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?
Lead being an element means you would either need to make it radioactively decay somehow(which I’m not sure any form of lead is want to do) or perform some kind of alchemy.
Artificial elemental transmutation of lead into other elements is not just fantasy, it’s entirely possible and happens in particle accelerators and nuclear reactors. It’s just extremely impractical as it’s an extremely slow process at anywhere near the particle fluxes we can practically achieve. Plutonium is made through a similar process (though the exact mechanism used to produce plutonium is relatively more efficient) as well as small quantities of useful radioisotopes, but it is also possible with lead.
https://en.m.wikipedia.org/wiki/Nuclear_transmutation