PLUGFLOW DISSOLVED AIR FLOTATION

In a conventional rectangular flotation basin, acceptable separation e fficiencies in excess of 90% can rarely be achieved with an operationa l surface loading in excess of 15 m/h, because of the great degree of dispersion, turbulence, and dead space present in the basin. A pilot-s cale coaxial cylinder-type flotation column was built to fulfill the r equired plugflow performance, to reduce dead space, and to optimize th e size. Using a step stimulus-response test, it was observed that the column exhibits near-plugflow performance within surface loading of 5 to 30 m/h. The influence of the air bubble cloud concentration in the stream on the degree of dispersion in the column was investigated. The performance of the pilot column has been verified for an industrial w aste water under winter conditions.