Cleaning contaminated water by gravity flotation

New constructions are considered for single- and multistage flotation units. It is shown that in single-stage equipment high quality cleaning of liquid insoluble suspensions from water with a continuous operating regime is impossible. Six-stage cleaning is necessary with a periodic water cleaning regime in order to remove the content of liquid impurities within it (for example industrial oil) to 40 mg/liter. The advantages of gravity flotation compared with gravity settling are noted.