Effective Membrane Distillation of Landfill Leachate Concentrate Using a Superhydrophobic SiO₂/PVDF Membrane for Resource Recovery

The formidable challenge of membrane fouling and wetting, spurred by the elevated concentration of pollutants in the landfill leachate concentrate during membrane distillation, necessitates substantial costs on membrane cleaning for retaining high separation efficiency. Herein, a durable superhydrophobic poly(vinylidene fluoride) (PVDF) membrane constructed by spray-coating of fluorinated SiO₂ nanoparticles was proposed to treat landfill leachate concentrate via membrane distillation. The influence of operational parameters, including transmembrane temperature difference, feed flow rate, and feed salinity, on the membrane distillation performance was explored. Specifically, the increased transmembrane temperature difference and feed flow rate had a strongly positive dependence on the permeation flux during membrane distillation. The superhydrophobic PVDF membrane showed impressive antiwetting and antifouling properties, as indicated by consistently stable superhydrophobicity, obtaining an extremely high rejection of salts and humic substances (>99.99%) over an 8 h membrane distillation for treating landfill leachate concentrate. Furthermore, the tested superhydrophobic PVDF membrane yielded a complete solute removal, resulting in high-quality freshwater production with a 90.13% pure water recovery from landfill leachate concentrate during a 50 h membrane distillation-based concentration procedure with a concentration factor of 10.13. These results manifested the superhydrophobic PVDF membrane as a promising avenue for pure water production from complex waste streams via membrane distillation.