Developing efficient methods on how to desalinate water may be one of the easiest ways to solve the freshwater shortage in the world. The ocean is vast and the processes of desalinization are simple and straightforward. Desalinization is a process that occurs in nature as the ocean waters and brackish waters are turned into rain. Reproducing the desalinization process in the most simple manner is done by distillation with a man-made still that is heated via solar power or another heat source, replicating these natural processes.
There is a worldwide movement towards increasing our knowledge of how to desalinate water on a large scale, however, it has been met with efficiency and cost prohibitions. Desalination on an individual or family basis is much more manageable and as a survival tool, it is invaluable.
Individuals may wish to learn how to desalinate water as a method of ensuring their family has an adequate supply of fresh water for drinking and cooking. Distillation, or the desalinization technique we will teach here step-by-step, also has the benefit of removing many other water contaminants and is the basis of many water purification techniques. We will also review reverse osmosis and freezing and thawing as a way in how to desalinate water.
What Is Water Desalination?
Desalinization is not a new science and has existed as a purposeful technique of water treatment for thousands of year. Converting saltwater to drinking water was, and still is, important in areas where fresh water is scarce or unavailable. Sea-going ships are where the most obvious needs have been as long-haul vessels could not always carry all the freshwater that would be needed for a journey.
Water desalinization is the process of turning saltwater, of various saline consistencies, into drinkable freshwater. When discussing how to desalinate water, it is important to be aware of a few key terms:
How to Desalinate Water Using Distillation: 9 Simple Steps
Desalinating water is actually quite simple if you use distillation. Removing the salt from seawater or brackish water can be done on an industrial scale or on a personal scale, and can even be taught to children. Creating your own distillation and desalinization device requires only a few simple tools and sunshine. We are going to use standard household items to demonstrate this technique, but you can adapt it or scale it to your need provided you follow the same principles.
Step One - Gather Supplies
First, you will need a large-bottomed container such as a bowl. Second, a smaller, inner container such as a mug that will fit easily inside the bottom container and not float when surrounded by saltwater. You will need a cover such as plastic wrap or a tarp, to completely cover the container. Lastly, you will need a small, weighted item such as a rock. When first practicing building your own distillation device, start with small, manageable items. When you master a technique, it is easy to size up.
Step Two - Sunlight
The distillation process requires sunlight to heat the water and create humidity inside your desalinization device. Choose a sunny location out of doors or a brightly lit window to allow enough heat and sunlight to enter the device. If you do not have access to sunlight, gentle heating from the bottom of the device, such as placing on a radiant heater or heated floor or by boiling will work as well although is less energy efficient.
Step Three - Get Your Saltwater
If you live near an ocean, you have a ready supply of saltwater waiting for desalinization. If you are practicing using your desalinization setup away from the ocean, create saltwater by combining enough salt with bottled or tap water to make the water taste salty to you. You will want enough saltwater to fill your inner container to at least one inch and only what would fill the inner container completely. Pour this saltwater into container 1.
Step Four - Place Second Container
Place container 2 into the saltwater already in container 1. You will now have an empty container in the center of a bowl of saltwater. Ensure that the salt water does not reach the lip of container 2 and that container 2 sits with some stability in the bottom. The lip of container 2 should be above the saltwater but below the lip of container 1.
Step Five - Cover
Cover containers 1 and 2 so that the two containers are well sealed and covered. Plastic wrap works best for this. Be sure the plastic wrap is stretched and sealed so no humidity will be lost. If you are using plastic that is not plastic wrap, consider sealing with tape.
Step Six - Place in Sunlight
Put the containers in direct sunlight. Putting the container in a window sill where the sun shines in for the majority of the day, or outdoors on a porch both work great. Be sure the device is on firm and stable ground and will not be disturbed for a few hours.
Step Seven - Weigh the Plastic
Place the weight on the plastic wrap so that it is directly over container 2. It will sag just slightly at the center, which is what you want.
Step Eight - Wait
Leave the device undisturbed in the sunlight for a few hours. Humidity will build up and form water droplets on the plastic wrap. The water droplets will flow down towards the center where you've placed the weight and fall into the waiting container 2.
Step Nine - Drink
Once there is no more water in container 1, check container 2 for freshwater. If your set up was correct, you should taste fresh water with all salinity removed.
This device, which is really just a miniature solar still, uses heat from sunlight to warm saltwater. The warming process turns the water to vapor while the salt remains solid. Humidity and condensation cause the water to collect on the plastic wrap and then fall towards the cup. Freshwater is the result.
Desalination by Reverse Osmosis
In contrast to a distilling process, a reverse osmosis process can work on how to desalinate water just as well. The downside is those reverse osmosis systems, although effective for how to desalinate water, are generally more complex, require more expertise to build and maintain, and usually require more active forms of energy. Membranes and filters must be regularly replaced and cleaned, and electricity is usually required unless significant sources of heat from solar or firepower can be created.
In contrast to a distilling process, a reverse osmosis process can work on how to desalinate water just as well.
The downside is those reverse osmosis systems, although effective for how to desalinate water, are generally more complex, require more expertise to build and maintain, and usually require more active forms of energy. Membranes and filters must be regularly replaced and cleaned, and electricity is usually required unless significant sources of heat from solar or firepower can be created.
Reverse osmosis requires an intake pump at the seawater source and a way to create a flow through the membrane. Most often that will require electricity to create some pumping pressure. The pump must be powerful enough to force the pressurized water from a column on the salted side to the freshwater side.
Feed water is pumped into a pressurized container and when full, will be forced through a membrane designed to allow the water through but not the salt. In summary, saltwater is pushed through a membrane that is semi-permeable meaning that it allows some things to pass, in this case, water molecules, and others get caught, such as salt.
Reverse osmosis as a process of how to desalinate water may be superior to distillation in a couple of ways. Solar heat is required by distillation, so in areas where solar power is limited other methods of desalination are superior. Reverse osmosis desalinization devices are much smaller than distillation devices and they tend to be better and more cost-effective on large scales.
Desalinization by Freezing and Thawing
When salt water freezes, the water molecule freeze while the salt does not, so the process of freezing and thawing is one way of how to desalinate water. However, it is highly energy inefficient to freeze water in warm climates so this method works best in a place where natural freezing of ice occurs.
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How to desalinate water is not tricky, although it does require a little knowledge. Using the laws of nature, humans have learned how to use heat, vaporization, and condensation in a process called distillation, such as outlined here, for how to desalinate water simply and on a small scale.
Freezing and thawing have also been used as methods for how to desalinate water as has reverse osmosis. Learning how to desalinate water can ensure that individuals and families always have access to fresh drinking water, and hopefully, in time we will learn how to desalinate water on a large scale to benefit larger swaths of society.