denitrification, flotation sludge thickening, dissolved carbon dioxide flotation (DCDF), dairy wastewater treatment (WWT), and tannery WWT.