Hybrid electrocoagulation–microfiltration technique for treatment of nanofiltration rejected steel industry effluent

Abstract

ABSTRACT Nanofiltration (NF) rejected effluent from TATA Steel, India having high concentration of chloride, sodium, potassium, manganese, magnesium, sulphate, calcium and iron was treated by electrocoagulation (EC) followed by microfiltration (MF) process. Ceramic membranes were prepared from Linz-Donawitz (LD) slag obtained from Tata Steel Ltd, India and was utilised for the separation of electro-coagulated by-product. LD slag is a byproduct of the LD process which is constantly produced as pig iron and processed into crude steel. EC was studied at various operating parameters like current density (10, 20, 50 Am−2), run time (20 min) and inter-electrode distance (0.005, 0.01, 0.02 m). The concentration of Mg and Ca was reduced to 54 and 18 mg L−1, respectively, at current density of 50 Am−2, inter-electrode distance of 0.005 m with residence time of 20 min. Mn and Fe were found to be completely removed from the effluent. Produced flocs were analysed using EDX to confirm the removal of metals by EC followed by MF process. The treated water was recycled back for various process unit operations.