Electrolytic Coagulant Generation for Treating Flowback and Produced Water for Reuse

This research investigated a novel electrochemical process for producing a ferric iron coagulant for use in treating flowback and produced water from hydraulic fracturing and oil production operations. The electrolytic coagulant generation system uses an electrochemical cell to produce acid and base from oilfield brine solutions. The acid is used to dissolve scrap iron to provide a Fe³⁺ coagulating agent, and the base is used to neutralize the treated water. The costs for generating the ferric iron coagulant were determined as a function of current density and feed water salinity. The process was shown to be effective for removing colloidal bentonite particles from brine solutions. The process has several advantages over conventional electrocoagulation using iron anodes, including: the ability to treat anoxic waters, elimination of electrode fouling, lower cost for the coagulant, and the ability to deliver Fe³⁺ doses greater than 1 mM, since it is not limited by the amount of dissolved oxygen required to oxidize ferrous to ferric iron.