Treatment of simulated electroplating wastewater containing Ni(II)-EDTA by Fenton oxidation combined with recycled ferrite process under ambient temperature

Developing low cost and efficient method for the treatment of electroplating wastewater containing heavy metals complexed with chelating agent has attracted increasing attention in industrial wastewater treatment. This study involved a system combining Fenton oxidation (FO) and recycled ferrite (RF) process for treating synthetic solution containing Ni(II)-EDTA at ambient temperature. In this system, the FO reaction can produce hydroxyl radicals with high redox potential to decomplex the metal-organic complexes and degrade the organics, thereby enhancing the removal efficiency of heavy metals. The RF process is to incorporate the non-iron metal into the spinel ferrites at room temperature, and stabilize the sludge. As a result, the toxicity characteristic leaching procedure can fulfill the relevant standards. Furthermore, the ferrous ions in Fenton reaction could be used as the source of irons in RF process. After treatment by the combined process, the effluent water fulfills the relevant standard in China. In comparison with conventional alkaline precipitation, the sludge sedimentation velocity of FO-RF is 2.16 times faster than that of conventional alkaline precipitation and the volume of sludge is reduced by half, which strongly demonstrated the advantages of the presented FO-RF system and indicated the huge potential for the treatment of EDTA-chelated nickel.