[HN Gopher] Turning desalination waste into a useful resource
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Turning desalination waste into a useful resource
Author : thereare5lights
Score : 36 points
Date : 2021-01-24 12:17 UTC (10 hours ago)
(HTM) web link (news.mit.edu)
(TXT) w3m dump (news.mit.edu)
| dj_mc_merlin wrote:
| > The researchers have discussed the concept with companies that
| may be interested in the next step of building a prototype plant
| to help work out the real-world economics of the process. "One
| big challenge is cost -- both electricity cost and equipment
| cost," at this stage, Kumar says.
|
| Huh, I thought their big breakthrough would be figuring out how
| to make this economically viable. It's not a big surprise you can
| make useful chemicals out of brine, right?
| detritus wrote:
| Use it to maintain salinity levels in deep ocean currents, to
| sustain current circulation patterns and reduce the impact of
| arctic runoff, impacting weather systems. Or something.
|
| https://www.nature.com/articles/s41467-020-14474-y
| heimatau wrote:
| HN community seems to really like desalination. Various
| innovations seem to hit the FP occasionally.
|
| I'll say this to the general sentiment. My 9th grade chemistry
| teacher say 'your generation will face two major problems: xxxxxx
| and water'[1]. He's been a sage in my life, retired for about 1.5
| decades.
|
| I say all this to attempt to say that 'this is refreshing' that
| this community understands that we are in an impending crisis of
| water. Onward! :)
|
| [1] - I'm a millennium and I won't reveal 'xxxx' because I'm not
| trying to incite anger but he was correct about 'xxx'.
| billfruit wrote:
| Also another thing I hear a lot of hype about is Atmospheric
| Water Extraction, but as of now remains longway from being
| practical at scale.
| enkid wrote:
| Why do the x's keep getting fewer? Is the crisis a lack of x's?
| heimatau wrote:
| > Why do the x's keep getting fewer? Is the crisis a lack of
| x's?
|
| Yeah. I ran out of ink.
| inglor_cz wrote:
| xxx = Mass migration?
|
| Depends on where you live, it is already happening. And it is
| sometimes caused by long droughts, actually.
| umvi wrote:
| xxx = misinformation
| klyrs wrote:
| I've got karma to burn, so I'll come out and address the
| controversy straight on. xxxx is the rarity of Charizard in
| Pokemon Go.
| simonebrunozzi wrote:
| xxx = pollution? energy?
|
| edit: or a certain political guy?
| andromeduck wrote:
| My thesis in grade school thesis from ~17 years ago was that
| the two most important problems to by solved in my lifetime
| were going to be low cost, low emission and low land use energy
| production and efficient information processing and
| communication.
|
| I think desal is much less of a problem if we had a cheap,
| clean, and reliable source of energy to power it such as
| nuclear.
|
| Quality of life is strongly correlated with energy intensity.
| heimatau wrote:
| I'm not entirely sure how but in the past two years, I've
| become a believer in the capitalism structure for the markets
| and that it's _able_ to solve any given problem (including
| what you 're saying). Capitalism just needs to get nudged
| into a direction and the solutions will be a product of
| markets.
|
| To elaborate my point, through government subsidies: -
| American has seen massive production of food (so much that we
| waste an insane amount every year) - Massive creation with
| minimal resources (via petrol innovation; even if y'all don't
| like it, it was an easy win for society and we're living with
| the second order effects) - Vehicle fuel efficient rise -
| Green revolution is almost profitable without government
| subsidies.
|
| I'm not an economist but the game theory does seem to playout
| in such a way, for the past century, to confirm 'we'll find a
| way, given a nudge in the right direction'.
| andromeduck wrote:
| You should check out the Decouple podcast :)
|
| https://podcasts.apple.com/us/podcast/decouple/id1516526694
| toiletfuneral wrote:
| Capital has shown it will not fix climate change but only
| try and profit on the destruction. If free markets could
| solve healthcare or the island of plastic in the pacific,
| it would've happened.
|
| Literally nothing is getting better while corporate
| earnings increase, so wake me up when the market figures
| out how to respond to actual problems, not just automate
| away labor.
| rbanffy wrote:
| We don't have a water crisis. We have a clean energy one. With
| abundant energy we could simply boil sea water to get drinkable
| water. The biggest problem of the various desalination methods
| are their energy cost, and this method to reprocess the brine
| is meant to offset it by extracting commercial value from the
| desalination residue. While it's great to make desalination
| commercially viable, we also need to remember our energy needs
| will not drop.
|
| I have the nagging feeling that the "commercial" part is what
| we'll need to solve if our species is to survive long term. In
| some matters, whether its commercially viable should not be a
| concern.
| mschuster91 wrote:
| > With abundant energy we could simply boil sea water to get
| drinkable water.
|
| That still leaves you with either solid salt that needs to be
| disposed of (preferably, somewhere where it can't eventually
| leach out into groundwater) or highly concentrated brine
| which will kill anything near it.
| hutzlibu wrote:
| "highly concentrated brine which will kill anything near
| it."
|
| That sounds a bit dramatic, for salt in water, don't you
| think?
|
| Sure, it is not a enviroment, live can prosper and it kills
| most living things, that would have to live in it, but it
| is also not deadly toxic, "killing anything near it" like
| your comment implies.
| philwelch wrote:
| How much waste salt would we have compared to the amount of
| salt that we are going out of our way to extract or mine
| already? I mean, I literally pay money for sea salt at the
| grocery store.
| enkid wrote:
| How much salt do you use in a month? How much water do
| you drink?
| hansvm wrote:
| That's not really a fair comparison. There's easily 25x
| as much water vs salt in the ocean, and a 10x higher
| fraction of water usage is residential than salt usage.
| The break-even point you're pointing to is closer to
| 250:1, not 1:1.
| enkid wrote:
| That's fair enough, but I still doubt you use 1/250 of
| water in salt, even when you're cooking. If you add
| things like showering, washing clothes, and lawn care,
| it's not even close
| hansvm wrote:
| The numbers I gave did include factors like showering.
|
| Edit: I do think that you use more than 1/250 salt vs
| water in cooking though (whether by mass or volume). By
| mass that's around 1tsp of salt per 6.3 cups of water,
| and soup recipes for example will often call for that
| much extra salt on top of whatever is already in the
| other ingredients you're using.
|
| Edit: Individual recipes are probably the wrong way to
| look at that. It's recommended to eat under 1tsp of salt
| (actual usage is higher in the USA) and drink over 10
| cups of water each day, so whatever combination of
| food/beverages you're taking in you still wouldn't quite
| hit that crude 1/250 threshold.
| philwelch wrote:
| Salt is also useful for things other than eating it, and
| more of those uses may be cost-effective if salt were
| more plentiful.
| throwawayboise wrote:
| Sea salt contains microplastics. You should seek out
| mined salt.
| rbanffy wrote:
| Or we could find a way to remove them from, say, the
| brine.
| andromeduck wrote:
| Just put it back from whence it came. The extracted water
| doesn't exactly leave the environment, it will find its way
| back into the oceans anyway.
|
| If the excess brine is diffused over a wide enough area or
| as is often the case, the outlet of an estuary, local
| disruption is minimal and global disruption is exactly
| zero.
| doodlebugging wrote:
| I would also point out that there is an endless stream of oil-
| field brines and related contaminated waters available for
| processing should anyone want to have a continuous source of raw
| material.
|
| The industry, in its never-ending quest to monetize waste
| products or to place the cleanup burdens on someone else (the
| public usually) is currently trying to get Texas to agree to
| allow pumping of these highly contaminated wastes into aquifers.
|
| Any time you produce oil or gas you always produce some waste
| water with it. Volumes will vary from well to well depending on a
| lot of variables unique to a field or a well. This water, or most
| of it, is not all water from production if I read the article
| correctly, a lot of it is flow-back water from the fracking
| process. That means it is not water that would normally be
| reinjected to help maintain formation pressures to allow
| continued production. It is water pulled from public and private
| potable water supplies including, lakes, aquifers, etc. This
| water should have been reserved for human consumption or for use
| in farm or ranch maintenance.
|
| T Boone Pickens set in motion the whole idea of gathering rights
| to large volumes of water and selling it to users far from the
| source. This really set the stage for the massive over-use of
| public water in fraacking in the Permian Basin and other related
| areas that saw a large fracking boom.
|
| The potable water is gone now, polluted by the O&G industry, and
| now they want to be able to just put it back where they found it
| and let God sort out the contaminants. Disgusting really.
|
| But, it sounds like a great opportunity for someone operating in
| the water treatment space to test and validate options for
| wastewater treatment and for recovering chemical and mineral
| contaminants from non-potable water.
| stareatgoats wrote:
| > The team also continues to look at the possibility of
| extracting other, lower-concentration materials from the brine
| stream, he says, including various metals and other chemicals
|
| Lithium from desalination brines seems to be one potential (and
| promising) such [0], environmentally better in more than one way
| than the current methods of lithium mining [1].
|
| [0]
| https://www.researchgate.net/publication/313372304_Towards_l...
|
| [1] https://www.wired.co.uk/article/lithium-batteries-
| environmen...
| philwelch wrote:
| You can also extract uranium from seawater, and use it to fuel
| nuclear reactors, and use the nuclear reactors to power your
| desalination.
| enkid wrote:
| Do you get enough volume for this to work? My intuition would
| be the levels of Uranium would be low enough that it would
| not be energy positive. Do you have more information about
| this process?
| vilhelm_s wrote:
| Googling a bit: it takes about 13 MJ to desalinate 1 m^3 of
| water by reverse osmosis. Seawater contains 3mg uranium per
| m^3, which gives 2 MJ, So it's not energy positive.
| 08-15 wrote:
| Energy consumption of reverse osmosis is about 4kWh/t. The
| byproduct is a ton of brine. Sea water contains about 3ppb
| Uranium, so our brine contains 6mg of U per ton of fresh
| water produced.
|
| A 1GW nuclear power station consumes about 1t of U per year
| and produces about 8000GWh of electricity in that time. So
| we need about 1mg/8kWh. We got 12 times that much.
|
| So, it sort of works out. Of course, this assumes a breeder
| reactor and I pretended that brine is purified uranium. If
| breeders are commercialized, it might be worth looking into
| this. Right now, it isn't.
| enkid wrote:
| Awesome, thanks!
| wolfhumble wrote:
| So 4kWh/t is used to desalinate 2 tons of seawater that
| turn into 1 ton of freshwater and 1 ton of brine?
| credit_guy wrote:
| Nice analysis. But the premise of the discussion here is
| that people do the desalination for its own sake, not in
| order to harvest Uranium.
|
| This [1] article from 2012. It presents a Uranium
| extraction method from seawater that would put the
| extraction cost at $300/kg. Nowadays the market price is
| about $70/kg. However, if method were to be applied to
| brine instead of regular seawater, maybe the cost would
| go down. Hard to see it going down by a factor of 5
| though.
|
| [1]
| http://large.stanford.edu/courses/2012/ph241/ferguson2/
| vilhelm_s wrote:
| I think you overestimate the energy in uranium. 8000GWh
| per tonne and year would be 28.8 TJ/kg, while the numbers
| I have seen is more like 0.7 TJ/kg
| (http://www.plux.co.uk/energy-density-of-uranium/).
| 08-15 wrote:
| What part of "this assumes a breeder reactor" did you not
| understand?
| jbay808 wrote:
| I remember some projects going on at MIT on this topic.
|
| https://dspace.mit.edu/handle/1721.1/111821
| HarryHirsch wrote:
| For a long time, bromine was an important product made from
| brine. But that market has fallen away, since the lions share
| used to be made into lead scavengers for leaded petrol. The
| bromine works at Amlwch on Anglesey closed in 2004:
| https://www.octelamlwch.co.uk/
|
| The other obvious product would be magnesium, but they didn't
| isolate magnesium chloride at the bromine plant. The Wylfa
| nuclear power station was nearby, and Rio Tinto had an
| aluminium smelter nearby to provide a base load. Since
| magnesium is oftentimes produced through electrolysis a
| magnesium plant would have made sense, but somehow they didn't
| build one, likely for economic reasons.
| dzhiurgis wrote:
| There was some research into using it in concrete.
|
| I thought perhaps it can be shipped to northern territories that
| spray brine onto streets in winter to melt snow.
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