Experimental and Theoretical Investigations of a Novel Multi-Stage Direct Contact Membrane Distillation Module

Global climate change and variability have a negative impact on a water supply and quality in remote areas by reducing water availability and contaminant dilution. This will continue to be exacerbated by limited and inadequate water supply, insufficient water treatment and low infrastructure. Thus, an economic desalination system with a small scale and footprint for such regions is strongly demanded in the desalination markets. Here, a direct contact membrane distillation (DCMD) process has the simplest configuration and potentially the highest permeate flux among all the possible MD processes. And it also can be consisted easily by a multi-stage manner to achieving an enhancement of compactness, productivity, versatility and cost-effectiveness. In this study, therefore, an innovative multistage direct contact membrane distillation module under countercurrent-flow operation is first designed and both theoretically and experimentally investigated to identify the feasibility and operability of its design for the desalination. For a three-stage DCMD module with a membrane area of 0.01 m at each stage, the daily water production is found to be 21.5 kg at the inlet feed and permeate flow rates of 1.5 l/min and the inlet feed and permeate temperature of 70 °C and 25 °C.