Cleaning former colliery spoil waterways with Flocculants

I'm placing this under organic because it pertains to Britains former colliery waterways.

Is it possible to add Flocculants to Britains former colliery spoil waterways to rejuvenate them back to their original state ?

I understand that soft rock on the British coastline will contain sediment, along with limestone, which will give the water a natural cloudy appearance, but there is still much colliery spoil that could be dealt with.

There is a wonderful video here of something similar being done in a river bordering Peru and Bolivia : 

If it were that easy then surely the U.K. government (given the chemistry was invented by a British Chemist, one Philip Souter) should have chosen to do so ?

Are these things ever that easy ?