Abstract:
This research was proposed to find the optimum condition of color and pollutants reduction in pulp and paper mill wastewater by using the electrocoagulation techniques in batch and continuous reactors. Six pieces of iron plates constructed in parallel configurations were used as electrodes. The parameters investigated in the batch treatment process were current density, initial pH of wastewater, type of polyelectrolyte and circulating flow rate of wastewater in reactor. The preliminary results indicated that the polyelectrolyte had no effect on the pollutants removal. The optimum condition for treating pulp and paper mill wastewater in batch reactor was found at current density of 2.07 A/m , initial pH of wastewater of 7.58, circulating flow rate of wastewater in reactor 0f 2.6 I/min electrolysis time. According to this condition, the removal efficiency of color, COD, BOD, TSS and TDS were 97.0%, 87.8%, 50.4%, 89.8% and 37.5%, respectively. The pollutants in treated wastewater were less than the standard values of Thai Government except BOD. The total operating cost of the treatment process was approximately 0.29 US$/m wastewater. For the wastewater treatment in continuous system, the optimum condition was found at current density of 20.7 A/m initial pH of 7.58, circulating flow rate of wastewater in reactor of 2.6 I/min and flow rate of wastewater of 66.7 mI/min. The treatment process reached the study state condition within 4.50 hrs. At this condition, the removal efficiency of color, COD, BOD, TSS and TDS were 90.9%, 76.8%, 61.5%, 89.9% and 35.3%, respectively. The pH of the treated wastewater and the iron content were around 8.05 and 0.098 mg/I, respectively.