Development of an industrial symbiosis implementation for the evaluation of electrocoagulation residues containing heavy metals

This research experimentally investigates the treatment of original electroplating wastewater with high Cr(VI) content with two different studies by electrocoagulation and electrofenton. In electrocoagulation, Rushton type iron electrode and cylindrical batch stirred iron reactor were used. pH, current density, supporting electrolyte type and supporting electrolyte concentration parameters were studied. The best performance was observed at an initial pH of 2.4, 20 mA /cm2 current density and 0.05 M NaCl electrolyte values. At an initial Cr (VI) concentration of 1000 mg /L, 100% recovery was achieved with an energy consumption of 2.68 kWh/ m3; with a concentration of 0.017 mg/L. The sludge was characterized using XRD and XRF showing the sludge is a rich source of iron and chromium and can be reused to produce value added ceramic pigments. Prepared pigments appeared to be reddish brown and black color in transparent glaze. Zero waste process is successfully introduced with 100% Cr(VI) removal and reuse of the resulting sludge as an industrial symbiosis case study. The effect of electrofenton was investigated in the treatment of another wastewater with an initial Cr (VI) concentration of 518.9 mg/L from the metal coating plant. A blade stirrer iron electrode and a cylindrical batch iron reactor were used. The effects of pH, current density and H2O2 concentrations were investigated. Before each treatment H2O2 was added to the solution. The best removal efficiency occured at a current density of 10 mA/cm2, at a pH of 3 without H2O2 addition with a removal efficiency of 99.92 % with 0.523 mg/L.