Yeah, you're right about the radiation-eating algae Closterium moniliferum. It's actually very interesting, and I want to make a post about them in the future, because this is a really unique feature for a biological organism to have.
It would be very interesting to find out if other mosses are able to remove other heavy metals. The one in the article was only good at removing lead, and very small amounts of gold, but I don't think anyone have problems with too much gold in their drinking water. I would definitely like to see someone make a complete household hydroponic water filtration! That would be very cool.
That's a nice quote regarding water filters :)
Best regards from @valth