Air-sparged hydrocyclone treatment of water contaminated with volatile organic compounds

Application of the air-sparged hydrocyclone (ASH) as a contacting reactor was implemented and evaluated for the first time. Stripping of volatile organic compounds (VOCs) from contaminated water was the application considered. The experimental approach can be divided into two parts, (1) flow characterization—examination of the multi-phase flow details and (2) engineering analysis—mass transfer considerations of VOC stripping in pilot plant tests.; Multiphase flow characteristics included measurements and calculations of flow texture (including apparent bubble size distributions), radial water distributions, hold-up volumes and residence times for both water and air. Experimental results collected for Q* (air to water flowrates ratio) higher than 5 were obtained for the first time. Corresponding air hold-up volumes and residence times were determined. The radial water distribution was the first direct measure of this characteristic. The main outcome of the multi-phase flow characterization was the identification and description of three, Q* dependent, flow regimes, with different phase continuities and/or textures.; The effectiveness of the ASH system for VOCs stripping was demonstrated through a number of experiments, using trichloroethylene (TCE) as a model contaminant. Results from these tests show that the ASH technology is very competitive with other stripping technologies and that single stage contaminant removal exceeding 90% can be achieved. Calculated volumetric mass transfer coefficients are three orders of magnitude higher than those for conventional stripping methods.; ASH combines advantages of conventional hydrocyclones with an air sparging system into an unique piece of equipment with a specific capacity many times higher than conventional stripping systems. Industrial areas where space is at a premium, or where the wastestream cannot be held indefinitely for later treatment, are primary targets for the application of ASH technology. ASH stripping technology provides an excellent opportunity for both high-capacity, fast separation of VOCs from large volume flows for emergency situations or site-specific services for small volume flows with a compact mobile system.