Patent ID: 9580343
Date: 2017-02-28
CPC Classifications: B01D,C01B,C01D,C01F,C01P,C02F

Claim:
1. A method of treating a gas well hydrofracture flowback and/or production wastewater (production wastewater), comprising: Placing a production wastewater comprising an amount of barium ions into a first tank; Adjusting the pH of the production wastewater in the first tank to be within the range of from 3.0 to 3.5 and maintaining an oxidized condition, to form a pH-adjusted production wastewater comprising barium: Contacting the pH-adjusted production wastewater comprising barium, with a source of sulfate ions, in the first tank and under conditions to precipitate barium sulfate, the source of sulfate ions comprising an amount of sulfate ions that is stoichiometrically equivalent to from about 100% to about 150% based on the amount of barium ions in the first tank; Precipitating barium sulfate from the pH-adjusted production wastewater in the first tank to form a slurry of precipitated barium sulfate and a wastewater brine, the wastewater brine comprising sodium, magnesium, strontium, and calcium chlorides; Moving the slurry to a second tank; Mixing the slurry with an alkaline agent in the second tank; Clarifying the slurry on an inclined plate clarifier to form a clarified brine and barite sludge comprising precipitated barium sulfate; Recycling the clarified slurry, including precipitated barium sulfate, to the first tank and repeating the adjusting, contacting, precipitating, moving, mixing, and clarifying to form a clarified wastewater brine; Moving the clarified wastewater brine to a third tank; Adding sulfate ions to the third tank; Precipitating strontium sulfate in the third tank; and Evaporating the clarified wastewater brine to form water and evaporation products, the evaporation products comprising crystalline sodium chloride.