Chemical co-precipitation process for recovery of flow-back water, produced water and wastewater of similar characteristics

A method for treating a flow-back water, comprising:

• providing a volume of flow-back water;
• admixing an oxidizing agent comprising chlorine dioxide with the volume of flow-back water;
• adding a base to the volume of flow-back water to adjust a pH of the flow-back water to about 8.0;
• admixing a source of sulfate ions and a source of carbonate ions with the volume of flow-back water;
• after the previous steps, admixing a flocculating agent with the volume of flow-back water to form a first precipitate comprising at least one of a metal oxide, a metal sulfate, or a metal carbonate, wherein the flocculating agent comprises sodium bentonite clay, poly aluminum ferric chloride and a polymer;
• removing the first precipitate from the flow-back water to form a first treated flow-back water and a metal sludge cake;
• adding a base to the first treated flow-back water to adjust a pH of the first treated flow-back water to about 7.0;
• admixing calcium hydroxide with the first treated flow-back water to adjust the pH to about 10.5;
• after admixing the calcium hydroxide, removing a second precipitated solids from the first treated flow-back water to form a second treated flow-back water and a synthetic gypsum precipitate;
• and
• adding an acid to the second treated flow-back water to adjust a pH of the second treated flow-back water to between 7.0 and 8.0.