THE ELIMINATION OF CHANNELING AND FOAM OVERTURNING IN CONTINUOUS-MODEADSORBING COLLOID FLOTATION WITH A SODIUM DODECYL-SULFATE DODECANOIC ACID MIXTURE

The effect of hydraulic loading, surfactant concentration, and air flo w rate on the removal of Cr(III), Ni(II), and Zn(II) from chromium str eam electroplating wastewater by adsorbing colloid flotation using a s odium dodecylsulfate/dodecanoic acid mixture was investigated. Typical ly, heavy metal concentrations of 81 ppm Cr(III), 55 ppm Ni(II), and 3 .3 ppm Zn(II) were reduced to 1.2 ppm Cr(III), 3.2 ppm Ni(II), and 0.0 5 ppm Zn(II) at a hydraulic loading of 22.9 m3/m2.h (3 L.min-1), an ai r flow rate of 45.8 m3/m2.h (6 L.min-1), 40 ppm dodecanoic acid, and 8 0 ppm sodium dodecylsulfate, and using a 10-cm inner diameter column. A novel mode of operation (high liquid carryover) was used whereby a l arge proportion of the liquid entering the column leaves the column wi th the foam.