Treatment of Reactive Brilliant Blue X-BR Synthetic Wastewater by Asynchronous Periodic Reversal Electrocoagulation and Its Strengthening Mechanism

Abstract

Electrode surface passivation and polarization are the important reasons why traditional electrocoagulation process is restricted wide application in the field of wastewater treatment. In order to solve this, asynchronous periodic reversal electrocoagulation (APREC) with Al/Fe electrodes was used by the authors’s team. By this method, iron and aluminum plates were used as electrodes at the same time and the current switched the direction periodically, so the surface of original anode will be reduced when becoming cathode, the passivation film on its surface and polarization between two electrods will be removed, and the different advantages of iron and aluminum ions will be adopted in the electrocoagulation process at the same time, which makes improvement on treatment efficiency. However, this method easily leads excessive aluminum ions to remain in the wastewater, and it is harmful. To avoid this, the author uses the asynchronous periodic reversal electrocoagulation (APREC) with Al/Fe to treat reactive brilliant blue X-BR synthetic wastewater. Influencing factors include asynchronization alternating period, voltage, stirring speed, initial wastewater concentration, initial pH value, electrolyte (Na2SO4) concentration, and plate spacing on the treatment efficiency are investigated first, then based on the optimal experimental conditions, the concentration of Al3+ in the treated water is monitored to make comparison with SPREC method. Date shows that under the optimal conditions, almost 100% chromaticity and more than 76% chemical oxygen demand (COD) are removed after 30 min of treatment, and the content of Al3+ could not be detected after treatment with 20 min to 45 min. According to the analysis, better structures and particle size of Fe3+/Al3+ coagulant make it easier to remove COD and chrominance in the wastewater when using the APREC method.