Homebrew PCBs

Stefan Trethan wrote:
> 
> You can buy small commercial stations now that use ion exchangers for
> treatment of rinsing water.
> 

Traditionally, people precipitate the copper in large tanks and after 
the solids settle, it should be below about 5ppm and ready to dump. ion 
exchanges are only required when precipitation fails , for example, 
rinse waters containing chelators, which keep metal ions soluble.

Are you sure the discharge limit in Europe is 0.5mg ?, That level is 
lower than what is considered safe to drink. Heck , some natural water 
supplies are higher than 0.5mg.