Optimization of the operation process of a continuous flow electrocoagulation reactor for the treatment of dye effluents

Abstract

Water pollution by dyes is still considered as a serious environmental issue. In the present work, a pilot electrocoagulation reactor was designed and applied to treat a local craft dyeing wastewaters. The objective was to develop a robust, less expensive and efficient pilot that could threat highly polluted dyes effluents. This reactor with a capacity of 10 L, operates in recirculation mode with aluminum or iron electrodes. The reactor operation was optimized by varying some key experimental parameters during the treatment of a synthetic textile effluent, prepared with Reactive Black 5, a well-known synthetic reactive dye. The iron electrodes were by far more efficient than aluminum electrodes, with a maximum removal percentage near 100% after only 25 min. Considering the most advantageous power consumption, other optimal operating conditions were highlighted: current density of 1.09 A m⁻², initial pH of the solution of 7.0 and monopolar series connection of iron electrodes. These optimal conditions were successfully applied for the treatment of two craft dyeing effluents. Appreciable removal percentages of some water pollution parameters (Chemical oxygen demand (83.3–91.7%) and suspended solids (⁓100%)) were obtained as well as treatment costs not exceeding 2 USD m⁻³.