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Saudi Thirst for Water Is Creating a Toxic Brine Problem

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Re: Saudi Thirst for Water Is Creating a Toxic Brine Problem

#31

Post by Retric »

sp332 wrote: post #23
Retric wrote: post #19

Earlier quoted context omitted.

At worst these dead zones would be tiny. They could dilute the waste stream by dumping it into the local sewage system, but I don’t think that’s going to change much. It’s on the order of building a mall parking lot. Sure bad for the local ecosystem, but we have vastly larger issues.

It's going to be dumped near the shoreline, where sea life is very different from what is supported in the open ocean. If the shoreline is made uninhabitable, the marine life there might not have anywhere else to go.

Near in this case would need to basicly be directly into. Actual desalination plants don’t do this.

Further by parking lot I mean an actual parking lot. Dump it even 1000 feet from the shoreline and you would have trouble detecting the extra salt in the surf.

Re: Saudi Thirst for Water Is Creating a Toxic Brine Problem

#33

Post by z2 »

ryanmercer wrote: post #27
swebs wrote: post #17

Earlier quoted context omitted.

How about dumping it into a shallow pit and letting the water evaporate, creating new salt flats.

>Saudi Arabia emits 31.5 million cubic meters of liquid effluent a day You'd need some massive pits and you'd have to displace way more than 31.5 million cubic meters of soil as it isn't all going to evaporate in a day. Ideally you'd want really shallow pools so you'd eat up an insane surface area. For some reference an Olympic sized swimming pool is about 2,500 cubic meters so you'd need 12,600 (pools) just to hold…

Wait. Do you mean a cube of silver|gold that's 55|20 meters on one side, as in the width of the cube and not its volume? As in 55^3 = 166,375 m^3 of silver, and 20^3 = 8000 m^3 of gold? That 5.36m diameter cube illustration representing a single year's gold production in the source is already 154 cubic meters.

Re: Saudi Thirst for Water Is Creating a Toxic Brine Problem

#34

Post by philipkglass »

swebs wrote: post #17
dsfyu404ed wrote: post #6

Earlier quoted context omitted.

Even if it's just extra salty it's still a local problem. You can't just dump it all in the ocean because it would still kill everything. You'd need to dump it out slowly or over a much wider area for the concentration not to be harmful. It's like a polluted river killing everything where it dumps out even if the amount of pollution is inconsequential overall.

How about dumping it into a shallow pit and letting the water evaporate, creating new salt flats.

At 35 degrees Celsius (308 K, 95 F), it takes about 44 kilojoules to evaporate 1 mole of water [1]; at 55.6 moles/liter, that's 2.4 megajoules per liter.

Averaged over a year, the energy available to evaporate water over a given area is roughly equal to insolation from the sun. Saudi Arabia has excellent solar resources averaging 2200 kWh/m^2/year [2], e.g. 6 kWh/m^2/day, e.g. 21.7 MJ/m^2/day. With perfect sunlight absorption you could evaporate 9 liters per m^2 of evaporation-pit per day.

They're currently discharging 31.5 billion liters of liquid per day, per the article. That translates to about 3,500,000,000 m^2 (3500 square kilometers) of pit area. So that's probably one reason why nobody deals with desalination brine this way. It would require very large evaporation pits even if you have excellent sun levels to evaporate the waste. It seems like it would be technically possible in SA, as they have a low population density and lots of unused land, but it sounds expensive. Some countries that rely on desalination, like Israel, don't have the spare land area even in theory.

[1] https://en.wikipedia.org/wiki/Enthalpy_of_vaporization#/medi...

[2] https://www.sciencedirect.com/science/article/pii/S101836391...

Re: Saudi Thirst for Water Is Creating a Toxic Brine Problem

#35

Post by ryanmercer »

blunte wrote: post #4

Imagine what the extraterrestrial anthropologists will say about humans someday...

"It appears plastic-based life forms co-evolved alongside carbon-based life on this body, how interesting, we thought only carbon-based life was possible but there is just so much microplastic with large concentrations in these ancient civilization centers! It also appears they dug up, refined, and relocated the bulk of the uranium and plutonium to this cave system, they must have worshiped it. How bizarre, they could have used this in Snarlsfarogogogog reactors with almost 100% efficiency and only had transmuted metals left as a byproduct. And what is with all of these 'AOL' squares and circles?! This must have been their servant class but there's no discernible means of locomotion"

Re: Saudi Thirst for Water Is Creating a Toxic Brine Problem

#37

Post by paulcole »

Johnny555 wrote: post #21
hughdbrown wrote: post #14

> Saudi Arabia’s desalination plants produce about 31.5 million cubic meters of contaminated water each day. That volume of liquid, most of which is pumped back into the ocean, is equivalent to about 20 million barrels of oil a day, or, double the amount of crude it currently produces I don't understand the math. 31.5e6 cubic meters * 1e3 liters/cubic meter = 31.5e9 liters 31.5e9 liters / 3.78 liters/gallon = 8333333…

I don't understand the equivalence to oil at all -- are they saying that one barrel of this contaminated water has the same environmental impact of dumping a barrel of oil in the water? I don't really understand the relevance of equating water waste to exports, if it were a nation known for pork exports, would they put the water volume in terms of hogs?

It's an analogy. The average person knows Saudi Arabia exports a LOT of oil. This is 2x a LOT. So a WHOLE LOT.

Re: Saudi Thirst for Water Is Creating a Toxic Brine Problem

#38

Post by mrfusion »

philipkglass wrote: post #34
swebs wrote: post #17

Earlier quoted context omitted.

How about dumping it into a shallow pit and letting the water evaporate, creating new salt flats.

At 35 degrees Celsius (308 K, 95 F), it takes about 44 kilojoules to evaporate 1 mole of water [1]; at 55.6 moles/liter, that's 2.4 megajoules per liter. Averaged over a year, the energy available to evaporate water over a given area is roughly equal to insolation from the sun. Saudi Arabia has excellent solar resources averaging 2200 kWh/m^2/year [2], e.g. 6 kWh/m^2/day, e.g. 21.7 MJ/m^2/day. With perfect sunlight a…

Nice analysis! Three things to consider:

I don’t think you can just look at insolation over a given area. Wind and even the cooling itself will cause the air over the area to redistribute with warmer dryer air that can continue picking up water.

Besides that it’s more important to consider how saturated the air in the region is. If it can hold more water it will.

Other things to consider

Some of the water would seep into the ground instead of waiting around to evaporate. Maybe there are ways to speed that up too.

Finally Another option is the spay the water into the air to speed up evaporation a bit.

Re: Saudi Thirst for Water Is Creating a Toxic Brine Problem

#39

Post by WillPostForFood »

sp332 wrote: post #23
Retric wrote: post #19

Earlier quoted context omitted.

At worst these dead zones would be tiny. They could dilute the waste stream by dumping it into the local sewage system, but I don’t think that’s going to change much. It’s on the order of building a mall parking lot. Sure bad for the local ecosystem, but we have vastly larger issues.

It's going to be dumped near the shoreline, where sea life is very different from what is supported in the open ocean. If the shoreline is made uninhabitable, the marine life there might not have anywhere else to go.

There are over 7500km of shoreline in Saudi Arabia, so marine life can move along the coast away from the salt water outlets.

Re: Saudi Thirst for Water Is Creating a Toxic Brine Problem

#40

Post by philipkglass »

mrfusion wrote: post #38
philipkglass wrote: post #34

Earlier quoted context omitted.

At 35 degrees Celsius (308 K, 95 F), it takes about 44 kilojoules to evaporate 1 mole of water [1]; at 55.6 moles/liter, that's 2.4 megajoules per liter. Averaged over a year, the energy available to evaporate water over a given area is roughly equal to insolation from the sun. Saudi Arabia has excellent solar resources averaging 2200 kWh/m^2/year [2], e.g. 6 kWh/m^2/day, e.g. 21.7 MJ/m^2/day. With perfect sunlight a…

Nice analysis! Three things to consider: I don’t think you can just look at insolation over a given area. Wind and even the cooling itself will cause the air over the area to redistribute with warmer dryer air that can continue picking up water. Besides that it’s more important to consider how saturated the air in the region is. If it can hold more water it will. Other things to consider Some of the water would seep…

I considered mentioning wind from warmer neighboring regions but at this scale you are basically remaking geography, so I wouldn't count too much on said winds reaching the middle of your evaporation ponds. ("Manmade shallow hypersaline lakes", rather than ponds, at this scale.)

Seepage into the ground -- good point. If there is existing groundwater, seepage would taint it. If there is no existing groundwater, but ground is permeable, that helps.

Spray water into air? That costs more energy. Just waiting for natural evaporation is nice because it doesn't require any more human-added energy.

Of course you'd want to analyze more than the One Big Factor if you were pondering implementing this in practice. But I think that the one-factor approach illustrates why this hasn't been an "obvious" disposal solution for waste brine.

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