A novel technology for optimizing dissolved air flotation unit efficiency via secondary saturation of the flotation cell with air bubbles and thin-layer settling

Specific ways to improve the technology for flotation (DAF) wastewater treatment have been determined. Prospects to increase functioning of DAF units via using thin-layer cells, and improving the hydraulic size of the emerging flotation aggregates have been shown. The latter is feasible due to secondary saturation of the flotation cell with air bubbles of 0.1-0.3 mm diameter floating in laminar flow regime and creating light turbulence thereof. The possibility of obtaining an air-water mixture with air bubbles during their breaking up in the annular space of the saturator-separator is experimentally proven. It is feasible to separate the air bubbles from the major fluid flow in the centrifugal field due to rotational and translational motion of the separated mixture. It is established that converting the Q-H vane pump characteristics, which provides for pumped flow circulation and useful flow selection for the two medium-pressure ejectors operating in series, allows to: ensure stable air ejection from the atmosphere; significantly increase the vane pump head H via reducing the supplied useful flow; exclude a compressor and replace an expensive high-pressure pump with a lower operating pressure one.