Novel Treatment Technologies for Desalination and Selective Ion Removal Lucy Mar Camacho, Ph.D. Department of Environmental Engineering Texas A&M University - Kingsville Eagle Ford Center for Research, Education and Outreach City of Cotulla, Texas November 15, 2013
Outline Background The Fact The need The opportunity Novel Desalination Technologies Electrodialysis/Electrodialysis metathesis (ED/EDM) Membrane distillation (MD)
Background
The Fact Water pumping, treatment, and distribution Energy production and generation
The Need Growing competition for freshwater supplies has motivated interest in use of saline groundwater for water supply. USGS, Delineating and assessing saline groundwater water resources, 2009.
Saline-Water Withdrawals Texas Withdrawals Fresh Saline Total Million gallons per day 23,600 3,130 26,730 USGS, Delineating and assessing saline groundwater water resources, 2009.
The Opportunity Natural Gas Production Unconventional Sources Shale Gas Flowback from Hydraulic Fracturing Formation Water
Water use in US Shale Gas Plays Average water use for drilling and hydraulic fracturing a shale gas well (Million gallons ) Texas 2.8-5.7 Oklahoma 3.0 Marcellus shale 2.0 7.0 Initial volume returned as flowback (%) 8-15% 30-70% TDS concentrations (mg/l) 8,000 360,000 U.S. Energy Information Administration based on data from various published studies; May 9, 2011. Shaffer et al.; Environ. Sci. Technol. 2013, 47, 9569-9583.
The Challenge Growing restrictions on produced water disposal Strong incentives for produced water desalination for external reuse Higher water quality than for internal reuse within the shale gas industry
Desalination Challenges for High- Salinity Water Reuse Water Corrosion and scale products. Calcium sulfate. Barium sulfate. Strontium sulfate Organic fouling. Dissolved organics. Suspended organics Naturally occurring radioactive. Barium and radium isotopes TDS. Hardness. Heavy metals Energy Thermal separation process. Technically feasible. Economically relevant Alternatives for high-salinity produced water Municipal wastewater treatment Industrial wastewater treatment Underground injection wells Reuse for subsequent hydraulic fracturing operation (90%) (Internal Use).
Novel Desalination Technologies
Thermal and Membrane Separation Technologies Mechanical Vapor Compression (MVC) Forward Osmosis (FO) Membrane Distillation (MD) Electrodialysis Metathesis (EDM) Efficiency Achieve stringent permeate TDS concentration limits for external reuse. Modular nature Facilitate on-site treatment at shale gas well sites. Energy requirements Competitive compared to conventional thermal technologies. 10.4 13.6 kw-h/m 3 21.0 37.0 kw-h/m 3 30-40 kw-h/m 3 (with energy recovery) Less than 10 kw-h/m 3 (based on NaCl purity) Shaffer et al.; Environ. Sci. Technol. 2013, 47, 9569-9583. CIDS, 2013
Electrodialysis
EDM Process Mixed Sodium Mixed Chloride Mixed Sodium Mixed Chloride Mixed Sodium C A C A C A C A C A C1 D1 C2 D2 C1 D1 C2 D2 C1 Anode (+) SO 4 = Cl - Na + Mg +2 Ca +2 Na + Mg +2 Ca +2 Cl - SO 4 = Na + Mg 2+ Ca 2+ Cl - SO 4 = (-) Cathode Na 2 SO 4 Feed: NaCl Feed: NaCl Na 2 SO 4 High-salinity water High-salinity water
EDM Process H 2 O H 2 O Feed + EDM - Mixed Mixed NaCl Feed Na Cl C1 C2 D2 D1 E-Rinse (Na 2 SO 4 )
EDM Experimental Electrodes EDM Operating Conditions Number of repeating cells (quads) 5 Compartments per cell 4 Number of membranes 20 Anode: Pt/Ti Cathode: Stainless steel Membrane type Anion-, cation-exchange Active membrane area per cell (m 2 ) 0.02 Current (Amp) (constant) 1.56 Applied voltage (Volts) 8-12 Pressure (psi) 3.0 EDM system Average flow rate (gpm) D1: 0.45; D2: 0.45 C1: 0.60; C2: 0.50 E-Rinse: >1.3
EDM - Experimental C1 Mixed Sodium Stream
EDM - Experimental C2 Mixed Chloride Stream
Voltage (Volts) EDM - Experimental 14 Effect of D2 impurities on cell voltage 12 10 8 6 4 0 2 4 6 8 10 12 14 16 Time (hours) Pure 1350 mg/l SO4 563 mg/l Ca SO4, Ca, Mg mixture High recovery mixture
MD - Principle Water vapor pressure difference Heat transfer By diffusion Heat transfer by conduction
Membrane Distillation - Process
MD - Configurations
MD Modules & Membranes Flat Sheet Spiral Wound Hollow Fiber
MD - Experimental Combined water outfall sample Parameter As received After treatment with AGMD After treatment with DCMD Ca (mg/l) 41.1 0.6 1.1 Mg (mg/l) 10.21 below D.L. 0.07 Hardness as CaCO3 (mg/l) TDS (mg/l) 144 1150 2 90 3 10 TOC (mg/l) 101.8 36.9 2.975 Iron (mg/l) 1.367 0.014 0.065 silica (mg/l) 24.25 0.88 0.33 ph 6.74 9.02 6.57
MD - Experimental Selenium unit outfall sample Parameter As received After treatment with AGMD After treatment with DCMD Ca (mg/l) 2.3 0.2 0.4 Mg (mg/l) 0.61 0.02 0.03 Hardness as CaCO3 (mg/l) TDS (mg/l) 8 875 1 60 1 5 TOC (mg/l) 320.4 141 3.091 Iron (mg/l) 1.208 0.014 0.049 silica (mg/l) 4.4 1.5 0.333 ph 5.42 7.6 5.94
MD Heavy Metals Removal S. Yarlagadda, S. Gnaneswar, L.M. Camacho. J. Hazardous Materials, 2011, 192, 1388-1394. Camacho, L.M. et al., Water, 2013, 5, 94-196.
MD - Water-Energy Nexus Energy alternatively obtained from waste Heat. DCMD module
Thank you!!