Our waterways are becoming more and more polluted due to PFAS, plastics, medicines, drugs, and new chemicals made by companies that just hand over the responsibility of cleaning to plants paid for by public moneys. Detecting the different chemicals and filtering them out if getting harder and harder. Could the simple solution of heating up past a point where even PFAS/forever chemicals decomposes (400C for PFAS, 500C to be more sure about other stuff) be alright?
sounds expensive, you need alot of electricity to do that, its like desalination, its not cheap. heat my not dissociate chemical compounds. that high temp would probably degrade whatever container its in overtime. you’re better of using wastewater treatment and filtration systems.
Raising water temperature from 10 to 500 degrees requires about 500 calories/mm3. That’s 2 MJ/litre, meaning if you want to heat 1 liter/second you need 2 MW with perfect insulation, so a power plant of say 10 MW.
A post industrial world citizen could probably get by on 200 l/day (US averages about 300/day). That needs 2 kW/person/day.
Total global energy production is about 630 EJ which averages out at about 12 TW.
Meaning if the whole global energy production went to treat water in that way, we have enough clean water for about 6 million people.
Yes, with our current energy output it would not be possible, but I’m asking about whether even theoretically it could be an easier way to clean water. Maybe in 10, 20, 50 or 100 years it’s a method worth pursuing.
This is simple math. We would need to increase our energy production by 1000 times to just treat water, maybe only 250 times if we used more efficient systems than simply heating it and letting the heat dissipate. If we doubled our energy production every year, it would still take a decade to do it (8 years if we were aiming at 250 times). That isn’t a realistic amount for a civilization at our tech level.
You say 1000, another poster says 11, and yet another gives another number I can’t remember.
If I’m reading the graph right on page 20 of Homo Sapiens’ Energy Dependence and Use Throughout Human History and Evolution, in 1820 we needed about 20 EJ. That’s a 31 fold increase to ~530 EJ in 2010 (190 years). Looking at the chart, you can see that the rate of increase has sped up, not slowed down. In 1960 it was ~120 EJ making it a 4x increase in years.
It might take time, but it’s not impossible. And unless a great calamity happens upon us, we will not stay at our current tech level for another 200 years.
I understand the pessimism, but my question wasn’t about “is this possible within our lifetimes” or “how much energy would this need” but “Could wastewater plants simply heat up water past 500C to decompose all chemicals and output clean water?”. I just want to know if with our understanding the water will be clean after going through a procedure where it’s heated past 500C. That could be once or multiple times, it could involve adding a filter, removing deposited waste material, etc.
The part you’re studiously ignoring is plenty of people saying yes, you could do this, but that it’s wildly inefficient. You could also power a bike by getting the biggest rock you could throw, tying a rope to it, applying the brakes on your bike, throwing the rock, releasing the brakes, and then pulling on the rope until you’ve collected your rock, and repeating until you’ve reached your destination. This will always work. But as long as your bike is in earthlike conditions, there will always be easier ways to do it. This is also the case for your idea.
You’re ignoring that I’m responding to the messages that say it’s wildly inefficient by saying things can change. Nowhere am I debating it’s not inefficient. You’re arguing with a strawman you built.
How the hell do people use that much water? Are they including water consumption needed for the products we use or? Let’s say a flush is 8L and the average person flushes 5 times a day, that’s 40L. The average person needs about 2L of water a day. Let’s say an average shower is 100L. Cleaning dishes at worst is probably like 20L per person without a dishwasher. That’s like 160L of water per day and I feel like most of those were over-estimates. How did they get to that number?
They eat meat.
They use AI.
How much water do you believe AI consumes? The 31 billion land animals we keep in captivity and the crops we grow to feed them dwarf most human water consumption.
The global AI demand may even require 4.2 – 6.6 billion cubic meters of water withdrawal in 2027, which is more than the total annual water withdrawal of 4 – 6 Denmark or half of the United Kingdom
https://oecd.ai/en/wonk/how-much-water-does-ai-consume
AI’s projected water usage could hit 6.6 billion m³ by 2027
That’s a lot, but by some back of the envelope math I calculated that American consumption of cheese alone uses four times that amount in a year.
Based on this, 4 oz of cheese uses 450 liters of water. https://foodprint.org/blog/dairy-water-footprint/
Based on this, the average American consumes 41 lbs of cheese per year. Each lb of cheese uses 1800 liters of water per the above. https://www.statista.com/statistics/183785/per-capita-consumption-of-cheese-in-the-us-since-2000/
That means that each US citizen uses 73,800 liters of water per year on cheese alone.
Multiply that by 340E6, the US population, you get 25 trillion liters of water per year. That’s 25 billion cubic meters of water a year.
Not that AI is environmentally friendly by any stretch, but dairy is the equivalent of like, a dozen AI industries all stacked on top of each other. Feel free to check my math and correct me as needed.
For the record, dairy production and consumption has been around for almost all of human civilization. It had time to really embed itself in society, and it served a very real, practical purpose. It kept people alive.
The AI hype has only being going for like a decade and shows no signs of slowing down. Those numbere are literally rookie numbers.
Yes; this is something that has been studied. However as other commenters have said it requires a lot of energy, and is better suited for processing smaller quantities of water with a high level of PFAS contamination than massive quantities of water with an extremely low level of PFAS. It’s also not a standalone solution, as plenty of harmful chemicals survive heating past 400/500C (heavy metals like cadmium, lead, and mercury do not break down at any temperature).
Thank you for the only response that actually answers the main question and linking to a scientific paper. Much appreciated.
Regarding harmful chemicals that do not decompose beyond 500C, could it be more likely that the number of such chemicals/materials (known and unknown) is much lower than the number of chemicals/materials at the temperatures used for current clarification processes?
At the risk of sounding silly - Instead of focusing on burning the solids, boil the water. Water boils at 100C, at which point the water vapor should separate and leave all the solids behind. Then capture the vapors and condense it back down into clean water. Now, if you later want to incinerate the leftover solids, sure, go for it, fire’s always cool in my book.
I’ll add, simply boiling water is energy intensive. What you are proposing probably won’t work at any scale.
This would be carcinogenic beyond imagination
Please explain.
Because you’re essentially cooking a cocktail of complex chemicals, many of which were never designed to be heated, and the result is often airborne toxins and volatile organic compounds (VOCs) that are far worse than drinking trace amounts of the original chemicals.the chemicals dont vanish or turn into pure air when vaporized. they degrade into other more harmful chemicals. which are carcinogenic and more toxic.
My guy you’re burning plastic
Can the degraded chemicals withstand sustained exposure to 500C?
The chemicals don’t just disappear, whatever they’ve degraded into will still remain.
Yes, but will they all be harmful?
At this point I think we’ve figured out that all chemicals should be considered harmful unless we have specifically tested and concluded otherwise.
they can get even worse than previous forms, so yes.
Got an example?
Molten Salt Nuclear Reactors (like the one China’s making with thorium) operate at something like 700* C to generate electricity. With the waste heat, we could desalinate water. Instead of Yucca Mountain as a nuclear waste repository, it becomes Yucca Mountain Molten Salt Nuclear Reactor and brackish groundwater distillation for Las Vegas.
This, I like. The water would be radioactive though, wouldn’t it? I wonder if “exchanging” the unknown toxins for radioactivity in the dispelled water would be better or worse. But, it could maybe help decompose some of the toxic chemicals during in the process.
No. Radioactivity isn’t like a disease. Specific particles are radioactive. If you remove it prevent contamination form the first place, there is no reason the water would become radioactive. Heat is just heat.
That made no sense at all. Do you think toxic water is 100 toxins or that when somebody is sick they become one big walking disease?
And “water can’t become irradiated” is a great take. So radioactive radiation has no effect on water whatsoever? “High energy particles don’t exist and they can’t hurt you🧠”
Seems like a bit of a mean-spirited response out of nowhere
Ok so i think the disconnect here is that you are visualizing the water literally passing into the reactor and out the otherside.
In reality the water would pass around the outside of the shielding, where it is still plenty hot, but the radiation from the reactor isnt passing through.
This is more or less how a nuclear power plant operates today. We sont get the power directly from the reaction, we get it by using the heat fenerated to boil water to operate steam turbines. In fact, they are just steam engines with the coal replaced with nuclear fission.
When someone more knowledgeable than you is giving you good answers to your questions you should maybe show a bit more respect
Not how reactors work, they are very much closed systems specifically to avoid this problem.
Think of it like and air conditioner or refrigerator. The the attempt that cool the inside by dumping heat outside uses a closed loop and the two mediums do not directly interact or mix, which is why your home isn’t full of pollen when running an air conditioner all day if your windows and doors all properly seal.
