Optimization and reaction kinetics on the removal of Nickel and COD from wastewater from electroplating industry using Electrocoagulation and Advanced Oxidation Processes

Suzuki Indomobil Motor Plant (SIMP) Cakung, East Jakarta, Indonesia generates wastewater containing heavy metals such as nickel, zinc, chromium, copper, and COD derived from the metal coating process using the electroplating system. Electroplating wastewater produced by this company contains Nickel and COD above the quality standards set by the Government of DKI Jakarta (Governor Regulation No. 69/2013). This research aims to analyze and compare the efficiency and kinetics of Nickel complexes and COD removal using the Advanced Oxidation Process (AOP) and Electrocoagulation (EC) method. Electroplating wastewater generated by SIMP Cakung (ratio of plating wastewater to overflow plating wastewater is 1:30) in this study had characteristics of 379-568 ppm (effluent standard = 75 ppm) of COD, and 87.555-121 ppm (effluent standard = 1 ppm) of Nickel. Preliminary experiments with the factorial design method indicated that independent variables (pH, current density, ozone flow rate, and contact time) had a critical influence/significance on the removal efficiency of Nickel complexes, while the influence of the above variables in COD removal efficiency was not significant. Optimum operating conditions for Nickel complexes and COD removal using both AOP and EC reactor were found in this study as well as the reaction kinetics of the removal rate. Our study found that the optimum operating conditions for Nickel complexes and COD removal using the AOP reactor were at the pH of 10, the ozone flow rate of 2 L/min, the contact time of 60 min (99.75% and 51.25% for Nickel and COD removal, respectively). For the EC reactor, the optimum condition for Nickel and COD removal are pH of 6.5, the current density of 20 mA/cm(2) and the contact time of 50 min (99.75% and 51.25% for Nickel and COD removal, respectively). In these conditions, the AOP reactor in its optimum condition could remove Nickel and COD more compared to the EC reactor. This finding suggests that AOP technology is not only reliable in removing Nickel from electroplating industrial wastewater, but also it could reduce the loading of COD for further treatment units by more than 50%. Further studies in the effect of the longer contact time and higher ozone flowrate on COD removal is suggested.