Process for fast cleaning of effluent from coal works

Effluent containing 20-­80g/l suspensions of which 50­-70% is clay is treated at pH=7.5-­8.5 with a strongly turbulent solution consisting of an aqueous solution of 0.1 % medium anionic acrylamide/acrilate polyelectrolyte in 50g/l calcium chloride, i.e. 3­-9 mg/l polyelectrolyte dose, obtaining after 10-­15 minutes
decanting, a clear supernatant with 100 mg/l suspensions and a 15-­25% lower sludge volume than volume of treated effluent.