Cheap Desalination (Midterm Project)

The Problem

The world is filled with water.  There is more water than land on Earth, but yet millions of people go thirsty daily.  That's because less than 1% of the water on Earth is safe to drink.  A solution to this problem has been created, and it's called desalination, a process that turns unclean salt water into fresh drinking water.  Desalination plants have been produced in many parts of the world, but not in poor areas of the world where people need it most.  Desalination plants cost billions of dollars to build and operate, and many poor communities do not have this money. Cheaper, efficient ways to desalinate water need to be created before millions more go thirsty as the global water supply continues to decrease.

The Solution

Dr. Robert Murray-Smith offers a solution to this problem with a filtration device that can be made in a household at a very low price.

Murray-Smith's graphene coated sand is a water filter that can be made from ordinary sand, sugar, and carbon.  It removes pathogens, organic substances, and some metals from water that are harmful to drink.  The graphene coated sand needs to be created using very high temperatures and takes a while to make, but it is very inexpensive, and the cost to produce it is not even comparable to the cost of desalination plants.  The graphene coated sand removes some salt from water, but it is still noticeably present after the filtration.  

In this video, Murray-Smith demonstrates how to make a conductive ink using graphene.  It is very conductive, and it has some properties of the sand in addition to the conductivity necessary for the desalination process.

Murray-Smith uses the concept of capacitive desalination in combination with the conductive ink to create a possible filtration device.  The idea is to use a battery to create a charge in two porous objects (in this case, sponges).  One sponge will take on a positive charge that will attract and keep Chlorine, and the other will have a negative charge that will attract the sodium in the water, leaving fresh water in the end.  The filter is very cheap and fairly easy to make, and it offers a possible solution to the problem.

The Product

The large-scale filter uses the same science for the desalination process as explained above, but it is has been made into a real filter that can be easily used in poor seaside countries.  The clear plastic container with the stand is five feet tall, and the container has a diameter of two feet.  Circular sponges are used for the filter that are slightly smaller than the water container, and the plastic separator is larger so that the filter can be taken off of the container and be cleaned when needed. The container holds all of the fresh water, and a faucet has been attached to efficiently access the fresh water.  The container can also be removed from the stand so that it can be cleaned.

To activate the filter, a battery and wire is required to charge the sponges.  The wires can be unattached once the sponges are wet and the charges are given, and they can be attached again when the process needs to be repeated.  Salt water is poured in from the top of the filter and drips out of the bottom as clean, drinkable water ready to be accessed by the faucet.

This filter is easy to make, very inexpensive, and does not require the large amount of energy other forms of desalination do.  It could not help all people without access to clean water, but it could still help millions in need who live near saltwater.  Desalination is the future for providing access to clean water to everyone in the world, and without the impossible costs of desalination plants, small filters such as these could put a dent in the problem.