> 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
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?
I dunno if that's a good analogy if the desire is to make it sound huge. If it's a small enough quantity that it can be shipped by tankers (even huge super tankers), that doesn't sound like a lot compared to the size of the ocean.
bash$ units
You have: m^3
You want: barrels
* 6.2898108
/ 0.15898729
It seems you're right, yes, should be 200. (Gee, so a cubic metre is ~6 barrels? A 'barrel' is tiny, if that's right, 160 litres or so, much smaller than I imagined.)
The article isn't clear where the metals are coming from. It could be that the desalination process simply concentrates what's already in the seawater.
> Combined low concentrations of copper (5 μg/l and chlorine (50,μg/l have been effective in preventing both micro and macro-fouling in over 120 seawater installations since 1987.
It's also done in freshwater (great lakes) to prevent zebra mussels from clogging the intake pipes. Things like to grow where other things bring food by for free, and are sheltered from predators.
IMO the right direction is not conventional treatment, but as Swebs said, either create new salt flats, or use it as feedstock for algae or other single cell organisms that can be converted to feed, or biofuel.
"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"
Unless they are adding chemicals to the water before desalination (which I don't see mentioned anywhere), that sounds like the 'brine' is just ~1.5x concentrated seawater, which will get diluted back again? What am I missing?
It's from anti-fouling and general corrosion. Not sure what makes these plants special though since a population's regular water supply infrastructure would end up producing the same type of waste from pumps and what not.
Also raising the concentration of salts in the oceans, especially in the immediate area where they're dumping it back into the ocean in the gulf that has weak ocean currents (due to being a gulf). I can't imagine the wildlife will enjoy that much. It also makes it harder for future desalination, as it's having to desalinate an ever increasing percentage of salt since they just dump it back into the ocean.
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.
Someone correct me if I'm wrong (not the best at math), but the ocean is massive. The entire amount of brine they mention (31.5 million cubic meters) fits in one 300m square cube. Even if you drop it in an enclosed 1km-wide area of seawater, it will barely increase concentration by 0.01%. It would take millenia for us to increase sea salinity by this method, and all that treated water is eventually coming back.
Even if you took the total daily water consumption of the entire human race - 150l per person * 7 billion, or 1^12 liters, and made it extra salty, it is dwarfed by the total of 1.26^21 [mostly sea]water on earth.
This would be harmless assuming we are not adding anything to the byproduct, which unfortunately seems to be the case according to the other comments.
The concern is not ocean-level damage through the salt directly but in localized ecological system destruction. The mangrove forest encompases a tiny portion of the ocean overall but removing this forest affects a large portion of sealife. The creation of 'deadzones' through salinity will have knockoff effects elsewhere that cannot necessarily be predicted.
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.
The local sewage systems can't deal with volumes this large. The sewage systems of the entire UK, population 66 million, deal with about 11 billion liters per day:
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.
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.
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.
>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 one day worth of the contaminated water.
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.
Couldn't they just run a big pipe out into the middle of the desert and pump it there? Maybe they could create giant salt flats and extract rare earth elements from them, even...
It says 'about 1.5 liters of liquid polluted with chlorine and copper are created', but doesn't explain if these are additives or some kind of byproduct.
.png){kind=link}
https://www.indexmundi.com/agriculture/?country=sa&commodity...