Study of water desalination techniques and a review on active solar distillation methods

Abstract

Energy crisis and water born diseases caused by impure water are two major concerns of the present era. Various techniques have been used to make saline/brackish water potable. Filtration, precipitation, sterilization, chemical treatment, etc. are some processes that remove macro impurities from impure water. Distillation is thermal energy‐based process that effectively removes contaminants from impure water. Reverse osmosis is a membrane‐based technique widely used for the purification purposes. Electrodialysis, Ion‐exchange, and Freezing are some other processes used to get soft/distilled water for various commercial and domestic uses. Most of the desalination techniques utilize energy from the nonrenewable energy sources. Solar distillation is one of the solutions of getting potable water using solar energy. Solar distillation unit coupled with thermal collectors, photovoltaic panels, and concentrators makes the system active and increases the distillate three to six times than conventional units. Multistage, multieffect active solar still is observed to give an average distillate output of 20 kg/m2/d. Economic analysis also shows that active solar still is a good replacement of nonrenewable energy based water purification techniques. In this article, different water desalination techniques with their economic analysis are briefly discussed. Detailed comprehensive review of researches carried out on active solar still system considering their designs, performance parameters, different hybrid combinations, along with challenges, opportunities, future scope of improvements have also been highlighted. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 444–464, 2018