ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Direct Contact Membrane Distillation with Crystallization Applied to NaCl Solutions

M. Gryta

Department of Water Technology and Environmental Engineering, Institute of Chemical Technology and Environmental Engineering, Technical University of Szczecin, PL-70 322 Szczecin

E-mail: margryta@mailbox.tuniv.szczecin.pl

Received: 1 April 2001

Abstract: Preparationof NaCl supersaturated solutions by direct contact membrane distillation (DCMD)integrated with salt crystallization has been studied. For the purpose of thisstudy a module assembled from macroporous polypropylene capillaries was used.The feed temperature was kept at 353 K or 358 K, and the temperature ofdistillate stream was changed from 293 K to 328 K. Salt crystallization on themembrane surfaces has been observed during the process when the distillate temperaturewas kept below 308 K. As a consequence of that phenomenon an increase ofmembrane wettability and reduction of the distillate flux were observed. Whendistillate temperature was raised to 328 K, salt crystallization on themembrane surfaces was eliminated, and permeate flux was stabilized during theprocess runs. After 138 h of the process operation, the permeate flux decrease ofabout 40 % was observed. Additionally, the DCMD process integrated withcrystallization yielded average NaCl production of 55 kg m⁻² d⁻¹.

Full paper in Portable Document Format: 561a14.pdf

Chemical Papers 56 (1) 14–19 (2002)