A simple, low cost set up presented in this article will give you a clear idea regarding how to desalinate sea water at a fast rate and in large quantities.The conventional method of solar sea water desalination process is quite sluggish and cumbersome. A simple, low cost but effective idea presented here will show you how to desalinate sea water much efficiently.
A Simple Sea Water Desalination Apparatus
A simple and a low cost set up (Exclusively Developed By Me) as shown in the diagram should be able to convert sea water into fresh drinking water in large quantity, depending upon the size of the sphere.
The main feature of this system unlike other conventional ways is the fast conversion rate of waste water into fresh water.
Also, since the whole process is solar operated, cost incurred is zero. Another great advantage of this design is that it's not dependent on the position of the sun and will work throughout the day as effectively.
Let’s study how to desalinate sea water through a simple the set up: The system is basically made up of a large hollow glass sphere with a “T” shaped glass tube extension coming out of its top portion. The sphere is made up of solid glass at the bottom, up to the focal point of the sphere.
This base surface may be painted black to increase the efficiency of the unit. As can be seen in the diagram, the short vertical arm of the tube which extends upwards terminates into a funnel.
The funnel carries a valve in the form of a tap. The long horizontal arm is bent at 90 degrees and terminates inside the reservoir tank.
The whole set up is placed outdoors in an open area where clear sunlight is accessible throughout the day.
Sea water is poured through the funnel and the glass sphere is allowed to fill completely, only up to the circumference of the globe. Now the tap is closed.
How the Desalination System Works?
Once the sphere is filled with water, it behaves like a big, solid and a powerful convex lens. In our childhood days we all have played with this amazing piece of lenses.
We have seen how it is able to focus and concentrate sun rays at one single point when placed at a particular angle under sunlight.
(Click Image to Enlarge) The created focal point is in fact a concentrated beam of the sun rays collected and deflected at a small point.
This point is very hot, and is able to produce burning effect over anything placed under it. The above principle has been simply exploited in the present design.
Without water the sphere is ineffective and will act just like a normal glass. The sunrays entering into it thus cannot generate much of a heat. But the moment it is filled with water, it is transformed into a big solid convex lens having a focal point exactly at its center.
Sun rays hitting the glass sphere are instantly refracted through the entire curvature of the filled water to reach exactly at the center.
Here the rays concentrate into single hot spot. Water at this point starts heating up instantly and the heat is gradually transferred to the whole mass of the filled water.
As the temperature rises, water molecules are converted into vapor. The water vapor formed, rise through the “T” shaped glass tube and the reservoir tank.
The tank being relatively much cooler helps in converting the received water vapor into clean, drinkable water* (see comments) on its roof.
Water molecules accumulated on the roof of the reservoir tank slowly gather to form water drops which ultimately fall into the tank and pure water is thus collected inside the tank.
This water is absolutely pure, and free from viruses, bacteria or dust particles. The efficiency of this apparatus will decrease if the filled water is murky or muddy.
Because in such a case the focal point will be comparatively dull and won’t be able to create enough heat. The above method should have certainly made you understand regarding how to desalinate sea water simply and efficiently.
Craig says
Dear Sir,
I am emailing from Cape Town. Cape Town (about 4 million people) has less than 100 days water left at 1 Feb 2018.
Please can I ask about your brilliant home desalinsation plant? I live near the sea.
Where would I get the correct glass sphere? Must it be round like a ball or oval? What size or type of opening should the sphere have at the top?
Just trying to think of the best type of supplier to source the glass sphere?
Is it best that the other components are glass?
I am keen to try build your desalinization plant, but just want to get a feel for the correct components?
Especially the size and shape of the sphere and where best to source it?
Thank you so much for sharing your knowledge and invention.
Kind regards Craig Cape Town email address as below 🙂 🙂
Swag says
Dear Craig, I think glass sphere method has too many limitations, first of all you cannot desalinate large amounts of water at one go, and being glass it could be vulnerable to damages.
Instead you could try the following concept
https://homemade-circuits.com/make-free-drinking-water-from-sea-water/
this one will be much more effective
Craig says
Dear Swagatam,
Thank you very much for your time and valuable guidance.
I am not a technical person so I am trying to find ways to understand evaporation and condensation and then how to speed up process. It is said 97% of water on Earth is sea water. To change sea water into fresh water cheaply would make a huge difference. Easier said than done. I see some researchers at Alexandria University have made some interesting discovery re converting sea water into fresh water. All the best and thank you so much for your valuable guidance 🙂 🙂 Craig Cape Town
Swag says
You are most welcome Craig!
Talon p.s. says
quick question,
Provided a person could find the necessary equipment to do this, (thinking along the lines of an event that would decimate drinking water) Approx. how many times do you think the aparatice would work before clouded out by the salt which doent disappear, but would remain inside the heating cyphere? Thanks in advance.
Okay another question, (since realisticly if someone were under such harsh conditions, a local lab supplier is not likely to available), What alternative items would you consider to build the apparatise? I can imagine a coffee pot being used and a fish tank for the resevoir, but how could they be attached to creat the T tubing. Thanks again.
Unknown says
Seems like this tech is no outdated. Try doing a search for "large scale solar desalination" and you will see why…
Swagatam says
it needs to be extremely cheap, extremely effective and within layman's reach
Sirvglam says
Can I share this article?
thewanderlust says
Hi Swagatam,
This certainly seems to be a very good idea. Would like to go into more details of this.
Will it be possible for me to get in touch with you?
Regards
Sameer
Swagatam says
Thank you Sameer,
You can also read the following article which shows an alternative method of achieving the same, but in a more efficient way:
https://homemade-circuits.com/2015/09/make-free-drinking-water-from-sea-water.html
Please feel free to contact me at:
admin @ homemade-circuits.com
LymeThrive says
Unclear regarding how much to fill sphere.Fill to top or to middle?
Swagatam says
it should be full from the top,
the inner bottom concave surface of the dome could be made mirror finish so that this issue is permanently solved.
yousef alotay says
A demester layer above heated sea water should contribute reduces salty droplet carrying over to Reservoir tank.
Swagatam says
OK, thanks for the input!
irfan hossain says
How can i make a RO system for desalination at home easily ?have u any idea?…
Swagatam says
sorry i do not have idea regarding RO systems.
surya s says
sir,will the suitable sphere available in chemical lab shop?(solid glass up to the focal point?
Swagatam says
Hi Surya,
An ordinary sphere type flask will also do, but the "lens" effect will work only as long as the water in it is above the focal point, that means the flask will need to be filled every now and then as it becomes empty.
There's another solar project that's even better than the above, you may refer to the following link:
https://homemade-circuits.com/2012/02/how-to-make-simple-solar-cooker-at-home.html
Regards
surya s says
thank you sir,i m going to try this.
surya s says
sir,i have a doubt,how the water vapour get directed to the reservoir?wont it come back to the same sphere of salt water?
Swagatam says
Hi Surya,
Water vapor always heads from high temperature toward low temperature area, that's why the vapors will travel toward the reservoir which is assumably cooler than the sphere.
Anonymous says
Dear Swagatam, it is a nice idea, its basically a distillation process that I studied in my lower classes, we even tried experimenting using a distillation flask in our school. But the thing is you have said "clean, drinkable water" is collected in the reservoir tank- my question is are we not supposed to dink distilled water since it is devoid of essential minerals, it is 100% clean but not drinkable right ?
regards
Parvath (coimbatore).
Swagatam says
Dear Parvarth,
You may be right, but it's better to drink distilled water than die without any water. Anybody would use this type of system only under severe lack of normal water supply, such as in middle east, Africa etc.
My commonsense says, water is required for compensating fluid requirements in body, minerals can be acquired by having balanced food and external pills etc. so according to me it's extremely safe to drink distilled water:-)
Regards.
Anonymous says
In that regard it is fine because something is better than nothing but still there are contradicting views regarding health issues from drinking distilled water- some say that it leaches vital minerals & ions from your body in long term.
Here is a quote from Wikipedia "Health concerns:- The drinking of distilled water has been both advocated and discouraged for health reasons. The lack of naturally occurring minerals in distilled water has raised some concerns."
So i think you can put this health concern in your blog and advocate people to do it on their own discretion. Moreover you can put a blog for Homemade RO water purifier as RO membrane filter, pre and post filters are available separately one can easily do it at home for half the price of the commercial RO systems.
To concluded- As i have said in my first comment no words can describe the effort and pain you are putting here, Keep up the good work.
Parvath
Swagatam says
OK, Thanks Parvarth,
However the sole purpose of the above experiment is to acquire drinking water from sea water by renewable method, so perhaps the concerned folks can mix correct proportions of minerals available from the market such as Electral in the distilled water for elominating the said dangers.
Great suggestion! I will try to include an article regarding making of RO filters at home soon.
Thanks for the info and your kind words, appreciate it.
Regards.
esam Saleh says
We can add few ml of boiled salty water to provided the minerals needed
Anonymous says
Hi
To me that seems so easy – where can I get the necessary equipment to make it.
Regards
Diana
Anonymous says
What parts do i need exactly?
govind rajan says
after water become stream it flows through the pipe towards the reservior tank.but the salt still intact with the stream,so salt never been removed from water.atually in sea the sun rays evoporate the seawater as stream that goes up and form the cloud., the distance between the seawater and cloud is appriciable ,the sea wind remove the salt from the stream.but in ur project the stream never been exposed to wind and the salt and florid neverbeen removed completly .ultimately the water from the reservior tank is not drnikable.is it?
thoomsati@gmail.com
Swagatam says
salt cannot evaporate with water molecules, salt will remain in the flask and only water molecules will evaporate and pass through the tube and finally condense in the reservoir tank.