Remediation of wastewater from pulp and paper mill industry by the electrochemical technique

This research attempted to find the optimum condition for color and total COD reduction in wastewater from the pulp and paper mill industry by using electrocoagulation techniques in batch and continuous modes. Six pieces of iron plates constructed in parallel configurations were used as electrodes. The effect of key parameters including the type of polyelectrolyte, current density, initial pH of the wastewater, and the circulating flow rate of wastewater in the reactor were investigated. The results indicated that the polyelectrolyte had no effect on pollutant removal. At optimum conditions, greater than 97% of color and 77% of total COD were effectively removed with a total operating cost of approximately 0.29 USD/m3 wastewater. First order rate kinetics best explained the reduction of color and total COD concentration, the model fitting the actual data very well. For the continuous mode, the treatment process reached the steady state condition within 2.15 h and the efficiency of color and total COD reduction was greater than 91% and 77%, respectively. The properties of wastewater including color, total COD, BOD5, TSS, TDS, pH and iron ions content were in the range of the acceptable values of current Thai Government standards.