Waste water

From Wikimarcellus

Waste water or flowback water from hydro-fracturing shale gas wells generally needs to be processed in a water treatment plant before being discharged.

It typically has in it high levels of total dissolved solids (TDS), chlorides, and chemicals.

Such treatment removes toxic chemicals and salt from the water used to fracture shale as well as the naturally occurring underground water that is produced by drilling and bought up to the surface.