Distillation is the one of the water treatment process involves the evaporation of water. In the Distillation watertreatment process the evaporated water leaves behind all hardness compounds and becomes soft. Distillation watertreatment plants produce a high-quality product water that ranges from 1.0 to 50 ppm TDS.
In the distillation water treatment process, feed water is heated and evaporated to steam and separating out dissolved minerals. The steam is then condensed and collected as product water. When the water is boiled most contaminants do not vaporize and, therefore, do not pass to the condensate. The most common methods of distillation water treatment include solar distillation, multistage flash (MSF) distillation.
For heating water solar energy can be harnessed by the use of a system of mirrors following the path of the sun to focus the sunlight on sheets of water in a solar still. In solar stills, salt water is filled in basins with glass panes as roof at an angle of 10 to 18; tightly sealed to the holding frame and the joints between the still cover and the vertical walls perfectly tight. Upon heating by solar heat the water molecules are converted into steam leaving behind the salts at the basin. The steam is condensed at the bottom of the glass roof of the still and water slides along the slopes of the glass panel and collected in the collecting troughs. The collecting troughs at the foot of the glass pane cover of the still must be constructed in such a way that water will drain freely to the pipe which carries the distillate to the fresh water tank.
In multi stage flash (MSF) distillation, the feed water is heated and the pressure is lowered, so the water flashes into steam. This process constitutes one stage of a number of stages in series, each of which is at a lower pressure.