The application of membrane distillation for the concentration of oil-water emulsions

The influence of the oil presence in the feed on the performance of membrane distillation (MD) has been investigated. The capillary membranes made from polypropylene with a maximum pore diameter of 0.62 mu m were used in these studies. The concentration of oil in the concentrated feed was in the range of 0-2000 ppm. A decrease of the permeate flux obtained in the process along with the increase of oil concentration in the feed was observed. In the case of solutions containing up to 1000 ppm of oil, its presence in the permeate was not detected. However, at its higher concentration, the oil permeated into the distillate, for example at c(F) = 2000 ppm, the oil concentration in the distillate amounted to c(D)=0.6 ppm. The combination of MD with a system for oil separation obtained from the emulsion breaking enables maintenance of the oil content in the feed below 1000 ppm.