EFFECT OF USING DISSOLVED AIR FLOTATION SYSTEM ON INDUSTRIAL WASTEWATER TREATMENT IN PILOT SCALE

In the present paper the application of Dissolved Air Flotation (DAF) system for wastewater treatment, especially for industrial wastewater on a designed pilot system has been investigated. It is for the first time in dissolved air flotation system that instead of air dissolving tube, hydro cyclone technology is used to dissolve air in water with ratio of 1:1 (almost 100%) in the form of small air bubbles and a circular flotation tank instead of rectangular tank. The advantage of usage of circular tank in DAF system is the capability of being treated in higher rate of mass, so less space is needed. Although application of hydro cyclone with different diameters of holes for producing mixing energy which also has the capability of direct injection of chemical coagulant and polymeric materials leads to the higher efficiency of treatment and so reduces the cost of pump and consumed air. Investigations on the efficiency of this system were done by providing and analyzing samples of wastewater with and without adding of PAC (Poly Aluminum Chloride). Sampling and analyzing was done according to standard methods. The results of the analyses show that pilot system has high efficiency, especially for oil removal.