Desalination is a process by which dissolved salts are removed from seawater or brines water thereby converting it into potable water. There are two classes of desalination: thermal or, distillation process, heats the saltwater to boiling, collects and condenses the steam producing purified water; the membrane class Reverse Osmosis (RO) and Electro-Dialysis reversal (EDR) method involves forcing salt water across a semipermeable membrane that separate the salts from the water leaving a saline solution or brine on one side and a “de-saline” solution (drinkable water) on the other. The following are the most frequently used types of desalination:
Multi-Stage Flash Distillation (MSF) is a type of thermal desalination. Salt water is heated under extreme pressures and lead through a series of chambers. The first chamber is under a lower pressure than the salt water that enters it allowing a portion of the salt water to vaporize and be collected. Upon leaving the first chamber the salt water enters several more chambers each with a lower pressure than the previous one allowing even more of the pressurized salt water to vaporize. The sum of the vaporized water is collected and re-condensed into distilled water. The water that did not vaporize leaves the system with a higher saline concentration than when it entered; this is discarded properly as waste while the distilled water is put into the municipal water supply as drinkable water .
Multiple Effect Distillation (MED) is a type of thermal desalination. Salt water is heated under pressure and and forced through a chamber. A portion of the salt water evaporates leaving behind a slightly more saline solution than the original salt water. However, in this system the water vapor from the first chamber is used to heat the water in the next chamber (that is under a lower pressure than the previous chamber). Though this pattern repeats throughout several chambers to increase the efficiency of the overall system, the underlying process is trying to use the heat of condensation to heat the next batch of salt water; this produces distilled water (the condensed water vapor) and more water vapor (the cycle repeats) .
Reverse Osmosis (RO): is a type of membrane desalination. Here salt water is forced under high pressures through a semipermeable membrane that produces relatively pure water on the downstream side and leaves saline-rich water on the source side. Because membrane cleanliness is crucial to the efficiency of this mechanism, salt water is treated with some initial filters to remove particulate matter. Additionally, after the water passes through the designated membrane, a post treatment generally occurs to to kill any microbes in the water as well as adjustment of the water’s pH back to normal .
Relevance to Mission 2017
Human population is growing at a rate that puts stress on our current freshwater supply. If global water use is already at 9 trillion cubic meters a year and this rate is expected to increase by approximately 60 billion cubic meters more per year, according to our model, then humans must either use the water we have in a sustainable fashion or find another source for water.
Desalination allows to people to have access to water that was previously not potable (finding another source). In most cases this means coastal cities can use seawater for their municipal water supply (many islands in the Caribbean also use desalination) or landlocked cities can use brackish groundwater for the same purpose. Desalination combined with Water recycling are both integral components of our “water crisis” solution.
Figure 1: Various country’s usage of desalination. Worldwide usage is expected to grow with climate-induced water stress and as desalination technology becomes cheaper .
Of the more than 12,500 desalination plants in operation or in construction worldwide, 60 percent are located in the Middle East and North Africa (MENA). Saudi Arabia paves the way for desalination usage by obtaining roughly 24 million cubic meters of water from the Persian Gulf a day . Here, the desalination method of choice is MSF because of its ability to operate in conjunction with the waste-heat water from a power plant (given Saudi Arabia’s abundance of oil) . At the present nearly 70 percent of the nations water comes from desalination but there are plans from within to make the nation completely water independent (i.e. independent from fossil groundwater) within the next few decades . Currently, but not surprisingly, Saudi Arabia hosts the world’s largest desalination plant that alone produces 800,000 cubic meters of water a day that travels through a maze that consists of 2500 miles of pipes to reach the various inland cities of the country . Such an extensive pipe system gives Mission 2017 reason to believe that desalination technologies are not necessarily restricted to servicing coastal cities. Further still, Saudi Arabia plans to achieve its complete independence of water by constructing desalination plants that run purely on solar. Specifically, for the cost of $500 billion, the country can increase its desalinated water production by a factor of 5 (which is required amount to meet the needs of its growing population) and produce several solar farms that will harness approximately 60 terawatts of energy from the sun and power the desalination plants . This country’s long term goal provides the ideal blueprint of all other nations (that are not landlocked) in that desalination and solar cells, when used in a conjoint manner, can make a country both water and energy sustainably independent.
The benefits of desalination are straightforward: more water. The drawback, unfortunately, is the cost. Currently, the average cost of desalination is roughly $5 for 1000 gallons of water while a typical municipal water supplier charges about $1.50 for 1000 gallons . This difference in priced is incurred from the costs it takes to build and run a desalination plant compared to simply pumping water from an aquifer or lake. Regardless most people would avoid paying 3-4 times more for anything if they do not have to.
There are three situations that Mission 2017 identified as possible for any given location:
- A region has a water supply that is large enough to meet the population’s needs and is sustainable at present.
- A region has a water supply that currently meets the populations needs but is not sustainable (water stress within 10 years)
- A region does not currently have enough water to meet its demand.
If a region’s water supply is currently meeting the needs of the people in a sustainable manner, then switching to desalination, unless it is economically productive, is not an urgent issue. The places that fall under category two, on the other hand, will have to examine their situation with more thought. If the supply is unsustainable at the rate consumption is now, then some action must be taken to insure that future generations will have access to water (part of Mission 2017 declarations). Desalination will be appropriate if the area is then either rapidly running out of water or if the effort it would take to make the water supply sustainable (see Artificial Recharge) is not feasible (i.e 100 percent of the water supply must be reused indefinitely). Additionally, if a location can be categorized as the third category, then desalination should be seriously considered. Another way of putting this is “if your backyard well is dry [or running out quickly], you cannot solve your household water supply challenges by reusing or conserving more of the well water which you do not have” .
Where to Implement
Mission 2017 believes that desalination needs to be implemented in any ocean bordering region that falls under the third category because the current conditions would warrant its use. As Saudi Arabia has already demonstrated, water can be pipped inland to landlocked cities which means desalination is not limited to coastal cities and can ensure the prosperity of sizeable regions. In the following image, every region colored with a light tan (representing infrequent rain) is an area Mission 2017 would like to see supplied with desalinated water.
Figure 2: shows the global distributions of rainfall across the globe highlighting the regions that have water access and the regions that lack it .
The major preliminary issues that must be addressed before desalination can used are:
- Is desalination compatible? Desalination is cheapest per cubic meter the larger the scale so it is more efficient to build a large plant to supply a city (or several villages) then to build a local desalination plant for a town. Mission 2017 is looking first and foremost for compatible regions to implement desalination
- Will desalination have a competitive place in the market? Even if desalination were implemented in every category 3 place on the planet, there are still a lot of places that fall under category 2 where desalination could be utilized if it produced water at a competitive level. Mission 2017 is thus also looking to implement desalination in areas besides deserts.
- Who will pay for building and maintaining desalination plants? Theoretically, desalination plants can pay for themselves in two decades if the price per cubic meter of water is set appropriately. As a result, the issue is now limited to upfront costs.
- Where will the energy come from? Desalination plants require over 15,000 kilowatt hours of electricity a day when operating . As a result, any region that has a desalination plant must be able to produce enough energy.
To address these issues we have developed an initiative based system to promote the further use of desalination. Countries will have to first do some preliminary research to make sure that there are locations within their borders where it is feasible to construct a desalination plant; this includes proving that the water will be used (i.e. they have some sort of water distribution system), proving that they can appropriately dispose of the saline waste without impacting the environment, proving that the plant will be supplied sufficient energy, and demonstrating that their country’s corruption rate is low enough to be trusted. If a country meets these qualifications they can apply for our support. Post application, we will determine the most appropriate way to organize the funds for the construction of desalination plants on a case to case basis by cooperating with business, banks, and other resources willing to participate. Even though this initiative will be a rolling application, getting the word out, and finding countries that want to participate will take at least 5 years. Additionally, drawing up the plans to implement desalination as well as physically making the blueprints for a plant will take another 2-3 years . Finally, building the plants themselves would take anywhere from another 3-4 years . As a result, we would expect to see the working effects of desalination as soon as 2023.
What is Water Recycling and How does it help?
In every location that has a centralized sewage system, the sewage is pumped through pipes to a sewage treatment facility. The treatment process occurs in a few steps. The first step is Preliminary Screening which removes large debris such as wood, dead animals, or clothing. Once sewage has passed through screens, it is then mixed vigorously and pumped with air induce the decaying process of organic waste. After aeration, the sewage enters settling tanks where the heavy sludge sinks to the bottom and the lighter materials float to the top; both of which are removed from the water (scraped from the or bottom of the tanks). After the majority of the macro waste is removed, the water is then chlorinated to kill any remaining microbes that could cause harm. The last step of the process is to neutralized chlorine in the water and stabilizing the pH. Once, the sewage has been processed, it can now be safely return to the river or ocean .
The only thing difference between the sewage treatment process and water recycling is what happens to the water when it leaves the plant. Water that leaves a sewage plant can be used for any number of non potable purposes instead of disposing it .
Current Uses of Water Recycling
For as simple as water recycling is, only a few nations actually implement water recycling on a noticeable scale. Currently, Israel leads the way with water recycling because it recycles 100 percent of its sewage water. The result of this is that Israel now has 70 percent more water to use for agriculture (the other 30 percent is used as grey water or water used by industry). Considering that the 70 percent of the world’s water is already used for agriculture, water recycling, on a global scale, could reduce the amount of water pulled from sources by 25 percent .
The American Southwest is another location that implements water recycling as that portion of the country is a desert and is constantly under water stress. Irvine California uses recycled water for toilet flushing which only adds 9 percent to plumbing costs . However, by using recycled water for the number one source of domestic water use (26.7 percent of domestic water is used for toilet flushing) , the city requires almost a quarter less water per year. The other major use of recycled water is industry. For example, recycled water is used to cool the Palo Verde Nuclear Reactor in Phoenix Arizona . As can be seen by the purple arrow in the image below, water recycling can supplement many different needs in society.
Figure 3: The purple arrows represent uses of recycled water (also known as grey water) and the blue arrows represent “new” water .
Where To Implement More Water Recycling
Because water recycling simply reuses treated water that would have otherwise been disposed of, it is both a cheap and highly effective method to reduce net water usage. The component of water recycling, however, is that the water must be treated it is to be used again. Mission 2017 would thus like to encourage cities worldwide, that already have sewage systems, to implement water recycling.
Our plan to implement water recycling on a worldwide basis would include spreading the word about the the simplicity and benefits of the process as well as using subsidies. Specifically, if a nation demonstrates interest in wanting to implement water recycling technologies (this could include wanting sewage treatment facilities), Mission 2017 will work with them on a case by case basis to find businesses and banks that are willing to provide the upfront costs of building the plants (they would make their money back by selling the treated wastewater).
The timeline of implementing water recycling on a global scale (it could be done is as little as 15 years):
- 5 years of spreading the word (or more as it catches on)
- 2 years to review the nations current capabilities of water distribution and the optimal location of recycling plants
- 2 years to design the the recycling plants and the pipes systems that will distribute the water 
- 2-3 years to build the recycling plants .
- 3 or more years build the pipes to distribute the water
- Time will also be needed to establish legislation regarding the use of recycling water (this aspect will be unique to each country), however, this will begin when the plans are drawn up to build the recycling plants and thus will not require more time than listed above
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