LAUSR

Abstract Membrane distillation is a promising technique for numerous applications, namely in desalination, wastewater treatment, food, textile and chemical industry. Vacuum membrane distillation (VMD) offers numerous advantages in terms of flux, thermal efficiency and relevance for specific products. On the other hand, direct contact membrane distillation (DCMD) is the most studied configuration and it is preferred due to its conceptual simplicity. The literature is addressing their performance considering mainly the transmembrane flux, which is leading to a lack of full understanding of the phenomena behind each configuration. In this work, the concentration of carbonate solutions using vacuum and direct contact membrane distillation is performed, and results are analyzed by the flux and the overall mass transfer coefficient. This analysis has allowed the evaluation of the real performance of each configuration by keeping the effect of the driving force out of the discussion. The results reveal higher and more stable mass transfer coefficients in VMD, and a much more significant impact of concentration in DCMD. Thus, even though DCMD presents a very attractive configuration in terms of simplicity, its performance is poorer in comparison with VMD.