Flotation Techniques in Waste Water Treatment

In today’s world of environmental strain, waste water treatment is becoming a more or less conventional application of flotation as, for instance, in the oil, food or chemical industries, sewage treatment, etc. In this paper, different flotation methods (ion flotation, precipitate flotation, adsorbing colloid flotation), and techniques (dispersed-air, electrolytic and dissolved-air flotation) are rewiewed and several applications of these for waste water treatment are presented, noting the need for further chemical engineering development and knowledge of this process. Selected bench- scale experimental results are also given, specifically for the removal of dyes, phosphates and toxic metals, including chromium, silver and copper, the latter on pyrite fines. The processing of dilute aqueous metal solutions for precious metals recovery is stressed, possibly as an alternative to hydrometallurgy.