A simple and direct method for Desalination of salty water by solar energy with innovative design

Popular methods for purifying water are  Filtration in stages, Boiling, Distillation (De-salination of seawater), Reverse osmosis, In Situ Chemical Oxidation(ISCO) . Boiling is the oldest and most effective method  since it eliminates most microbes causing intestine related diseases, but it cannot remove chemical toxins or impurities. However for human health, complete sterilization of water is not required, since the heat resistant microbes are not intestine affecting. In general distillation involves boiling the water to produce water vapour. The vapour contacts a cool surface where it condenses as a liquid. Because the solutes are not normally vapourized, they remain in the boiling solution. Even distillation does not completely purify water, because of contaminants with similar boiling points and droplets of unvapourised liquid carried with the steam. However, 99.9% pure water can be obtained by distillation.
Solar disinfection  is a low-cost method of disinfecting water that can often be implemented with locally available materials .No complicated technical knowledge is required so that it can be well used by all kind of people even uneducated. One of the main advantages of this method is it has low impact on the environment .It does not require any fire-wood, or electricity ,and it is well suitable to country like India where solar flux is available almost throughout the year. By adopting this method by all the nationals for their requirements of water, the nation can solve both the energy crisis (by reducing the energy used for water purifications) and drinking water problem.

Distillation by solar energy at NTP will remove from water almost anything, even heavy metals, poisons, bacteria and viruses. But if it done under reduced pressure, as the process is carried out at lower temperature, the removal of such unwanted things will not be complete. A simple and very ingenious method of achieving desalination under reduced pressure is given below:

  Requirements: one cylindrical aluminium vessel (little broad) and a similar vessel made of plastic or glass, a broad twice bend glass tube( like  inverted      ) 

Initially the bend tube is fully filled with pure water and kept  such that one end is kept immersed in the salty water taken in the aluminium vessel placed on the flat plate collector  and the other end is kept immersed in the pure water taken in the glass vessel placed outside the system.The connecting bend tube is fixed so that it is slightly inclined towards the glass tube .It helps the condensed water to flow towards the glass container.When the water filled bend tube is erected like this the pressure inside the connecting tube will be less than the NTP which will help promoting the process of vapouraization.