Electroplating Wastewater Concentration System Utilizing Mechanical Vapor Recompression

Abstract

Electroplating wastewater must be properly treated before being discharged to the environment. A new type of evaporation system, called mechanical vapor recompression (MVR), was designed and studied in this paper. A series of experiments were performed to determine the evaporation and chemical characteristics of the wastewater. During MVR operation, the wastewater and treated water were sampled hourly at the monitoring points. The results showed that after the MVR evaporation, the chemical oxygen demand (COD) decreased from 5,45 to 55 mg/L, the average Cu content decreased from 55 to .5 mg/L, and the Ni and Zn contents decreased from 65 and 5 mg/L to less than .2 mg/L. In addition, the evaporation was approximately 26 kg/h at an evaporative temperature of 9°C and increased with increasing compressor frequency; the variation in the compressor power followed the same trend as the variation in the evaporation capacity.