Tanning Wastewater Pre-Treatment Using Electrocoagulation Process

The leather industry is one of the most polluting industries in the country (Iran), which annually produces several hundred tons of industrial sewage. Electrocoagulation is one of the purification methods for this wastewater. This research aimed to remove COD and turbidity from real wastewater originating from one of the leather tanning units in Charmshahr industrial park with use of electrocoagulation process. The research was conducted in laboratory scale in a 480-millimeter EC reactor. The wastewater was collected from a leather tanning unit. The main variables considered were current intensity (1.5, 2.5, 3.5 and 5 A), retention time (5, 10, 15 and 30min), initial pH (5, 6 and 8.6) and electrode material (i.e., iron, aluminum, and steel). The optimum conditions in the electrocoagulation process to achieve the maximum removal efficiency for COD equal to 63.57% were obtained in an experiment with time of 5 minutes, the current density of 23.5% mA/cm2, pH=8.62 and 2 steel electrodes. Also, in an experiment with time of 30 minutes, the current density of 23.5 mA/cm2, pH=8.62 and 4 electrodes, the removal rate of 62.88% was obtained. The results of the present study showed that the electrocoagulation can be an effective method for tannery wastewater pre-treatment and the optimum conditions can be obtained using aluminum electrodes, time of 5 minutes, the current density of 7 mA/cm2 and pH of 8.62.