This system based on ion exchange principle, will remove both Hexavalent chromium as anion and Trivalent chromium, Nickel, Iron etc. as cation, in a two bed ion exchange system.
The static rinse after chrome palting drag out tank, containing Hexavalent chrome ions and othe cationic impurities like trivalent chrome, Nickel, iron, copper etc. is pumped through chrome recovery coloumns. The strongly acidic cation exchanger removes trivalent chromium (and other cations) while the macroracticular weak base anion exchange resin removes the haxavalent chrome. This produces deionised water which can be recycled in a closed loop system.
The hexavlent chromium is eluted from anion exchanger with sodium Hydroxide in a concentrated solution. This solution is further passed through a third column containing strongly acidic resin in the hydrogen form. to recover chromic acid which can be recycled to the plating bath after concentrating in an evaporator.