Quick extraction and concentration of valuable metals from electroplating sludge through a novel cycle of regeneration − bioleaching in membrane bioreactor

Membrane bioreactor (MBR) has been widely applied worldwide in full scale. In this work, the MBR was used to continuously concentrate the valuable metals from the electroplating sludge through a novel cycle of regeneration-bioleaching for the first time. Quick and continuous generation of active bioleaching solution containing high dosage of H⁺, Fe³⁺ and Fe²⁺ in a 200 L of MBR. Valuable metals were rapidly and efficiently extracted from electroplating sludge using the active bioleaching solution. Afterwards continuous enrichment of the valuable metals from the electroplating sludge via regeneration-bioleaching for 20 times. Finally, the separation and purification of heavy metals in the bioleachate by displacement reaction. After 20 times of regeneration-circulation process, Zn, Cr, Cd, Ni, Cu extraction concentration were 40 g/L, 16 g/L, 8 g/L, 4 g/L, 4 g/L respectively. Through displacement reaction, Zn, Cr, Cd, Ni, and Cu in the bioleachate were separated and purified with efficiencies of 99.5 %, 99.9 %, 98.5 %, 99.9 %, and 98.5 %, respectively. By significantly improving bioleaching efficiency and reducing the leaching cycle, the MBR plays a crucial role. Furthermore, the reflux of the bioleaching solution concentrates heavy metals, facilitating subsequent purification and solidification stabilization.