Thing is, how much energy would you need to evaporate a high amount of water? It's fine with small pans, because the water is always near the top and gains enough energy to be evaporated, but with massive amounts of water this is not feasible. You would need either a huge pan (I mean like the size of a town), or something stronger than sunlight as a heat source. It would cost too much.
There's not more salt in human waste than in saltwater, otherwise we'd all die of massive sodium intake.
Treating waste is pretty lengthy, but not a complicated process. And there are some useful by-products, whereas the only by-product of desalination is salt (which can irreparably damage the environment is not disposed of correctly, which is expensive).
In the end, the products are the same, so why not choose the cheaper?
If the salt content of human waste is stronger than that of seawater, this is nullified by huge water content of the waste that goes out of our houses through the pipes. Every time you flush the toilet, loads of water is flushed away for what, 3 cubic inches of turd?
Stuckboy
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It's a bit harder with huge amounts of water, since saltwater boils at a high temperature, a huge pan would need a LOT of heat to get it to that temperature (but not more than say... the amount it would take to melt steel in a huge pan).
"There's not more salt in human waste than in saltwater, otherwise we'd all die of massive sodium intake."
> That's why salt water is so dehydrating... because the salt is flushed out of the body, which is why there's salt in waste. Try comparing the taste of sweat to seawater.
"If the salt content of human waste is stronger than that of seawater, this is nullified by huge water content of the waste that goes out of our houses through the pipes. Every time you flush the toilet, loads of water is flushed away for what, 3 cubic inches of turd?"
> Good point.
Disclaimer: Any sarcasm in my posts will not be mentioned as that would ruin the purpose. It is assumed that the reader is intelligent enough to tell the difference between what is sarcasm and what is not.
A bit harder? Muz, you do realize that you're actually talking about quite a shitload of saltwater there? I don't know the exact numbers, but the average daily water consumption per person in first world countries is about 200 liters. Multiply that with the number of inhabitants of the city in question, and you should have the amount of water you'd have to boil (and I tell you, that's quite a big number for places like Queensland, etc). Where exactly are you hoping to find the energy to do that?
Yeah I got my facts wrong, once, on that newspage, because of a silly misunderstanding on my part, which I already admitted. And I clearly stated that I might be wrong about the water consumption rate. So how about you stop harassing me, and get over the whole thing already? Kthx?
"That's why salt water is so dehydrating... because the salt is flushed out of the body, which is why there's salt in waste. Try comparing the taste of sweat to seawater."
But salt water isn't dehydrating. How can something that is mostly made of water be dehydrating? It's like when people say alcohol dehydrates you - it does, but the liquid it is contained in more than makes up for it.
Sweat is a lot less salty than seawater. Seriously, have you ever tasted salt water?
"It's a bit harder with huge amounts of water, since saltwater boils at a high temperature, a huge pan would need a LOT of heat to get it to that temperature (but not more than say... the amount it would take to melt steel in a huge pan)."
Why compare water with steel? It is true that steel takes a lot of energy to melt, but it is the only way to make it. There are fair cheaper and more environmentally friendly ways of treating water, so why not use them?
Actually, to use your own water/metal comparison - which is cheaper? Recycling or electrolysis of aluminium?
"But salt water isn't dehydrating. How can something that is mostly made of water be dehydrating?"
I believe that salt holds onto water. Also it increases your blood pressure since the salt going through your blood will still have water attached to it.
I think thats part of the problem.
I heard you can extract gold from seawater is you process enough of it, However that too is just too expensive to be worthwhile.
It's not exactly dehydrating, but it has the same effect in that the salt in the water causes the water to deliver less... well, hydration that it normally does, so it feels like dehydration.
Axel:
You get the energy from powerplants . It only takes 0.66 kcals/liter to treat sea water. Really, the energy used is NOTHING compared to the energy food factories use. However, since countries like Singapore can point a few tanks and missiles at their neighbors and demand water at < US$0.01 per 1200 gallons, threatening your neighbors is a cheaper option..
"But salt water isn't dehydrating. How can something that is mostly made of water be dehydrating?"
> Alcohol, caffiene only requires a bit of water to process. However, the human kidney requires a lot more water to process seawater than it gains from the water, so that results in dehydration. Why do you think people stranded at sea die of thirst if they can just drink the water around them? The first rule of survival at sea is to never drink seawater .
"Sweat is a lot less salty than seawater. Seriously, have you ever tasted salt water?"
> Well, ok, they're actually about the same, 7.5% for seawater, 3-4% for sweat. There's probably more in urine, but like someone said, that's counter by the 5 gallons it takes to flush the toilet.
Disclaimer: Any sarcasm in my posts will not be mentioned as that would ruin the purpose. It is assumed that the reader is intelligent enough to tell the difference between what is sarcasm and what is not.
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. It only takes 0.66 kcals/liter to treat sea water. Really, the energy used is NOTHING compared to the energy food factories use. However, since countries like Singapore can point a few tanks and missiles at their neighbors and demand water at < US$0.01 per 1200 gallons, threatening your neighbors is a cheaper option..