Slug flow-enhanced vacuum membrane distillation for seawater desalination: Flux improvement and anti-fouling effect

Abstract

Vacuum membrane distillation (VMD) is characterized by high permeate flux and low conductive heat loss among the membrane distillation technologies. However, the inescapable polarization effect severely deteriorates the distillation performance and service life. Thus, this study aimed at establishing a novel slug flow-enhanced VMD system to effectively address the polarization problem and investigating the influence of flow behaviors on MD process. First, a novel slug flow-enhanced VMD system was developed. The transmembrane permeate flux was intensified by 28.1 %. The performance enhancement was mainly ascribed to the increased turbulence and intensified shear stress. What’s more, further anti-fouling test demonstrated that the effect of slug flow on membrane fouling was divided into two stages. In Stage I, the permeate flux just dropped from 18.1 to 17.7 kg/(m2·h) and only 2.2 % reduction was observed in slug flow-enhanced VMD system, while it dropped rapidly from 15.2 to 12.9 kg/(m2·h) and a significant reduction of 15.2 % was observed in conventional VMD system. This research would be useful to membrane distillation for seawater desalination.