Sea salt and water desalination

[dkjretired]

That reminds me that I haven't shoveled snow in the last ~35 years since moving from Shaker Heights to Texas. Go Tribe!

 

Sounds to me like some in this thread are shoveling more than snow...

[boscobeans]

If anyone is intrigued enough to shell out $16, Amazon.com sells a test meter that shows salinity ranging from 0 to 9990 ppm. Take one along and be the first to report ship by ship.:D

 

http://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY/ref=sr_1_6?ie=UTF8&qid=1381867685&sr=8-6&keywords=salinity+test

 

This product measures TDS in water not just salinity. TDS means Total Dissolved Solids.

Water desalinated on a ship may be totally free of what most people mean by SALT (Sodium Chloride) but may have other salts (carbonates etc..) added to give the water some taste. Bunkered water may also contain dissolved salts of all kinds including Sodium Chloride.

 

bosco

[jcrandle]

This product measures TDS in water not just salinity. TDS means Total Dissolved Solids.

Water desalinated on a ship may be totally free of what most people mean by SALT (Sodium Chloride) but may have other salts (carbonates etc..) added to give the water some taste. Bunkered water may also contain dissolved salts of all kinds including Sodium Chloride.

 

bosco

 

Correct me if I'm wrong, but my understanding is that the product measures the electrical conductivity of a liquid. Scientists have known the research of Galvani that measuring conductivity can give insight into the physical properties of matter. Once you have established the change in conductivity for a particular concentration of a dissolved solid, like NaCl, or table salt, it is simple to determine the ppm concentration of that solid. The difficulty is that there can be other combinations of other solids in the solution. These can have very different electrical characteristics, so the tester described likely makes the assumption that the only dissolved solid in the water is NaCl. If this is true, the reading is likely very accurate.

[boscobeans]

... so the tester described likely makes the assumption that the only dissolved solid in the water is NaCl. If this is true, the reading is likely very accurate.

 

I didn't see any claims in that ad ( could be I missed them ) stating it was for any specific solids such as sodium, just for total solids.

 

However you are correct, if you as the tester assume there is nothing other than sodium chloride in the water.

 

If there is nothing but sodium chloride in the water the instrument will have nothing but sodium chloride to measure. To be sure of that a qualitative analysis of the water would have to be done to see what was actually in it.

 

Our local water is extremely hard so we have a water softening system installed. It removes most of the carbonates (the major part of our hardness) only to replace it with sodium chloride. Our water already has 50mg per liter of salt from the tap ( 20mg or less per liter is what the dept. of health recommends ) so to remove the ambient salt along with the added salt from the softener we have a reverse osmosis water system installed. This removes almost anything that gets past the water softener including the salt that is added..

 

It would be interesting to see what the readings are on board a ship.

 

bosco

[robtulipe]

Our local water is extremely hard so we have a water softening system installed. It removes most of the carbonates (the major part of our hardness) only to replace it with sodium chloride. Our water already has 50mg per liter of salt from the tap ( 20mg or less per liter is what the dept. of health recommends ) so to remove the ambient salt along with the added salt from the softener we have a reverse osmosis water system installed. This removes almost anything that gets past the water softener including the salt that is added..

 

It would be interesting to see what the readings are on board a ship.

 

bosco

The above is not quite correct. It is only the sodium portion of salt that does the transfer, not the chlorine and likewise for the carbonate portion in the H2O as only the calcium and magnesium ions go into the brine solution of the water softener forming chloride salts of these two.

In a typical water softening ion exchange operation, hard water, due to the calcium and magnesium ions it contains, moves into the mineral tank and these ions are replacied by sodium ions to make the water soft since it now contains sodium carbonate, washing soda. The health problem with softened water is that the intake of sodium ions is bad for you.

Read more:

http://www.popularmechanics.com/home/improvement/interior/1275126

[boscobeans]

The above is not quite correct. It is only the sodium portion of salt that does the transfer, not the chlorine and likewise for the carbonate portion in the H2O as only the calcium and magnesium ions go into the brine solution of the water softener forming chloride salts of these two.

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Thanks for the clarification. It has been 13 years since we had the softener and RO system installed along with how the whole thing works.

 

bosco

[sddsddean]

For those wondering what the machines look like, here are some pics from the Independence of the Seas. First, two views of one of the pair of desalination plants, each producing 45,000 litres/hour (if needed).

 

 

 

Here is one of the 2 osmosis filters, producing 10,000 litres/hour from 'grey' water on the ship.

 

 

 

Simon

[retafcruiser]

For those wondering what the machines look like, here are some pics from the Independence of the Seas.....Simon

 

Really interesting! Thank you, Simon.