Experimental study of low intensity cyclone flotation on wastewater treatment

Key words:  oily wastewater  water treatment  cyclone flotation  low intensity swirl field  jet device

Abstract:

Low intensity cyclone flotation is an unconventional flotation based on low intensity centrifugal force field, which uses centrifugal force to enhance the collision and adherence between oil droplet and bubble, and therefore improves the flotation efficiency. To optimize the separation performance of low intensity cyclone flotation, the influences of swirl intensity, oil content, reflux ratio, bubble injection method(downstream, upstream) on the flotation performance were studied. The results show that, when the swirl flow field is turbulent flow of low Reynolds number, the oil droplets can collide and adhere with the bubbles effectively, and then can avoid the destruction of the oil droplet-bubble polymer caused by the high intensity turbulent flow. The performance of downstream flotation is different from one of upstream flotation. The low intensity cyclone flotation unit has strong ability to adapt to hydraulic fluctuations, and can treat wastewater of low oil content effectively. The optimum operating condition of cyclone flotation unit is:when the inlet centrifugal acceleration is 17.0 g(downstream) or 13.0 g(upstream), oil content is 500 mg/L, reflux ratio is 20%-35%(downstream) or 30%-35% (upstream), the oil removal rate is not less than 75%.