Treatment of wastewater from adhesive-producing industries by electrocoagulation and electrochemical oxidation

Adhesive wastewater from adhesive-producing industries is a kind of refractory organic wastewater containing high chemical oxygen demand (COD) and ammonia nitrogen. In this study, the electrocoagulation and electrochemical technology were in series attempted to treat adhesive wastewater from adhesive-producing industries. The effects of operating parameters such as current density and initial pH were investigated to determine the optimum electrocoagulation parameters. The removals of COD and ammonia nitrogen achieved 81.62%, and 50.92%, respectively, under the optimum electrocoagulation conditions (current density of 5 mA/cm2, pH 3, 2 g/L Na2SO4 supporting electrolyte solution, 60 min of electrocoagulation). The effluent of electrocoagulation was subsequently treated by electrochemical oxidation. The effects of operating parameters, such as current density, initial pH, and supporting electrolyte, on the degradation of COD and ammonia nitrogen were investigated. The COD and ammonia nitrogen removal ratios were both as high as nearly 100% after electrolysis of 120 min (current density of 35 mA/cm2, pH 8.4, 2 g/L NaCl supporting electrolyte solution). The results of excitation-emission-matrix (EEM) revealed the changes of different dissolved organic matter after electrocoagulation and electrochemical oxidation treatment. The experimental results proved that the electrocoagulation combined with electrochemical oxidation methods are the potential technologies for treatment of adhesive wastewater.