Heavy metals and organics are always presented an important rule in the pollution control. In Taiwan, there are large amounts of toxic wastewater produced from electrical plating, metal surface-treating, steel, IC, electrics, photo-electrics, printed PC board, refinery, medicals, oil painting and foods manufactory industries. Those wastewater are contained toxic and hazardous materials materials to human body or environment quality. Thus, we believe it need immediately to develop the innovative process on removal of wastewater containing heavy metals and organic compounds.
This study uses the strong oxidation of Fenton’s Process to first remove the organic pollutant, EDTA, and then uses Ferrite Process to incorporate heavy metal ions into spinel structure for facilitating removal of heavy metal ions, and through this work, the best operation model of series treatment “Fenton/Ferrite Process” is established.
With respect to batch reaction in Fenton’s Process, the emphasis in this work is placed the effect on EDTA removal by pH, ferrous ions concentration, and hydrogen peroxide . The results show that the best removal of EDTA occurs when Fenton is under acid condition (pH=2); and the removal of EDTA increase as the ferrous ions and hydrogen peroxide increase adequately, but when its quantity exceeds a certain value, the removal of EDTA would decrease as follows. Such a result may be caused by the excess of ferrous ions and hydrogen peroxide which could restain generation of hydroxyl radicals.
As followed the Fenton’s process, Ferrite Process is next used for treatment of wastewater in series; Ferrite Process has three stages, and the operating conditions are controlled temperature and pH. For the first stage, the operating condition is 70℃, and pH is 9.0; and the operating condition is 90℃, and pH is 9.0 in the second stage; and the operating condition is 80℃, and pH is 10.0 in the last stage.
From the results of series experiments, with respect to reaction time, each concentration of heavy metal in supernatant could meet the standards of discharge water when the total time of A-4 experimental condition is 90 minutes; if Hg ion is not included in wastewater, then the reaction time could be reduced to 50 minutes. I shows benefit for short reaction it the time. Under A-3 experimental condition, the reaction time is 56 minutes when Cd and Hg ions are not included in the wastewater, then each ions concentration of heavy metal could also reach the standards of discharge water, and this experiment need of ferrous ions is least of all. Thus, this experiment in this work has the economic benefits both for regarding time and cost-effectiveness.
Keywords：Fenton’s Process、Ferrite Process、EDTA、Heavy metal