Our goal is to find a way to have more access to fresh water because water is a valuable resource to the world. With the exponential increase of the human population, water has become an essential to life. Almost three quarters of Earth's surface is covered with water, but most of it is too salty to drink. The 2.5 percent that is freshwater is locked up either in soil, remote snowpacks and glaciers or in deep aquifers. That leaves less than 1 percent of all freshwater for humans and animals to drink and for farmers to use to raise crops—and that remnant is shrinking as rising global temperatures trigger more drought. Our design will offer a cheap and efficient way of desalinating sea water for people to use.
Ways that this problem has already been addressed include distillation, membranes that contain aquaporins, and reverse osmosis. Distillation is when water is evaporated and then condensed as fresh water, but this is energy expensive and is only used in the Middle East. Reverse osmosis is based on high tech polymer membranes that are permeable to water, but reject the passage of salts. Membranes that have already been considered contain pumps and aquaporins that push water through and hold back the salt. These desalination techniques are realistic on a large scale because they both require high amounts of energy to either boil the water or create pressure. Even though these techniques are expensive, they are still considered pretty effective because it considered quite economical in the long run. For example, reverse osmosis typically creates one gallon of fresh water for every gallon of rejected water while distillation produces six gallons of water for every rejected gallon of water.
The most feasible approach would be the membrane idea because it is already being looked at by scientists. Membranes occupy through a selective separation wall. Certain substances can pass through the membrane, while other substances are caught. Membrane filtration can be used as an alternative for flocculation, sediment purification techniques, adsorption (sand filters and active carbon filters, ion exchangers), extraction, and distillation. Our design is of a membrane that uses a sodium co-transporter paired with an electron transport chain to move water and sodium directly across the non-permeable membrane in opposite directions. Our membrane would be responding to the concentration of sodium compared to the amount of water in saltwater. Without sodium, the membrane would essentially be useless.
Reverse Osmosis: A semipermeable membrane is used to filter out ions, molecules, and large particles from drinking water. It could be used to filter out sea salt from ocean water.
Our ideal approach is to find more efficient membranes. If it were to work perfectly, we would expect our membrane to use Na+-glucose cotransporter paired with electron transport chains from photosynthesis to move water and sodium in opposite directions across the membrane. The membrane would be nonpermiable so that the water would only travel directly through the cotransporter pump. Even if this system were to not work exactly in the way that we intend it to, there are several ways that we could tell that the system was beginning to work. The pump may not work as efficiently as we plan and move the water and salt across the membrane at a slower rate than expected. There also may still be small amounts of salt that remains in the "filtered" section of the water.
This may offer a solution to the decreasing levels of fresh water available to us as it offers a relatively cheap and simplistic.
More info on Na+-glucose cotransporters: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2230848/
- It is a process that is inexpensive and simple to use/understand
- It is a process with low energy cost. Most of the energy that is required is used to pump liquids through the membrane. The total amount of energy that is used is minor, compared to alternative techniques, such as evaporation.
-These are some of the reasons why our design is worth funding
- The cotransporter may not be able to function without the presence of glucose as it is the molecule that creates the flow of the water and sodium through the pump itself.
- The membrane may be susceptible to tears if not working with another membrane or pair of membranes.
- There are risks of potentially harming sea life when collecting the salt water
- There is a quandary regarding where the left over salt would be disposed of
- Our design would benefit people. It does not pose a threat to the safety of people.
- A possible shortcoming of our design could be that it has not been fully formed yet. Other technologies have been tested and are known to work. Whereas, our design is merely a theory.
- Our design is worth any risks because there is a decreasing amount of available fresh water and competing technologies are expensive and complicated to run. Our design is simple and cheap enough to be used frequently as it does not use large amount of energy (just energy from sunlight and whatever method that we use to obtain the salt water).
TESTING: We would test the effectiveness of our design by placing salt water next to it. If it began to separate the salt from the water, then we would know that the membrane is effective. The first phase of this testing may be to see if the electron transport chain is effective in creating a sufficient supply of ATP for the cotransporter. The second component tested could be seeing if the ATP is being picked up efficiently. The last part would be to observe how much salt the cotransporters were pumping across the membrane. Testing could help to improve our system as it would allow us to weed out any potential errors made and make sure that as much salt as possible was being removed (ideally all of it). If testing reveals that the system is efficient and effective, then we may be able to apply it to other things or possibly add more effective ways of generating energy for the system biologically.