Desalination Using Membrane Distillation: A Review

As the water demand increases continuously, large capacities of desalination plant are added every year to meet freshwater demand. The higher carbon footprint of desalinate- ton raises concern on global climate change. The integration of desalination and renewable energy source could mitigate this water-energy nexus. Due to lack of rain-fall and seawater intrusion, conversion of underground water to salt water is inevitable. Hence, a large capacity of desalination plants has to be installed in various places to convert the saline water in to potable water. Membrane distillation (MD) is a non- isothermal desalination process in which the low-grade heat is used as the driving force. Many researchers have tried to integrate solar energy and MD for sustainable water desalination. Moreover, an alternative source of energy which is from the heat stored in the lower zone of the solar pond was investigated by using the combination of MD and salinity gradient solar pond (SGSP). Solar powered MD systems have been investigated for last few decades. However, its commercialization is very limited due to low flux, high specific energy consumption and large collector area requirement. A Concentrated Photovoltaic (CPV) and Direct Contact Membrane Distillation (DCMD) hybrid system is available solution to address water shortage in arid and rural areas. We see the recent developments in MD membrane, innovative MD modules and the importance of optimization, which was able to improve the performance of solar MD.