The separation membrane,polytetrafluoroethylene(PTFE) hollow fiber hydrophobic membrane,was applied in direct contact membrane distillation(DCMD) and vacuum membrane distillation(VMD) processes for the concentration treatment of multivariate heavy metal solution.The variation of the membrane distillation(MD) flux,the conductivity of product water and membrane fouling were investigated,separately.The influence of heavy metal ions on the MD performance was also studied.The differences between the tube-side an...