Effect of brine concentration on membrane distillation process for seawater desalination

Membrane distillation (MD) process was systematically evaluated for concentrating brine of reverse osmosis process. Basic characteristics of MD membrane were first examined. Synthetic seawater brine was used as the feed solution of MD test. To investigate the flux variation of brine treatment process by the flow rate. In the MD process operated using high concentration artificial seawater, the flux was continuously decreased in both flow rates. However, the flux was rapidly decreased when the flow rate was high. The experimental result of membrane cleaning with deionized water and sulfuric acid solution showed that the flux was not affected by the membrane cleaning. The scanning electron microscope image analysis showed that the NaCl crystals were affected by cleaning but confirmed that pore block by the NaCl crystals is not significantly correlated with the decrease of the flux. Further studies will be conducted by using various kinds of cleaning agents to investigate the effect of cleaning the NaCl crystals.