Treatability Study of the Industrial Effluent by Electrocoagulation

Various techniques such as physical, chemical, biological, advanced oxidation and electrochemical are used for the treatment of industrial effluent. The commonly used conventional biological treatment processes are time consuming, need large operational area and are not effective for effluent containing toxic elements. Advanced oxidation techniques result in high treatment cost and are generally used to obtain high purity grade water. The chemical coagulation technique is slow and generates large amount of sludge. Electrocoagulation (EC) has recently attracted attention as a potential technique for treating the industrial effluent due to its versatility and environmental compatibility. The aim of this research is to assess the treatability of electrocoagulation process for the industrial effluent. Therefore, in the present study, the use of electrocoagulation has been explored for the treatment of different industrial effluent. Electrochemical treatment of the synthetic solution containing acid red 131 dye and industrial effluents containing mixture of dyes were studied by performing experiments in batch mode of operation using aluminum electrodes. The effect of various parameters, such as pH of the solution, current density, inter-electrode distance, agitation speed, etc., was investigated. Color removal efficiency (CRE) of more than 97 % was obtained for each of the dyes for an electrolysis time of 120 min. Experiments were also performed using aluminum sulphate as a coagulant to compare the CRE obtained by EC and chemical coagulation for the treatment of the dyes. Electrochemical treatment of the distillery spent wash was carried out using different combinations of aluminum and iron electrodes. The maximum COD removal efficiency of 81.3 % was obtained with Al-Al electrodes at the current density of 187 mA/cm 2 and solution pH 3 for an electrolysis time of 120 min. Efforts have been made to study the effect of shape of the electrodes on the performance of EC. The shape of the electrode was changed from plane to punched hole electrodes. The effect of the number of holes and the geometry (square, triangular and random pitch) of the punched holes on the performance of the electrocoagulation has been investigated. Electrocoagulation using direct current power supply source leads to passivation and increases the power consumption as well as the operating cost. Therefore, efforts were made to reduce the passivation problem by performing experiments using alternating current (AC) in place of direct current (DC) in the electrocoagulation process.