PLUGFLOW DISSOLVED AIR FLOTATION

In a conventional rectangular flotation basin, acceptable separation efficiencies in excess of 90% can rarely be achieved with an operational 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-scale coaxial cylinder-type flotation column was built to fulfill the required plugflow performance, to reduce dead space, and to optimize the 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 waste water under winter conditions.