Nanofiltration applied in gold mining effluent treatment: Evaluation of chemical cleaning and membrane stability

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 323; pp. 545 - 556
• Main Authors: Andrade, L.H., Ricci, B.C., Grossi, L.B., Pires, W.L., Aguiar, A.O., Amaral, M.C.S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2017
• Subjects: Gold mining effluent; Membrane cleaning; Membrane lifetime; Nanofiltration; Nanofiltration; Membrane cleaning; Membrane lifetime; Gold mining effluent
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2017.04.116

•The best cleaning procedure proved to be 90-min recirculation with HCl solution.•Membrane exposed to combined effluent and cleaning solution had lower retention.•In 285days of exposure, membrane hydrophobicity and effective pore radius changed.•No indication of degradation of the polymeric material of the membrane was observed.•Results demonstrate the robustness of NF for gold mining effluent treatment. The objectives of this study were (1) to determine the best conditions of chemical cleaning of a nanofiltration (NF) membrane (NF90) employed in the treatment of gold mining effluent, and (2) to investigate the effects of continuous exposure to mining effluent and an acid cleaning agent on NF characteristics. NF fouling was mainly due to inorganic species, and calcium sulfate (CaSO4·0.5H2O) was identified over membrane surface. Therefore, acid solutions were the most efficient in membrane cleaning, and among them hydrochloric acid (HCl) showed the best performance. Cleaning without recirculation (soak) was not effective and thus 90-min recirculation was chosen as the best cleaning procedure. The NF membrane was exposed to the effluent and to the combined effluent and HCl solution for 285days. Modifications in hydrophobicity, effective pore radius, fouling, and surface charge were observed. The retention of magnesium sulfate and glucose by the membrane exposed to the combined effluent and cleaning solution was statistically lower, what endorses the importance of cleaning conditions optimization. No indication of degradation of the polymeric material of the membrane was observed. Thus, the results of this study are promising and demonstrate the robustness of NF technology for gold mining effluent treatment.