Comprehensive bench- and pilot-scale investigation of NF for gold mining effluent treatment: Membrane performance and fouling control strategies

[Display omitted] •An integrated UF-NF pilot-plant was used for the treatment of gold mining effluent.•Fouling control strategies (hydrodynamic, antiscalant, cleaning) were studied.•Improvement in hydrodynamic conditions caused better flux and removal efficiency.•Antiscalant dosing was found to be an important tool for fouling control.•The cost of the proposed treatment was estimated at $ 1.34/m3. Despite being widely used, large differences in filtration-time and hydrodynamic conditions between bench- and large-scale membrane units make the scaling up of bench-scale results an issue. On the other hand, pilot tests allow obtaining more reliable information on hydrodynamic conditions, fouling rates, and cleaning methods. Hence, the aim of this study was to evaluate nanofiltration (NF) membrane fouling control strategies in an integrated ultrafiltration (UF)-NF pilot plant applied to the treatment of gold mining effluent. Increasing the pressure increased the permeate flux as well as the concentration polarization and did not improve the membrane performance. The development of mass transfer condition by increasing the feed cross-flow velocity effectively reduced the concentration polarization and fouling, allowing the achievement of higher permeate flux and removal efficiency. The addition of antiscalant was important for the system studied, for reducing the flux decay up to 36%. The difference between some results in bench- and pilot-scale underscores the importance of evaluating design parameters using pilot-scale units. The cost of the proposed treatment was estimated at US$ 1.34/m3.