M.GH. - Flotation Unit
From Production Machinery
Clarification by flotation can be used alternatively to clarification by gravity. Dissolved air flotation is a method for separating and removing suspended solids from liquid, based on changes in the solubility of gas as pressure varies.
Air is dissolved under pressure in a clean liquid, usually recycled effluent from the Daf unit, and injected into the raw fees stream. Upon entering the DAF unit, the air pressure is released and combined with the liquid, which becomes supersaturated with micron.sized air bubbles.
Suspended materials attach to the anionically-charged, micron-sized air bubbles producing a lower specific gravity for the agglomerate less than that of water, thus effectively raising the suspended particles to the liquid surface, forming a floating sludge layer that is removed by skimmers. Heavier solids settle to the bottom of the tank and are raked to a sludge pocket for removal. Clear subnatant liquid is withdrawn under the tank baffle and over the weir for disposal or re-use.