The Influence Of Complex On COD Determination For Electroplating Effluent

Electroplating is one of three polluting industries at the present world. According to the estimating, the wastewater discharge from electroplating process is approximately 40 million m3 in domestic electroplating industry every year. In electroplating process, a numbers of metal ions and additives while the cleaning processes inflow the flume, this is the so-called electroplating wastewater. Nowadays there are the various methods of processing electroplating wastewater, but mostly methods are about recycling of heavy metal ions from electroplating wastewater, and the study based on the view of treatment complex in electroplating wastewater and discuss the influence on COD is less relatively. The complex how much affect on COD, that will be discussed in this study.The complex how to form and break was investigated through the experiment. Many additives which contain organic reducing substances were used to enhance the plating effect, and form a stable complex with metal ions in water. Those complex led to the measured values of COD is less than the real value of COD. The conventional approach to electroplating wastewater is only focus on the removal and recovery of heavy metal ions in water, and not attention to substances relating to COD, namely, not consider the complex to impact on COD. Although the treated wastewater is compliance on the surface, in fact its real value of COD value has not been able to achieve permitted emission standards. We used to break complex, and investigate real values of COD in water. Through physical and chemical methods to break complex, and testing COD value before and after the treatment. The experimental results show that the values of COD changed. The presence of complex result in the measured values of COD lower, therefore, the breaking complex should be considered while treating electroplating wastewater.In this study, chemical breaking complex such as ferrous sulfate and sodium sulfide method were applied, physical breaking complex such as pulse discharge technique was applied. After the chemical treatment, the COD value of sample and the COD value of complex agent are consistent, but the physical treatment effect is not ideal. We recommend the use of chemical breaking complex is better.