Abstract:With the growing emphasis on environmental protection, discharge standards of chemical oxygen demand (COD) for smelting wastewater have also been continuously raised. In response to the problem that COD in drainage from a certain process in a copper smelting plant fluctuated between 50 and 100 mg/L, the sources of COD in drainage were traced by examining COD variation patterns of water samples in the technical process. In addition, properties of influent water samples, such as composition, COD variation patterns and contribution to the COD of the day, were analyzed. Traceability of COD throughout the process facilitated the source management and control of COD. Results showed that COD in drainage was correlated with that in the neutralization water in the technical process. COD in the neutralization water was mainly from six types of influents. Among them, wastewater from the first acidification stage (influent water ①), the second acidification stage (influent water ②), and the material preparation process (influent water ③) was main contributor to the amount of COD of the day. Considering that COD in drainage was mainly indicated as organic matter, high-performance liquid chromatography was used to identify pollutant source. It was found that organic components in drainage were related to influent water①, ②, and ③. It could be inferred that COD in drainage mainly originated from the three influents. Influent water①, ②, ③ and their mixture were treated by oxidation using YJY-O-1, resulting in 40%~65% COD reduction, therefore reducing fluctuation of COD in drainage. This study innovatively employed the pollutant source tracing method to identify sources of COD in smelting wastewater, and then controlled the amount of pollutants at the source, providing certain reference values for smelting wastewater treatment.