Supercritical Treatment of Fracking Water

With the continuous growth of hydraulic fracking, the volume of fracking wastewater that needs to be treated prior to disposal is also growing and is a major challenge and concern for society. The improper treatment of wastewater prior to disposal has multiple consequences to the environment, including contamination to the soil and drinking water source.The recycling and reuse of water and chemicals from the frack water would be a cost saving measure for oil and gas operators. The purpose of this program is to demonstrate the cost and energy impact of an advanced supercritical water treatment (SCWT) process. The SCWT process effectively removes biological, organic and inorganic contaminants in water. The supercritical water process destroys any biological matter, activates oxygen to oxidize organic and biological compounds, and precipitates salt and metal inorganics. The technical advancements made under this initiative will reduce the energy consumption of the SCWT process, making it very competitive to existing processes such as Reverse Osmosis (RO). The SCWT process scales very well making it ideal for frack water treatment, municipal water treatment and other applications, like Pharma and Dyes waste streams. During SBIR Phase I, the focus was on understanding two barriers to commercialization of the supercritical water treatment system; salt clogging and metal corrosion. The first barrier is overcome by developing a process to remove salts selectively, via precipitation, without clogging system components. The second barrier of metal corrosion is overcome by introducing a reducing agent, such as hydrocarbon, that reduces corrosion thereby increasing equipment life. Work was performed to develop compact microchannel recuperators and cyclone separators that will not clog, but can recycle 90% of the energy, so it can be efficiently reused in the process. In addition, the external energy heat source needed to bring the water to a supercritical state can be replaced with internal energy generated from the reaction between oxygen and the organic and biological contaminants in a specially designed combustor. The central focus of this Phase II effort is to build and operate a pilot water treatment system capable of converting frack water and other wastewater into potable water (<500 ppm levels) using the properties of supercritical water. Operation of the pilot plant will demonstrate that existing technology gaps have been overcome promoting technology commercialization. It is anticipated that the system will be capable of achieving a thermal energy recovery efficiency of 95%. Under these conditions the current operating costs under 0.53 $/m3 ($2/1,000 gallons). This is ~25% of the cost of the DOE RO base case. The high energy density of the SCWT process makes the equipment compact and easily transportable. For frack water application, the SCWT equipment can be transported to the well site for onsite water treatment. Finally, new manufacturing techniques for the microchannel recuperators and cyclone separators will drive down the overall cost of the equipment. Additional water treatment markets actively being pursued include dyes and pharma water waste streams and water desalination.