Mmmm, Water

Written by Colton Lowry, ESLLC 2015-2016

The earth’s surface is 71% water, but water is still the most valuable resource on earth. This is due to the fact that 96.5% of the world’s water is stored in the oceans. This means that 7 billion people are expected to share only 3.5 percent of the drinkable water on earth. It is expected that the availability of water in the second half of the 21st century water will cause international hostile conflicts, specifically in the Middle East, South Asia, and North Africa. All of these regions have a very low amount of freshwater available for their residents, but are surrounded by large bodies of water with high levels of salinity, salt water. If there was an efficient way to create drinkable water out of salt water then the world would be one step closer to becoming fine and dandy.

Currently the most widely used process of converting salt water into drinking water is through the use of reverse osmosis. Reverse osmosis uses a semipermeable membrane in order to remove larger particles in water. The issue with reverse osmosis is the amount of money it requires to build and maintain a reverse osmosis water treatment plant. Also only 40-60% of the water input into a reverse osmosis treatment plant turns into drinkable water while the rest of it is considered reject water.

Some students at MIT partnered up with Jain Irrigation Systems and have come up with a new and improved way to desalinate water. They created a machine that can pull salt out of the water as well as go a step farther to disinfect the water using ultraviolet rays. This new machine uses a system of solar panels in order to charge a bank of batteries which then powers the process of electrodialysis. Electrodialysis works by passing a stream of water through two electrodes with opposite charges, and since salt in water consists of positive and negative ions, the electrodes pull the ions out of the water. This leaves only fresher water at the centre of the flow, and a series of membranes separate the freshwater stream from increasingly salty ones. This machine causes less pressure on the membranes in the process of desalination than when compared to reverse osmosis, and can be cleared by reversing the electrical polarity. This means the membranes should last longer and require maintenance; this means the process of electrodialysis is cheaper than the normal process of reverse osmosis.

This machine won the top $140,000 Desal Prize from the U.S. Department of Interior (USID). Since then, this invention has been sent around the world in order to test the system. There is now testing going on in several villages across India and in New Mexico. During the testing of this system, it was found that within a 24 hour period 2,100 gallons can be desalinatedThey are planning on expanding the tests throughout more parts of underdeveloped countries, and hope that small farms can start to use them as irrigation systems.

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