Performance Evaluation of Low Current Density Electrocoagulation in Textile Dyeing Wastewater Treatment under Different Salinity

The increasing salinity of industrial effluents, particularly from textile dyeing, poses a major challenge to conventional wastewater treatment. This study evaluated the performance of an electrocoagulation (EC) system at low current density for treating synthetic textile wastewater containing an azo dye under three salinity levels: ۵, ۲۰, and ۳۵ g/L NaCl. Experiments were performed in batch mode using iron electrodes at ۱ mA/cm², an initial dye concentration of ۱۰۰ mg/L, and an influent COD of ۸۸۰ _x۰۰۱۷_۷ ۳۴.۶ mg/L. The effects of salinity on color removal, COD reduction, turbidity, and anode corrosion were analyzed.The results revealed that increasing salinity enhanced electrical conductivity and accelerated Fe۲+/Fe۳+ generation, strengthening both coagulation and electrochemical oxidation mechanisms. At ۵ g/L NaCl, the EC system achieved ۷۷.۸۴_x۰۰۱۷_۷۰.۰۰ % color removal and ۶۷.۰۵_x۰۰۱۷_۷۱.۶ % COD reduction. When salinity increased to ۲۰ g/L, performance improved to ۸۷.۷۱_x۰۰۱۷_۷۰.۰ % color removal and ۷۳.۸۶_x۰۰۱۷_۷۱.۶ % COD reduction, representing the optimal balance between removal efficiency and system stability. A further increase to ۳۵ g/L NaCl yielded only a slight improvement in color removal (۸۸.۰۳_x۰۰۱۷_۷۰.۰ %) but enhanced COD removal to ۹۰.۹_x۰۰۱۷_۷۰.۰ %, likely due to intensified oxidation reactions. However, excessive salinity led to partial floc destabilization and mild electrode passivation.Overall, a salinity level of ۲۰ g/L NaCl was identified as the optimum condition, offering the best balance between pollutant removal, electrode stability, and operational cost. The findings confirm that the low-current-density EC process provides a simple, efficient, and sustainable solution for treating saline textile wastewater.

کلیدواژه ها:

Textile Dyeing Wastewater ، Electrocoagulation ، Current density ، Color removal ، Salinity