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Desalinization
Three quarters of the earth is covered with water, but you can’t drink it. Turning salt water into fresh water for drinking and for watering crops is vital for the future of the human race. Questions about desalinization (or desalination) are answered here.
245 Questions
Why is desalination expensive?
Desalination is primarily accomplished through reverse osmosis (forcing water molecules through a semi-permeable membrane) or distillation (evaporating salt water and then condensing the vapor). Both processes require large energy inputs to accomplish.
Carbon footprints will be increased by 180 kgs per 60, 000 of water, and that equates to a full tank of gasoline; however, that is less than traveling from Perth to Sydney!
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On the other foot, the construction costs are very large, the running costs are big and ongoing, and there is still resistance from the neighbors on the impact on the local community from construction and also from having a large, noisy, 24/7, industrial-size building stuck on your local beach between the houses bought for the ocean view and the ocean.
Where is the largest desalination plant in the southern hemisphere located?
Its 59 miles ouside Melbourne in the state of Victoria.
How is desalination of water done?
Multi-stage flash distillation
Multi-stage flash distillation (MSF) is a desalination process that distills sea water by flashing a portion of the water into steam in multiple stages of what are essentially regenerative heat exchangers. First, the seawater is heated in a container known as a brine heater. This is usually achieved by condensing steam on a bank of tubes carrying sea water through the brine heater. Heated water is passed to another container known as a "stage", where the surrounding pressure is lower than that in the brine heater. It is the sudden introduction of this water into a lower pressure "stage" that causes it to boil so rapidly as to flash into steam. As a rule, only a small percentage of this water is converted into steam. Consequently, it is normally the case that the remaining water will be sent through a series of additional stages, each possessing a lower ambient pressure than the previous "stage." As steam is generated, it is condensed on tubes of heat exchangers that run through each stage.
Reverse osmosis
Reverse osmosis is a filtration process typically used for water. It works by using pressure to force a solution through a membrane, retaining the solute on one side and allowing the pure solvent to pass to the other side. This is the reverse of the normal osmosis process, which is the natural movement of solvent from an area of low solute concentration, through a membrane, to an area of high solute concentration when no external pressure is applied. The membranes used for reverse osmosis have a dense barrier layer in the polymer matrix where most separation occurs. In most cases the membrane is designed to allow only water to pass through this dense layer while preventing the passage of solutes (such as salt ions). This process requires that a high pressure be exerted on the high concentration side of the membrane, usually 2-17 bar (30-250 psi) for fresh and brackish water, and 40-70 bar (600-1000 psi) for seawater, which has around 24 bar (350 psi) natural osmotic pressure which must be overcome.
Normally in osmosis when two solutions with different concentrations of a solute are mixed, the total amount of solutes in the two solutions will be equally distributed in the total amount of solvent from the two solutions. Instead of mixing the two solutions together, they can be put in two compartments where they are separated from each other by a semipermeable membrane. The semipermeable membrane does not allow the solutes to move from one compartment to the other, but allows the solvent to move. Since equilibrium cannot be achieved by the movement of solutes from the compartment with high solute concentration to the one with low solute concentration, it is instead achieved by the movement of the solvent from areas of low solute concentration to areas of high solute concentration. When the solvent moves away from low concentration areas, it causes these areas to become more concentrated. On the other side, when the solvent moves into areas of high concentration, solute concentration will decrease. This process is termed osmosis. The tendency for solvent to flow through the membrane can be expressed as "osmotic pressure", since it is analogous to flow caused by a pressure differential.
In reverse osmosis, in a similar setup as that in osmosis, pressure is applied to the compartment with high concentration. In this case, there are two forces influencing the movement of water: the pressure caused by the difference in solute concentration between the two compartments (the osmotic pressure) and the externally applied pressure.
Comparison between the two
The more efficient method is multi-stage flash distillation and hence currently produces the world's largest quantity of desalinated water. However, MSF requires a large system and works mainly in industrial production, hence reverse osmosis is more appropriately used in homes as a smaller household system despite its lower efficiency, due to its far quieter operation and smaller mechanism.
What countries use desalination plants?
Perth and Melbourne use it in Australia because they are near the sea, Israel, Saudi Arabia, and several Persian Gulf countries use desalination plants as well given the amount of desert they contain.
Desalination has very high energy requirements and since most countries with desalination plants do not have nuclear power, it results in the burning of lots of more coal. Additionally, the methods by which salt is removed from water create a resulting "salt-slurry" which is ejected as waste in to the original saltwater body. This salt-slurry makes the area around the desalination plant poisonous for the local sea-life.
However, in almost every case, the positives of desalination outweigh these negatives.
What are the positives and negatives of desalination?
the only negative thing will be africans getting healthy again and taking control over their resources, wait, that's a positive thing - happyboog
oh, and the only positive thing will be thousands and thousands of fishies and other marine life dying, hold on, that's a negative thing
and even though the plant is going to be very useful to humankind, we gotta think about mother nature too :) - gummi bears
Desalinization is good because you can't drink salt water. If you want fresh water and you live in a place with very little, but have a lot of energy, you can use desalinization to make fresh water.
Desalination is used to remove salt and other impurities from seawater or brackish water to make it suitable for human consumption or irrigation in areas facing water scarcity. It helps to increase the available freshwater resources and reduce dependence on limited water sources.
How will desalination help with your water shortage?
Desalination provides extra reserves of water by removing the salt from salt water.
What are the benefits of desalination?
u can still get high quality drinking water even if there is no rain, so the rural community can have good water.
Hey to all of my freinds's, xoxoxox. JASMINNNE hhehe
yes but the Carbon footprint will be increased by 180 kgs per 60, 000 of water and that equates to a full tank of gasoline, however, that is less than travelling from Perth to Sydney!
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On the other foot, the construction cost are very large, the running costs are big and on-going, and there is still resitance from the neighbors on the impact on the local community from construction and also from have a large, noisy, operating 24/7, industrial size building stuck on your local beach betwen the houses bought for the ocean view and the ocean.
How does a desalination plant work?
Desalination starts out like any other water treatment plant- the water is filtered and treated to get rid of particles, debris, unwanted chemicals, etc.
In desalination, this water is then forced through membranes which have holes big enough to let water through but too small for the salt particles.
Desalination has traditionally been too expensive for most municipalities to use, but as water becomes more scarce, it has become increasingly popular.
See the link below under "Related Links" for a website describing a desalination plant in Tampa Bay, Florida.
Recently seawater desalination process is focused on developing cost-effective ways to provide fresh water for human consumption in areas where the availability of fresh water is becoming more limited.
Seawater is forced through a semi-permeable membrane, which removes all of the dissolved solids and produces fresh, potable water on the other side. The desalination process will reject about 98 percent of salts, contaminates and pollutants from seawater. Salt or brackish water first enters in the RO via a through-hull fitting and is then filtered through the sea strainer. The feed water is boosted to 30 psi by the booster pump and filtered through 25 and 5 micron pre-filters. If oil is present, it is then separated and removed by the oil/water separator. These filters remove sediments and suspended solids from the feed water before entering the high-pressure pump.
The High Pressure Pump supplies the required force to drive the feed water through the semi-permeable Reverse Osmosis (R.O.) Membrane. An automatic high pressure safety relief valve protects the water maker if pressure exceeds recommended levels.
The fresh water produced flows out of the Reverse Osmosis Membrane where it is up to 99.2% free of salts, minerals, and other ions. It then passes into the Product Flow Meter where the amount of potable water produced per minute is registered. Next, the Salinity Probe registers the salt content of the product water. If the water is good quality, it passes through the 1 Micron Carbon Block Post-Filter and ½ Micron Ceramik Post-Filter, which purifies the water of unpleasant odors and taste. Finally, the last filtration process is completed by an optional Ultraviolet Sterilizer where 99.8% of all micro-organisms, including viruses and bacteria are destroyed.
Why are there no desalinization plants being built in the US or elsewhere?
In the US it's historically been cheaper to bring water in from elsewhere than to desalinate seawater. As water usage grows, that may eventually stop being true; southern California in particular is nearing the point where aqueducts from water sources such as the Sacramento river and the Colorado river are effectively tapped out. There have been attempts in California, but politics have hindered a project thus far. Apparently, there is at least one operational desalinization plant in the US in Tampa Bay. Tampa Bay link: http://www.tampabaywater.org/watersupply/tbdesal.aspx There is a reverse-osmosis desalination plant at Kwinana, Western Australia which was commissioned in 2005 and supplies Perth with around 20% of its water. There is a second plant under construction near Bunbury.
How do countries use desalination and irrigation to offset the problems faced by the Sahara desert?
Does the Sahara desert face problems? I don't think so.
it separates it in to two streams :)
Answerremoval of saltA more fancy pants answer is that desalinization is the process of extracting salt from sea water to make drinking water. An easy way to do it is to boil salt water and capture the water vapor as it leaves the boiling pot. When the vapor cools, it condenses and reforms into water drops that through coagulation reform into fresh water.
Answerthe remove of salt from a solution.e.g. removing salts from seawater to produce drinking water
AnswerIt means taking the salt out of a liquid.Many methods for water purification and seawater desalinization have been used for a number of years starting in ancient times with good old fashion distillation (boil the water and catch the condensate leaving the bad stuff behind). The leading method now is membrane based...reverse osmosis. Expensive to build, expensive to operate and maintain.
Reverse Osmosis uses pressure to force water molecules through a special membrane with very small pores that trap salts and other dissolved solids (retentate) and results in up to 99% pure water (solute). In low pressure home use, RO usually results in 80% or more waste...5 gallons of waste water are produced for every gallon of useable water. In high pressure systems (1000 psi or more) used in saltwater desalinization, recovery rates can exceed 90%. High pressure systems require alot of energy to run however.
New studies are underway to improve membrane efficiencies (particularly in energy use) include forward osmosis which actually uses an ionic salt process and then removing the special salts from the solute..or good water side..of the membrane process.
Carbon nano-tubes built into membranes and electrically charged to repel salt ions before reaching the membrane, and biomimetic membranes utlizing aquaporins in a similar charged fashion hold some promise to improving the efficiency of RO systems but are still in the theory and development stage.
One new process that is actually in commercial development is Capacitive De-ionization which uses a flow-through capacitor designed to eliminate dissolved solids from water using a small electrical charge.
freeze both of the waters and them put them in the barrel. you could still tell them apart since they will be frozen. freeze the water from both jugs and put them in the barrell you could mix the water with (different) coloured jello and lots of sugar so that they harden into two non-mixing lumps in the barral. And not only have you solved the riddle but have a yummy snack afterwards.
Are desalination plants good or bad for your environment?
There are many bad things about desalination plants. they are very expensive to use, and also let off a lot of carbon emissions which damage the ozone layer. The government spends a fortune on the chemicals needed to desalinate the water, then they discharge all the waste back into the ocean which can kill fish and damage the marine life.
How is science and technology utilized in desalination?
Desalination is the process of removing salt from sea water in order to make drinking water. The method of doing this typically uses reverse osmosis. Distillation is sometimes employed, usually using vacuum distillation.
category of desalination types:
1- thermal type (multi stage flash, multi effect,vapor compression)
2-membrane type.( reverse osmosis. electro dialysis)
3-ion type. (ion exchange)
Why are desalination and dip irrigation not used more in Southwest Asia?
it sounds like a simple solution right, that's what i thought but its not. desalination systems are very costly and with the recession right now, its not the first thing on peoples lists.
Since south west Asia isn't one of the most richest countries, its very costly to install a new desalination system, which other countries such as North Africa have others to come in and pay for it. for example, Hyflux won US$100m to install a new one there. If they had someone pay for theirs too, i bet they would use it more...
What is the process of taking salt out of sea water and making it drinkable water?
The process is desalination.
What is the term used for people who worry what others think of them whether it is good or bad?
The term is "people pleaser" or "approval seeker." These are individuals who are overly concerned with gaining the approval and acceptance of others, often at the expense of their own needs and well-being.
