Expansional osmosis flotation

Abstract

Waste water is a multiphase dispersion contact medium (MDM) that contains solid particles of homogenously dispersed components, dilute solutions of hydrated salts and colloidal dispersions. It is considered that impurities in waste water consist of different kinds of entities dispersed in clear water. They can be divided in two scales, micro scale that includes objects and nano scale that includes molecules. Transformation of (MDM) from raw dispersions to solutions is continuous, but in practice it is classified into dispersions, emulsions, colloids and solutions. This paper promotes an idea of expansional osmosis flotation which is suitable for application on both scales of entities for all mentioned multiphase dispersion contact mediums. Expansional osmosis is designed in a way that colligate properties of waste water in separation processes are utilized. Decrease of impurities content in flotation pulp outlet flow is on the base of osmotic pressure. Expansional osmosis flotation unit consists of two separate units: pump that increases pressure in waste water and expansion vessel where flotation takes place. Due to the increased pressure in pump, level of dissolved air in water is increased. Decrease of pressure in expansion vessel creates a possibility to separate molecules of dissolved impurities from molecules of water. That way with use of semi-permeable membrane, such as certain type of flocculant, an increase of less volatile component-impurity content from MDM in flotation foam can be obtained. While classic flotation process conforms to the continuous model, expansional osmosis flotation conforms to the discontinuous model. Periodical dumping of impurities is regulated by the automated valve mounted on the outlet pipe of the flotation cell.