[Constable]

Something more that I found about that topic:

Using nanoparticles to remove pollutants and contaminants from wastewater. Nanostructures adsorb toxic ions from polluted water.

Nanoparticles are the good direction in a contamination removal process - as well as graphene (which is a carbon nano structure of graphite) might be worth to mention here (one of it's abilities is to unsalt the sea water - maybe it would be possible to use it for clearing the water from contaminations as well)

Ref: nano-man.co.uk