Wang, LK, and Wang, MHS (2022). innovative process system consisting of dissolved air flotation, recarbonation and filtration, using lime and sodium aluminate for removal of hardness, iron and manganese from groundwater. In: “Evolutionary Progress in Science, Technology, Engineering, Arts and Mathematics (STEAM)”, Wang, LK and Tsao, HP (eds.), 4 (10A), STEAM-VOL4-NUM10A-OCT2022. 34 pages. October 2022, Lenox Institute Press, Massachusetts, USA. …….ABSTRACT: The Lenox Institute of Water Technology (LIWT) has conducted a basic research: (a) a new softening and Fe-Mn removal process system consisting of dissolved air flotation (DAF), recarbonation and filtration has been demonstrated by operating a continuous water treatment plant (WTP); (b) a new chemical combination including lime, sodium aluminate and carbon dioxide has been used successfully for simultaneous removal of Ca-Mg hardness, iron and manganese from groundwater; (c) DAF (3-15 minutes detention time) replaces conventional sedimentation (4-6 hours detention) to become much more cost-effective; (d) DAF-filtration efficiently removes Fe-Mn without an additional oxidation step; (e) sodium aluminate enhances or replaces conventional soda ash for better removal of non-carbonate hardness (NCH) and better removal of manganese after DAF oxidation due to its flocculating nature; (f) the authors call for further basic research regarding the chemistry of Ca-Mg removal by sodium aluminate noting that both calcium aluminate and magnesium aluminate are insoluble substances; (g) further call for research is directed toward simultaneous removal of hardness, Fe-Mn and dissolved organic matter (DOM) by the new process system and new chemical combination; and (h) LIWT new process systems and new chemical combinations can be applied to any manufacturers’ DAF, recarbonation and filtration process equipment (Sandfloat, Supracell, AquaDAF, Clari-DAF, etc. )