
MIT team invents efficient shockwave-based process for desalination of water - matttah
http://news.mit.edu/2015/shockwave-process-desalination-water-1112
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Animats
He patented this five years ago.[1] Here's the 2015 paper.[2]

Flow rates are very, very low. Note the reference to the fluid source being a
"Harvard Apparatus Syringe Pump".[3] That's just a motorized device for very
slowly pressing the plunger on a syringe, for very low flow rates. If they're
using that after five years of work, the process is still limited to very low
flow rates.

This is not necessarily a killer limitation. Reverse osmosis started that way,
but has been scaled up to industrial scale. But the technology is not here
yet.

[1]
[http://www.google.com/patents/US8801910](http://www.google.com/patents/US8801910)
[2]
[http://web.mit.edu/bazant/www/papers/pdf/Schlumberger_2015_s...](http://web.mit.edu/bazant/www/papers/pdf/Schlumberger_2015_shock_ED_justaccepted.pdf)
[3]
[https://www.harvardapparatus.com/webapp/wcs/stores/servlet/h...](https://www.harvardapparatus.com/webapp/wcs/stores/servlet/haisku3_10001_11051_68275_-1_HAI_ProductDetail_N_37295_37313_44353)

~~~
Animats
MIT Technology Review announced this last year, too.[1]

[1] [http://www.technologyreview.com/view/524606/new-
desalination...](http://www.technologyreview.com/view/524606/new-desalination-
technique-also-cleans-and-disinfects-water/)

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matthewmcg
Probably the first time "efficient" and "shockwave-based" have appeared
together in a Hacker News headline ;)

~~~
Rexxar
Indeed: [https://hn.algolia.com/?query=efficient%20shockwave-
based&so...](https://hn.algolia.com/?query=efficient%20shockwave-
based&sort=byPopularity&prefix&page=0&dateRange=all&type=story)

And your comment is the first one with this two words:
[https://hn.algolia.com/?query=efficient%20shockwave-
based&so...](https://hn.algolia.com/?query=efficient%20shockwave-
based&sort=byPopularity&prefix&page=0&dateRange=all&type=comment)

~~~
taberiand
What is joke?

~~~
twic
Perhaps
[https://en.wikipedia.org/wiki/Adobe_Shockwave](https://en.wikipedia.org/wiki/Adobe_Shockwave)
? If so, expect a joke about using tables for layout next.

~~~
samstave
Just make sure to use a salt on the data to keep your tables secure

~~~
Bjartr
You should keep both salt and pepper on your table, lest you confuse dinner
guests.

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eveningcoffee
Unfortunately

 _Initially at least, this process would not be competitive with methods such
as reverse osmosis for large-scale seawater desalination. But it could find
other uses in the cleanup of contaminated water, Schlumpberger says._

But it could help to make portable desalination modules:

 _Unlike some other approaches to desalination, he adds, this one requires
little infrastructure, so it might be useful for portable systems for use in
remote locations, or for emergencies where water supplies are disrupted by
storms or earthquakes._

~~~
nlh
Other than that statement, TFA didn't really go into why it wouldn't be
competitive with reverse osmosis.

Any thoughts or ideas?

Edit: New comment basically explained it. Very very low flow rates.

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hackuser
MIT's PR is more amazing than their research. How many science and technology
programs are there in U.S. universities, all of them producing new
discoveries? How about universities outside the U.S.?

The rate and impact of discoveries vary by school, yet it seems like half the
discoveries I read about come from MIT, and often via links directly to MIT
press releases (i.e., not to coverage in the news). MIT is a great school, but
they can't be that great.

~~~
x1798DE
Whenever I see one of these MIT press releases, I know to take it with a giant
grain of salt. I wonder if HN will eventually start penalizing links from them
as low quality.

~~~
dannypgh
If you run out of grains of salt, I know how you can get some more with
shockwaves...

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leot
Does anyone know why forward osmosis (e.g.
[https://www.youtube.com/watch?v=R63zYZZuRvQ](https://www.youtube.com/watch?v=R63zYZZuRvQ))
hasn't taken off yet? It seems like it has the biggest potential to do
desalination at an extremely low cost energy-wise.

~~~
jjoonathan
Sure, if you don't account for the energy needed to form the high-energy
carbon and nitrogen compounds ("special salts") in the first place. In
practice the "special salts" are either a very low efficiency fossil fuel (if
you dig them out of the ground) or a really roundabout and inefficient way to
spend other forms of energy.

The Haber process reduces N2 and plants reduce CO2, giving you the "special
salts" (energy inputs: H2 and pump pressure for Haber, sunlight for plants).
Then you burn the high-energy nitrogen+carbon compounds back into N2, H2O, and
CO2 to remove them from the "forward-osmosis" solution. The sunlight, H2, and
mechanical work used to create the special salts could almost certainly be
used more effectively to generate electricity for reverse osmosis or
distillation.

~~~
leot
But in the video I shared, it's claimed that the fancy salts can be entirely
reused, and that extracting them takes relatively little energy. Thus their
ongoing energy impact, and the longer-term impact of their initial cost should
be relatively low, no?

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chris_va
_In this 170 first SED prototype, the impressive salt removal and water
recovery come with significant energy costs, in the range of 10−1 to 103 kWh
/m3 171 (hydraulic pumping makes up about 0.5 kWh/m3 172 )_

That is quite the energy range...

------
godgod
Humanity can really benefit from this. I am waiting to see what becomes of
this breakthrough.

