Europium is also used in Euro banknotes as an anti-counterfeiting measure, again as a phosphor that glows under UV light (in physical terms it's the same application as a fluorescent tube)
Now I wonder how much inflation would be necessary to make "mining" europium from low denomination Euro banknotes profitable. There's places were "mining" copper from street poles is already profitable, and wire theft is a huge problem.
Mercury isn't mentioned in the paper (1). Keep in mind this is less about cleaning up than finding an economical way to recover and recycle rare earth metals
