Membrane distillation of NaCl solution containing natural organic matter

The concentration of NaCl solution containing natural organic matter by membrane distillation (MD) has been performed. The salt solution produced during animal intestines processing was used as a feed. The presence of organic compounds in the feed caused the fouling of MD membranes. The experiments were performed with polypropylene capillary membranes. A rapid flux decline caused by the deposition of organic matter on the membrane surface has been observed. The morphology and composition of the fouling layer was studied using scanning electron microscopy (SEM) coupled with energy dispersion spectrometry (EDS) and Fourier transform infrared with diffuse reflectance spectroscopy (FTIR-DRS). Protein and sodium chloride constituted the major components of the gel layer. Rinsing of the MD module with a 2 wt.% citric acid solution removed a part of the fouling layer. Boiling of spent NaCl solution followed by filtration resulted in the separation of the organic matter in the form of a deposit. This enabled a significant reduction in the occurrence of fouling phenomenon. (C) 2001 Elsevier Science B.V. All rights reserved.