Key Considerations for Frac Flowback / 

Produced Water Reuse and Treatment

NJWEA Annual Conference – Atlantic City, NJ May 2012
Today’s Agenda

• Overview of Hydraulic Fracturing Process

• Water Quality

• Treatment Alternatives

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Hydraulic Fracturing

Source: ALL Consulting. Handbook on Coal Bed Methane Produced Water: Management and Beneficial Use Alternatives, July 2003.

• Frac Method: Typically 

slick water frac

• Wells: 4 to 8 wells per pad

• Frac Water Volume: 4 to 6 

million gallons per well 

(95k to 142k bbl)

• Flowback: 15 – 35% return

3
Composition of a Fracturing Fluid

• Fracturing solution consists of sand and water

• Additives include biocides, corrosion inhibitors, O2 scavengers, 

friction reducers, surfactants, etc.

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Reference: All Consulting 2009
Frac Flowback Water Quality

All values in mg/L Parameter Feed Water Flowback

pH 8.5 4.5 to 6.5

Calcium 22 22,200

Magnesium 6 1,940

Sodium 57 32,300

Iron 4 539

Barium 0.22 228

Strontium 0.45 4,030

Sulfate 5 32

Chloride 20 121,000

Methanol Neglible 2,280

TOC Neglible 5,690

TSS Neglible 1,211

TDS <500 182,273

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Typical Flowback Characteristics

The longer Frac

water is in the 

formation, the 

higher the TDS 

levels may 

become.

Source: Siemens AG 2009 6
Wide Variation in Frac Flowback Chemistry

Parameter Frac 1 Frac 2 Frac 3 Frac 4 

Barium 7.75 2,300 3,310 4,300 

Calcium 683 5,140 14,100 31,300 

Iron 211 11.2 52.5 134.1 

Magnesium 31.2 438 938 1,630 

Manganese 16.2 1.9 5.17 7.0 

Strontium 4.96 1,390 6,830 2,000 

TDS 6,220 69,640 175,268 248,428 

TSS 490 48 416 330 

COD 1,814 567 600 2,272 

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All values in mg/L

Ref: ProChemTech International, Inc. 
Total Dissolved Solids from the Produced 

Water Database in the United States

• Typical Produced Water TDS Levels – Selected Areas

– Powder River CBM – 1,200 mg/l

– San Juan CBM – 4,500 mg/l

– Greater Green River – 8,000 mg/l

– Eagle Ford Shale – 20,000 mg/l

– Fayetteville Shale – 25,000 mg/l

– Barnett Shale – 60,000 mg/l

– Woodford Shale – 110,000 mg/l

– Haynesville Shale – 120,000 mg/l

– Permian Basin – 140,000 mg/l

– Marcellus Shale – 180,000 mg/l

Source: USGS 8
Key Water Management Concerns

• Wasting water 

and general water 

resource concern

• Surface water 

quality impacts

• Shallow groundwater 

quality impacts

• Long-term soil 

damage from salinity 

• Transportation –

100,000 bbl = 770 trucks

BOTTOM LINE: 

• Huge unconventional gas 

resources are driving 

development; and 

water solutions are key

• Water quality concerns leading to 

more treatment and reuse

• Solutions can be simple to very 

complex – Reduce, Reuse, Recycle 

are key goals

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Design Basis

Critical First Step

• Feed Water Volume

• Feed Water Quality

• Treated Effluent Requirements

• Site Specific 

Considerations

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Flowback / Produced Water Treatment Solutions

• Treatment for Reuse Without TDS Removal

• Treat for Reuse / Discharge with TDS Removal

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12

TREATMENT FOR REUSE

WITHOUT TDS REMOVAL
Range of Applicability vs. Cost

RO 

Evaporation

Crystallization

3,000 40,000 260,000 1,000,000

Total Dissolved Solids ( mg/L TDS)

$ Costs per Barrel

750

Treatment for Reuse

TDS Removal

No TDS Removal

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Example Feed Water Quality

• Water May Also Contain:

– Polymers

– Other Organics

– Radium

– Other Inorganics

(e.g., boron)

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Parameter Feed Water

pH 6.09

Bicarbonate 144

Calcium 11,595

Magnesium 690

Sodium 33,250

Iron (diss) 76

Barium 2,775

Strontium 3,633

Chloride 81,000

TSS 295

TDS 132,265
Example Treatment Requirements

• pH: 6.5 to 7.5

• Iron: < 10 mg/L

• TSS: < 50 mg/L

• Bacteria: None

• Treatment Residuals: 

Non-hazardous

• Mobile system required 

(5,000 to 10,000 BWPD)

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Keys Design Considerations

• Water Chemistry

– Presence of organics, oxygen, and 

nutrients 

will result in bacteria growth!

– Precipitation of barium sulfate 

will tend to adsorb radium, which may 

cause the sludge to become hazardous

• Treatment Selection

– Efficient solids / liquid separate 

required (small footprint)

– Sludge management

– Chemical consumption / dosing

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Pretreatment Clarifier

Chemicals

Waste Sludge

Produced 

Water Reuse
Treatment Technology Options

Technology Bact. CH3OH O/G DRO GRO TA HCO3- TH Ca Mg Fe Ba St SO4 Cl TDS TSS Poly

mers

API Separators X

Dissolved Gas Flotation X X

Activated Carbon X X X X

Nut Shell Filters X

Organi-Clay Adsorbants X

Chemical Oxidation X X X

UV Disinfection X

Biological Processes X X X

Air Stripper X X X

Chemical Precipitation X X X X X X X

Lime/Soda Softening X X X X X X X

Clariifers X

Settling Ponds X

Ion Exchange X X X X X X X X X

Multi- Media Filtration X

Membrane Filtration X X

Greensand Filters X X

Cartridge Filters X

Reverse Osmosis X X X X X X X X

Evaporation X X X X X X X X X

Steam Stipping X X X

Acidification X X

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Example of Reuse Treatment Solution

Without TDS Removal

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Sand Filter:

TSS Removal

Frac

Flowback

Water

Treated 

Water

Chlorine 

Dioxide Air

Oil 

Byproduct

Chemical 

Oxidation

Free Oil and 

TSS Removal

TSS and O/G 

Polish

Sludge for 

dewatering/ 

disposal

Chlorine 

Dioxide

Disinfection
Step 1. Chlorine Dioxide Oxidation

• Chlorine dioxide is strong 

oxidant that provides selective 

chemical oxidation

• Breaks oil / grease emulsions

• Destroys friction reducers and 

other chemical additives

• Kills Bacteria

• Oxidizes reduced compounds, 

such as Fe, Mn, Sulfide, etc.

• More efficient than bleach –

does not react with ammonia 

and many other organics

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Ref: Sabre Technologies
Step 2. Dissolved Air Flotation

• Fine bubble diffusion floats oil / grease and TSS to top

• Skimmer potentially recovers saleable oil

• Covered designs also available for VOC emission control

• Skid-mounted design

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Ref: Pan America

Environmental Website

NOTE: Dissolved Gas 

or Induced Gas Flotation 

may also be considered
Step 3. Multi-Media Sand Filtration

• Conventional sand filter 

removes TSS before reuse

• Acid or carbon dioxide addition 

ahead of filter to reduce pH and 

eliminate calcium carbonate scaling

• Periodically backwashed 

with filtered water. BW 

returned to front of system. 

• Chlorine dioxide disinfection 

of final product water

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Summary of Reuse Treatment 

Without TDS Removal

• Simplest and least expensive form of treatment 

• Multiple technology and design options available

• Reduces fresh water makeup 

requirements and off-site disposal costs

• Applicable only if drilling operations that 

need frac flowback water are on-going

• Bench and pilot-scale testing recommended to 

select best treatment options and minimize cost

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23

TREATMENT OPTIONS

FOR TDS REMOVAL
Viable TDS Removal Alternatives

• Membrane Treatment

• Evaporation

• Crystallization

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Range of Applicability vs. Cost

RO 

Evaporation

Crystallization

3,000 40,000 260,000 1,000,000

Total Dissolved Solids ( mg/L TDS)

$ Costs per Barrel

750

Treatment for Reuse

25
Reverse Osmosis

• Membrane separation technology that 

removes dissolved solids (TDS) from water

• Membrane is semi-impermeable - allowing only 

water to pass; 99%+ of all ionized species are rejected

• Non-selective 

treatment process

• Degree of all ion 

rejection is dictated 

by size and charge

• NF is a loose RO membane

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Reverse Osmosis (continued)

• Maximum concentrate TDS is approx. 80,000 mg/L

• Energy costs are 1/10th to 1/15th

the cost of mechanical evaporation

• Skid-mounted, compact design

• Operating pressures 

up to 1200 psig

• Multiple membranes and 

manufacturers available

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Historical Problems with RO 

Treatment for Produced Water

• Limited success due to inadequate pretreatment, 

resulting in fouling and scaling from:

– Calcium Hardness

– Iron

– Barium and Strontium

– Silica

– Microbiological Growth

– Organics

– Silt and Suspended Solids

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Scale Forming Salts 

Salt Saturation 

Concentration (mg/L)

Calcium Carbonate (CaCO3) 8

Calcium Fluoride (CaF2) 29

Calcium Orthophosphate (CaHPO4) 68

Calcium Sulfate (CaSO4) 680

Strontium Sulfate (SrSO4) 146

Barium Sulfate (BaSO4) 3

Silica, amorphous (SiO2) 120
Key to Success: Efficient Pretreatment

• Pretreatment Steps:

– Organics removal (oil / grease, polymers, etc.)

– Efficient management of hardness and metals

– Particulate removal

– Bacteria control

Result: Better pretreatment leads to less membrane fouling, 

higher water recovery and a lower cost of brine disposal

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Example Treatment Solution for TDS Removal

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RO:

TDS Removal

Treated 

Water

Antiscalant

Cartridge 

Filtration:

TSS Polish Brine Sulfite

Conc.

Sand Filter:

TSS Removal

Frac

Flowback

Water

Chlorine 

Dioxide Air

Oil 

Byproduct

Sludge for 

dewatering/ 

disposal

Chlorine 

Dioxide
Range of Applicability vs. Cost

RO 

Evaporation

Crystallization

3,000 40,000 260,000 1,000,000

Total Dissolved Solids ( mg/L TDS)

$ Costs per Barrel

750

Treatment for Reuse

32
Evaporation

• Ideal TDS Range of Feed Water 

is 40,000 to 120,000 mg/L

• Produces high quality distillate 

and liquid brine concentrate 

• Brine concentrate requires further 

treatment or disposal (max TDS 

concentration is approx. 260,000 mg/L)

• Evaporation systems more 

energy intensive than RO

• Most evaporation systems 

cannot handle any solids

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Types of Evaporation Systems

• Forced Circulation

• Falling Film

• Rising Film

• Agitated Thin Film

• Plate and Frame

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Selection Considerations

• Chemical Composition of Feed Stream

• Scaling / Fouling Potential

• Foaming Potential

• Materials of Construction

– Chloride concentrations

– Temperature

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Economization

• Multiple Effects

– Vapor From Each Effect is used in the Next / Previous 

Effect Depending on Set-up to Reduce Steam Use

• Vacuum

– Reduces Boiling Point 

– Maximizes Efficiency When Used in Concert With Multiple Effects

• Mechanical Vapor Recompression

– Recompresses the Vapor to Reduce Steam Use

– Usually Uses Just One Effect

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MVR Evaporator

Most Economical for this Application

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Range of Applicability vs. Cost

RO 

Evaporation

Crystallization

3,000 40,000 260,000 1,000,000

Total Dissolved Solids ( mg/L TDS)

$ Costs per Barrel

750

Treatment for Reuse

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Crystallizer

• Complex system capable of 

producing purified salt products

from impure solutions

• Multiple Types of 

Crystallizers available

• Principals of Crystallization include:

– Evaporation to form 

supersaturated solution

– Nucleation and 

growth of salt crystals

– Harvesting, washing 

and drying of salt crystals 

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Parameter Feed Water

pH 6.09

Bicarbonate 144

Calcium 11,595

Magnesium 690

Sodium 33,250

Iron (diss) 76

Barium 2,775

Strontium 3,633

Chloride 81,000

TSS 295

TDS 132,265

Application of a Crystallizer in the Marcellus

• Crystallizer Products:

– Calcium Chloride Liquid

– Sodium Chloride Dry Salt

– Distilled Water

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Crystallizer Block Flow Diagram

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Pretreatment Feed 

Water

Evaporator Crystallizer

Chemicals

Waste 

Sludge

Centrifuge

Reuse/Discharge

Drilling Fluid or 

Road Deicing

Road Salt

Distilled Water

Calcium Chloride 

Liquid (28-40%)

Sodium Chloride

Dry Salt (99+%)

Liquid Waste 

Purge
Key Considerations

• Proper Design

• Feed Water Management

• Economics – Byproduct Chemical Sales (ASTM specifications)

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TDS Treatment Options Summary

• RO membranes have found little use in the Marcellus

• Evaporation technology using Mechanical Vapor 

Recompression most common form of TDS Treatment

• Crystallization technology is complex but can be cost 

effective with sale of commodity chemical byproducts

• All technologies generally produce some 

amount of waste brine that requires disposal

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Questions and Answers

Robert J. Kimball, P.E., BCEE

Technical Director Produced 

Water Treatment

50 West 14th Street

Helena, MT 59601

406-441-1441 (office)

Kimballrj@cdmsmith.com (email)

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