Abstract:
To study the removal of cyanide and heavy metals from typical small and medium electroplating industries wastewater by ion exchange process. Typical cation and anion exchange resins were used. Batch and column experiments were performed on synthetic wastewater (cyanide, cyanide and chromium, cycanide and copper, cyanide and nickel, cyanide and zinc and cyanide and 4 heavy metals) at pH of 10 and 12 to investigate the removal efficiency. In batch experiment, the removal efficiency of 0.15 l-resin/water anion resin IRA 402 CI for removing 200 mg/I of cyanide was more than 94%. For the mixture of cyanide and heavy metals, this resin removed at least 91% and 96% of cyanide and heavy metals, respectively. the compared results of pH 10 and 12 showed no significant differences for the removal efficiency. The cation resin IR 120 Na removed up to 1.5 and 3 percent for cyanide and heavy metals, respectively. For column experiment, it was also found that anion resin should be adequate for removal of cyanide and heavy metals in synthetic wastewater at pH 12 and 12. Different type of heavy metals showed variations on the resin capacity. The bed volumes to reach the cyanide discharge standard were 50 bed volumes for 200 mg/I of cyanide wastewater. For the mixture of cyanide and chromium, mixture of cyanide and copper, and mixture of cyanide and nickel the bed volumes to reach cyanide discharge standards were similary at 40 bed volumes. For the mixture of cyanide and zinc and 4 heavy metals, they were 60 and 110 bed volumes, respectively