Fe and Zn removal from steel making industrial wastewater by electrically enhanced membrane bioreactor

This study aimed at investigating the removal of iron (Fe), zinc (Zn) and bacteria from steel making wastewater. Current density varying between 10 and 20 A/m² was applied. Hydraulic retention time (HRT) and sludge retention time (SRT) of 13.5 h and 10 d were maintained, respectively. Each run was carried out for 45 d. Fe and Zn concentrations in influent wastewater and treated effluent were measured by HACH LCK 321 and LCK 360 vials, respectively. Bacteria content was determined using colony forming unit (CFU). XRF was used to analyze the concentration of Fe and Zn on electrodes deposits and sludge precipitates. Results showed that Fe removal of 98.4 ± 1.1%, 81.1 ± 12.3%, and 38.8 ± 4.2%, and Zn removal of 93.8 ± 2.7%, 71.8 ± 17.7%, and 50.1 ± 17.2 % were reported at 10, 15, and 20 A/m², respectively. Bacteria was reported to have been completely removed by eMBR. Also, XRF analysis at 10 A/m² revealed higher Fe concentration on the electrodes deposits (214.5 ± 8.7 and 3.0 ± 0.1 g/kg on the cathode and anode, respectively) compared to sludge precipitate (48.8 ± 4.9 g/kg). Similarly, XRF analysis at 10 A/m² revealed higher Zn concentration on the electrodes deposits (19.7 ± 3.2 and 0.6 ± 0.3 g/kg on the cathode and anode, respectively) compared to sludge precipitate (8.2 ± 1.8 g/kg).