The Separation of Tramp Elements From the Heavy Metal Ions Containing Wastewater, and Treatment by Crystal Growth and Cake Filtration

摘要

Much of sludge, which is produced by neutralization of the heavy metal ions containing wastewater from pickling and plating lines, is dumped out as industrial waste. To recycle the sludge as iron source, the tramp elements, such as nickel, zinc, must be separated from iron in the treatment of wastewater. This paper describes the experimental study on the separation of tramp elements using the crystal growth with pH control. The results are summarized as follows. Fe~(3+) ions are separated from the wastewater containing heavy metal ions as solid at pH 4, and Ni~(2+), Zn~(2+) ions are separated at pH 9. With the treatment of wastewater containing Ni~(2+) and Zn~(2+) ions using the crystallization reactor which has a cake filtration unit, the mean particle size increased into 35.5 mu m by the crystallization. The growth of particle lowers the specific resistance of cake by two orders.