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?
That might be possible but there are particles that also will be present in vapor which might be toxic. Simply sending the out into the atmosphere would probably not be a good idea. PFAS for example do not break down under ~400C and just creating a fine PFAS mist is probably not what we want.
But yes, of course while heating up the water there will be residue. How to dispose of that will probably also have to be thought of. Maybe 500C is also the answer, but I don’t know.