Advanced Treatment of Shale Gas Frac Water to Produce NPDES Quality Water

Advanced Treatment of Shale Gas Frac Water to Produce NPDES Quality Water

Bob Dahlin, Bill Chatterton, Behrang Pakzadeh, Austin Vaillancourt

Southern Research Institute, 5201 International Drive, Durham, NC, 27712

Natural gas extraction by fracking produces two types of wastewater that must be managed:  1) Flowback water is produced when the fracking is complete and pressure is released.  Approximately 10% to 30% of the water used for fracking flows out of the well over a period of about ten days, and 2) Produced water, a mixture of water that was trapped underground with the gas deposit and frac water, flows out of the well with the natural gas over the several years life of the well at a rate of 100 to 1,300 gallons per day.

All wastewaters produced by drilling and fracking are regulated by the Clean Water Act (CWA) and are subject to the technology-based regulations (40 CFR Part 435, Subpart C) which apply to onshore facilities “engaged in the production, field exploration, drilling, well completion and well treatment in the oil and gas extraction industry.”  The effluent guidelines at 40 CFR 435, Subpart C establish best practicable control technology currently available (BPT) requirements for onshore facilities and prohibits the discharge of waste water pollutants into navigable waters from any source associated with production, field exploration, drilling, well completion or well treatment. 

Southern Research Institute, with project partners M2 Water Treatment, Inc. and BKT United, has been awarded a contract by RPSEA (Research Partnership to Secure Energy for America) to develop an innovative, cost-effective, and robust approach for treatment of shale gas frac water to produce National Pollution Discharge Elimination System (NPDES) quality water for discharge and/or reuse. The approach comprises optimizing the combination of four technologies, two for frac water treatment and two for treatment and disposal of residues (high solid slurry and membrane concentrate) from the frac water treatment.  The frac water treatment technologies are  magnetic ballast clarification (MBC) for removal of total suspended solids (TSS), metals, and  naturally occurring radioactive materials (NORMs) , and vortex-generating and nano filtration membranes, for removal of TSS and/or total dissolved solids (TDS).  The residue treatment/disposal technologies are hydrogel adsorbent for metals, NORMs, and trace element removal, and precipitation, solidification and stabilization. 

The project began in May of 2013 and is anticipated to continue for a period of 24 months.  The project tasks include bench-scale simulation, onsite field research/testing, and a feasibility analysis.  The objective of the bench-scale simulations is to develop a method to allow for a quick evaluation as to whether waters from a specific well are amenable to treatment with MBC, membranes, and hydrogel media or precipitation/solidification/stabilization.  The objective of the onsite field research/testing is to provide a linkage from the bench-scale simulations to what can be expected in the field.  The objective of the feasibility analysis is to bring together the technical, economic and environmental data to assess the advantages and disadvantages of the proposed integrations compared to conventional technologies.  If selected, Southern Research plans to present the detailed analysis and results from the bench-scale testing and any available preliminary data from the onsite field testing.