Effect of membrane fouling on wetting in membrane distillation system

Although membrane distillation (MD) has attracted significant attention as a promising technology for seawater desalination and wastewater reuse, membrane fouling and pore wetting are two major problems to be overcome prior to its widespread application. In this study, a series of MD experiments were carried out to investigate the effect of foulant characteristics on fouling and wetting of MD membranes. The interactions among different foulants and their impact on fouling and wetting were also examined. Synthetic feed solutions were prepared using model foulants including alginate, CaCO3, and colloidal silica. Water flux and liquid entry pressure (LEP) were simultaneously monitored to quantify the extents of fouling and wetting. Results showed that fouling propensities of single foulant and the mixtures of different foulants were quite different, suggesting the "positive" and "negative" synergic effects of multiple foulants. Pore wetting was not observed in the treatment of feed solutions containing single foulant. However, a combination of different foulants led to reduction in LEP, indicating the occurrence of pore wetting by the synergic effect of multiple foulants.