I think I saw this somewhere else earlier, and one of the ideas listed was: don't use seawater, use other wastewater, like mining leachate, or similar. This get

I think I saw this somewhere else earlier, and one of the ideas listed was: don't use seawater, use other wastewater, like mining leachate, or similar. This gets rid of the water in it, making it more concentrated, and gives a useful product. The more concentrated heavy metal contaminated waste would then potentially be used as feed stock for extraction. Or if you're using seawater, and have a convenient large area nearby, just make sea salt from it.