Why is it so difficult to remove salt from water at a reasonable cost and on a large scale?

Question

Given the increasing global need for water and man's ability to achieve incredibly complex scientific endeavours why is it so difficult to remove salt from water? After all nature does it all the time and we are able to treat human sewage and create potable water!
Thank you.

Answer 1

because when salt is dissolve in water what you have is a lot of individual ions of Cl- and Na+ floating around surrounded by the conversely polar sides of the water molecules (that dont want to part with their ionic friends.

Evaloration is the method of choice to break these two apart,... but the thermal energy to raise water to the boiling point and then to change it to steam is very high.

At present... the benefits of having that amount of salt and water in their pure forms available is not financially beneficial compared to the cost of doing it.... perhaps in a few dozen years... water will become a more profitable commodity... but til then...

Answer 2

If you have ever seen one of those high school experiments with a bunsen burner, a flask of salt water, a flame and a couple of tubes running through cold water. You would know it is not that hard to treat salt water to make it clean. All you do is heat the salt water, the water evaporates and is carried up the tube at the top of the flask it is in. Fresh water only evaporates because the salt is a solid and will not evaporate. When the evaporated water hits the cold of the tube in cold water it forms drops and rains down into a flask underneath the end of the tube coming out of the the flask under the flame. The result is a flask full of fresh water eventually. I am sure this could be done on a much larger scale using solar power to heat the salt water.

Answer 3

Desalination is not a new idea at all. In fact, much of the Middle East gets its fresh water from desalination of ocean water.

The problem is economical. It is expensive to desalinate ocean water on a large scale. Countries like Saudi Arabia can afford to do it but other countries in the developing world cannot afford it.

Another problem is that desalination is difficult to do on a large scale because of the energy requirements (another reason desalination is popular in the Middle East). A country would need excellent infrastructure and access to vast energy resources to rely on desalination as its water source.

Technology is catching up though. There are already plans for nuclear powered desalination plants.

Answer 4

Desalination is not new to anyone. It can be done. But to removw salt from water on a large scale at reasonable prices is almost impossible. Firstly, the fuels needed is expensive. Fossil fuels are running out and prices are almost skyhigh. Secondly, the prices of the machinery are expensive. Third, there's not enough land in urban or suburban areas to build the plant. Fourth, money is needed to ensure the exhaust released is not harmful. Fifth, fines are handed out if wastes are dumped into waters. Next, plants need to be planted to ensure sufficient oxygen supply. Then, the cost of gas needed for combustion is to be considered. Then, the waters must be given out to people to make sure its not a waste. Next, the price of plumbing and maintainace of the pipes are needed. Lastly, reasonalbe prices to charge the people who receive the water and earning profit in the process of manupacturing and maintainace. Therefore it would be difficult to remove salt at reasonable prices.

Answer 5

Its all a matter of economics. It still costs money to do the desalinization. And there are many methods to do this as well. However, it is cheaper to import water than to desalinate it. Go figure. We live in a wierd world.

Answer 6

desalinizing water to make drinking water takes more than 3 times as much money as conventional methods.

there is no telling what the impact of desalinization on a massive scale would be

how about them apples?

Answer 7

you could evaporate the water which separates it from the salt. The complicated area of that is doing it effectively. in case you get the water heat sufficient to evaporate coming up water vapor you will desire to cool that vapor right down to confirm that it to condense. this could take greater ability than heating the water contained in the 1st place. The performance fee of condensation will matter on the variation in temperatures between the warmth vapor and the condensing equipment. The salt won't evaporate out of the preliminary container.

Answer 8

evaporation