The water produced by fracking operations contains a lot of nasty stuff. However, commercially interesting amounts of lithium might be recoverable. The article below doesn’t deal with the question of what we do with all other rest of the nasty stuff. It says, “And once the lithium is extracted, there is still the issue of disposal of the remaining wastewater that could still contain toxic substances, whether it gets used to frack another well or if it gets shipped off to a deep injection well for disposal.”