How to Make a Desalination Unit
Desalination is the process of removing salt and other minerals from water. There are several methods by which desalination is accomplished: multi-stage flash distillation, vacuum distillation, vapor pressure, reverse osmosis and thermal desalination. Focus on desalination has grown in recent years as the overwhelming need for potable water in developing countries has become apparent. Thermal desalination is the easiest form of desalination to practice at home.
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Things You'll Need
- Polythene sheet
- Stapler
- Staples (2 to 3 boxes)
- Scissors
- Fishing line/string
- Empty water bottle
- Insulation tape
- Drinking water container
- Shovel
- Newspapers
- Bricks
- Small stones
- Tape measure
- Bucket
- Clean rag
Instructions
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1
Choose and mark out a suitable plot. Decide on the size of the unit you want to design, and mark it using fishing line secured by sticks pushed into the ground. Make sure your unit is not in a depressed area, or rainwater will flood it and pollute or dislodge the clean water container. Select a level area. An accurately leveled plot ensures that the evaporation basin can fill properly.
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2
Build the exterior walls for your desalination unit. Build the first wall to be approximately 2 feet tall and 13 to 33 feet long. Walls can be made of brick or clay. Build a second wall parallel to the first wall, with approximately 36 inches of separation. This second wall should be lower than the first. The second wall should be 3 1/2 inches tall and should run the full length of the first wall. Build another wall below this second wall, which should now become the middle wall. This third wall should be 5 inches tall and 3 to 4 inches wide and the same length as the other two walls.
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3
Create the water collection channel, which will lie between the two smaller walls. Dig a ditch between these two walls. The ditch should be 1 inch deep at each end, increasing in depth 1 inch per 3.3 feet as you move toward the center. At your center point, the ditch should be up to 6 inches deep, depending on how long your walls are. This ditch will hold unclean, or base, water. Dig a hole big enough for a water canister and funnel to fit in the middle of this water collection channel.
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Place the collection cup in the center of the water collection channel in the hole you created. An empty water bottle can serve as a collection cup. Add a funnel to the top for easier water collection.
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5
Lay out the polythene sheets. Take the black polythene sheet and line the bottom of the water collection channel. The black polythene will absorb the sun and create more heat to help evaporate water faster in your desalination unit. Place the clear polythene over the desalination unit by spreading it over all three walls. Place a rock over the collection cup, on top of the plastic. After saltwater has evaporated, clean water will condense on the polythene sheet. The construction of your unit will encourage the condensed water to run down to the position of the stone and drip into the collection cup.
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Tips & Warnings
Pour approximately twice as much water as has evaporated into your collection ditch every day, to prevent a buildup of salt in the evaporation unit.
The drinking water container needs regular emptying. Its size and the amount of condensation water produced both determine the frequency of emptying. The polythene sheets need to be checked twice daily to ensure they are not flapping in the wind and are kept tight.
Allowing the top sheet of plastic to grow dusty will keep your system from working and could lead to decomposition of the plastic sheet.
References
Resources
- Photo Credit ocean image by yam from Fotolia.com
