Paper: Induced Gas Flotation Process For Water Clarification

Removal of emulsified oil from waste water is receiving renewed attention in light of best practical control technology and treatment level requirements. This paper presents a discussion of the induced-gas flotation process as a method for cleaning waste waters by removing suspended contaminants using, froth floration. The origin of the process is briefly reviewed and a comparison is made to dissolved-air flotation showing that the two processes have both similarities and differences. A method of inducing and dispersing gas bubbles into water with individual cell mechanisms is discussed. Consideration is given to both the hydraulic and chemical characteristics of the stream. The complete flotation machine incorporating multiple cells in series is assessed from the mechanical design standpoint. The operation of induced-gas flotation equipment is explained. Consideration is given to the interrelationship of various design and operational aspects of this process. Both the importance and the limitation of chemical treatment additives are pointed out. A bench test method for selecting chemical treatment is discussed with a critical review of its ability to predict scale-up unit performance and the chemical formulation and volume requirements. Review of past oilfield experience with induced gas flotation machinery, shows that this is a viable method for cleaning produced water of suspended oil and solid particles.