Saline wastewater treatment in membrane distillation crystallizer

The studies concerning the application of membrane distillation (MD) for the concentration of saline spent solution integrated with salt crystallisation have been reported. The MD experiments were performed with polypropylene capillary membranes. These membranes had pore sizes with a nominal and maximum diameter of 0.2 and 0.6 ujn, respectively, and 70% porosity. The crystallisation of salt onto the membrane surfaces has been observed during the concentration of the supersaturated solution (at low temperature of distillate), which resulted in a membrane wettability and a decline of the distillate flux. An increase of the distillate temperature to 328 K allowed eliminating this problem, and as a consequence the stabilisation of the distillate flux was achieved. During the MD process integrated with crystallisation, the amount of NaCl in the range of 15 - 80 kg nrxr'was obtained.