CHROMIUM (VI) REMOVAL FROM WASTEWATER BY ELECTROCOAGULATION IN A BATCH AND CONTINUOUS MODE

Abstract

The toxicity of hexavalent chromium (Cr(VI)) is well recognized, and its use is highly regulated in EU countries, including restrictions under frameworks like the REACH regulation in the European Union. In Republika Srpska, the use of Cr(VI) is also limited by current legal regulations, ensuring strict control over its use and discharge. Effective treatment of wastewater containing Cr(VI) is crucial for minimizing environmental and health risks. Under REACH, hexavalent chromium (chromium trioxide) is classified as a Substance of Very High Concern (SVHC) and is subject to authorization and restriction lists. Despite these measures, it is still primarily used in the electroplating, metal processing, steel, paint and varnish, and leather industries, particularly outside the EU. In this paper electrocoagulation treatments were used for removing of hexavalent chromium from synthetic wastewater. The concentration of Cr(VI) before and after treatment was determined spectrophotometrically. Experiments were performed in an electrocoagulation reactor with a capacity of 1 dm3, which can operate in batch and continuous mode. The reactor is made of acrylic, in which 8 electrodes of dimensions (10x12.3x0.3cm) are placed. The impact of electrode material, current density, supporting electrolyte, pH, as well as reactor operation mode and flow rate in continuos mode on Cr(VI) removal efficiency were tested and the high efficiency of this type of electrocoagulation reactor was proven.