# Unconventional Oil & Gas Extraction Wastewater Treatment Technologies

March 2015

DCN SGE00692Disclaimer



## D ISCLAIMER



### This report was prepared by the EPA with assistance from Eastern Research Group, Inc., an EPA contractor, to support the EPA’s Technical Development Document for Proposed Effluent Guidelines and Standards for Oil and Gas Extraction (DCN SGE00704)

. This report

c ompiles information and data from the literature and provided by industry representatives

. Mention of trade names or commercial products does not constitute endorsement or recommendations for use.Contents



### ii CONTENTS Page

P ART 

### A. U NCONVENTIONAL 

### O IL AND 

### G AS 

### : I NTRODUCTION AND 

### B ACKGROUND



### ............. 1

1 UOG Extraction Wastewater Characteristics

................................ ................................ ...... 2 1.1 Total Dissolved Solids in UOG Extraction Wastewater

................................ ......... 3 1.2 Hardness of UOG Extraction Wastewater

................................ .............................. 4 1.3 Other Constituents in UOG Extraction Wastewater

................................ ............... 4

2 UOG Extraction Wastewater Management Strategies and Treatment

............................... 4 2.1 Applicable Effluent Limitations Guidelines and Standards

................................ .... 6 2.2 Types of UOG Wastewater Treatment Technologies

................................ ............. 7 2.3 Treatment of UOG Extraction Wastewater

................................ ............................. 9

3 Summary of Information Reviewed

................................ ................................ .................. 10 3.1 How the Technology Works

................................ ................................ ................. 10 3.2 Capabilities and Limitations

................................ ................................ ................. 10 3.3 Costs

................................ ................................ ................................ ...................... 11 3.4 Summary of Vendors

................................ ................................ ............................ 12

P ART 

### B. W ASTEWATER 

### T REATMENT 

### T ECHNOLOGIES 

### C URRENTLY 

### U SED BY THE



### UOG I NDUSTRY



### ................................ ................................ ................................ .... 13

1 Non

- TDS Removal Wastewater Treatment Technologies

................................ ............... 13 1.1 Filtration/Flotation/Sedimentation

................................ ................................ ........ 13 1.2 Chemical Precipitation

................................ ................................ .......................... 20 1.3 Electrocoagulation

................................ ................................ ................................ 29 1.4 Advanc ed Oxidation and Precipitation

................................ ................................ . 37 1.5 Disinfection

................................ ................................ ................................ ........... 44

2 TDS Removal Treatment Technologies

................................ ................................ ............ 48 2.1 Evaporation/Condensation

................................ ................................ .................... 50
2.2 Crystallization

................................ ................................ ................................ ....... 67 2.3 Reverse Osmosis

................................ ................................ ................................ ... 76

P ART 

### C. P OTENTIAL 

### T ECHNOLOGIES



### ................................ ................................ ................ 86

1 Potential Technologies for Application in UOG Extraction Wastewater Treatment

....... 86

2 Description of How Each Potential Technology Works

................................ ................... 89 2.1 Ion Exchange

................................ ................................ ................................ ........ 89 2.2 Electrodialy sis Reversal

................................ ................................ ........................ 90 2.3 Capacitive Deionization

................................ ................................ ........................ 94 2.4 Membrane Distillation

................................ ................................ .......................... 97 2.5 Forward Osmosis

................................ ................................ ................................ .. 99

P ART 

### D. R EFE RENCE 

### L IST AND 

### S OURCE 

### F LAGS



### ................................ .............................. 101

P ART 

### E. A TTACHMENTS



### ................................ ................................ ................................ ... 114List of Tables



### iii LIST OF TABLES

Page

Table A

- 1. Summary of Treatment Technologies Currently Used to Treat UOG

Extraction Wastewater

................................ ................................ ................................ ... 8

Table A

- 2. Reported Reuse/Recycle Criteria

................................ ................................ ................... 9

Table B

- 1. Filtration Removal Efficiency in UOG Extraction Wastewater Applications

............. 17

Table B

- 2. Filtration/Flotation/Sedimentation Capital and O&M Costs for UOG

Extraction Wastewater Applications

................................ ................................ ............ 20

Table B

- 3. Filtration Costs to UOG Operators at CWT Facilities

................................ ................. 20

Table B

- 4. Filtration/Flotation Technology Vendors for UOG Extraction Wastewater

............... 20

Table B

- 5. Common Additive Chemicals and Targeted Constituents for UOG Extraction

Wastewater

................................ ................................ ................................ ................... 22

Table B

- 6. Chemical Precipitation Removal Efficiency in UOG Extraction Wastewater

Applications

................................ ................................ ................................ ................. 25

Table B

- 7. Sludge Gene rated by Chemical Precipitation of UOG Extraction Wastewater

........... 27

Table B

- 8. Chemical Precipitation Capital and O&M Costs for UOG Extraction

Wastewater Applications

................................ ................................ ............................. 28

Table B

- 9. Chemical Precipitation Costs to UOG Operators at CWT Facilities

........................... 28

Table B

- 10. Chemical Precipitation Technology Vendors for UOG Extraction

Wastewater

................................ ................................ ................................ ................... 29

Table B

- 11. Electrocoagulation R emoval Efficiency in UOG Extraction Wastewater

Applications

................................ ................................ ................................ ................. 33

Table B

- 12. Electrocoagulation Energy Use in UOG Extraction Wastewat er Applications

......... 36

Table B

- 13. Electrocoagulation Capital and O&M Costs for UOG Extraction Wastewater

Applications

................................ ................................ ................................ ................. 36

Table B

- 14. Electrocoagulation Technology Vendors for UOG Extraction Wastewater

.............. 37

Table B

- 15. AOP Removal Efficiency in UOG Extraction wastewater Applications

.................. 40

Table B

- 16. AOP Rental Costs for UOG Extraction Applications

................................ ................ 43

Table B

- 17. AOP Technology Vendors for UOG Extraction Wastewater

................................ .... 44

Table B

- 18. Disinfection Technology Vendors for UOG Extraction Wastewater

........................ 48List of Tables



### LIST OF TABLES (Continued) Page

iv Table B

- 19. Performance Data of Evaporation/Condensation in UOG Extraction

Wastewater Application

................................ ................................ ............................... 58

Table B

- 20. Concentrated Brine Composition Evaporation/Condensation

................................ ... 62

Table B

- 21. Evaporation/Condensation Energy Use in UOG Applications

................................ .. 64

Table B

- 22. Evaporation/Condensation Capital and O&M Costs for UOG Extraction

Wastewater Applications

................................ ................................ ............................. 65

Table B

- 23. Evaporation/Condensation Costs to UOG Operators at CWT Facilities

................... 66

Table B

- 24. Evaporation/Condensation Technology Vendors for UOG Extraction

Wastewater

................................ ................................ ................................ ................... 66

Table B

- 25. Energy Usage of Crystallization in UOG Extraction Wastewater

Applications

................................ ................................ ................................ ................. 73

Table B

- 26. Crystallization Capital and O&M Costs for UOG Extraction Wastewater

Applications

................................ ................................ ................................ ................. 74

Table B

- 27. Crystallization Costs to UOG Operators at CWT Facilities

................................ ...... 75

Table B

- 28. Crystallization Technologies for Treating UOG Extraction Wastewater

.................. 76

Table B

- 29. RO Removal Efficiency in UOG Extraction Wastewater Applications

.................... 79

Table B

- 30. Influent TDS Concentration Versus Water Recovery

................................ ............... 82

Table B

- 31. RO Energy Use in UOG Extraction Wastewater Applications

................................ . 83

Table B

- 32. RO Capital and O&M Costs for UOG Extraction Wastewater Applications

............ 84

Table B

- 33. RO Costs to UOG Operators at CWT Facilities

................................ ........................ 84

Table B

- 34. RO Technology Vendors for UOG Extraction Wastewater

................................ ...... 85

Table C

- 1. Potential Technologies for Ap plication in UOG Extraction Wastewater

Treatment

................................ ................................ ................................ ..................... 87

Table C

- 2. Resin Type and Corresponding Regenerate Solutions

................................ ................ 90

Table D

- 1. Reference List

................................ ................................ ................................ ............ 101List of Figures



### v LIST OF FIGURES Page

Figure A

- 1. UOG Produced Water Wastewater Management Methods

................................ .......... 5

Figure A

- 2. Drilling Wastewater Manageme nt Methods

................................ ................................ 6

Figure B

- 1. Flow Diagram of Sedimentation Principle

................................ ................................ . 15

Figure B

- 2. Flow Diagram of Gas Flotation Principle

................................ ................................ .. 16

Figure B

- 3. Flow Diagram of Chemical Precipitation Principle

................................ ................... 22

Figure B

- 4. pH Versus Concentration of Constituents

................................ ................................ .. 23

Figure B

- 5. Flow Diagram of Chemical Precipitation and Settling Principle

............................... 24

Figure B

- 6. Principle of Electrocoagulation

................................ ................................ .................. 31

Figure B

- 7. Flow Diagram of Electrocoa gulation

................................ ................................ ......... 32

Figure B

- 8. Flow Diagram of AOP Treatment On

- the

- Fly with Hydraulic Fracturing in

UOG Extraction Wastewater Applications

................................ ................................ .. 39

Figure B

- 9. Flow Diagram of AOP Treatment at Wastewater Impoundments in UOG

Extraction Wastewater Applications

................................ ................................ ............ 40

Figure B

- 10. AOP Performance in Reducing Scaling Potential in the Eagle Ford Shale

Formation

................................ ................................ ................................ ..................... 42

Figure B

- 11. Cost of TDS Removal Treatment Technologies versus Influent TDS

..................... 49

Figure B

- 12. Diagram of Evaporation/Condensation Principle

................................ ..................... 51

Figure B

- 13. Evaporation/Condensation Mechanical Vapor Compression Process Flow

Diagram

................................ ................................ ................................ ........................ 54

Figure B

- 14. Flow Diagram of a Multiple Stage Flash (MSF) Evaporator

................................ ... 55

Figu re B

- 15. Heartland LM

- ® Concentrator Flow Diagram

................................ ......................... 56

Figure B

- 16. Schematic of Heartland LM

- ® Evaporation Zone and Entrainment

Sepa rator

................................ ................................ ................................ ...................... 57

Figure B

- 17. Typical Distillate Recovery versus Influent TDS Concentration for MVC

Technology

................................ ................................ ................................ .................. 61

Figure B

- 18. Mechanical Vapor Compression Crystallization Process

................................ ......... 68

Figure B

- 19. INTEVRA’s EVRASTM Crystallization Process

................................ ...................... 69

Figure B

- 20. Flow Diagram of Reverse Osmosis Principle

................................ .......................... 77

Figure B

- 21. Spiral

- Wound Membrane Flow Diagram

................................ ................................ . 78List of Fig ures



### LIST OF FIGURES (Continued) Page

vi Figure B

- 22. TDS Concentration Versus Water Recovery Percent

................................ ............... 82

Figure C

- 1. Ion Exchange Process Using a Cation Exchange Resin

................................ ............. 89

Figure C

- 2. Regeneration Process of a Cation Resin

................................ ................................ ..... 90

Figure C

- 3. Flow Diagram of Electrodialysis Prin ciple

................................ ................................ 92

Figure C

- 4. Flow Diagram of Electrodialysis Reversal Principle

................................ ................. 93

Figure C

- 5. Flow Diagram of Electrodialysis Reversal

................................ ................................ . 93

Figure C

- 6. Flow Diagram of EDR Units in Parallel and in Series

................................ ............... 94

Figure C

- 7. RDI TM 

### Purification Process Diagram

................................ ................................ ......... 95

Figure C

- 8. RDI TM 

### Regeneration Process Diagram

................................ ................................ ....... 96

Figure C

- 9. Membrane Distillation Pressure Gradient

................................ ................................ .. 97

Figure C

- 10. Process Flow Diagram from Refrakt Vacuum Membrane Distillation

System

................................ ................................ ................................ .......................... 99

Figure C

- 11. Flow Diagram of Forward Osmosis

................................ ................................ ....... 100Acronyms



### vii ACRONYMS

API American Petroleum Institute
AWWA American Water Works Association bbl barrels BOD biochemical oxygen demand bpd barrels per day CBM coalbed methane C.F.R. Code of Federal Regulations
COD Chemical Oxygen Demand CSM Colorado School of Mines
CWT centralized waste treatment EC electrical conductivity
ED electrodialysis
EDR electrodialysis reversal
EIA Energy Information Administration
ELGs Efflue nt Limitations Guidelines and Standards
EPA U.S. Environmental Protection Agency
ME multiple effect mg/L milligrams per liter MSF multiple stage flash
MVC mechanical vapor compression MWCO molecular weight cutoff
O&M operation and maintenanc e PA DEP Pennsylvania Department of Environmental Protection pCi picocurie
POTW publicly owned treatment works psi pounds per square inch
RO reverse osmosis RS rapid spray TDS total dissolved solids
TOC total organic carbon
TPH total petro leum hydrocarbons
TSS total suspended solids TVC thermal vapor compression UOG unconventional oil and gas
UV ultraviolet VC vapor compression
ZLD zero liquid dischargePart A



### 1 

## Part A. U NCONVENTIONAL 

## O IL AND 

## G AS 

## : I NTRODUCTION AND



## B ACKGROUND



### Recent advances in oil and natural gas well development that combine hydraulic fracturing and horizontal drilling have dramatically improved the technical and economic feasibility of oil and gas extraction from unconventional oil and natural gas (UOG) 1 

### resources. As a result, in 201 2 , U.S. crude oil and natural gas production reached their highest level s in more than 15 and 3 0 years , respectively . Further, the U.S. Department of Energy ( DOE) projects that natural gas production in the U nited S ta tes will increase by 56 percent by 2040, compared to
201 2 production levels . Similarly, the DOE projects that by 2019, crude oil production in the United States will increase by 48 percent compared to 2012 production levels ( DCN SGE00989 )

. As a result of i ncreased UOG extraction, industry experts such as IHS Inc. and Lux Research, Inc. expect volumes of wastewater that are co

- produced with UOG to continue to increase (DCN SGE00709; DCN SGE00479; DCN SGE00722; DCN SGE00479) and, consequently, that industry i nvestment in wastewater treatment will also continue to grow (DCN SGE 00708 ; DCN SGE00709; DCN SGE00479).

This report provides background information and data related to wastewater treatment technologies considered in the development of revised effluent limitations guidelines and standards (ELGs) proposed for the Oil and Gas Extraction point source category to address discharges from onshore UOG extraction facilities to municipal wastewater treatment facil ities (referred to as publicly owned treatment works or POTWs)

. Specifically, this report focuses on wastewater treatment technologies used to treat UOG extraction wastewater that enable UOG operators to manage their extraction wastewater by means other th an discharge to POTWs. The two management strategies that involve treatment are reuse/recycle in drilling or hydraulic fracturing 2 

### and transfer to centralized waste treatment (CWT) facilities 3 

### . Because some CWT facilities treat UOG extraction wastewater, m any examples of treatment technologies used by CWT facilities are relevant to this review of treatment technologies and are discussed further in this report (see Section A. 2.1 for further background on the ELGs as they relate to CWT facilities). Some of these technologies may also be used to treat wastewaters from conventional oil and gas extraction operations and/or coalbed methane (CBM) extraction operations, as w ell as wastewater from other industrial categories, including CWT facilities.

1 UOG is defined in the proposed rule as “ crude oil and natural gas produced by a well drilled into a low porosity, low permeability formation (including, but not limited to, shale gas, shale oil, tight gas, tight oil) ”

. UOG resources include shale oil and gas, resources that were formed, and remain, in low

- permeability shale. UOG resources also include tight oil and gas, r esources that were formed in a source rock and migrated into a reservoir rock such as sandstone, siltstones, or carbonates. While coalbed methane (CBM) is sometimes referred to as an unconventional resource, it is not generally further discussed in this re port because it is not within the scope of this propos ed rule

. 2 Reuse in fracturing occurs through blending wastewater with other sources to create the hydraulic fracturing base fluid. B ase fluid is the final fluid to which proppant (sand) and chemicals a re added. Base fluids are typically water

based; however there are cases of non

- aqueous fracturing fluids (e.g., compressed nitrogen, propane, carbon dioxide). Water

- based fluid can consist of only fresh water or a mixture of fresh water, brackish water (e .g., treated municipal wastewater, groundwater) and reused/recycled wastewater.

3 40 CFR Part 437 defines a CWT facility as one that treats (for disposal, recycling or recovery of material) any hazardous or non

- hazardous industrial wastes, hazardous or non

- hazardous industrial wastewater, and/or used material received from off

- site (DCN SGE 00601 ).Part A



### 2 This report comprises five parts:

 Part A

– the remaining subsections of Part A describe the characteristics of UOG extraction wastewater , management strategies for UOG extraction wastewater, the targeted constituents for each management strategy that utilize wastewater treatment, and the treatment technologies used to remove these targeted constituents.

 Part B

– describes technologies that are c urrently used to treat UOG extraction wastewater at full

- scale treatment operations

.

 Part C

– describes technologies that the U.S. Environmental Protection Agency (EPA) did not identify as currently used to treat UOG extraction wastewater at full

- scale operations but the literature suggests may be used in the future.

 Part D

– provides a list the list of references the EPA identified during this review

 Part E

– provides the excel file where the E PA documented all costs and performance data as reported by literature that are summarized throughout the report.

The data included in this report are based on data generated or obtained in accordance with EPA’s Quality Policy and Information Quality Guid elines. EPA’s quality assurance (QA) and quality control (QC) activities for this rulemaking include the development, approval, and implementation of Quality Assurance Project Plans (QAPPs) for the use of environmental data generated or collected from samp ling and analyses, existing databases, and literature searches. 4



### Information presented in this document was taken from existing data sources, including state and federal agency databases, journal articles and technical papers, technical references, vendor websites, and industry/vendor telephone calls, meetings, and site visits. As shown in Table D

- 1 , the EPA assigned a source flag (A, B, C or D) to all references used in these calculations. Part D provides definitions of each source flag.

1 UOG E XTRACTION 

### W ASTEWATER 

### C HARACTERISTICS



### This section focuses on constituents found in UOG extraction wastewater that may be targeted for removal during treatment for reasons that are explained in Part A.2 . The EPA is proposing to define “UOG extraction wastewater” as “sources of wastewater pollutants associated with production, field exploration, drilling, well completion, or well treatment for unconventional oil and gas (UOG) extraction ”. 5 

### This includes the following wastewater streams, relevant to this report:

4 The relevant QAPPs for this rulemaking are the Environmental Engineering Support for Clean Water Regulations Programmatic Quality Assurance Project Plan (PQAPP) (DCN SGE00957) and the Unconventional Oil and Gas (UOG) Supplemental Quality Assurance Project Plan (SQAPP) (DCN SGE00958).

5 Stormwater is not considered a source of UOG extraction wastewater. In general, no permit is required for discharges of stormwate r from any field activities or operations associated with oil and gas production, except asPart A



### 3  P roduced water

— the water (brine) brought up from the hydrocarbon

- bearing strata during the extraction of oil and gas. This can include formation water, injection water, and any chem icals added downhole or during the oil/water separation process . Based on the stage of completion and production the well is in, produced water can be further broken down into the following components:

— Flowback

— the produced water generated in the initial p eriod after hydraulic fracturing prior to production (i.e., fracturing fluid, injection water, any chemicals added downhole, and varying amounts of formation water)

.

— Long

- term produced water

— the produced water generated during the production phase of the w ell after the initial flowback process (includes increasing amounts of formation water)

.

 Drilling wastewater 6



### — the liquid waste stream separated from recovered drilling fluid and drill cuttings during the drilling process. 7



### The following subsections briefly describe the primary constituents in UOG extraction wastewater that have been targeted for removal in treatment operations. Refer to Chapter C of the Technical Development Document for Proposed Effluent Limitations Guidelines and Standards for Oil and Gas Extraction (TDD) , Document No. EPA

- 821

- R

- 1 5

- 003 (DCN SGE00704), for more information on the constituents in UOG extraction wastewater.

1.1 Total Dissolved Solids in UOG Extraction Wastewater

Total dissolved solids (TDS) are one of the primary constituents fou nd in UOG extraction wastewater. TDS provides a measure of dissolved matter including salts (e.g., sodium, chloride, nitrate), metals, minerals, and organic material ( DCN SGE 00046 ; DCN SGE00704 ). T DS is not a specific chemical, but is defined as the portio n of solids that pass through a filter with a nominal pore size of 2.0 micrometers ( μm ) or less ( Standard Method 2540C

- 1997, ASTM D5907

- 03, and USGS I

- 1750

- 85 )

. 8



### Based on data reported in literature across many different types of UOG operations (e.g., sha le gas, tight oil), TDS concentrations in UOG extraction wastewater vary by UOG formation and are often greater than that of seawater (i.e., 35,000 milligrams per liter (mg/L)) (DCN SGE00704). 9 

### Reported data also shows that TDS concentrations are typically higher in long

- term produced water than in flowback and drilling wastewater (DCN SGE00704)

. TDS concentrations in UOG long

- term produced water can be higher than 350,000 mg/L, which is over ten times the concentration of TDS typically found in seawater.

specified in 40 C.F.R. part 122.26(c)(1)(iii) for discharges of a reportable quantity or that contribute to a violation of a water quality standard

. 6 Additional in formation about drilling wastewater can be found in ERG’s Unconventional Oil and Gas (UOG) Drilling Wastewater memorandum (DCN SGE00740).

7 Drilling fluid is the circulating fluid used in the rotary drilling of wells to clean and condition the hole and to counterbalance formation pressure. Drill cuttings means the particles generated by drilling into subsurface geologic formations and carried out from the wellbore with the drilling fluid.

8 40 C.F.R. p art 136 lists standard method 2540C

- 1997 as an approved test method for TDS.

9 All characterization data in this section about TDS, hardness, and other constituents is based on the EPA’s
memorandum Unconventional Oil and Gas (UOG) Produced Water Volumes and Characterization Data Compilation (DCN SGE00724) which is based on data identified as of February 2015.Part A



### 4 Salts (primarily sodium chloride) constitute over 50 percent of the TDS in UOG extraction wastewater (DCN SGE 00046 ; DCN SGE00704). Calcium and other group II alkaline earth metals (e.g., strontium, barium, magnesium) may also contribute to TDS. Similar to UOG produced water, sodium chloride is also the largest contributor to TDS in UOG drilling wastewater (DCN SGE00704).

1.2 Hardness of UOG Extraction Wastewater

Water hardness is a measure of the sum of multivalent cations dissolved in water, where the primary contributing cations are calcium (Ca +2 

### ) and magnesium (Mg +2 

### ). Total hardness is a measure of the sum of carbonate hardness and non

- carbonate hardness . C arbonate hardness is due to the presence of bicarbonate and carbonate in the wastewater ; non

- carbonate h ardness is due to salts (e.g., calcium chloride, magnesium sulfate) (DCN SGE 00178 ).

Based on data reported in literature across many different types of UOG operations (e.g., shale gas, tight oil), UOG extraction wastewater is classified by the EPA as a “v ery hard” water (>300 mg/L hardness) (DCN SGE 00178 ; DCN SGE00704 ). Reported data shows hardness concentrations in UOG extraction wastewater is often greater than 1,000 mg/L with the primary contributors being calcium and magnesium (DCN SGE00704). In fact, hardness concentrations in UOG produced water can be higher than 100,000 mg/L.

1.3 Other Constituents in UOG Extraction Wastewater

UOG extraction wastewater contains many other constituents that, as Part A.2 explains, may be targeted for removal in UOG extraction wastewater. Depending on the fate of the treated wastewater, these constituents include but are not limited to: total suspended solids (TSS), o il and grease, metals (e.g., barium, strontium, iron, boron), radioactive elements (e.g., radium 226, radium 228), and certain anions and cations (e.g., sulfate, bromide). pH is another parameter that is often monitored as it can vary significantly with th e type of UOG extraction wastewater. UOG extraction wastewater may also contain microbial contaminants that can lead to growth of sulfate reducing bacteria (SRB), which are further discussed in Part B.1.4 : Advanced Oxidation and Precipitation . On average, the pH and TSS in UOG drilling wastewater are higher than in UOG produced water (DCN SGE00704). Depending on how well drill cuttings are removed from drilling wastewater by the o perator, solids can be as high as 50 percent by mass (DCN SGE00245; DCN SGE00704) in UOG drilling wastewater

.

2 UOG E XTRACTION 

### W ASTEWATER 

### M ANAGEMENT 

### S TRATEGIES AND 

### T REATMENT



### For management of UOG produced water, UOG operators primarily use the three method s listed below and shown in Figure A

- 1 ( DCN SGE 00613; DCN SGE 00276; DCN
SGE 00528).

 Dispose of wastewater via underground injection for disposal wells (“disposal wells ”)

 Reuse /recycle wastewater in subsequent fracturing jobs

 Transfer wastewater to a CWT facilityPart A



### 5 For management of UOG drilling wastewater, UOG operators primarily use the methods listed below and shown in Figure A

- 2 (DCN SGE00740).

 Dispos e of wastewater via disposal wells

 Reuse/

recycle wastewater in subsequent drilling

 Transfer wastewater to a CWT facility

 Other (e.g., Onsite burial 10 

### , disposal via l andfill , land application)

Across the United States, operators most often manage their produced water via disposal wells (DCN SGE00704)

. However, reuse/recycle in hydraulic fracturing or drilling and transfer to CWT facilities are becoming more popular to handle increasing volumes of UOG extraction wastewater, both of which require some level of wastewater treatment (DCN SGE00596; DCN SGE00704). 11 

### Part B describes the types of wastewater treatment currently used to treat UOG extraction wastewaters and the targeted constituents.

Figure A

- 1 . UOG Produced Water Wastewater Management Methods

10 Onsite burial involves t emporary fluid storage in on

- site open earthen or lined pits with burial of residual solids after fluids are solidified, removed from the top, or evaporated.

11 Wastewater pretreatment may be required prior to i njection into class II disposal wells

, but this treatment is not the subject of this report.Part A



### 6 Figure A

- 2 . Drilling Wastewater Management Methods

Although operators have discharged UOG extraction wastewater to publicly owned treatment works (POTWs), these discharges were discontinued in 2011 (DCN SGE00704). Therefore, the EPA does not consider discharge to POTWs a primary UOG extraction wastewater management process. In select areas, UOG operators also use evaporation ponds for disposal of UOG produced water and drilling wastewater. However, there are certain requirements for using evaporation ponds, including very dry climates, which mainly occur in the western United States (DCN SGE00710).

2.1 Applicable Effluent Limitations Guidelines and Standards

EPA promulgated the first Oil and Gas Extraction ELGs (40 C.F.R. part 435) in 1979,

an d substantially amended the regulation in 1993 (Offshore), 1996 (Coastal), and 2001 (Synthetic

- based drilling fluids). The Oil and Gas Extraction industry is subcategorized in 40 C.F.R. part 435 as follows: (1) subpart A: Offshore; (2) subpart C: Onshore; (3) subpart D: Coastal; (4) subpart E: Agricultural and Wildlife Water Use; and (5) subpart F: Stripper.

The existing subpart C regulation covers wastewater discharges from field exploration, drilling, production, well treatment, and well completion activi ties in the oil and gas industry. Although unconventional oil and gas resources occur in offshore and coastal regions, recent development of UOG resources in the U.S. has occurred primarily onshore in regions to which the regulations in subpart C (Onshore) and subpart E (Agricultural and Wildlife Water Use) apply. 40 C

. F

. R

. 435, Subpart C specifies no discharge of wastewater pollutants from onshore oil and gas extraction facilities to waters of the U.S

. The existing regulations do not include national categorical pretreatment standards for discharges to POTWs. 40 C

. F

. R

. 435, Subpart E specifies that onshore oil and gas extraction facilities located west of the 98th meridian may discharge produced water in to navigable waters for use in agriculture or wildlife propagation. The EPA hasPart A



### 7 not found that these types of permits are typically written for unconventional oil and gas extraction wastewater

. 12



### Discharges from centralized waste treatment (CWT) facilities that accept oil and gas extraction wastes are not subject to 40 C

. F

. R

. part 435, but rather are subject to the effluent limitations guidelines and pretreatment standards under 40 C

. F

. R

. part 437 , the Centralized Waste Treatment Category

. EPA defines a CWT at 40 C

. F

. R

. 437.2(c) as “any facility that treats (for disposal, recycling or recovery of material) any hazardous or nonhazardous industrial wastes, hazardous or non

- hazardous industrial wastewater, and/or used material received from offsite

.

2.2 Types of U OG Wastewater Treatment Technologies

EPA classifies the treatment technologies discussed in this report by the types of constituents they remove, as described below.

 Non

- TDS removal technologies

– Technologies that remove non

- dissolved 13



### constituents from wastewater. Examples in UOG extraction wastewater applications include suspended solids, oil and grease, metals, bacteria, and /or certain ions that potentially cause scale to form on equipment and interfere with fracturing chemical additives. These technol ogies do not remove sodium and chloride ions, which make u p more than 50 percent o f the TDS in UOG extraction wastewater, as well as some other dissolved constituents that contribute to TDS.

 TDS removal technologies

– T echnologies capable of removing dissolved constituents that contribute to TDS (sodium, chloride, calcium, etc.), in addition to the constituents removed by non

- TDS removal technologies.

Table A

- 1 summarizes the UOG extraction wastewater treatment technologies the EPA reviewed (see Part B ) that are currently used to treat UOG ext raction wastewater, by treatment type. The table indicates the maximum influent TDS concentration for cost effective operation, residual waste streams generated, and range of cost for UOG operators to purchase or rent, operate, and maintain the technology (Total Cost Range for Treatment by UOG Operator). The EPA also identified prices charged to UOG operators by CWT facilities that accept UOG extraction wastewater (Cost to UOG Operator at CWT Facilities). Section A. 3 provides more information about the type of information the EPA reviewed in this report that is summarized in Table A

- 1

.

12 EPA notes that the requirements in the existing effluent guidelines for onshore oil and gas extraction facilities (Subpart C and Subpart E) do not apply to coalbed methane extraction, as this industry did not exist at the time that the effluent guidelines were developed and was not considered by the Agency in establishing the effluent guidelines (DCN SGE00761).

13 EPA has cat egorized treatment technologies into two categories in this report: those that are designed to remove dissolved constituents and those that are not designed to remove dissolved constituents. However, it should be noted that some of the technologies in the non

- TDS removal category do in fact remove some dissolved constituents. For example, chemical precipitation will remove certain metals. However, these technologies typically will not remove salts and hardness, which are the primary components of TDS in UOG extraction wastewater.Part A



### 8 Table A

- 1 . Summary of Treatment Technologies Currently Used to Treat UOG Extraction
Wastewater

Level of
Treatment Technology Maximum Influent TDS (mg/L) Types of

Residual
Wastes Generated Total Cost

Range for Treatment by UOG Operator ($ per barrel) a Cost to UOG

Operator at CWT Facilities ($ per bbl) b

Non

- TDS
Removal Technologies Disinfection None None

-- d N/A e

Filtration/Flotation/Sedimentation None Sludge/solid

waste 0.15

– 0.50 1.00

Chemical precipitation None Sludge/solid

waste 0.50

– 4 .00 2.20

– 5.30

Advanced oxidation and precipitation None None c 0.50

– 1.30 N/A e

Electrocoagulation None Sludge/solid

waste 1. 00

– 3. 10

-- d

TDS Removal Technologies Evaporation/ Condensation 150,000 Concentrated brine 2. 00

– 6. 50 3.00

– 10.00

Crystallization No limit Solid waste; potential liquid purge stream 5.00

– 1 1 .00 5.00

– 1 1 .00

Reverse osmosis (RO) ~50,000 Concentrated brine 3.50

– 4. 40 2.00

– 3.50

Source: DCN SGE00692.A01

N/A

— Not applicable ; mg/L

— milligrams per liter; bbl

— barrel; TDS

— total dissolved solids

.

a

— The total cost range is the sum of operating and maintenance (O&M) costs and amortized capital costs when UOG operators purchase a treat ment system. This range also includes the range of typical contractual fees UOG operators pay third party entities to treat their wastewater at the well pad or at the operator owned CWT facility. The total cost range does not include transportation costs.

b

— This total cost range is what operators pay CWT facilit i es to have UOG extraction wastewater treated. This range is for returning the treated wastewater back to the UOG operator for reuse in fracturing or treating the wastewater for discharge to surface water or POTWs. The total cost range does not include transportation costs.

c

— AOP vendors report that the solids generated by the technology remain suspended within the treated wastewater.
See Part B.1.4 for more detail.

d

— Cost information is unknown.

e

— These costs may not be applicable because the EPA did not identify any CWT facilities that accept extraction wastewater from UOG operators that use t hese technologies.Part A



### 9 2.3 Treatment of UOG Extraction Wastewater

UOG extraction wastewater may require some form of treatment dependent upon the fate of the treated wastewater (DCN SGE 00691 ) . Reuse/recycle is one management strategy that may involve treatment of UOG extraction wastewater. 14 

### When using this strategy, operators either transport UOG extraction wastewater directly to the next well they are fracturing or transport it to a temporary storage area until needed. Treatment typically consists of non

- TDS remo val technologies for removal of m ultivalent cations, microbial constituents , metals, TSS , and/or other specific constituents (DCN SGE00704). The wastewater is typically blended with other source water to reuse/recycle in fracturing, which may occur either before or after treatment (DCN SGE00616; DCN SGE00691). When this treatment occurs concurrently with fracturing at the next well , it is referred to as “on

- the

- fly” treatment, and is described in more detail in Part B.1.4

.
If operators reuse/recycle UOG extraction wastewater with elevated concentrations of certain constituents, the fracturing fluid, well, and/or formation may undergo one or more of the following problems:

 Fluid inst ability (change in fluid properties)

 Well plugging (restriction of flow)

 Well bacteria growth (buildup of bacteria on casing)

 Well scalin g (accumulation of precipitated solids)

 Formation damage (restriction of flow in the res ervoir)

Therefore, it may be necessary to remove constituents that can interfere with fracturing fluid chemicals, damage the formation, and /or cause scaling down the wellbore and in equipment prior to reuse/recycle

. Table A

- 2 shows the associated issues that the fluid or well may experience with elevated concentrations of certain constituents or concentrations outside of a specified range as reported by industry. The importance of and the exact constituent concentration depend s on operator preference, geology, and the fracturing fluid chemistry (e.g., slickwater, gel) (DCN SGE00704; DCN SGE00693)

.

Table A

- 2

. Reported Reus e/ Recycl e Criteria

Constituent Reason for Limiting Concentrations for Reuse/Recycle

Bacteria Bacterial growth

T otal dissolved solids (T DS ) Fluid stability

Chloride Fluid stability

Sodium Fluid stability

Oil Fluid stability

Boron Fluid stability
pH b Fluid stability

14 Treatment may not be required for reuse/recycle and blending (with additional source waters) alone may be used to control TDS concentrations in the final base fluid. No constituents are actually removed by blending (DCN SGE00616; DCN SGE00691)

.Part A



### 10 Table A

- 2

. Reported Reus e/ Recycl e Criteria

Constituent Reason for Limiting Concentrations for Reuse/Recycle

T otal suspended solids (T SS ) Plugging

Iron Scaling

Strontium Scaling

Barium Scaling

Silica Scaling

Calcium Scaling Magnesium Scaling

Sulfate Scaling

Potassium Scaling

Other s cale f

ormers a Scaling

Source: DCN SGE 00693

a

— Includes barium, calcium, manganese, and strontium.

b

— Operators require a specific range of pH rather than a limit as pH has a direct impact on the fracturing fluid chemistry.



### CWT facilities may also treat UOG wastewater for reuse/recycle or for discharge indirec tly to POTWs or directly to waters of the U.S. If being reused, the level of treatment depends upon operator needs. Discharges from CWT facilities directly to waters of the U.S. or indirectly to POTWs are subject to effluent limitations guidelines and pret reatment standards under 40 C.F.R. part 437.

3 S UMMARY OF 

### I NFORMATION 

### R EVIEWED



### This report describes technologies that are currently used, or may potentially be used in the future, to treat UOG extraction wastewater. The report describes how each technology works, capabilities and limitations (e.g., effectiveness, design considerations, residual generation, energy use), costs, and vendors. The following subsections describe the scope of the EPA’s technology reviews and provide relevant background information and definitions.

3.1 How the Technology Works

EPA reviewed the basic wastewater treatment principles for each technology to determine how the technology removes or controls the targeted constituents in UOG extraction wastewater and how treatment operators us e the technology.

3.2 Capabilities and Limitations

EPA reviewed information for each technology to determine the following for UOG applications:

 Targeted constituents and effectiveness

– Describes the targeted constituents that each technology is able to rem ove or control, as well as available performance data for removal efficiency in UOG applications.Part A



### 11  Design considerations

– Describes considerations specific to UOG applications, such as pretreatment requirements and maximum influent TDS concentrations for optimal performance.

 Residual generation

– Describes wastes a treatment technology may generate that operators must disp ose of or otherwise manage. Some residuals may be disposed of in landfills. As levels of radioactivity in treatment residuals exceed landfill acceptability limits, the treatment technology operator may be required to screen the waste stream for radioactivi ty prior to transport to landfills (DCN
SGE 00299 ; DCN SGE 00300 ; DCN SGE 00245). If radioactivity levels exceed the thresholds, residuals must be disposed of in landfills specifically licensed to accept such waste and typically impose a surcharge (DCN SGE003 00).

 Energy use

– Describes the types of energy sources (e.g., electricity from on

- site diesel generator, natural gas boiler) a technology requires. When available, the EPA also quantified energy requirements in kilowatt hours (kWh) per barrel (bbl) of was tewater treated.

3.3 Costs

EPA reviewed available information on the costs associated with each technology. The EPA reviewed three types of costs:

 Total Cost Range for Treatment by UOG Operator

– This is the cost for UOG operators to purchase or rent, operate, and maintain the technology . These costs can further be broken to down into:

— Capital and O&M costs

– Capital and O&M costs as reported by treatment vendors, UOG operators, and CWT facility operators to purchase, operate, and maintain the technology.

— Renta l or Effective Cost

– Rental cost UOG operators must pay vendors when they contract with a vendor to provide treatment with O&M costs included. This category also includes effective costs to the UOG operator reported by literature when the technology is pu rchased and capital costs are amortized to be combined with O&M costs.

 Cost to UOG Operator at CWT Facilities

– Cost charged to UOG operators by CWT facilities that accept UOG extraction wastewater.

Because literature reports costs associated with differen t elements of treatment systems, the EPA assigned one of the following terms to each cost reported in the tables of this report:

 Plant

– Includes the fac ility, land, necessary infrastructure; treatment system infrastructure (e.g., connect ing pipes, monito ring systems); storage of wastewater

, treated wastewater

, and chemicals ; and all treatment units , including any required pretreatment units.

 System

– Includes treatment system infrastructure (e.g., connecting pipes, monitoring systems) and all treatment units , including any required pretreatment units.Part A



### 12  Mobile System

– S ame as system

, but also includes a traile r as part of the infrastructure.

 Unit

– I ncludes the treatment unit being discussed (i.e., does not include infrastructure or any required pretreatm ent units)

.

3.4 Summary of Vendors

EPA identified vendors that currently offer treatment systems either for purchase or on a contract basis to UOG operators 15 

### . This includes the types of facilities at which the UOG industry uses the technology and, when availab le, which UOG formations the technology is used in.

15 The EPA’s lists of vendors for each treatment technology described in Part B are not exhaustive, but rather include all vendor information that was available to EPA at the time of publication of this report.Part B



### 13 

## Part B. W

ASTEWATER 

## T REATMENT 

## T ECHNOLOGIES 

## C URRENTLY 

## U SED BY

THE 

## UOG I NDUSTRY



### The following two sections discuss technologies currently used in full scale projects by the UOG industry. Part B.1 discusses non

- TDS removal treatment technologies and Part B.1.4 discusses TDS removal treatment technologies.

1 N ON



### - TDS R EMOVAL 

### W ASTEWATER 

### T REATMENT 

### T ECHNOLOGIES



### One management strategy for UOG extraction wastewater is to treat it using non

- TDS removal technologies so it is “just clean enough” to be reused in fracturing (DCN SGE00710; DCN SGE00638.A11). Non

- TDS removal technologies reduce or destabiliz e materials such as suspended solids, microbial constituents, metals, and multivalent cations, but are not designed to remove sodium chloride and other salts. Non

- TDS removal technologies target constituents that contribute to corrosivity, cause scale, int erfere wit h fracturing chemical additives (e.g., boron is removed to prevent its interference with gel fracturing fluids), and/or interfere with well production and integrity. Because they often reduce hardness, they are sometimes referred to as

wastewater softening technologies. Non

- TDS technologies used to treat UOG extraction wastewater include (DCN SGE 00667 ):

 Filtratio n/gas flotation/sedimentation

 Chemical precipitation

 Electrocoagulation

 Advanced o xidation and precipitation (AOP)

 Disinfection

Th ese tec hnologies may also be used as pretreatment prior to TDS removal treatment that may be required for other management strategies of UOG extraction wastewater. Some TDS removal treatment technologies are vulnerable to scaling and/ or fouling caused by certain non

TDS constituents found in UOG extraction wastewater . Reducing concentrations of these undesired constituent s prior to TDS treatment allows TDS removal technologies to operate more efficiently

.

1.1 Filtration/Flotation/Sedimentation

Physical separation treatment technologies that remove free oil and TSS include filtration, flotation, and sedimentation. These technologies do not remove multivalent cations, hardness, or TDS (sodium chloride or other salts). Filtration/sedimentation/flotation is typically

u sed to treat UOG extraction wastewater prior to reuse in fracturing, or to pretreat wastewater prior to TDS

- removal treatment. In addition, these technologies may be used following chemical precipitation to remove precipitates.

Th is section describes the f iltration/sedimentation/flotation processes, treatment capabilities and limitations, treatment cost s , and vendors that market the technology for UOG extraction wastewater treatment

.Part B



### 14 1.1.1 How Filtration/Sedimentation/Flotation Works

This subsection describes fil tration/sedimentation/flotation operating principles and how these processes have been used to treat UOG extraction wastewater.

Principle and Process Description: Filtration

Filtration works by routing wastewater through a porous media such as a rock, glas s, walnut shell, or sand to filter out oil and suspended solids. Gravity, centrifugal force, pressure, or a vacuum forces the wastewater through the media, which may be a single fixed bed, multiple fixed layers, or a moving bed (DCN SGE00 195 ). Suspended so lids are trapped in the pores between the grains of the media (typically greater than 3 μ m) and remain as the water passes through. As the media filter captures increasing amounts of solids, the pressure drop across the filter bed increases until it reache s a threshold at which point a backwash cycle is used to remove the accumulated solids. Other filter types use disposable bags or cartridges as filter materials. Filter backwash is typically recycled to the first unit of the treatment system, such as a sed imentation basin.

Wastewater may also be routed through ceramic or polymeric membranes by using a pressure differential. Membrane filtration systems include media with pore sizes 0.1

- 3 μ m (microfiltration) and 0.01

- 0.1 μ m (ultrafiltration) and 0.001

- 0.0001 μ m (reverse osmosis). Microfiltration removes conventional clays, humic acids, bacteria, algae, cysts, and other suspended solids. Ultrafiltration removes viruses, color, odor, and some colloidal natural organic matter. Microfiltration and ultrafiltration require trans

- membrane pressure of 1

- 30 pounds per square inch (psi) to operate. (DCN SGE00264). Reverse osmosis operates at applied pressures ranging from 250 to 1,180 psi to push water through the membrane while blocking ions and other dissolved materia l (TDS) from passing (DCN SGE00175) . Accordingly, reverse osmosis is well suited for desalination and described as a TDS removal technology in Part B

. 1.4

.
Many applications for UOG extraction wastewater use multiple stage filtration where each subsequent stage uses a smaller pore size than the previous stage to optimize perfo rmance. For example, one CWT facility that treats UOG extraction wastewater that the EPA visited uses 100, 50, 25, and 10 micron filters sequentially to remove suspended solids (DCN SGE00299). In addition, another UOG operator reported they use 100 followe d by 20 micron filters prior to reuse (DCN SGE00635).

Principle and Process Description: Sedimentation

Sedimentation remove s suspended solids by gravity settling. Sedimentation work s by allowing water to stagnate or flow very slowly through an impoundment or tank , thereby allowing suspended solids to settle to the bottom and dispersed oil and grease to float to the surface. Figure B

- 1 illustrate s the principle of sedimentation. Constituents A ( TSS) and O (oil and grease) are targeted for removal. UOG extraction wastewater also contains dissolved constituents (represented by constituent D) which sedimentation does not remove as illustrated in Figure B

- 1

. Treated wastewater is gradually removed through the middle portion of the tank/impoundment so that it no longer contains the solids that have settled or the oil and greasePart B



### 15 that h as risen to the surface. Sedimentation is most effective in removing suspended solids with specific gravity significantly greater than 1.0.

Figure B

- 1 . Flow Diagram of Sedimentation Principle

In reuse/recycle applications, some UOG operators may rely on storage prior to reuse in fracturing as a means to simultaneously reduce suspended solids through sedimentation. UOG operators typically store the wastewater in fracturing tanks until they are r eady to fracture the next well. Depending on logistics, the length of time the wastewater is stored may be relatively long (one month). One UOG operator, who typically stores wastewater for one month, reported they see a reduction in suspended solids befor e and after storage. This operator must periodically clean out these tanks to remove solids from the bottom (DCN SGE 00275).

Principle and Process Description: Flotation

Gas flotation is the process of using fine bubbles to induce oil and suspended particle s to rise to the surface of a tank where they can be collected and removed. Gas bubbles are introduced into the wastewater and attach to the particles. With the bubbles and oil and particles attached, the effective specific gravity of the two combined is l ess than that of water allowing the suspended particles to rise to the surface with the bubbles (DCN SGE00 195 ). The gas bubbles are typically air, nitrogen, or other inert gases (DCN SGE 00264). Flotation is most effective in removing suspended solids with specific gravity slightly greater than 1.0.

Figure B

- 2 illustrate s the principle of flotation. Constituent A, which is suspended solids and oil, is targeted for removal. The influent UOG extraction wastewater also contains dissolved constituents, represented by constituent D in Figure B

- 2 , whic h are typically not removed by flotation. Bubbles are generated at the bottom of the tank and float upwards towards the surface, sweeping up constituent A as they rise through the water column. A mechanical skimmer rotates and physically removes the consti tuent A out of the wastewater and transfers it into a collection tank. The treated wastewater leaves the unit from the middle or bottom portion of the tank. Note that dissolved constituent D is not removed during the process.Part B



### 16 Figure B

- 2 . Flow Diagram of Gas Flotation Principle

The UOG industry uses two categories of gas flotation technologies: dissolved gas flotation and induced gas flotation. These two categories differ by the method used to create the bub bles. Consequently, the bubble sizes are also different for each method, which affects treatment efficiency (DCN SGE00264).

 Dissolved gas flotation

– Gas is injected into wastewater in a pressurized retention tank or pipe, allowing the gas to dissolve in the wastewater. When the wastewater enters the flotation tank, the pressure is reduced, causing fine air bubbles to be released.

 Induced gas flotation

– Bubbles are generated or injected near the bottom of the flotation unit by mechanical means such as a propeller or diffuser.

1.1.2 Capabilities and Limitations

Th is subsection describe s the targeted constituents and effectiveness, design and operation considerations, residuals, and energy use of filtration, sedimentation, and flotation

.
Targeted Constituents an d Treatment Effectiveness

Filtration/sedimentation/flotation technologies primarily remove suspended solids and free oil and grease (DCN SGE 00264 ; DCN SGE 00625). The EPA identified publically available performance data for filtration in UOG applications, which is shown in Table B

- 1

. The table includes untreated influent constituen t concentrations, effluent constituent concentrations, and the resulting constituent removal efficiencies. Data in Table B

- 1 indicate that the removal of constituents other than TSS and free oil in UOG extraction wastewater is generally low for this technology

. The EPA did not identify removal efficiency data for sedimentation or flotation in the context of UOG extraction operations.Part B



### 17 Table B

- 1 . Filtration Removal Efficiency in UOG Extraction Wastewater Applications

Constituent Reported Influent Range (mg/L) Reported Effluent Range (mg/L) Removal Efficiency

(%) a ,b Reference ID

Total dissolved solids (TDS) 11,000

– 190,000 8,100

– 190,000

– 6.1 to +27 153

Chloride 15,000

– 150,000 12,000

– 110,000

– 19 to +29 153

Sodium 5,600

– 45,000 5,800

– 43,000

– 3.7 to +41 153

Metals Magnesium 190

– 2,200 180

– 2,300

– 5.1 to +35 153

Strontium 280

– 5,100 250

– 5,300

– 8.1 to +19 153

Iron 6

– 64 8

– 66

– 33 to +53 153

Calcium 1,600

– 21,000 1,500

– 22,000

– 5.6 to +26 153

Potassium 120

– 1,800 130

– 1,900

– 120 to +14 153

Barium 35

– 2,300 37

– 2,400

– 5.7 to +54 153

Other Oil and grease 13 ND >99 153
Total suspended solids (TSS) 99

– 880 81

– 680 18

– 67 153

Sulfate 0

– 410 0

– 100 60

– 76 153

Hardness 4,900

– 66,000 4,700

– 74,000

– 17 to +42 153

ND

— Not detected ; mg/L

— milligrams per liter

.

a

— The EPA calculated all removal efficiencies using paired influent and effluent concentrations reported in literature. Attachment 1 ( DCN SGE00692.A01 ) presents these removal efficiency calculations. The number of data points that these removal efficiencies are based on are also presented in Attachment 1.

b

— Occasionally, literature reported higher constituent concentrations after treatment t han before treatment. These instances are indicated by negative removal efficiencies

. The following are potential reasons for these negative values: inaccuracy of reported paired influent and effluent samples , addition of chemicals, or the technology does not remove the constituent.



### Flotation has been demonstrated with following performance in removal efficiency when treating UOG extraction wastewater (DCN SGE00264):

 Oil and grease: 93 percent removal efficiency

 Chemical Oxygen Demand (COD): 75 percent rem oval efficiency

 TSS: Removal of suspended solids down to 25 microns in size

Design and Operation Considerations for UOG Extraction Wastewater

This section provides information on design and operation considerations when filtration/sedimentation/flotation technologies are used in UOG applications. Data indicates that the performance of all three of these technologies is not affected by influent TDS concentration.Part B



### 18 Filtration

One of the most significant issues with filtration of UOG extraction wastewater is the presence of guar gum. Guar gum is a natural polymer UOG operators commonly use in gel fracturing fluid to assist in carrying heavy loads of proppant. It can be found in UOG extraction wastewater at concentrations between 100 and 20,000 mg/L, especially during early flowback (DCN SGE 00616 ). This constituent can cause serious complications during filtration. When UOG operators expect the presence of guar gum they add a cation to chemically breakdown the polymer prior to filtration (DCN SGE 00616 ).

Most fil trations systems designed to treat UOG extraction wastewater include a pressure differential monitoring system. When a target pressure differential is detected across the filter, it indicates a backwash cycle is required or the filter bag or cartridge need s replacement (DCN SGE00616).

Sedimentation

Large particles settle quickly, but smaller suspended particles take longer to settle. For this reason, the removal rates of TSS increase with residence time (i.e., the amount of time that it takes a discrete qua ntity of water to flow through the system) and particle size and density (DCN
SGE00264 ). This treatment method requires a relatively large infrastructure footprint and may result in water volume loss due to evaporation (DCN SGE00264).

Circulation within t he settling tank or basin reduces the effectiveness of treatment. Circulation may be caused by the inertia of incoming fluid, density currents due to temperature differences between the incoming wastewater and the rest of the volume, or wind effects. Tank or basin design and operation should minimize these effects (DCN SGE 00167 ). Gravity settling in ponds can be enhanced by several mechanisms including gas flotation and chemical coagulant addition.

Flotation

Optimal removal efficiencies occur with uniform distribution of a high density of bubbles with small interstitial spacing. These are achieved by appropriate design of eductors to generate bubbles, nozzles or headers to distribute the bubbles, and interchamber divisions to prevent short circuits and oth er undesirable flow patterns (DCN SGE 01044 ). Flotation is most effective when operating in low temperature conditions, as higher temperatures require higher pressures to dissolve the gas in the water. Addition of chemical coagulants increases the range of particle sizes which may be removed by flotation (DCN SGE00264).

Residuals

Filtration

During filtration, solids are collected in the filtration media that periodically need to be removed to restore optimum removal. This can be achieved by backwashing the f ilter, with the backwash water typically recycled to the treatment system inlet, or by replacing and disposingPart B



### 19 the filter bag or cartridge. Nearly 100 percent of the influent wastewater is recovered as treated wastewater. However, a small fraction may be l ost from backwash cycles (DCN SGE00264).

Sedimentation

Depending on the amount of suspended solids in the UOG extraction wastewater

, sedimentation may require limited or no removal of the solids that settle at the bottom

. In cases where sedimentation is pe rformed in an impoundment

, solids are typically dredged from the bottom of the impoundment on a periodic basis and disposed of offsite , typically at a landfill

. One UOG operator who reported settling suspended solids during long

- term storage of UOG

extract ion wastewater in fracturing tanks stated that they periodically must clean the tank bottoms and dispose of the solids at a landfill (DCN SGE00275). Typically all of the influent is recovered as treated wastewater. However, depending on the region, some vo lume may be lost to evaporation (DCN SGE00264).

Flotation

During flotation, air bubbles, particulates, and free oil droplets form foam on the surface. This foam is skimmed off for disposal. Note that flotation does not remove soluble oil constituents, which remain in the effluent (DCN SGE00264).

Energy Use

Energy use associated with sedimentation is very low, limited to that required to pump water to or from the settling area (DCN SGE00264). Flotation requires energy to compress gas and skim the foam o ff the surface. Filtration requires energy to maintain the pressure differential.

1.1.3 Costs

Capital costs of filtration, sedimentation, and flotation include costs for settling tanks, basin liners, pressurized gas tanks

, piping, low

- pressure pumps, and monito ring equipment.
O perating costs associated with filtration, sedimentation, and flotation include energy to pump water and pressurize the system

, replacement filters, additive chemicals, disposal of generated sludge solids, and labor costs.

Table B

- 2 shows approximate capital and operating costs for purchased or rented floatation, sedimentation, and filtration treatment systems, as reported in the literat ure. Table B

- 3 shows approximate costs UOG operators pay CWT facilities to treat UOG extraction wastewater using filtration

.Part B



### 20 Table B

- 2

. Filtration/Flotation /Sedimentation Capital and O&M Costs for UOG

Extraction Wastewater Applications

Technology Vendor Cost Basis Capacity

(MGD) Capital

Cost ($ per gpd) O&M Cost

($ per bbl) Rental or

Effective Cost ($ per bbl) a Reference

ID

Filtration NR Purchase 0.025 12.00 low NR 10

Sedimentation NR Purchase or Rental 0.63 NR NR 0.15

– 0.40 171

Gas Flotation Purestream Purchase or Rental 0.11 2.40

– 3.80 NR 0.50 126 ; 154

NR

— Not reported ; MGD

— million gallons per day; gpd

— gallons per day; bbl

— barrels

.

a

— Represents rental cost if the cost basis was rental and is inclusive of O&M. Represents total effective cost when cost basis is purchase, which includes amortized capital costs and O&M costs combined.



### Table B

- 3

. Filtration Cost s to UOG Operator s at CWT Facilities

CWT Facility Name Type of UOG Reported

Typical Influent TDS (mg/L) Type of

Service Cost to UOG

Operator at CWT Facilities ($ per bbl) Reference
ID
Clean Streams, LLC Shale gas 100,000 Reuse Only 1.00 69 mg/L

— milligrams per liter; bbl

— barrels. Note: Data in this table are as

- reported in literature.



### 1.1.4 Summary of Vendors for UOG Extraction Wastewater

Table B

- 4 lists vendors of filtration and floatation technologies that offer treatment systems designed specifically for UOG extraction wastewater. The EPA did not identify any sedimentation vendors sp ecific to UOG applications in the literature.

Table B

- 4 . Filtration/Flotation Technology Vendors for UOG Extraction Wastewater

Vendor Technology Technology Name Surface Footprint (ft 2 ) a Capacity

( bpd ) Reference

ID

FilterSure Media Filtration NR Trailer mounted 5,000 153

Purestream Gas Flotation IGF and IGF+ Trailer mounted 2,500 154

NR

— Not reported ; IGF

— induced gas flotation separator; IGF+

— induced gas flotation separator plus; bpd

— barrels per day; ft 2

— square feet.

a

— Only includes the primary treatment unit

, not storage for wastewater, chemicals, or sludge ( solid waste ).



### 1.2 Chemical Precipitation

Chemical precipitation uses chemical addition to precipitate targeted constituents, followed by solids removal to remove the precipitate. It reduces metals, hardness, TSS, and other constituents, but does not remove TDS (sodium chloride or other salts). Chemical precipitation is most often used to treat UOG extraction wastewater prior to reuse in fracturing, or to pretreat wastewater prior to TDS

- removal treatment. Both of t hese management strategies typically require removal of these types of constituents.Part B



### 21 Th is section describes the chemical precipitation process, treatment capabilities and limitations, treatment cost, and vendors that the EPA is currently aware of that mark et the technology for UOG extraction wastewater treatment

.

1.2.1 How Chemical Precipitation Works

This subsection describes chemical precipitation operating principles and how the process has been used to treat UOG extraction wastewater.

Principle

In c hemical pr ecipitation

, chemicals are added to wastewater to change the physical properties of dissolved and suspended constituent s so they can be removed by settling or filtration. Chemical precipitation works by destabilizing colloids and by converting soluble

cons tituent s to insoluble forms. This is accomplished by adding a treatment chemical (precipitant) to the wastewater that reacts with the target constituent and forms an insoluble solid (precipitate) . The insoluble solids are suspended in the wastewater

, and t hen removed through solids removal such as settling or filtration.

Equation 1 and Figure B

- 3 illustrate the principle of chemical precipitation . Constituent B (which is soluble in water) is targeted for removal. Chemical A is added to the solution and reacts with B to form a new chemical

, AB, which is insoluble; unable to dissolve, AB becomes a suspended solid. Chemical C represents a constituent unaffected by these reactions, illus trating that chemical precipitation does not remove all constituent s.

Equation 1

A (additive chemical) + B (soluble constituent ) → AB (insoluble constituent )Part B



### 22 Figure B

- 3 . Flow Diagram of Chemical Precipitation Principle

Table B

- 5 shows different additive chemicals and the constituents they remove

. In UOG extraction wastewater applications, the targeted constituents include TSS, multivalent cations, and metals (e.g., iron) (DCN SGE00704). Therefore, the most commonly used chemicals include calcium hydroxide (i.e., lime) and sodium hydroxide (i.e., caustic soda). Because differe nt constituent s have different solubilit ies at different levels of pH , it may not be possible to remove all constituent s in a one

- step precipitation process. T o maximize constituent s removed , multiple stages of precipitation may be necessary, using differe nt pH levels and additive chemicals (DCN SGE 00127 ).

Table B

- 5 . Common Additive Chemicals and Targeted Constituents for UOG Extraction
Wastewater

Additive Chemical Targeted Constituent s Reference ID

Caustic soda (sodium hydroxide) Noncarbonate hardness and TSS 64
Lime (calcium hydroxide) Carbonate hardness and TSS 

### 8 ; 64

Sodium sulfate Barium, strontium, radium 64



### One of the underlying principles dictating chemical precipitation design and operation is that a constituent’s solubility is correlated to pH. Each constituent has a different solubility at different pH ranges (DCN SGE00167 ). As a result, a chemical precipitation operation involves careful control of pH to maximize constituent removal. Figure B

- 4 shows how pH affects the solubility of different metals. The minimum of each curve represents the minimum solubility and optimum pH for chemical precipitation of that metal

. Constituents shown in Figure B

- 4 most relevant to UOG extraction wastewater include iron, calcium, and magnesium.Part B



### 23 Source: DCN SGE00133

.



### Figure B

- 4 . pH Versus Concentration of Constituents

Process Description

Figure B

- 5 is a flow diagram of a typical chemical precipitation process to remove dissolved and suspended constituent s from wastewater.

1. First, wastewater enters a mixing tank where the treatment chemi cal is added. Typical times required for proper mixing range from less than one second to 30 seconds.

2. The wastewater enters a flocculation tank, where a n organic polymer is added.
F locculation is used to increase the size of precipitated solids , thus incre asing the rate of settling (DCN SGE00167 ).

3. Finally, the wastewater flows into a settling tank where the heavy suspended constituent s fall to the bottom and are collected as sludge. The treated wastewater (decant water) is removed from the top of the tank.

4. Sludge is typically routed to a dewatering unit (e.g., filter press). Decant water is recycled to the head of the treatment system, and the solid waste that is generated is disposed of or otherwise managed.Part B



### 24 Figure B

- 5 . Flow Diagram of Chemical Precipitation and Settling Principle

1.2.2 Capabilities and Limitations

Th is subsection describe s the targeted constituents and effectiveness, design and operation considerations, residuals, and energy use of chemical precipitation

.
Targeted Constituent

s and Treatment Effectiveness

The primary constituent s removed by chemical precipitation in UOG extraction wastewater applications include hardness, TSS, and metals (DCN SGE00167 ). When these constituent s are removed, TD S concentrations are only slightly reduced , if reduced at all. 16 

### This is because TDS in UOG extraction wastewater is primarily sodium chloride, a dissolved solid that is not removed by chemical precipitation

.

Table B

- 6 shows chemical precipitation performance data in UOG extraction wastewater applications. The table includes untreated influent constituent concentrations, effluent constituent concentrations, and the res ulting constituent removal efficiencies. Data in Table B

- 6 indicates that the removal of TDS from UOG extraction wastewater from chemical precipitation is low. In

gen eral, chemical precipitation is effective at any influent TDS concentration.

16 It is also possible that TDS increases using chemical precipitation due to the addition of treatment chemicals.Part B



### 25 Table B

- 6 . Chemical Precipitation Removal Efficiency in UOG Extraction Wastewater Applications

Constituent Typical Influent

Range (mg/L) Typical Effluent

Range (mg/L) Removal

Efficiency (%)

a ,b Chemical

Additive Used Reference ID

TDS 33,000

– 47,000 31,000

– 48,000 −6 to +5 Lime, NaOH 

### 8 ; 91 ; 81

Chloride 13,000

– 22,000 13,000

– 21,000 2

– 3 NR 14 ; 

### 8

Sodium 7,100

– 17,000 6,800

– 17,000

– 13 to +4 NR 14 ; 

### 8 ; 81

Metals

Barium 7

– 600 0.1

– 43 14

– >99 Lime, NaOH 81 ; 

### 8 ; 14

Boron 18

– 25 16

– 23 7

– 11 Lime, NaOH 81 ; 

### 8

Calcium 740

– 2,600 37

– 2,700

– 5 to +97 Lime, NaOH 14 ; 

### 8 ; 81

Iron 8

– 180 ND

– 2 >87 Lime, NaOH 14 ; 81 ; 

### 8 ; 91

Lithium 11 11 0 NaOH 81
Magnesium 130

– 1,200 49

– 520

– 2 to +61 Lime, NaOH 14 ; 

### 8 ; 81
Manganese 0.6

– 1.5 ND

– 0.1 >83 Lime 

### 8 ; 91

Nickel 0.11 0.1 11 Lime 

### 8
Phosphorous 3 2 33 NaOH 81

Potassium 36

– 560 35

– 350

– 18 to +43 Lime, NaOH 14 ; 81 ; 

### 8

Strontium 150

– 470 6

– 480

– 3 to +96 Lime, NaOH 14 ; 

### 8 ; 81
Organics

BTEX 2.9 2.1 28 NaOH 81

HEM 2,100 6 >99 Lime 

### 8

TOC 12

– 18 6

– 9 25

– 67 Lime, NaOH 81 ; 

### 8

TPH 19 4 79 NaOH 81

Other
Alkalinity 240

– 750 4

– 330 39

– >99 Lime, NaOH 

### 8 ; 91 ; 14 ; 81

Ammonia 84 84 0 NaOH 81

Hardness 301

– 2,400 560

– 1,600

– 87 to +41 Lime, NaOH 

### 8 ; 91 ; 81

Silica 150

– 190 18

– 40 78

– 89 Lime; NR 91 ; 

### 8

Sulfates 10

– 320 27

– 210

– 170 to +35 Lime, NaOH 14 ; 

### 8 ; 81

TSS 120

– 780 18

– 130 48

– 98 NaOH; Lime 14 ; 91 ; 81 ; 

### 8
Turbidity 44

– 100 3 93

– 97 NR 91

NR

— Not reported ; mg/L

— milligrams per liter; NaOH

— sodium hydroxide; TDS

— total dissolved solids; BTEX

— benzene, toluene, ethylbenzene, and xylenes; HEM

— hexane extractable material; TOC

— total or ganic carbon;
TPH

— total petroleum hydrocarbons; TSS

— total suspended solids

.
a

— The EPA calculated all removal efficiencies using paired influent and effluent concentrations reported in literature. Attachment 1 ( DCN SGE00692.A01 ) presents these removal effic iency calculations. The number of data points that these removal efficiencies are based on are also presented in Attachment 1.

b

— Occasionally, literature reported higher constituent concentrations after treatment than before treatment. These instances are indicated by negative removal efficiencies

. The following are potential reasons for these negativePart B



### 26 values: inaccuracy of reported paired influent and effluent samples , addition of chemicals, or the technology does not remove the constituent. 

### Design and Operation Considerations for UOG Extraction Wastewater

In UOG extraction wastewater applications, chemical precipitation is typically utilized at CWT facilities where there is sufficient area for setup. A typical system, as shown in Figure B

- 5

, will fit inside one to three trailers, depending on flow and the vendor. However, this does not include storage (e.g., impoundments, fracturing tanks) for influ ent and treated wastewater or a staging area for chemicals. One UOG operator the EPA visited owned a CWT facility designed for treating UOG extraction wastewater for reuse, using chemical precipitation as the primary treatment. The entire treatment system required a site that was approximately the same size as a well pad. It included (DCN SGE00635):

 Chemical storag e area

 Two trailer

- sized treatment units and a separate filter press

 Multiple sludge storage bins

 Multiple 500 barrel fracturing tanks for untrea ted and treated wastewater storage 17



### To improve chemical precipitation reliability , advanced systems to monitor concentrations, pH, and flow rates may be installed (DCN SGE 00127 ). The appropriate quantity and type of treatment chemical are determined based on influent wastewater characteristics

. Testing wastewater prior to treatment is required because constituent concentrations in UOG extraction wastewater can vary greatly over time (DCN SGE00299; DCN SGE00300; DCN
SGE 00245 ). Important parameters include th e influent pH, TDS, hydrocarbons, and TSS (DCN SGE 00245 ).

Residuals

In addition to treated wastewater, chemical precipitation processes generate sludge that is typically dewatered before landfill disposal. Table B

- 7 shows estimated sludge generation from chemical precipitation units processing UOG extraction wastewater

. In general, higher influent TDS and TSS results in higher sludge generation (DCN SGE 00285 ). Most of these units associated with the data in Table B

- 7 are operated to remove barium, strontium, magnesium, calcium, and TSS from UOG extraction wastewater.

17 The number of 500 barrel fracturing tanks was not reported, but varies depending on the treatment rate and ability to move wastewater to and from the site.Part B



### 27 Table B

- 7 . Sludge Generated by Chemical Precipitation of UOG Extraction Wastewater

Type of Precipitation Influent TDS (mg/L) Influent Flow

Rate (bpd) Total Waste

Generation (tons per day) Waste Generation

(pounds per influent barrel) Reference

ID
Caustic (NaOH) Addition 45,000

– 80,000 4,000

– 6,000 5

– 6 1.7

– 3 81

Lime

- soda 34,000

– 59,000 N/A N/A 3.7

– 7.8 

### 8
Sulfate Precipitation 130,000 N/A N/A 3.7

– 8.2 64 ; 72

Lime

- soda 130,000 N/A N/A 14 72

Modified Lime

- soda 130,000 N/A N/A 1.5

– 8.2 64 ; 72

Unknown 100,000 4,000 10

– 30 5

– 15 70

N/A

— Not applicable ; mg/L

— milligrams per liter; bpd

— barrels per day; NaOH

— sodium hydroxide

. Note: Data in this table are as

- reported in literature.



### Energy Use

EPA has not quantified energy requirements for chemical precipitation

. E nergy is require d to operate low

- pressure pumps, mixers, equipment such as filter presses and any electrical monitoring devices.

1.2.3 Costs

Capital costs of chemical precipitation include costs for a precipitation tank

, mixing tanks, a settling tank (clarifier) and/ or filtration system, piping, low

- pressure pumps, and monitoring equipment. Advanced monitoring equipment may be necessary to improve system reliability

. In addition, using chemical precipitation will also req uire investment for wastewater storage to provide a relatively constant, homogeneous influent (e.g., impoundments, tanks) and sludge dewatering equipment.

The operating cost s associated with chemical precipitation include energy for low

pressure pumps and mixers, additive chemicals, and labor costs. O perating costs also depend on quality of influent wastewater, desired effluent quality of treated wastewater, and chemical cost s (which depend on the type and quantity of the additive chemical )

. The largest ope rating cost is typically the cost of the additive chemical.

Table B

- 8 shows approximate capital and operating cost s for purchased or rented chemical precipitation treatment systems, as reported in the literature

. Ta ble B

- 9 shows approximate costs UOG operators pay CWT facilities to treat UOG extraction wastewater using chemical precipitation. One CWT facility stated that when influent TDS concentrations are higher than 150,0 00 mg/L, they surcharge UOG operators to cover the increased chemical demand (DCN SGE00300).Part B



### 28 Table B

- 8 . Chemical Precipitation Capital and O&M Costs for UOG Extraction Wastewater Applications

Vendor and
Tech nology Name System

Description Cost

Basis Capacity

(MGD) Capital

Cost ($ per gpd) O&M Cost

($ per bbl) Rental or

Effective Cost ($ per bbl) a Reference

ID
Fountain Quail Water Management, LLC’s
Rover Mobile system Rental 0.29 NR < 1.00 2.00

– 4.00 81 ; 52

Not specified Plant Purchase 1.2 5.00 to 6.00 NR N/A 54 Not specified Plant Purchase 0.40 8.80 Not specified System Purchase or Rental NR NR 0.15

- 0.30 < 2.00 

### 8

Not specified Unit Purchase or Rental 0.022 21.00 NR 0.50

– 3.00 10

0.72 1.40

N/A

— Not applicable; NR

— Not reported ; MGD

— million gallons per day; gpd

— gallons per day; bbl

— barrels

.

a

— Represents rental cost if the cost basis was rental and is inclusive of O&M. Represents total effective cost when cost basis is purchase, which includes amortized capital costs and O&M costs combined. When the cost basis is purchased, total effective cost is provided only when a reference reported amortized capital costs.



### Ta ble B

- 9 . Chemical Precipitation Cost s to UOG Operator s at CWT Facilities

CWT Facility Name a Type of UOG Typical

Influent TDS (mg/L) Type of

Service Cost to UOG

Operator at CWT Facilities ($ per bbl) Reference

ID
Eureka Resources, LLC Shale gas 100,000 Reuse only 3.30 70
Clean Streams, LLC Shale gas 100,000 3.60 69
Reserved Environmental Services, LLC Shale gas NR 4.00 to 5.30 54 Hart Resource Technologies, Inc. Shale gas NR Discharge to surface water 2.20 

### 5
Pennsylvania Brine Treatment, Inc. Shale gas NR 2.30 

### 5

NR

— Not reported; mg/L

— milligrams per liter; bbl

— barrels

a

— All facilities listed are located in the Appalachian Basin where Marcellus and Utica gas are produced.

Note: Data in this table are as

- reported in literature.



### 1.2.4 Summary of Vendors for UOG Extraction Wastewater

Table B

- 10 lists vendors that offer chemical precipitation treatment systems designed specifically for UOG extraction wastewater

.Part B



### 29 Table B

- 10

. Chemical Prec ipitation Technology Vendors for UOG Extraction W astewater

Vendor Technology Name System Description Surface

Footprint (ft 2 ) a Capacity ( bpd) Reference
ID
Fountain Quail Water Management, LLC Rover Mobile system 1,100 10,000 81

AquaTech International Corporation MoTreat Mobile system Unit fits on mobile trailer 1,700

– 6,900 98

MI

- SWACO Frac Water Reclamation System Mobile system NR 3,000 141

NR

— Not reported; ft 2

— square feet; bpd

— barrels per day.

a

— Only includes the primary treatment unit

, not storage for wastewater, chemicals, or sludge ( solid waste ).



### 1.3 Electrocoagulation

Electrocoagulation is used to remove suspended solids, metals, microbial contaminants

, and colloids (organic and inorganic) in UOG extraction wastewater (DCN SGE00358; DCN SGE00638.A12; DCN SGE 00653 ). It does not remove TDS (sodium chloride or other salts)

. Instead of using chemical additives to facilitate removal of constituents (as in chemical precipitation), electrocoagulation uses electrical current. Because it is able to reduce microbial contaminants, oils, suspended solids, and metals, this technology is primarily used to treat UOG extraction wastewater prior to reuse and as pretreatment before TDS removal treatment technologies.

This section describes the electrocoagulation process, treatment capabilities and limitations, treatment cost, and vendors that the EPA is currently aware of that market the technology for UOG extraction wastewater treatment

.

1.3.1 How Electrocoagulation Works

This subsection describes electrocoagulation operating principles and how the process has been used to treat UOG extraction wastewater.

Principle

Electrocoagulation uses electrical current to destabilize and precipitate suspended, emulsified, or dissolved contaminants (as compared to chemical precipitation, which uses chemical additives). The particulates are then removed by settling, flotation, and/or filtration.

In a typical reactor, wastewater passes between pairs of electrode plates (usually aluminum or iron). One electrode is the anode and the other electrode is the cathode. Figure B

- 6 shows a simplified set up of an electrocoagulation reactor with aluminum electrodes and a constituent (B) in the wastewater. The reactions depicted in Figure B

- 6 are described below (DCN SGE 00653 ):

1. At the anode, the electrical current creates metal ions, freeing them from the surface of the electrode. This reaction is shown in Equation 2

.Part B



### 30 2. At the cathode, the electrolysis of water forms hydrogen and hydroxyl radicals. This reaction is shown in Equation 3

. 3. Some of the hydroxyl radicals react with the metal ions to form metal hydroxides (coagulants). This reaction is shown in Equation 4

. 4. The metal hydroxides formed in step 3 react with constituent B causing it to destabilize and precipitate. This reaction is shown in Equation 5

. 5. Some of the hydroxyl radicals formed in step 2 skip step 3, reacting directly with constituent B to destabilize it causing it to precipitate. This reaction is shown in Equation 6

.

Equation 2 (anode)

Equation 3 (cathode)

Equation 4 (in solution)

Equation 5 (in solution)

Equation 6 (in solution)Part B



### 31 Figure B

- 6 . Principle of Electrocoagulation

The remaining steps in electrocoagulation treatment are the same as in chemical precipitation (described in Part B.1.1 ). Constituents are attracted to hydroxyl radicals and metal hydroxides (e.g., Al(OH) 3 

### ), which cause them to become destabilize d colloids. The colloids are dense enough to be separated from the wastewater by settling or a mechanical method (e.g., induced gas flotation or mechanical skimmer). The hydrogen gas produced during the hydrolysis reaction (step 2 above) assists in raising coagulated particles to the surface of the wastewater (DCN SGE 00653 ).

Process Description

One UOG operator that uses electrocoagulation treatment systems described a typical

process at their own CWT facility , shown in Figure B

- 7 (DCN SGE00638.A12).

1. Influent waste water enters the main electrocoagulation reactor where targeted constituents are destabilized, coagulated, and precipitated.

2. Wastewater flows to a weir tank where precipitated particles are removed, either by gas flotation or settling.

3. The sludge from the weir tank is dewatered, creating solid waste.

4. The water from the weir tank and the decant water from the dewatering unit are filtered using a media filter (e.g., carbon filters, crushed glass) to further reduce suspended solids.Part B



### 32 Source: Adapted from SG E00638. A 12.



### Figure B

- 7 . Flow Diagram of Electrocoagulation

1.3.2 Capabilities and Limitations

Th is subsection describe s the targeted constituents and effectiveness, design and operation considerations, residuals, and energy use of electrocoagulation

.
Targeted Constituent

s and Treatment Effectiveness

Electrocoagulation removes hardness, suspended solids, metals, and colloids (organic and inorganic) (DC N SGE 00653 ). In electrocoagulation, TDS concentrations are only slightly reduced, if at all. This is because electrocoagulation does not destabilize or precipitate sodium or chloride, which are the primary dissolved ions that make up TDS in UOG extraction wastewater (see Part A.1 ). UOG operators use electrocoagulation to remove targeted constituents that interfere with fracturing additives or cause formation damage a nd fouling and scaling down the well bore. The specific metals removed depend on the electrode material (e.g., iron, aluminum) and pH.Part B



### 33 Table B

- 11 shows specific influe nt and effluent concentrations from electrocoagulation treatment of UOG extraction wastewater. The data shows how some of the multivalent cations are reduced in addition to sulfate reducing bacteria and suspended solids. Because electrocoagulation removes some dissolved constituents , TDS concentrations are slightly reduced. E lectrocoagulation has been used to treat UOG extraction wastewater with TDS concentrations up to 300 ,000 mg/L with no adverse effect on operation (DCN SGE 00638.A11 ).

Table B

- 11 . Electrocoagulation Removal Efficiency in UOG Extraction Wastewater Applications

Constituent Typical Influent Range (mg/L) Typical Effluent Range (mg/L) Removal Efficiency

(%) a,b Reference ID

TDS 39,000

– 270,000 27,000

– 270,000

– 2 to +31 113 ; 119

Chloride 17,000

– 160,000 13,000

– 160,000

– 1 to +26 77 ; 113 ; 119

Sodium 4,300

– 70,000 4,200

– 76,000

– 7 to +42 77 ; 113 ; 119

Metals

Aluminum 1.4 2.3

– 60 c 119

Barium 5

– 1,300 1

– 740 10

– >99 77 ; 113 ; 119

Boron 20

– 71 17

– 66 7

– 18 77 ; 119

Calcium 440

– 29,000 39

– 29,000 1

– 92 77 ; 113 ; 119

Chromium 0.06 0.05 9 77

Iron 18

– 160 ND

– 1 >92 77 ; 113 ; 119

Lead 0.020 0.015 33 77 Magnesium 37

– 4,300 17

– 3,100 22

– 85 77 ; 113 ; 119
Manganese 4.2 0.075 98 77

Potassium 35

– 1,700 31

– 1,700

– 2 to +15 77 ; 113 ; 119

Strontium 75

– 2,200 24

– 2,000 3

– 79 77 ; 113 ; 119
Organics

Benzene 0.13 0.04 72 77

BTEX 3,500 3 >99 77

TOC 610 600 3 77

Toluene 0.03 0.01 55 77 TPH (all ranges) 4

– 54 ND

– 6 59

– 92 77 ; 119Part B



### 34 Table B

- 11 . Electrocoagulation Removal Efficiency in UOG Extraction Wastewater Applications

Constituent Typical Influent Range (mg/L) Typical Effluent Range (mg/L) Removal Efficiency

(%) a,b Reference ID

Other
Alkalinity 710 580 18 77

BOD 100

– 26,000 81

– 210 20

– >99 77

Hardness 1,300

– 63,000 700

– 42,000 6

– 47 77 ; 113

Silica 17

– 66 0.27

– 13 80

– 99 77
SRB (cfu/100 mL) 1,200

– 450,000 200

– 4,200 84

– >99 77

Sulfates 28

– 410 13

– 88 5

– 79 113 ; 119

TSS 40

– 10,000 6

– 300 15

– 99 77 ; 113
Turbidity 180 15 92 119

ND

— Not detected; mg/L

— milligrams per liter; TDS

— total dissolved solids; BTEX

— benzene, toluene, ethylbenzene, and xylenes; TOC

— total organic carbon; TPH

— total petroleum hydrocarbons; BOD

— bioc hemical oxygen demand; SRB

— sulfate reducing bacteria; TSS

— total suspended solids.

a

— The EPA calculated all removal efficiencies using paired influent and effluent concentrations reported in literature. Attachment 1 ( DCN SGE00692.A01 ) presents these removal efficiency calculations. The number of data points that these removal efficiencies are based on are also presented in Attachment 1.

b

— Occasionally, literature reported higher constituent concentrations after treatment than before treatment. These instance s are indicated by negative removal efficiencies

. The following are potential reasons for these negative values: inaccuracy of reported paired influent and effluent samples , addition of chemicals, or the technology does not remove the constituent.



### Design and Operation Considerations for UOG Extraction Wastewater

Electrocoagulation treatment systems, as shown in Figure B

- 7 above, can be configured to fit inside one to t hree trailers (depending on the vendor), not including storage for influent and treated wastewater. One UOG operator described a typical set up with a maximum treatment rate of 60,000 barrels (2,520,000 gallons) per month, consisting of the following units (DCN SGE00638.A12):

 Two trailers containing the electrocoagulation unit, filtration unit, and weir tank.

 Solid waste bin (trailer size).

 Multiple 500 barrel (210,000 gallon) fracturing tanks for untreated and treated wastewater, or an impoundment. 18



### Some v endors offer electrocoagulation units able to treat wastewater at rates up to 20 barrels (840 gallons) per minute (see Part B.1.3.4 ). By using multiple treatment units in parallel, it is possible to treat wastewater on

- the

- fly with hydraulic fracturing (DCN SGE00638.A11). On

the

- fly treatment allows the UOG operator to re duce other costs, such as trucking and wastewater storage. These advantages are discussed in detail in Part B.1.4.2 . Although these treatment rates

18 The number of 500 barrel fracturing tanks was not reported, but varies depending on the treatment rate and ability to move wastewater to and from the site (Bosque, 2013).Part B



### 35 are higher than most other UOG extraction wastewater treatment technologies, they are still much lower than AOP rates, which can reach 80 barrels (3,360 gallons) per minute in mobile applications. As a result, data available to the EPA indicates that electrocoagulation i s not as frequently used on

- the

- fly with hydraulic fracturing as AOP.

Electrocoagulation does not require the purchase of chemical additives for precipitation. However, the electrodes in the main reactor must be periodically replaced, as metal ions are

con sumed by the electrochemical reactions. One vendor estimated approximately 500 pounds of anode material are required for every 100,000 barrels of UOG extraction wastewater treated (DCN SGE00638.A11).

Residuals

Electrocoagulation generates a sludge stream t hat is usually dewatered to form solid waste. However, electrocoagulation generates less waste than conventional chemical precipitation because no chemicals are added to the system, other than metal that dissolves from the anode (DCN SGE00638.A11; DCN SGE 0 0311.A 0 1 ; DCN SGE 00653 ). One vendor estimated that the total volume of residual waste generated in UOG applications is less than five percent of the influent wastewater volume, compared to 20 percent for conventional chemical precipitation (DCN SGE 00311.A 0 1 ; DCN SGE00638.A11).

Most treatment operators haul the dewatered solids (sludge) to a landfill for disposal

. Depending on the state and applicable permits, the operator may be required to screen the waste stream for radioactivity prior to transport to lan dfills (DCN SGE 00299 ; DCN SGE 00300 ; DCN SGE 00245). The radioactivity of the waste correlates to the radioactive constituents in the untreated UOG extraction wastewater, and varies by location (DCN SGE00704). Furthermore, the level of radioactivity in the s olid waste is dependent on the constituents removed from the wastewater. For example, one UOG operator reported they purposely do not remove barium or strontium in order to prevent precipitation of radioactive constituents, which typically co

precipitate w ith barium and strontium (DCN SGE00638.A12).

Energy Use

Electrocoagulation treatment units require electricity to operate pumps and to apply electrical current through the wastewater. Units specifically designed to treat UOG extraction wastewater typicall y include a diesel generator for locations where connection to the electrical grid is not possible (DCN SGE 00638.A11 ).

Table B

- 12 reports energy use per barrel of in fluent wastewater specific to UOG applications. The EPA expects t ypical energy consumption to be more than conventional chemical precipitation, but less than TDS removal treatment technologies.Part B



### 36 Table B

- 12

. Electrocoagulation Energy Use in UOG Extraction Wastewater Applications

Vendor Technology Name Influent TDS concentration (mg/L) Energy Use (kWh per bbl) Reference

ID OriginOil® Clean

- FracTM NR 0.84 124
Not specified Not specified 40,000 >0.25 110

NR

— Not reported; mg/L

— milligrams per liter; kWh per bbl

— kilowatt

- hours per barrel.



### 1.3.3 Costs

Capital costs of electrocoagulation include co sts for the primary treatment unit, settling tank, filtration system, piping, low

- pressure pumps, and monitoring equipment. The operating

cost s associated with electrocoagulation include energy for low

- pressure pumps and mixers, periodic electrode replacement , and labor (DCN SGE00638.A12; DCN SGE00638.A11)

. Table
B

- 13 shows approximate capital and operating cost s for electrocoagulation when a treatment system is purchased or rented (as reported in the referenced litera ture)

.

Table B

- 13

. Electrocoagulation Capital and O&M Costs for UOG Extraction Wastewater Applications

Vendor and Technology Name System

Description b Cost

Basis Capacity

(MGD) Capital

Cost ($ per gpd) O& M Cost

($ per bbl) Rental or

Effective Cost ($ per bbl) a Reference

ID Not specified Mobile system Purchase 0.063 12.00 NR NR 110 Not specified System Purchase 0.10 4.00 0.25 NR 113 Not specified System Purchase 0.14 4.20 0.25 NR 113

Not specified System at

centralized facility Purchase

or Rental 0.082 1.20 1.80

– 2.80 1.90

– 3.10 96

Halliburton CleanWaveTM Mobile system Rental 1.0 NR 1.50 1.00

– 3.00 74 ; 95

OriginOil CleanFracTM Mobile system Rental NR NR 0.52

– 1.10 NR 124

NR

— Not reported ; MGD

— million gallons per day; gpd

— gallons per day; bbl

— barrel

.

a

— Represents rental cost if the cost basis was rental and is inclusive of O&M. Represents total effective cost when cost basis is purchase, which includes amortized capital costs and O&M costs combined. When the cost basis is purchased, total effect cost is only included when a reference reported amortized capital costs.

b

— All systems include pre

- and post

- treatmen t (e.g., filtration, sludge dewater).



### 1.3.4 Summary of Vendors for UOG Extraction Wastewater

Table B

- 14 presents information on electrocoagulation units from vendors that the EPA is currently aware of that are producing and selling units specifically for treating UOG extraction

wastewater

. All of these systems can be trailer

- mounted or installed permanently. Because these technologies can be used on

- the

- fly with fracturing, capacity is also presented in barrels per minute.Part B



### 37 Table B

- 14

. Electrocoagulation Technology Vendors for UOG Extraction W astewater

Vendor Technology Name Surface Footprint (ft 2 ) a Capacity

( bpd ) Capacity

(bpm) b Reference

ID

OriginOil, Inc. EWSTM Petro P160 Fits into a 40 foot shipping container 7,200 5 124 ; 123

Ecolotron, Inc. E

- Floc© 500 11,000 7.5 77 Halliburton Company CleanWaveTM NR 29,000 20 74 ; 95

Bosque Systems, LLC Mobile Water Recycler 500 21,000 14 108

Baker Hughes, Inc. H2proTM Trailer mounted 8,500 6 107

NR

— Not reported ; ft 2

— square feet; bpd

— barrels per day; bpm

—

barrels per minute

.

a

— Only includes the primary treatment unit

, not storage for wastewater, chemicals, or sludge ( solid waste ).

b

— For comparison, a typical fracturing job will inject fracturing fluid at approximately 60 to 120 barrels per minute.



### 1.4 Advanced Oxidation and Precipitation

Advanced oxidation and precipitation (AOP) is a non

- TDS removal treatment technology that reduces mic robial constituents and destabilizes and precipitates multivalent cations in UOG extraction wastewater (DCN SGE00331; DCN SGE00616). UOG operators began using AOP for treatment prior to reuse in 2008 (DCN SGE00333). To date, the EPA has identified AOP used only in reuse applications. Most of these applications have been treatment on

- the

- fly with hydraulic fracturing, a concept that Part B.1.4.1 describes in detail ( DCN SGE00625; DCN SGE00705).

Destroying microbial constituents and destabilizing and precipitating multivalent cations in UOG extraction wastewater reduces the potential for scaling and biological growth inside the well (DCN SGE00705; DCN SGE 00331 ; DCN SG E00616; DCN SGE 00625 ). The fact that UOG operators use this technology suggests that, in some cases, microbial and scale control is all that is necessary for treatment prior to reuse (DCN SGE00616).

This section describes the AOP process, treatment capabi lities and limitations, treatment cost, and vendors that the EPA is currently aware of that market the technology for UOG extraction wastewater treatment

.

1.4.1 How Advanced Oxidation and Precipitation Works

This subsection describes AOP operating principles and how the process has been used to treat UOG extraction wastewater.

Principle

AOP generates highly reactive hydroxyl radicals (•OH) to oxidize targeted constituents. Hydroxyl radicals are produced in systems using processes including primary oxidants such as

ozone (O 3 

### ) , an energy source such as ultraviolet (UV) light, or catalysts such as titanium dioxide (DCN SGE 01048).Part B



### 38 Process Description

AOP for UOG extraction wastewater treatment includes the addition of ozone to kill bacteria and the generation of hydr oxyl radicals to destabilize targeted constituents and precipitate them out of the solution. The following sequence of processes occurs within an AOP treatment system (DCN SGE00705; DCN SGE 00331):

1. Wastewater enters static mixers that homogenize the wastewater and initiate hydro dynamic cavitation whereby the velocity of the wastewater is increased and the pressure is simultaneously decreased, resulting in the creation of small vapor cavities (i.e., bubbles). These cavities quickly collapse, releasing energy sufficient to cause water molecules to break down into hydroxyl radicals, which kill bacteria and oxidize target constituents.

2. Ozone (O 3 

### )

, created by oxygen separators and ozone generators

, is mixed w it h the wastewater in a flash reactor to kill bac teria. As residual ozone can potentially interfere with fracturing fluid chemicals, the treatment unit operator determines the appropriate dose of ozone by monitoring the oxidation reduction potential ( ORP ) in the UOG extraction wastewater.

3. The wastewater passes through an electrochemical oxidation unit, which uses electrical current to precipitate hardness and other target constituents and to convert water molecules into hydroxyl radicals to kill bacteria (see discussion of Electrocoagulation in Part B

. 1.3 below).

4. Next, the wastewater passes through ultrasonic transducers whic h generate sound waves with sufficient energy to initiate caustic cavitation to reduce the particle size of precipitated solids to less than one micron.

According to AOP vendors, precipitated solids in the treated wastewater are reduced to less than one micron in size so they do not cause scale or formation damage during fracturing and therefore do not need to be separated from the treated wastewater (DCN SGE00331; DCN SGE00705).

Operators most commonly use AOP to treat UOG extraction wastewater on

- the

- fly with hydraulic fracturing as shown in Figure B

- 8 19 

### . On

- the

- fly treatment is only possible because mobile AOP units are capable of treating wastewater at relatively high rates. 20 

### In on

- the

- fly treatment, other source water (e.g., fresh water, ground water) and the untreated wastewaters are mixed together for treatment by AOP. One vendor explaine d that mixing other source water with the untreated UOG extraction wastewater provides better consistency for treatment and hydraulic fracturing (DCN SGE00705). Although not shown in Figure B

- 8 , AOP typically requires pretreatment using bag filters to remove suspended solids (DCN SGE 00705).

19 UOG operators may store untreated wastewater in open pits or impoundments adjacent to well pad d epending on applicable regulations.

20 Treatment rates of 80 barrels per minute are typical for AOP treatment, but rates can be as high as 120 barrels per minute. For comparison, a typical fracturing job will inject fracturing fluid at approximately 60 to 1 20 barrels per minute. If needed, operators can use a second AOP system in parallel to meet the desired fracturing rate.Part B



### 39 Source: DCN SGE00705.



### Figure B

- 8 . Flow Diagram of AOP Treatment On

- the

- Fly with Hydraulic Fracturing in

UOG Extraction Wastewater Applications

Figure B

- 9 shows an alternative use of AOP in UOG extraction wastewater applications. Units can be dep loyed at existing impoundments construct ed at well sites to temporary store

wastewater

. 21 

### The treatment unit simply circulates the wastewater back into the impoundment after treatment. This use of AOP has many of the same advantages as on

- the

- fly (DCN SGE 00705). One additional advantage is that the AOP can operate continuously in this setup, whereas on

- the

- fly treatment requires periodic breaks while the fracturing job moves on to the next stage (DCN SGE 00705).

21 Applicable regulations for storing UOG extraction wastewater in open impoundments vary by state and sometimes even within states. For example, at the time of writing, in Pennsylvania within the jurisdiction of the Susquehanna River Basin Commission (SRBC) UOG extraction wastewater cannot be stored in open impoundments. However, outside of the SRBC, UOG extraction wastewater may be store d in open impoundments in Pennsylvania (DCN SGE00635).Part B



### 40 Source: DCN SGE00705.



### Figure B

- 9 . Flow Diagram of AOP Treatment at Wastewater Impoundments in UOG Extraction Wastewater Applications

1.4.2 Capabilities and Limitations

Th is subsection describe s the targeted constituents and effectiveness, design and

opera tion considerations, residuals, and energy use of AOP

.
Targeted Constituent

s and Treatment Effectiveness

UOG o perators use AOP for treatment prior to reuse because it focuses on microbial control and scale control , two parameters that UOG operators consider prior to reuse (DCN SGE 00331). Table B

- 15 shows specific influent and effluent concentrations from AOP treatment of UOG extraction wastewater from one vendor (Hydrozonix, LLC). Although AOP does not reduce TDS, the treatment also has no maximum limit on the influent TDS concentration

. For example, AOP has successfully treated extraction wastewater from the Woodford shale with a TDS concentratio n of 170,000 mg/L TDS (DCN SGE 00331).

Table B

- 15

. AOP Removal Efficiency in UOG Extraction wastewater Applications

Constituent Typical Influent Range (mg/L) Typical Effluent Range (mg/L) Removal Efficiency (% ) a Reference ID

Chlorides 18,000

– 19,000 17,000

– 19,000 0

– 2 147

Metals

Barium 56

– 290 42

– 250 12

– 25 147

Calcium 430

– 2,400 320

– 2,400 2

– 24 147

Iron 16

– 150 5.9

– 150 0

– 62 147
Magnesium 320

– 740 290

– 680 8

– 9 147

Other

Carbonate 4.5

– 92 2.8

– 58 37

– 38 147
Alkalinity 150

– 700 95

– 530 24

– 37 147Part B



### 41 Table B

- 15

. AOP Removal Efficiency in UOG Extraction wastewater Applications

Constituent Typical Influent Range (mg/L) Typical Effluent Range (mg/L) Removal Efficiency (% ) a Reference ID

Hardness 2,100

– 7,300 2,000

– 7,100 3

– 5 147

Calcium hardness 1,800

– 6,000 1,700

– 5,900 2

– 8 147
SRB (mpn/mL) 13,000

– 140,000 92

– 450 99

– 100 149

Sulfates 100

– 860 85

– 660 15

– 23 147 mg/L

— milligrams per liter; mpn/mL

— most probable number per milliliter; SRB

— sulfate reducing bacteria.

a

— The EPA calculated all removal efficiencies using paired influent and effluent concentrations reported in literature. Attachment 1 ( DCN SGE00692.A01 ) presents these removal efficiency calculations. The number of data points that these removal efficiencies are based on are also presented in Attachment 1.



### Data in Table B

- 15 confirm that the concentrations of many multivalent cations are not reduced using AOP . As explained in Part B.1.4.1 , AOP leaves the precipitated constituents suspended in the treated wastewater but reduces their size to less than 1 micron (DCN SGE00705)

. Results from UOG case studies (see Figure B

- 10 ) demonstrate how AOP is able to reduce scaling potential. This figure shows the results from dynamic tube block tests 22 

### of treated UOG extraction wastewater (red) and the a ssociated untreated UOG extraction wastewater (blue). The increase in pressure observed for the untreated UOG extraction wastewater indicates its higher potential to cause scale formation than the treated UOG extraction wastewater.

22 A dynamic tube block test is used by UOG operators to measure the scaling potential of a fluid. Operators use this test to determine the efficiency of chemical inhibitors that prevent scaling in the wellbore. This test measures the pressure change over time as a fluid (e.g., UOG extraction wastewater) flows through a tube apparatus. An increase in pressure indicates the buildup of scale within the apparatus. NACE International, The Corrosion Society, reports specific testing protocols in NACE 31105, Dynamic Scale Inhibitor Evaluation apparatus and Procedures in Oil and Gas Production

.Part B



### 42 psi

— pounds per square inch

Source: DCN SGE00705.



### Figure B

- 10 . AOP Performance in Reducing Scaling Potential in the Eagle Ford Shale Formation

Design and Operation Considerations for UOG Extraction Wastewater

AOP typically requir es bag filtration to reduce suspended solids prior to treatment, which AOP vendors may provide in an additional unit or UOG operators may provide (DCN
SGE 00264 ; DCN SGE00705 ). As residual ozone can potentially interfere with fracturing fluid chemicals, the treatment unit operator must carefully monitor ORP to determine the appropriate dose of ozone. Mixing untreated wastewater with source water provides a more consistent water quality for providing an appropriate ozone dosage without ozone residual (DCN SGE00705).

Residuals

The most recent AOP designs for UOG extraction wastewater applications do not generate solid or liquid waste streams (DCN SGE 00264 ; DCN SGE 00331 ). Instead of removing the precipitated constituents, their particle size is reduced to les s than 1 micron to mitigate the negative impacts of TSS in UOG extraction wastewater reuse (DCN SGE00705; DCN
SGE 00331 ).Part B



### 43 Energy Use

AOP treatment units designed for UOG extraction wastewater applications require electricity from an on

- site generator or fro m the electric grid, if available. Energy requirements to operate low

- pressure pumps, ozone generators, and mixers account for approximately 18 percent of the total operation and maintenance cost (DCN SGE 00264 ). One vendor reported specific energy consumpt ion of between 0.08 to 0.15 kWh per barrel of influent wastewater (DCN SGE 00 705).

1.4.3 Costs

Table B

- 16 shows approximate cost s for AOP when a treatment system is rented. The EPA did not identify any capital costs reported in the literature because available information indicates that UOG operators do not currently purchase AOP units. Even though they may not purchase the treatment units, UOG operators may still need to inv est in storage for influent and treated extraction wastewater, depending on how the treatment system is used. However, when this technology is used on

- the

- fly with hydraulic fracturing, additional investment in storage is not necessary beyond that already required for reusing UOG extraction wastewater in hydraulic fracturing.

Table B

- 16

. AOP Rental Costs for UOG Extraction Applications

Vendor and Technology Name System

Description Capacity (MGD) Rental Cost ($/bbl) a Reference ID

Hydrozonix, LLC Mobile system 4.8 0.50

– 0.75 147

EcoSphere OzonixTM Mobile system 4.8 0.60

– 1.30 75 ; 99

MGD

— million gallons per day; bbl

— barrel.

a

— Represents rental cost and is inclusi ve of O&M.



### 1.4.4 Summary of Vendors for UOG Extraction Wastewater

Vendors that offer AOP to UOG operators treat UOG extraction wastewater on a contract basis, mostly long

- term. The approximate number of wells completed using AOP in several formations are noted below 23 

### (DCN SGE 00298.A23 ; DCN SGE00305.A07; DCN SGE 00625 ; DCN SGE00616; DCN SGE00705; DCN SGE00331 ; DCN SGE00706):

 Woodford (s hale oil and gas): 200 wells

 Eagle Ford (shale oil and gas): 7 wells

 Fayetteville (shale gas): 120 wells

 Marcellus (sh ale gas): 9 wells

 Permian (shale oil and gas and tight oil and gas): 430 wells

23 This only includes deployments reported by Eco sphere Energy Services, Inc and Hydrozonix, LLC.Part B



### 44 Table B

- 17 shows vendors that offer treatment systems designed specifically for UOG extraction was tewater. Because this technology is often used on

- the

- fly with hydraulic fracturing, capacity is also presented in barrels per minute. Treatment rates as high as 120 barrels per minute are possible, but with reduced treatment effectiveness. One vendor repo rted a typical flow rate of 8 0 barrels per minute to keep up with most fracturing jobs (DCN SGE00705).

Table B

- 17

. AOP Technology Vendors for UOG Extraction W astewater

Vendor Technology

Name Surface

Footprint (ft 2 ) a Capacity (bpd) Capacity (bpm) b Reference
ID Hydrozonix, LLC OzonixTM 1 unit fits on a 53 foot trailer 120,000 80 147

Ecosphere Technologies,
Inc. OzonixTM 1 unit fits on a 53 foot trailer 120,000 80 75 ; 99

ft 2

— square feet; bpd

—

barrels per day; bpm

— barrels per minute.

a

— Only includes th e primary treatment unit . One or two additional small trailers may be required for generators and miscellaneous equipment. Because this technology is typically used on

- the

- fly with hydraulic fracturing, there is no additional equipment required such as untreated and treated wastewater storage. The UOG operator must already have sufficient storage onsite for the fracturing job regardless of whether treatment is conducted on

- the

- fly or not.

b

— For comparison, a typical fracturing job will inject fracturing fluid at approximately 60 to 120 barrels per minute.



### 1.5 Disinfection

Disinfection is a non

- TDS removal treatment technology that destroys harmful bacteria and is used to treat freshwater, flowback, and produced water before they are used to make up fracturing fluids. Bacteria of concern in oil and gas extraction operations include bacteria that thrive in the low oxygen, anaerobic environments of the formation, chiefly sulfate reducing bacteria (SRB) and certain types of acid

- forming bacteria (AFB). A lso of concern are bacteria that live in higher oxygen, aerobic environments on the surface and in the wellbore, including slime

- forming bacteria (SFB) and other types of AFB. Growth of SRB leads to generation of toxic hydrogen sulfide gas, which is a heal th and safety concern and may contribute to corrosion and formation damage. AFB and SFB may also impair oil and gas production (DCN SGE01118 ). Aerobic bacteria can degrade some fracturing fluid components (DCN SGE01119 ).

Biocides, chemicals intended to ki ll microbes, are a type of disinfectant added to fracturing fluid to inhibit bacterial growth and reduce the generation of hydrogen sulfide and to preserve the gelling agent integrity (DCN SGE00704). Commonly used biocides include quaternary ammonium compo unds, aldehydes (e.g., glutaraldehyde), bronopol, and others. Tischler et al. (DCN SGE01118) note that limitations to using biocides in fracturing fluid include environmental toxicity, limited effectiveness in the pH and temperatures found in UOG wells,

an d high cost. Also, bacteria may become resistant to long half

- life biocides, a particular concern when flowback is reused (DCN SGE01118).

Because of limitations to using biocide in fracturing fluid, operators use disinfection processes to reduce the conce ntrations of aerobic and anaerobic bacteria in make

- up water. Disinfection reduces the potential for scaling, hydrogen sulfide souring, corrosion, plugging, andPart B



### 45 emulsion problems (DCN SGE01034; DCN SGE01035). I n some cases, microbial and scale control is a ll that is necessary for treatment prior to reuse (DCN SGE00616). However, the level of treatment required for wastewater reuse varies depending on UOG formation, type of fracturing fluid design (e.g., gel, slickwater), and UOG operator preference (DCN SGE 00704).

Disinfection is accomplished using physical agents, chemical agents, or combinations of the two. The chief physical agent used to disinfect UOG wastewater is UV light, which at the appropriate wavelength and intensity will kill bacteria. Chemical a gents used in treating UOG wastewater are chiefly chlorine

- containing chemicals such as calcium

- and sodium hypochlorite and chlorine dioxide. Ozone is another chemical d isinfect ant. Ozone disinfection is a part of AOP where ozone is generated to kill bac teria and hydroxyl radicals are generated to destabilize and precipitate targeted constituents. See Part B.1.4 for more information on AOP.

Additional treatment pro cesses may be needed for effective disinfection. Aeration with sedimentation reduces the wastewater organic load, thus reducing the bacterial food supply, which drastically reduces bacterial population and makes effective disinfection easier. Also, aeratio n facilitates oxidation of reduced compounds which decreases chlorine demand, resulting in lower costs of chlorination disinfection (DCN SGE01118). The effectiveness of UV light for disinfection is dependent on how well the UV light penetrates the water to be treated. Because turbidity and TSS can impair UV effectiveness (DCN SGE01119), electro

- coagulation (EC) pretreatment that removes TSS can improve UV disinfection performance (DCN SGE01120).

This section describes the disinfection process, treatment ca pabilities and limitations, treatment costs, and vendors that EPA is currently aware of that market the technology for UOG extraction wastewater treatment. Because UV disinfection and chemical disinfection differ in a number of ways, they will be discussed separately throughout the remainder of this section.

How Disinfection Works

This subsection describes disinfection operating principles and how the process has been used to treat UOG extraction wastewater.

Principle s

Disinfection inactivate s bacteria in wastewater

. UV light absorbed by a microbe damages the DNA and/or RNA and renders the microbe non

- viable (DCN SGE01034). The damaged microbe can no longer reproduce (DCN SGE01041). The optimal wavelength of UV light to damage a microbe is approximately 254 nm (DCN SGE01033).

Hypochlorites (calcium hypochlorite (Ca(OCl) 2 

### ) or sodium hypochlorite (NaOCl)) dissociate to hypochlorous acid in water. This acid may kill bacteria through metabolic dysfunction or through DNA replication inhibition (DCN SGE01118). Ch lorine dioxide (ClO 2 

### ) is a strong oxidizer, highly reactive with certain amino acids, resulting in the destruction of cellular components (DCN SGE01118). In general, the mechanism of inactivation depends on the chemical disinfectant used. Non

- oxidizing che micals disrupt metabolic processes and are effective when microbes are active whereas oxidizing chemicals kill microbes by disrupting the flow of nutrients across the cell and are effective whether the microbe is active or dormant (DCN SGE01037).Part B



### 46 Disinfec tion effectiveness depends on the intensity of the UV light or the concentration of the disinfectant chemical, the time of exposure, and interfering substances (e.g., turbidity, TSS, organic material) in the wastewater.

Process Description

Operators may use disinfection to treat UOG extraction wastewater at centralized

treatment facilities (DCN SGE01118). Operators also treat water as it is placed into storage tanks at the fracturing location. Because bacteria may regrow while the water is stored, operat ors increasingly treat water on

- the

- fly as it flows from the storage tanks to the fracturing blender (DCN SGE01119). On

- the

- fly treatment is described in Part B.1.4.1 ( Figure B

- 8 ) (DCN SGE01058).

On

- the

- fly treatment requires mobile disinfection units capable of treating wastewater at relatively high rates. For example, one vendor described a mobile UV treatment unit that can disinfect wastewater at a rate of 50 to 75 bbl/min (DCN SGE01120 ). In on

- the

- fly treatment, other source water (e.g., fresh water, ground water) and the untreated wastewaters may be mixed together prior to treatment by disinfection to provide better consistency in the base fluid for hydraulic fracturing (DCN SGE00705).

Capabilities and Limitations

This subsection describes the targeted constituents and effectiveness, design a nd operation considerations, residuals, and energy use of disinfection

.
Targeted Constituents and Treatment Effectiveness

Disinfection controls bacteria of concern in oil and gas extraction operations including SRB, AFB, and SFB (DCN SGE 01 118 ).

The effica cy of UV disinfection is dependent on the wastewater flow rate, UV intensity, and ability of the wastewater to allow light to pass through (the transmittance level) (DCN SGE01033). The transmittance level is impacted by TDS, the microbial concentration,

s uspended solids, humic acids, and minerals . Pr etreatment may be needed to remove these constituents (DCN SGE01033). Vendors have demonstrated UV treatment effective at inactivating 96

– 100% of SRB present in UOG extraction wastewater of varying quality (D CN SGE00638.A11; DCN SGE01042; DCN SGE01057).

The efficacy of hypochlorite disinfection depends on dose, contact time, and the wastewater concentration of chlorine

- consuming materials such as ammonia, organic debris, soluble iron (chlorine demand). Hypoch lorite is extremely effective in killing bacteria once chlorine demand has been satisfied (DCN SGE01118 ). ClO 2 

### is also a potent disinfectant, and is less reactive with ammonia and organic material. Because it is unstable, ClO 2 

### must be generated at the poin t of use. One vendor demonstrated ClO 2 

### treatment effective at inactivating 100% of SRB present in UOG extraction wastewater (DCN SGE01059).Part B



### 47 Design and Operation Considerations for UOG Extraction Wastewater

An advantage of UV disinfection is that it does not require the addition of chemicals. However, while biocides leave a disinfection residual that continues to kill microbes after treatment, UV disinfection only kills microbes during treatment (DCN SGE01033). In order to prevent re

- growth of bacteria aft er UV disinfection, chemical biocides may be added. However, because UV disinfection is commonly performed on

- the

- fly with hydraulic fracturing such that treated wastewater is immediately used in fracturing, chemical biocide addition may not be needed (DCN SGE01058).

Advantages of hypochlorite disinfection are that it is relatively inexpensive, extremely effective in killing bacteria once chlorine demand is satisfied, and it leaves a chlorine residual that helps to minimize recontamination (DCN SGE01118). A dvantages of ClO 2 

### disinfection are that it is a potent disinfectant and oxidizer and may facilitate other wastewater treatment processes such as emulsion breaking, sedimentation, and oil/water separation (DCN SGE01118). Also, unlike hypochlorite, ClO 2 

### does n’t react with ammonia and most organics and it is less corrosive (DCN SGE01121).

Residuals

Disinfection is not a separation process, that is, it is not designed to remove microbes from wastewater. Instead, light or chemicals are added to the wastewater to inactivate bacteria. For this reason, disinfection generates minimum amount of treatment re siduals. UV disinfection can result in the formation of salt (DCN SGE01058). In some cases, chlorine dioxide reacts with iron forming a precipitate that can be removed by processes such as flocculation and sedimentation ( DCN SGE01046.A02). However, disinf ection vendors for UOG applications appear to design their treatment units to operate in a way that does not result in a residual waste generation.

Energy Use

Both UV and chlorine dioxide disinfection systems designed for UOG extraction wastewater applicat ions require electricity from an on

- site generator or from the electric grid, if available. For UV disinfection, Halliburton’s CleanStream ® 

### system requires a generator prime power rating of 160 kW (DCN SGE01058).

Costs

The EPA did not identify any costs re ported in the literature for disinfection treatment specific to UOG applications.

Summary of Vendors for UOG Extraction Wastewater

Vendors that offer disinfection to UOG operators treat UOG extraction wastewater mostly on a contract basis.

Table B

- 18 presents information on disinfection units from vendors that the EPA is currently aware of that are producing and selling units specifically for treating UOG extractionPart B



### 48 wastewater. All of these systems can be trailer

- mounted or installed permanently. Because these technologies can be used on

- the

- fly with fracturing, capacity is also presented in barrels per minute.

Table B

- 18 . Disinfection Technology Vendors for UOG Extraction Wastewater

Vendor Technology

Name Type of

Disinfection Surface

Footprint (ft 2 ) a Capacity

( bpd ) Capacity

( bpm ) b Reference

ID

Halliburton CleanStream ® UV 380 170,000 120 181
Atg UV Technology NA UV NA 180,000 130 178

Bosque Systems
LLC DIONIXTM ClO 2 30 foot trailer 720,000 500 162

PureLine CG and Pure 3

Series c ClO 2 700 c 7, 500 5.2 172

Sabre Energy Services DiKlor ® and

CHEMGEN ClO 2 NA 160,0 00 110 182

Baker Hughes H2prO HD ClO 2 NA 8,500 5.9 107

NA

– Not available; ft 2

— square feet; bpd

— barrels per day; bpm

– barrels per minute; UV

— ultraviolet; ClO 2 — chlorine dioxide.

a

— Only includes the primary treatment unit, not storage for wastewater, chemicals, or sludge (solid waste).

b

— For comparison, a typical fracturing job will inject fracturing fluid at approximately 60 to 120 barrels per minute.

c

— This footprint is for the entire coagulation, flocculation, sedi mentation system. The CG and Pure 3 Series generators are much smaller (footprint of approximately 10 ft 2 ).



### 2 TDS R EMOVAL 

### T REATMENT 

### T ECHNOLOGIES



### TDS removal technologies are typically used to treat UOG extraction wastewater at CWT facilities. The treated wastewater is typically reused in fracturing, reuse d in other oil and gas extraction activities, discharge d to POTW s, or discharged to surface waters (from CWT facilities)

. UOG industry use of TDS removal technologies has increased since UOG extraction began ramping up in the late 2000’s (DCN SGE 00596 ). The EPA identified three TDS removal technologies currently used by UOG operators and CWT faci lities:

 Evaporation followed by c ondensation (evaporation/condensation)

 Crystallization

 Reverse osmosis (RO)

When evaluating TDS removal treatment technologies , facilities consider not only costs and constituent removals, but also the “ treated wastewater r ecovery percentage ” . The treated wastewater recovery percentage is defined as the treated wastewater volume divided by the t otal influent wastewater volume (see Equation 7 ). The volume that is not recovered as treated wastewater is vented to the atmosphere or converted to concentrated brine and/or solid waste that must be managed at additional cost. Each TDS removal technology has a range of influent TDS concentrations at which the technology will perform optimally. At the maximum influent TDSPart B



### 49 concentration for each technology, treated wastewater recovery is lowest. As a result, as treated wastewater recovery percentage decreases, within the applicable ra nge, the overall performance of the technology also decreases.

Equation 7

Figure B

- 11 plots general ranges of costs associated with the three TDS removal technologies versus influent TDS concentrations. For comparison, this figure also shows the general range of TDS concentrations found in flowback and long

- term produced water. 24 

### Though treatment costs generally increase as TDS increases, Figure B

- 11 rep resents each technology in the shape of a rectangle to illustrate that costs vary with other factors as well (e.g., residual waste disposal cost, availability of energy).

RO

— reverse osmosis



### Figure B

- 11 . Cos t of TDS Removal Treatment Technologies versus Influent TDS

24 The range of TDS concentrations found in flowback and long

- term produced water are from the EPA’s Technical Development Document for Proposed Effluent Limitations Guidelines and Standards for Oil and Gas Extraction (DCN SGE00704). The reported range represents the 25 th to 75 th percentiles of TDS concentrations for flowback and long

- term produced water.Part B



### 50 2.1 Evaporation/Condensation

Evaporation/condensation is the most commonly used TDS removal technology, converting high TDS wastewater into distilled water (low TDS) and concentrated brine (high TDS). Evaporation/condensation may be used when v ery low TDS treated water is desired (e.g., to meet requirements at CWT facilities discharging to surface waters or POTWs) (DCN
SGE00167 ) or to reduce the volume of wastewater (brine) for transport and/or disposal (e.g., in the Marcellus where disposal costs are high because of a lack of disposal wells) (DCN
SGE 00300 ; DCN SGE 00264 ; DCN SGE00625; DCN SGE 00478)

.

This section describes the ev aporation/condensation process, treatment capabilities and limitations, treatment cost, and vendors that the EPA is currently aware of that market the technology for UOG extraction wastewater treatment

.

2.1.1 How Evaporation/Condensation Works

This subsection de scribes evaporation/condensation operating principles and how the process has been used to treat UOG extraction wastewater.

Principle

The evaporation/condensation treatment process removes water from wastewater through evaporation (converting liquid to vap or) , reducing the wastewater volume and concentrating wastewater constituents such as TDS in the resulting brine

. 25 

### The evaporated water vapor is either vented to the atmosphere or condensed as clean distillate/condensate. As evaporation continues, the cons tituents in the brine become increasingly concentrated . When constituent concentrations reach the ir solubility limits, dissolved material will precipitate out of the concentrated stream (which is not desired for normal operation).

Evaporation/condensation technologies differ in the method used for evaporation. Factors used to increase the rate of evaporation for wastewater treatment are listed below:

 Pressure

– As atmospheric pressure decreases, the rate of evaporation increases.
T his can be accomplished by technologies operated under vacuum.

 Temperature

– As temperature increases, the rate of evaporation increases. This can be accomplished using technologies that apply heat to wastewater.

 Surface area

– As the surface area of the w ater that is in contact with the air increases, the rate of evaporation increases. This can be accomplished by spraying the waste water into droplets.

 Air movement

– As the flow rate of air at the liquid surface increases, the rate of evaporation increases. This can be accomplished using fans to push or pull air through the unit.

25 Some constituent s, such as solvents and light hydrocarbons , may evaporate along with the water vapor. These may pass through the treatment or be recovered using a hydrocarbon recovery unit. Part B.2.1.2 provides more information on this limitation of evaporation/con densation.Part B



### 51 Figure B

- 12 is a flow diagram of evaporation/ condensation used for wastewater treatment. The diagram shows vapor and atmospheric pressures, using arrows to show that pressures are forces with directions. Vapor pressure is the force exerted by the water on the atmosphere and the atmospheric pressure i s the force exerted by the atmosphere on the water. In the process depicted in the figure, adding heat increases the vapor pressure, thus causing evaporation. There are other ways to cause vapor pressure to be greater than atmospheric pressure, which are e xplained later in this sub section. The following steps are shown in the flow diagram.

1. Heat is added to the influent wastewater to increase the vapor pressure (P vap 

### ) at the surface.

2. The liquid water vapor pressure (P vap 

### ) becomes greater than atmospheric pre ssure (P atm 

### )

, allowing the liquid water to evaporate into the vapor state (illustrated by the fact that the P vap 

### arrow is larger than the P atm 

### arrow).

3. The vapor comes into contact with a cool surface. As a result, the liquid water vapor pressure (P vap 

### ) de creases and becomes l ower than atmospheric pressure (P atm 

### ), allowing the water vapor to condense into the liquid state (illustrated by the fact that the P atm 

### arrow is larger than the P vap 

### arrow).

4. The condensate, or treated wastewater, is collected in a co llection pan as the liquid falls from the pipe.

Constituent s ( e.g., A+ ions) are unable to evaporate with the water and remain in the wastewater, creating a concentrated brine.

Figure B

- 12 . Diagram of Evap oration/Condensation PrinciplePart B



### 52 Process Description

F our types of evaporation/condensation processes are commonly used for wastewater

treatment:

 Vapor compression (VC)

 Multiple stage flash (MSF)

 Multiple effect (ME)

 Rapid spray (RS)

U nits deployed to treat UOG extraction wastewater operate on vapor compression, multiple stage flash , and multiple effect principles , with vapor compression being the most popular . The following subsections focus on these three evaporation processes

.
Vapor Compression (VC) Evaporation/Condensation

There are two types of v apor com pression processes: mechanical vapor compression (MVC) and thermal vapor compression (TVC). The difference between these two types is how the wa ter vapor pressure is increased. M echanical vapor comp ression primarily uses a mechanical compressor 26 

### to add energy into the system, while TVC uses a heat source to add

energy, such as a gas burner. Although both types of vapor compression technologies are used in UOG extraction wastewater applications, mecha nical vapor compression is more common because:

 Mechanical compressors start up more quickly and are less expensive to run on electricity than thermal vapor compression (DCN SGE00300).

 Thermal vapor compression requires a closed loop system consisting of a working fluid (e.g., steam, oil) and boiler. This set up increases the overall size of the system.

Figure B

- 13 is a flow diagram

, described by a CWT facility, of a MVC evaporator designed specifically for UOG extraction wastewater applications. The steps below describe the process in Figure B

- 13 . T VC evaporator s use a similar pr ocess except that a heat exchanger with working fluid heated by a boiler is used to heat the water vapor , rather than a mechanical

compressor

.

1. Influent wastewater is preheated through a series of cross

- flow heat exchangers referred to as the main, seconda ry, and tertiary heat exchangers. In these non

contact heat exchangers, energy is transferred from the downstream concentrated brine, distillate, and compressed water vapor to heat the influent wastewater. This transfer of energy greatly reduces the overal l energy requirements of the system.

26 Mechanical vapor compression also typically inc ludes a heat source (e.g., a gas

- fired boiler) but it only operates during start up operations and then periodically during steady state operation. The boiler only runs approximately two percent o f operational time

, according to one CWT facility operator (DCN SGE 00300). Because mechanical vapor compression does not rely on heat, it does not require steam or a boiler, making MVC more suitable for mobile treatment units than TVC.Part B



### 53 2. The wastewater enters the main vessel where water is evaporated from the wastewater. Constituents remain in the wastewater, resulting in concentrated brine. During startup, when concentrated brine, distillate, and compr essed water vapor are not yet available to preheat the influent wastewater, the influent wastewater is instead heated in the main vessel by steam from a small boiler (usually fuelled by natural gas). After start up, the boiler is shut off and operates only periodically to maintain the surface of the preheated wastewater at approximately 212o F.

3. Water vapor from the main vessel is vented to a mechanical compressor. The compressor, which is powered by electricity, increases the vapor’s temperature and pressu re. The compressed water vapor expands across the main heat exchanger, where its latent heat of condensation 27 

### is transferred to influent wastewater to preheat it. At this point, the water vapor becomes condensed wastewater (i.e., distillate).

4. Concentrated brine from the main vessel enters the tertiary heat exchanger where its thermal energy is transferred to the influent wastewater to preheat it.

5. The distillate flows through the secondary heat exchanger where it provides sensible heat 28 

### to preheat influent wastewater.

27 Latent heat of con densation is the heat release d by water vapor when it condenses from a gas to a liquid.

28 Sensible heat is the heat released or obtained by water during a change in temperature.Part B



### 54 Source: DCN SGE00 300

.


### Figure B

- 13 . Evaporation/Condensation Mechanical Vapor Compression Process Flow Diagram

Multiple Stage Flash (MSF) and Multiple Effect (ME) Evaporatio n/Condensation

In MSF and ME evaporation/condensation, the main evaporation vessel operates at reduced pressure and higher temperature to facilitate evaporation . When the pressure is decrease d , preheated wastewater can be evaporated at temperatures lower t han 212o F (DCN SGE 00264 ). The primary difference between MSF and ME evaporation/condensation is that the reduced pressure and high temperatures are carried out in separate vessels in ME evaporation, but in only one main vessel in MSF evaporation. Although decreasing the pressure requires energy input , less energy is then required to increase the temperature of the influent wastewater

.
Figure B

- 14 is a flow diagram of a MSF evaporator, which includes the following step s:Part B



### 55 1. The cool influent wastewater is piped through the main vessel, which acts as a heat exchanger. Hot water vapor within the vessel preheats the influent wastewater as it passes through.

2. The preheated influent wastewater enters a second heat exchanger, where it is further heated by a hot working fluid (which is heated by a boiler or burner).

3. The heated wastewater then enters the first column in the main vessel . Because the pressure in this column is close to atmospheric

, wastewater must be at high temperature to evaporate (P vap 

### >P atm 

### ).

4. Wastewater that does not evaporate in the first column enters a second column operated at lower atmospheric pressure than the first ( achieved by a vacuum system). The vapor pressure again exc eeds the reduced atmospheric pressure, causing further evaporation (P vap 

### >P atm 

### ).

5. As water vapor rises in each column, it contacts pipes containing cool influent wastewater (step 1). Water vapor temperature decreases until the atmospheric pressure becomes g reater than the vapor pressure, causing the vapor to condense (P vap 

### <P atm 

### ).

6. The condensate, or treated wastewater, is collected as the liquid falls from the pipe as it leaves the vessel.

7. Constituent s are unable to evaporate with the wastewater

, creat ing con centrated brine.

Figure B

- 14 . Flow Diagram of a Multiple Stage Flash (MSF) EvaporatorPart B



### 56 Rapid Spray (RS) Evaporation/Condensation

In RS evaporation, wastewater is evaporated by spraying it in small droplets into a heated air stream. The evaporation generates water vapor and concentrated brine as with other evaporation technologies.

Figure B

- 15 and Figure B

- 16 are process flow diagram s of Heartland Technology Partners’ low momentum

– high turbulence (LM

- HT®) Concentrator (DCN SGE 01047 )

. Note that this technology uses one unit to accom plish both wastewater evaporation and crystallization (see discussion of Crystallization in Part B

. 2.2 below). At the Seneca facility in Covington, PA, waste exhaust from the compressor station’s reciprocating engines is collected into an exhaust manifold and pulled by vacuum (provided by an induced draft fan) downflow into th e evaporator. UOG extraction wastewater feed from storage tanks is injected into the evaporator where it comes into direct contact with the waste exhaust. In the evaporator, the wastewater feed is subjected to a tortuous path flow ( Figure B

- 18 ), which breaks the liquid into small droplets, providing high interfacial surface area for heat transfer and evaporation.

Source : DCN SGE01047

.



### Figure B

- 15 . Heartland LM

- ® Concentrator Flow DiagramPart B



### 57 Source : DCN SGE01047

.


### Figure B

- 16 . Schematic of Heartland LM

- ® Evaporation Zone and Entrainment Separator

From the evaporator, the exhaust/brine mixture enters an entrainment separator where the concentrated brine is separated from the air and drains into a sump located under the separator. A sump pump transfers brine from the sump to a thickener tank, where salt solids/brine settle t o the bottom and are removed, while the supernatant is recycled back to the evaporator. The supernatant recycle rate is adjusted to achieve the target brine salt concentration (DCN
SGE 01047 ).

Water vapor (steam) is typically released directly to the atmosp here. However, as an option, the steam can be routed to a shell and tube heat exchanger to condense it for reuse. Cooling water for the heat exchanger is provided by wastewater feed (DCN SGE 01047 ).

2.1.2 Capabilit i es and Limitations

Th is subsection describe s the targeted constituents and effectiveness, design and operation considerations, residuals, and energy use of evaporation/condensation

.
Targeted Constituent

s and Treatment Effectiveness

Evaporation/condensation technologies can remove a wide range of wastew ater constituent s, including suspended solids, dissolved organic matter, dissolved inorganic matter

, biological contaminants (e.g., bacteria and viruses), and radioactive elements (DCN SGE00264 ). Typical influent TDS concentrations for cost effective opera tion can range from 2 0,000 mg/L to 125,000 mg/L

, and effluent concentrations can be less than 10 mg/L (DCN SGE00300; DCN SGE00625; DCN SGE 00144 ; DCN SGE00264). The effluent wastewater has very low TDS (DCN SGE00110 ).Part B



### 58 Influent TDS concentrations, in theory, can be as high as the supersaturation concentration for TDS (approximately 250,000 to 300,000 mg/L), 29 

### but at the expense of higher energy input and lower distilled water recovery. One CWT facility that uses evaporation/condensation suggested the ec onomics become unfavorable when TDS reaches 125,000 mg/L (DCN SGE00300). Case studies in the literature demonstrate that evaporation/condensation units can operate with TDS concentrations as high as 195,000 mg/L (DCN SGE00110)

. Heartland’s LM

- HT® Concentra tor is able to treat water with TDS up to 235,000 mg/L (DCN SGE 01047 ).

Constituents with evaporation temperatures lower than water will evaporate and exit the system in the water vapor stream . Examples include a mmonia (DCN SGE00625) and light hydrocarbons (DCN SGE 00244 )

. Light hydrocarbons can be separated from the evaporated wastewater using a dedicated recovery unit prior to condensation. The hydrocarbons recovered from this add

- on unit can be sold (DCN SGE00244).

Table B

- 19 shows performance data for evaporation/condensation used in UOG extraction wastewater applications. The table includes untreated influent constituent concentrations, effluent constituent concentrations (distillate) , and the resulting constituent

r emoval efficiencies for flowback and produced waters. Table B

- 19 demonstrates that evaporation/condensation is effective at treating wastewater with a wide range of TDS.

Table B

- 19 . Performance Data of Evaporation/Condensation in UOG Extraction
Wastewater Application

Constituent Flowback Long

- term Produced Water

Reference
ID Influent (mg/L) Effluent

(Distillate) (mg/L) Removal

Efficiency (%) a Influent

(mg/L) Effluent

(Distillate) (mg/L) Removal

Efficiency (%) a

TDS 41,000

– 47,000 76

– 100 >99 200,000 88 >99 81 ; 17

Chloride 20,000 35 >99 110,000 45 >99 17

Sodium 10,000

– 12,000 3.6

– 19 >99 21,000 25 >99 17 ; 81

Metals

Aluminum 2 0.1 95 2 0.1 95 17

Barium 6

– 160 0.1 >99

– – – 17 ; 81

Calcium 2,500

– 2,700 0.8

– 3.8 >99 15,460 5.1 >99 17 ; 81
Copper 0.52 0.08 85 0.8 0.02 98 17

Iron 2

– 8.3 0.02

– 0.1 >95 68 0.02 >99 17 ; 81

Lithium 11 0.1 99

– – – 81
Magnesium 220

– 300 0.1

– 0.4 >99 1,400 0.47 >99 17 ; 81
Manganese 2 0.02 99 5.2 0.02 >99 17
Phosphorous 2 0.1 95

– – – 81

Potassium 350 0.1 >99

– – – 81

29 This is the approximate supersaturation concentration for sodium chloride, the primary TDS found in UOG extraction wastewater. Several vendors indicated that supersaturation occurs at approximately 300,000 mg/L TDS (DCN SGE 00227 ; DCN SGE 00228 ; DCN SGE 00230 ).Part B



### 59 Table B

- 19 . Performance Data of Evaporation/Condensation in UOG Extraction
Wastewater Application

Constituent Flowback Long

- term Produced Water

Reference
ID Influent (mg/L) Effluent

(Distillate) (mg/L) Removal

Efficiency (%) a Influent

(mg/L) Effluent

(Distillate) (mg/L) Removal

Efficiency (%) a

Strontium 270

– 480 0.47

– 0.1 >99 2,200 0.7 >99 17 ; 81

Sulfate 160

– 210 2.2

– 5 >98 130 3.1 >98 17 ; 81

Zinc 0.4 0.16 60 0.4 ND >99 17
Organics

Benzene 0.055 0.001 98 0.76 ND >99 17

BTEX 2.1 0.1 95

– – – 81

Toluene 0.085 0.0022 97 0.95 ND >99 17

TPH 4 4 0

– – – 81

Other
Alkalinity 200 48 76 94 9 90 17

Ammonia 84 64 24

– – – 81

Bicarbonate 200 24 88

– – – 17

Boron 6.4

– 16 0.02

– 0.4 >98 11 0.02 >99 17 ; 81

Fluoride 9.5 0.15 98 8.5 0.16 98 17

Hardness 4,000 11 >99 44,000 15 >99 17

Silica 49 1 >99 52 ND >99 17

Sulfates 160

– 210 2.2

– 5 98

– 99 130 3.1 98 17 ; 81

TSS 22

– 130 3

– 4 86

– 97 35 3 91 17 ; 81

Radioactives (all units are pCi/L)
Gross alpha 76 ND >99 3,000 0.69 >99 17

Gross beta 240 ND >99 420 0.43 >99 17

Radium

- 226 33 ND >99 1,400 0.23 >99 17

Radium

- 228 27 ND >99 720 0.43 >99 17

Thorium

- 228 1.2 0.14 88 31 0.18 99 17

ND

— Not detected; mg/L

— milligrams per liter; TDS

— total dissolved solids; BTEX

— benzene, toluene, ethylbenzene, and xylenes; TPH

— total petroleum hydrocarbons; TSS

— total suspended solids.

a

— The EPA calculated all removal efficiencies using paired influent and effluent concentrations reported in literature. Attachment 1 ( DCN SGE00692.A01 ) presents these removal efficiency calculations. The number of data points that these removal efficiencies are based on are also presented in Attachment 1.



### Design and Operation Considerations for UOG Extraction Wastewater

One of the challenge s with evaporation/condensation is the tendency for heat exchange surfaces (e.g., piping) to lose their heat transfer quality due to scaling . When these surfaces have diminished heat transfer capabilities, the overall heat exchanger efficiency decreases. As heat exchanger efficiency decreases, more energy input is required, making the overall process less

energy effi cient

. Scaling occurs when high

- temperature environments cause inorganic salts toPart B



### 60 precipitate onto pipes. Constituent s that cause scaling include salts of multivalent cations (e.g., calcium, barium, magnesium).

Prior to evaporation/condensation, UOG extraction wastewater is typically pretreated using chemical precipitation and filtration to remove scale

- causing constituents. Rigorous pretreatment requirements can be avoided if the evaporation/condensation unit is operated at higher than atmospheric pressures. In creasing the pressure allows inorganic salts to remain dissolved in the water at higher temperatures, reducing the tendency for scaling (DCN SGE00227; DCN SGE 00095 )

. One exception is the Heartland LM

- HT® technology that is designed to operate at supersatur ated concentrations without the need for pretreatment, or for operating under pressure (DCN SGE 01047 ).

As previously explained, higher influent TDS concentrations decrease overall performance of evaporation/condensation because the water solubility limit i s reached more quickly within the evaporator (DCN SGE 00238 ; DCN SGE 00300 ). If the influent TDS is near the TDS solubility limit (approximately 250,000 to 300,000 mg/L) , crystals can grow in the concentrated brine

, causing significant fouling and plugging p roblems

. For reference, some UOG extraction wastewater, particularly long

- term produced water, can have TDS concentrations as high as nearly 400,000 mg/L (DCN SGE00704). As a result

, treatment unit operators must monitor influent TDS to ensure the solubility limit of the least soluble salt is not reached. CWT facilities using evaporation/condensation often test every influent truckload for TDS (DCN SGE00299; DCN SGE00300)

. Wastewater with excessive TDS may be rejected or subject to a surcharge.

Resi duals

E vaporation/condensation processes produce a concentrated brine stream. If evaporated water is vented to the atmosphere, organic compounds removed from the wastewater may also be released to the atmosphere. Where chemical precipitation is used for p retreatment in UOG applications, a solid waste stream will also be generated (see Part B.1.1 for solid waste generation from chemical precipitation). Table B

- 20 shows sample constituent concentrations in the concentrated brine generated by one evaporation/condensation unit. The concentrated brine stream contain s all of the salt products contained in the influent water , but at hig her concentrations than the influent

. This includes any present radioactive elements in the influent wastewater. However, literature and industry do not discuss issues related to elevated levels of radioactive elements in the concentrated brine. According to literature and communication with industry, brine can be managed in several ways, including: managed in several ways (DCN SGE 00300 ; DCN SGE 00299 ; DCN SGE 00095 ):

 Injected into a disposal well

 Used as kill fluid 30



###  Used as additive for drilling fluid

 Furthe r concentrated via crystallization

30 Kill fluid is the high density fluid injected into a well to eliminate the fluid flow from the reservoir through the wellbore

.Part B



### 61 Treated wastewater recovery is highly dependent on the influent TDS concentration. For economical operation in UOG operations, evaporation/condensation typically has a water recovery percentage between 60 to 95 percent ( DCN SGE00264; DCN SGE00144; DCN SGE00300). The recovery is inversely proportional to the influent TDS concentration, as illustrated in Figure B

- 17

. Figure B

- 17 is based on Equation 8 , which the EPA derived from actual operating data of an MVC evaporator/condensation system treating Barnett shale wastewater (DCN SGE00300; DCN SGE00415). 31 

### At higher influent TDS concentrations, water recovery decreas es, resulting in a larger volume of concentrated brine and higher disposal costs (DCN SGE00299; DCN SGE00300; DCN SGE0095; DCN SGE00109). The relationship between influent TDS and recovery is specific to each type of evaporator (e.g., MVC, ME).

Equation 8

Percent Recovery =

- 0.0005 * (Influent TDS Concentration in mg/L) + 100

Figure B

- 17 . Typical Distillate Recovery versus Influent TDS Concentration for MVC Technology 32

31 Underlying data are based on data from SGE00415. Equation was confirmed by a CWT facility that operat es the same treatment system in Pennsylvania (DCN SGE 003 00).

32 Distillate recovery data shown in Figure B

- 17 may not agree with data presented in Table B

- 20 because the two tables represent two different evaporation/condensation technologies. Figure B

- 17 represents MVC and Table B

- 20 represents ME.Part B



### 62 Table B

- 20 . Concentrated Brine Composition Evaporation/Condensation

Constituent Marcellus Shale Long

- Term Produced Water a Marcellus Shale Flowback Water b

Influent to Unit (mg/L) Treated

Wastewater (Distillate) (mg/L) Concentrated

Brine (mg/L) Influent to

Unit (mg/L) Treated

Wastewater (Distillate) (mg/L) Concentrated

Brine (mg/L)

TDS 200,000 88 350,000 41,000 76 110,000

Chloride 110,000 45 210,000 20,000 35 65,000

Sodium 21,000 25 86,000 10,000 19 32,000

Metals

Barium 160 <0.10 150 53 0.1 45

Arsenic <0.5 <0.5 <1.0 <0.5 <0.5 <5.0

Iron 68 <0.02 2.4 8.3 0.02 17

Zinc <0.4 <0.02 <0.4 <0.4 0.16 <0.4

Aluminum <2.0 <0.10 <2.0 <2.0 <0.1 <2 Copper 0.8 <0.02 0.8 0.52 0.08 0.8

Calcium 15,000 5.1 30,000 2,500 3.8 6,800

Strontium 2,200 0.70 5,000 270 0.47 790

Sulfates 130 3.1 550 160 2.2 280 Magnesium 1,400 0.47 3,100 220 0.36 660

Potassium 470 0.35 1,300 95 0.19 360 Manganese 5.2 <0.02 8.2 2 0.02 2.6 Organics

Benzene 0.76 ND 1.2 0.055 ND ND

Toluene 0.95 ND 0.0030 0.085 0.0022 0.0013 Ethyl benzene 27 ND ND ND ND ND

Other

Bicarbonate NR NR NR 200 24 150

BOD >78 >75 63 >74 >75 >380

Total hardness 44,000 15 87,000 4,000 11 20,000

Fluoride 8.5 0.16 11 9.5 0.15 12

Boron 11 <0.02 17 6.4 <0.02 17

TSS 35

– 400 <3 180 22 <3 32 Alkalinity 94 30 32 200 48 150

Radioactives Gross beta (pCi/L) 420 0.43 530 240 ND 87 Gross alpha (pCi/L) 3,000 0.69 1,900 76 ND 16 Thorium 228 (pCi/L) 31 0.18 23 1.2 0.14 5.3 Radium 226 (pCi/L) 1,400 0.23 1,500 33 ND 47 Radium 228 (pCi/L) 720 0.43 750 27 ND 18

ND

— Not detected; mg/L

— milligrams per liter; TDS

— total dissolved solids; BOD

— biochemical oxygen demand; TSS

— total suspended solids.

a

— Source: DCN SGE00110. Treated wastewater recovery of the long

- term produced water was 55 percent. b

— Source: DCN SGE00110. Treated wastewater recovery of the flowback was 72 percent.Part B



### 63 Energy Use

Evaporation/condensation is an energy

- intensive treatment technology. TVC systems require a burner or boiler that uses oil or natural gas (DCN SGE 00264 ). MVC units require compressors that run on electricity (DCN SGE 00230 ; DCN SGE 00227 ); t herefore, MVC designs are more popular for mobile units. 33 

### Mobile MVC system s also include auxiliary generators ( run ning on diesel fuel or wellhead gas ) for use when connection to the electrical grid is not possible (DCN SGE 00230 ; DCN SGE 00227 ). However, treatment unit operators desire electricity from the grid over the use of gen erators because it is less expensive (DCN SGE00625).

Evaporation/condensation systems can be designed to use waste or low

- grade energy. One example is a CWT facility near Mt. Jewett, Pennsylvania that treats UOG extraction wastewater. This facility is adja cent to the McKean County landfill and uses landfill gas 34 

### to power specifically

- designed boilers that run their treatment process. The facility can evaporate up to 100,000 gallons per day of Marcellus shale wastewater for reuse under its general permit
WMG R123NW005, or for discharge into a nearby surface water under its NPDES discharge permit PA0102288 (DCN SGE 00367 ; DCN SGE00616 ). Another source for low

- grade energy in UOG extraction wastewater applications is waste heat from compressor stations.

Table B

- 21 reports energy use per barrel of influent wastewater for some pilot and full scale projects using evaporation/condensation to treat UOG extraction wastewater. Table B

- 21 includes the associated influent TDS concentrations and resulting water recovery percentages. Because many of the units require both electricity and some type of fuel , the energy requirement is presented in three columns: electrical (e.g., pumps , compresso rs ), fuel (e.g., natural gas for a burner), and the total energy required

, if reported.

33 Most mechanical vapor compression systems still require a small boiler or burner to assist in start up operations (DCN SGE00300).

34 Landfill gas is low

- grade nat ural gas produced from decomposition of organic materials within the landfill.Part B



### 64 Table B

- 21 . Evaporation/Condensation Energy Use in UOG Applications

Pilot or Full Scale Project Vendor Technology Name Evaporator

Type Influent TDS

Concentration (mg/L) Energy Consumption (kWh, unless

otherwise noted, per bbl of influent

wastewater)

Water Recovery (%) Power Source Reference
ID Electrical Fuel

Energy (MCF) Total

Full scale Purestream AVARA Mechanical

vapor 20,000

– 40,000 6 N/A 6 80 Electrical 92

212 Resources Vacom Multiple effect ~30,000 1.3 NR 1.3 90 Electricity or wellhead natural gas 57 ; 47

Fountain Quail
Water Management, LLC Nomad Mechanical

vapor 60,000

– 80,000 NR 0.07 4.6 60

– 90 50 kW generator a 48 ; 81

Pilot project Altela Inc. AltelaRainTM Multiple effect b 25,000

– 200,000 2

– 2.5 5

– 10 NR 45

– 90 Electricity, natural gas, onsite waste heat, solar panels 17

GE Water &
Process Technologies NR Mechanical

vapor <130,000 NR NR 2.1

– 2.9 60

– 95 Electricity or natural

gas 49 ; 57

Technology in general N/A N/A N/A 110,000

– 130,000 NR NR 6.5

– 7.5 50 Wellhead gas generator 51

TBD

— To be determined.

N/A

— Not available; NR

— Not reported; TDS

— Total dissolved solids; mg/L

— milligrams per liter; MCF

— million cubic feet; kWh

— kilowatt

- hour; bbl

— barrel.

a

— Generator powered by natural gas directl y from well head or electricity.

b

— This vendor uses multiple effect technology in combination with membrane distillation.Part B



### 65 2.1.3 Costs

Capital costs of evaporation/co ndensation include co sts for the pretreatment system , the evaporation/condensation unit , low

- pressure pumps, and monitoring equipment. O perating cost s include energy for low

- pressure pumps and energy for evaporation, and labor (DCN SGE00638.A12; DCN SGE00638.A11)

. Because the technology is energy

- intensive, its operating cost is relatively high compared to treatment technologies that do not remove TDS. However, s everal studies concluded that if waste heat (e.g., low

- grade steam or low

- grade

natur al gas) is used, the technology remains effective and cost is significantly reduced (DCN SGE 00124 ; DCN SGE 00264 ; DCN SGE 00110 ).

Table B

- 22 shows approximate capital and operating cost s for evaporati on/condensation reported in the literature for purchased and rented treatment systems

. Costs include pretreatment systems such as chemical precipitation and/or filtration units. Table B

- 23 shows approximate

costs UOG operators pay CWT facilities to treat UOG extraction wastewater using evaporation/condensation (including pretreatment).

Table B

- 22 . Evaporation/Condensation Capital and O&M Costs for UOG Extraction Wastewater Applications

Vendor and Technology Name System

Description Influent

TDS (mg/L) Capacity

(MGD) Cost

Basis Capital

Cost ($ per gpd) O&M Cost

($ per bbl) Rental or

Effective Cost ($ per bbl) a Reference

ID

Altela Rain Plant 25,000

– 200,000 NR Purchase

or Rental 8.00 0.14

– 0.89 5.20 17

212
Resources Plant ~20,000 0.17 Purchase 30.00 0.30

– 0.50 b NR 97 ; 53 ; 47

AquaPure NOMAD Plant 45,000

– 80,000 0.32 Purchase

or Rental NR 2.60 5.00

– 6.00 81 ; 91 ; 82

Mobile system 45,000

–

80,000 0.11 Purchase

or Rental 38.00 0.94 4.00

– 6.00 52

General Mobile

system 110,000

– 130,000 0.060 Purchase

or Rental 100.00 2.40 5.40 51

Purestream Mobile

System 40,000

–

100,000 0.053 Purchase

or Rental 22.00 to

44.00 1.30 2.00

– 3.00 126 ; 154

GE Mobile

system <130,000 0.072 Purchase or Rental 34.00 NR 2.50

– 6.50 49 ; 126 ; 129

NR

— Not reported; TDS

—

Total dissolved solids; mg/L

— milligrams per liter; MGD

— million gallons per day; gpd

— gallons per day; bbl

— barrel.

a

— Represents rental cost if the cost basis was rental and is inclusive of O&M. Represents total effective cost when cost basis is purchase, which includes amortized capital costs and O&M costs combined. When the cost basis is purchased, total effect cost is only included when a reference reported amort ized capital costs.

b

— Electricity costs only.

c

— Cost for the entire plant and all treatment onsite.Part B



### 66 Table B

- 23 . Evaporation/Condensation Cost s to UOG Operator s at CWT Facilities

CWT Facility Name Treated Wastewater Influent TDS

concentration (mg/L) Type of Service Cost to UOG Operator at CWT Facilities ($ per bbl) Reference

ID
Clean Streams, LLC Shale gas 100,000 Reuse 6.30

– 8.30 69

212 Resources Tight gas ~20,000 Discharge to surface

water or reuse 3.00

– 4.00 47 ; 53 ; 57

Eureka Resources, LLC Shale gas 100,000 Discharge to POTW or

reuse 6.50

– 10.00 70

mg/L

— milligrams per liter; bbl

— barrel

. Note: Data in this table are as

- reported in literature.



### 2.1.4 Summary of Vendors for UOG Extraction Wastewater

EPA identified permanent deployments of evaporation/condensation treatment systems in the following UOG formations:

 Marcellus (shale gas)

 Barnett (shale gas)

 Eagle Ford (shale oil)

 Fayetteville (shale gas)

 Mes averde /Lance (tight gas) 35



###  Permian (shale oil and gas and tight oil and gas)

Table B

- 24 provides information about some evaporation/condensation units marketed for treating UOG extraction wastewater

. All of these systems can be trailer

- mounted or installed permanently.

Table B

- 24 . Evaporation/Condensation Technology Vendors for UOG Extraction
W astewater

Vendor Technology Name Surface

Footprint (ft 2 ) a Capacity (bpd) Reference ID

212 Resources Vacom 2,400 2,500

– 3,000 47 ; 53 ; 97 AquaTech International Corporation MoVap 420 1,000

– 1,700 140 ; 98 Fountain Quail Water Management, LLC NOMAD 2,500 2,500 126 ; 81 GE Water & Process Technologies NR NR 1,700 126 ; 49

Purestream AVARA Trailer mounted 1,000

– 2,500 126
AltelaRain, Inc. AltelaRainTM NR 100

– 600 134 ; 17

NR

— Not reported ; ft 2

— square feet; bpd

— barrels per day

.

a

— Only includes the primary treatment unit

, not storage for wastewater, chemicals, or sludge ( solid waste ).

35 This area is commonly referred to as the Pinedale field, which includes the Mesaverde and Lance tight gas formation s

.Part B



### 67 2.2 Crystallization

Crystallization is a TDS removal technology that converts high TDS wastewater into distilled water (low TDS) and solid salt crystals. To date, this technology has been used in full scale projects at CWT facilities and has also been pilot tested by UOG ope rators in the field. Industry has explored using crystallization at well pads, CWT facilities, and locations with low

grade waste heat, such as compressor stations (DNC SGE01047). Unlike evaporation/condensation (which always generates a treated wastewater stream) , crystallization can be operated such that all evaporated wastewater is vented to the atmosphere if desired. Similar to evaporation/condensation, t his technology may be used for treating UOG extraction wastewater when low TDS treated water is desired (e.g., to meet requirements for discharging to surface waters or POTWs) (DCN SGE00177 ) , or when costs for alternative disposal are high (e.g., lack of disposal wells in the Marcellus) (DCN SGE 00300 ; DCN SGE 00264 ; DCN SGE00625; DCN SGE 00478 ; DCN SGE01047 )

.

This section describes the crystallization process, treatment capabilities and limitations, treatment cost, and vendors that the EPA is currently aware of that market the technology for UOG extraction wastewater treatment

.

2.2.1 How Cry stallization Works

This subsection describes crystallization operating principles and how the process has been used to treat UOG extraction wastewater.

Principle

Crystallization is very similar to evaporation/condensation in that b oth technologies rely

on evaporation. They operate by changing temperature and pressure to evaporate water. Crystallization differ s from evaporation/condensation in that so much water is evaporated that the brine stream becomes “supersaturated ” with salts. This occurs when the con stituent s dissolved in a supersaturated solution have reached their maximum concentrations. Evaporating

water beyond this point cause s the constituent s to precipitate out of the s o lution, forming solid crystals (DCN SGE 00264 ).

Process Description

In cryst allization systems designed for UOG extraction wastewater treatment, the evaporated water vapor is either recovered through condensation or emitted into the atmosphere.
A ccording to the literature, both MVC and TVC technologies are used. The EPA is also aw are of one CWT facility that uses RS technology for both evaporation and crystallization (see Section
2.1.1 ).

Figure B

- 18 presents a flow diagram of a MVC crystallizer that includes vapor recovery :

1. Influent wastewater enters a pump, where it is pressurized.

2. The influent wastewater is routed through a heat exchanger, where it is heated by downstream hot, pressurized water va por from the crystallizer

.Part B



### 68 3. The atmospheric pressure of the hot, pressured water suddenly drops as it enters the crystallizer. When this happens, the vapor pressure becomes greater than the atmospheric pressure on the water (P vap 

### >P atm 

### ), causing the wastewa ter to evaporate.

4. As more wastewater evaporates, the remaining brine becomes supersaturated, causing dissolved solids to precipitate into solid crystals. The mixture leaves the vessel through a separator , which remove s the solid crystals. After separation , the remaining brine is mixed with influent wastewater at step 1.

5. The water vapor from evaporation (step 3) is pulled into a compressor, which increases the pressure and temperature of the vapor.

6. The hot, pressurized vapor then enters the heat exchanger, where it is used to heat the incoming brine and influent wastewater mixture from step 4

. Heat transferred from the water vapor to the wastewater mixture causes the atmospheric pressure of the vapor becomes greater than the vapor pressure, causing it to con dense (P vap 

### >P atm 

### ).

7. Finally, the condensed water exits the heat exchanger as treated wastewater (condensate)

.

Figure B

- 18 . Mechanical Vapor Compression Crystallization ProcessPart B



### 69 INTEVRAS Technologies, LLC (INTEVRAS) crystallizer ( EVRAS TM ) uses TVC and does not include vapor recovery. Instead, the water vapor is emitted to the atmosphere. Figure
B

- 19 is a flow diagram for an EVRAS TM unit (DCN SGE 00149 ) :

1. First, influent wa stewater enters a pump where it is pressurized.

2. The influent wastewater is routed through a heat exchanger, where it is heated by downstream hot, pressurized vapor from the crystallizer

. 3. The atmospheric pressure of the heated, pressurized water suddenly drops as it enters the crystallizer. When this happens, the vapor pressure becomes greater than the atmospheric pressure on the water (P vap 

### >P atm 

### ), causing the wastewater to evaporate.

4. As more wastewater evaporates, the remaining brine becomes supersaturat ed causing dissolved solids to precipitate into solid crystals. The mixture exits the vessel through a separator to remove the solid crystals. After separation, the remaining brine is mixed with influent wastewater at step 1.

5. This water vapor is either rel eased in the atmosphere (typical for the EVRAS TM ) or may be sent to a condenser to recover the water.

6. The working fluid is circulated between the heat exchanger (step 2 ) and a waste heat source or burner.

Figure B

- 19 . INTEVRA’s EVRASTM Crystallization ProcessPart B



### 70 2.2.2 Capabilities and Limitations

Th is subsection describe s the targeted constituents and effectiveness, design and operation considerations, residuals, and energy use of crystallization

.
Targeted Constituent

s and Treatment Effectiveness

Crystallizers are capable of treating wastewaters with extremely high TDS concentrations typical of some UOG extraction wastewater (DCN SGE 00 140 ). Crystallization treatment technologies operate most efficiently when the influent wastewater is already near its supersaturation concentration for TDS (250,000 to 300,000 mg/L)

. The EPA did not identify detailed data on constituent removal for crystallization

. Given the similarity of the process to evaporation/condensation

, constituent removal for crystallization is likely similar in effectiveness and efficiency to that of evaporation/condensation (see Par t B.2.2.2 )

. Evaporation/con densation typically produces effluent (condensate) TDS concentrations of less than 50 mg/L.

Design and Operation Considerations for UOG Extraction Wastewater

In UOG extraction wastewater applications, crystallizers have been added to existing evaporation/ condensation treatment systems. In these designs, the concentrated brine produced by evaporation/condensation becomes the influent to the crystallization unit (DCN SGE 00300). However, some UOG operators have used stand

- alone crystallization units. In eithe r case, the influent wastewater are typically pretreated to reduce concentrations of multivalent cations ( e.g., iron, calcium , magnesium, strontium, barium) (DCN SGE 00238 ; DCN SGE 00300). Removal of these cations has three benefits (DCN SGE 00238):

 Reduced scaling and capital costs

– Multivalent cations are corrosive to metals. Removing them reduces potential corrosion and scaling of metal equipment and piping. Pretreatment to reduce corrosion allows downstream equipment, such as

t he crystallization unit

, to be constructed of less expensive materials of construction, reducing capital costs.

 Reduced operating costs

– R emoving multivalent cations allows for a lower operating temperature, resulting in energy savings. This is because the solubility limit of conc entrated brine that contains multivalent cations is higher than that of concentrated brine that does not contain multivalent cations

.

 Purity of solid crystals

– When all multivalent cations and other constituents are removed prior to crystallization, the s alt crystal is very pure sodium chloride. One CWT facility suggested the solid crystals are 98 percent pure sodium chloride, which has potential value in industrial applications (DCN SGE 00300)

.
An alternative to rigorously removing multivalent cations befo re crystallization is to operate the crystallizat ion unit at reduced pressure using a vacuum and chilling system (DCN SGE 00238). Reducing the operating pressure of the crystallizer significantly decreases the boiling temperature of the solution. Ultimately , the unit can still be constructed of less

- expensive materials of construction , reducing capital costs, because the solubility limit of multivalent cations will not be reached. T his alternative design eliminates the need to rigorously pretreat thePart B



### 71 influen t wastewater to remove multivalent cations (DCN SGE 00238 )

. However, pretreatment may still be needed to remove other constituents (e.g., TSS, iron) (DCN SGE 00160 ).

Regardless of the type of crystallizer used, equipment is affected by scaling and corrosion
in the same way that evaporation/condensation units are affected (DCN SGE 00 140) . Common pretreatmen t alternatives include settling, chemical precipitation, and filtration to remove suspended solids and other undesired constituents (e.g., iron) (DCN SGE 0026 4 ; DCN SGE 00160 ; DCN SGE 00300 ).

A mbient temperature can be a design consideration

. B ecause crystallization is a thermal technology, lo w winter temperatures increase energy requirements. A fixed heat exchange capacity and lower temperatures result in a lowe r rate of evaporation and capacity (i.e., barrels treated per day). For example, one vendor reported that capacity may be as low as 200 barrels per day (bpd) in the winter and as high as 450 bpd in the summer for a specific mobile system (DCN SGE 00160 ).

Re siduals

If the crystallization unit is operated so that the water vapor is collected and condensed

, recovered treated effluent (condensate) can be reused for hydraulic fracturing or other purposes by UOG operators

. W hen the influent wastewater is concentr ated brine from an evaporator (TDS approximately 250,000 to 300,000 mg/L) , crystallization recovers m ore than 80 percent of the influent wastewater (DCN SGE 00300 )

.
Crystallization typically pr oduces a solid crystal residue of high quality sodium chloride (up to 98 percent purity) (DCN SGE 00300 ). A crystallizer treating 210,000 gallon s per day of UOG extraction wastewater would generate approximately 120 tons per day of solid crystals 36 

### (DCN SGE 00300 ; DCN SGE00616 ). There are several practices used for managing the solid crystals which have been documented in the literature, includ ing (DCN SGE00300) :

 Hauling to landfill for disposal 37



###  Return ing to UOG operators to use as an additive in drilling fluid 38



###  Sell for use as highway d eic er

 Sell for use as a raw m aterials for industrial process es

States may regulate the use of the crystallized solids. For example, Pennsylvania requires that all salts generated by oil and gas facilities that are used for deicing or as an industrial process raw material meet applicab le standards in Pennsylvania Department of Environmental Protection’s (PA DEP) General Permit. This permit provides 21 specific quality standards for

36 Actual waste generation will vary by influent TDS conce ntration. This estimation was based on Marcellus wastewater with a typical TDS concentration of 100,000 mg/L (DCN SGE00300).

37 Because the water has been removed, transport and disposal of salt crystals is less expensive than transport and disposal of bri ne. 38 Salt may be used as an additive in drilling fluid to increase density and/or increase the fluid’s electrical conductivity (EC).Part B



### 72 salt crystals, including maximum levels of two radioactive constituents: thorium 232 (2 pCi/kg) and uraniu m 238 (2 pCi/g).

Crystallization may also generate a calcium chloride brine purge stream that must be managed . A crystallizer treating 210,000 gallon s per day of UOG extraction wastewater wou ld generate approximately 38,000 gallons per day of purge 39 

### (DCN SGE 00300 ; DCN SGE00616 ). This purge stream would consist of calcium chloride at concentrations l ower than 35 percent (DCN SGE 00300 ). One CWT facility with a crystallization treatment unit reported that if the calcium chloride concentration is at least 35 p ercent, the purge stream would have high value for other industrial applications (DCN SGE 00300 ). As a result, this CWT facility is a lso considering additional purge treatment (e.g., flash evaporation and cooling to further concentrate the purge

stream and increase the calcium chloride concentration ) (DCN SGE 00300 ; DCN SGE00616 ). In the absence of this flash evaporation system, the CWT facility plans to dispose of the calcium chloride by off

- site underground injection, or by returning it to UOG operators to use as a drilling fluid additive (DCN SGE 00300 )

. 40



### Since crystallization is an evaporative technology, organic compounds removed from the wastewater may be released to the atmosphere along with evaporated water vapor. Therefore, consideration of air emissio ns may be necessary.

Energy Use

C rystallization is an energy

- intensive and expensive treatment technology. This is because nearly all of the influent wastewater is evaporated to generate solid crystals (DCN
SGE 00095 ). Most units use natural gas burners as an energy source, but a variety of alternatives have been tested.

V endors attempt to offset energy demand by designing units that can use alternative energy sources, such as waste heat from compressor stations and solar energy (DCN SGE 00160 ). For example, Epiphany Solar Water Systems offers a crystallizer treatment unit that use s concentrated solar energy 41 

### (DCN SGE 00298.A21 ). When this report was written, Consol Energy, Inc. was pilot testing the system.

Table B

- 25 reports energy use per barrel of influent wastewater based on data reported by vendors. Table B

- 25 also includes associated influent TDS concentrations

, and resulting water recovery percentages. Because many of the units require both electric al energy and fuels , the energy requirement is presented in three columns: electrical (e.g., pumps , compressors ), fuel (e.g., natural gas for a burner), and the total energy required if reported.

39 Actual waste generation will vary by influent TDS concentration. This estimation was based on Marcellus wastewater with a typical TDS concentration of 100,000 mg/L (DCN SGE00300).

40 Calcium chloride may be added to drilling fluid to increase density and/ or increase electrical conductivity.

41 In this technology, solar thermal energy is collected onto mirrors and reflected into a central point. A working fluid with high thermal energy capacity (e.g., antifreeze) is passed through this central point to be he ated by the concentrated solar energy. This process essentially replaces step 6 in Figure B

- 19

.Part B



### 73 Table B

- 25 . Energy Usage of Crystallization in UOG Extraction Wastewater Applications

Vendor Technology

Name Influent TDS concentration

(mg/L) Energy Consumption (kWh, unless

otherwise noted, per bbl of influent

wastewater) Water Recovery (%) Additional Notes Reference
ID Electrical Steam (tons) a Total

INTEVRAS EVRASTM Produced water TDS levels NR N/A 1.9

– 2.1 b No recovery Uses waste heat from compressor stations or powered by natural gas 32

Epiphany Solar Water Systems E3H Produced water TDS levels NR N/A NR NR Uses concentrated solar

energy 66

Heartland Technology Partners, LLC LM

- HT® Produced water TDS levels NR N/A NR NR Uses waste heat from compressor stations or powered by natural gas 116

Not specified Not specified 130,000 0.5

– 1.7 ~14 NR NR Assuming waste steam is available 51

Not specified Not specified >40,000 NR NR 4.2

– 11 NR None 57

N/A

— Not available; NR

— Not reported ; TDS

— total dissolved solids; mg/L

— milligrams per liter; kWh

— kilowatt

- hour; bbl

—

barrel

.

a

— Waste steam from other industrial processes may be used to improve economics.

b

— Vendor reported the power requirement for the pumps and fans alone as 30 kW to treat 325 barrels per day, assuming waste heat is available . Assuming a 90 to 95 percent capacity, electrical consumption is betw een 1.9 and 2.1 kWh per barrel of influent wastewater. Additional energy is required if waste heat is not available.Part B



### 74 2.2.3 Costs

Capital costs of crystallization include co sts for the pretreatment system

, evaporation/condensation unit , low

- pressure pumps, and monitoring equipment. T he operating

cost s associated with crystallization include energy for low

- pressure pumps and evaporation and labor costs (DCN SGE00638.A12; DCN SGE00638.A11)

. The energy costs are highest among all technologies used to treat UOG extraction wastewater, unle ss low

- grade or waste energy is used (such as waste heat from compressor stations or solar energy) (DCN SGE 00124 ; DCN SGE 00264 ; DCN SGE 00110 ). F actors that affect the costs for crystallization include feed water quality, energy source, and disposition of residuals

.

Table B

- 26 shows approximate capital and operating cost for crystallization when a treatment system is purchased or rented

. Table B

- 27 shows approximate costs UOG operators
pay CWT facilities to treat UOG extraction wastewater using crystallization (including pretreatment)

. One CWT facility the EPA visited (not listed in Table B

- 27 ) considered adding crystallization to their existing evaporation/condensation process. The company investigated at least eight different vendors and conc luded that the technology was too expensive given the current price of gas oline . The biggest problem was the lack of market for the solid waste (i.e., salt). Through their research, the CWT facility estimated that the crystallization process, alone, would cost UOG operators $15 to $18 per barrel ($0.36 to $0.43 per gallon), including pretreatment (DCN SGE 00299). However, other CWT facilities in the Marcellus have multiple facilities already permitted that will use crystallization (DCN SGE00300).

Table B

- 26

. Crystallization Capital and O&M Costs for UOG Extraction Wastewater Applications

Vendor or Technology Name System

Description Influent

TDS (mg/L) Cost

Basis Capacity

(MGD) Capital

Cost ($ per gpd) O& M

Cost ($ per bbl) Rental or Effective Cost ($ per bbl) b Reference

ID

NR Unit 100,000 a Purchase 0.21 33.00 NR NR 70

NR Plant 110,000

– 130,000 Purchase

or Rental 0.25 120.00 3.50 11.00 to 22.00 51

NR System 40,000

– 150,000 Purchase 0.25 45.00 3.70 NR 73

GE Plant ~130,000 NR 1.0 NR NR 5.00 to 6.80 129

NR System NR Rental NR N/A N/A 1.00

– 3.00 more than evaporation/ condensation 47

N/A

— Not available; NR

— Not reported; TDS

— Total dissolved solids; mg/L

— milligrams per liter; MGD

— million gallons per day; gpd

— gallons per day; bbl

— barrel.

a

— This represents the TDS of the untreated wastewater. The influent wastewater to crystallization is the effluent concentrated brine from evaporator/condensation, which contains TDS concentrations close to the supersaturation concentration (250,000 to 300,000 mg/L).
b

— Represents r ental cost if the cost basis was rental and is inclusive of O&M. Represents total effective cost when cost basis is purchase, which includes amortized capital costs and O&M costs combined. When the cost basis is purchased, total effective cost is only incl uded when a reference reported amortized capital costs.

c

— Cost for the entire plant and all treatment onsite.Part B



### 75 Table B

- 27

. Crystallization Cost s to UOG Operator s at CWT Facilities

CWT Facility
Name Treated

Wa stewater Typical Influent

TDS concentration (mg/L) a Type of Service Cost to UOG Operator at CWT Facilities ($ per bbl) Reference

ID

Fairmont Brine Processing Shale gas 250,000 to 300,000 Discharge to surface

water or reuse 6.00 194

Eureka Resources,
LLC Shale gas 250,000 to 300,000 a Discharge to POTW or

reuse 10.80

– 11.00 b 70

N/A N/A >100,000 Reuse only 5.00

– 6.80 c 129

N/A

— Not available; NR

— Not reported ; TDS

— total dissolved solids; mg/L

— milligrams per liter; bbl

— barrel

.

a

— The typical influent to the plant has a TDS concentration around 100,000 mg/L. The TDS concentration presented is the assumed concentration for the actual influent to the crystallization unit, which is the effluent wastewater from an evaporator.

b

— Cost may be as low as $7 per barrel to the UOG operator if the residuals can be sold for be neficial use to other industries.

c

— Costs were reported assuming that the hypothetical CWT facility is owned and operated by the vendor, and that the UOG operator brings wastewater to the plant for treatment on a contractual basis.

Note: Data in this table are as

- reported in literature.



### 2.2.4 Summary of Vendors for UOG Extraction Wastewater

Fairmont Brine Processing , LLC in Fairmont, West Virginia

, is a CWT facility that accepts UOG extraction wastewater from Marcellus and Utica shale operators and treats it using a crystallizer. Fairmont’s process includes chemical pre treatment of the wastewater , which is then crystallized into sodium chloride crystals. The EPA identified a second company, Eureka Resources, LLC, that accepts UOG extraction wastewater from operators and is currently constructing a crystallizer as an add

- on treatment unit to evaporation/condensation at their existing CWT facility in Williamsport, Pennsylvania

. Eureka Resources, LLC is also constructing a second CWT facility in the Marcellus that will include crystallization (DCN
SGE 00523 ; DCN SGE 00616 ). EPA also visited a UOG operator who uses a crystallization treatment unit at one of their compressor stations allowing them to utilize waste heat (DCN
SG E01047 ).

EPA identified several vendors that offer these units, most of which have been pilot tested. Table B

- 28 summarizes data gathered from vendors offer in g crystallization units.Part B



### 76 Table B

- 28

. Crystallization Technologies for Treating UOG Extraction W astewater

Vendor Technology

Name System

Description Surface

Footprint (ft 2 ) a Capacity

(bpd) Other Notes Reference
ID

INTVRAs Technologies,
LLC. EVRASTM Semi

- mobile 820 200

– 400 Can be designed for low

grade waste heat utilization. 102 ; 32 ; 30

Heartland Technology Partners, LLC LM

- HT® Mobile NR 1,000 Can be designed for low

grade waste heat utilization. 116 ; 173 Stationary NR 6,300

Epiphany Solar Water Systems E3H Non

- mobile NR, fits

on well pad 10

– 100 Each unit is sized for one

well, but can be scaled up for a multi

- well pad. Uses concentrated solar energy in lieu of fuel. 66

NR

— Not reported ; ft 2

— square feet; bpd

— barrels per day

.

a

— Only includes the primary treatment unit

, not storage for wastewater, chemicals, or sludge ( solid waste ).



### 2.3 Reverse Osmosis

Application of reverse osmosis (RO) is limited to treatment of flowback or long

- term produced water from formations where TDS is relatively low compared to typical concentrations. The typical upper limit of TDS concentration in the wastewater for cost

- effe ctive operation is 45,000 to 50,000 mg/L (DCN SGE00331; DCN SGE 00683 ; DCN SGE 00161 ).

This section describes the RO process, treatment capabilities and limitations, treatment cost, and vendors that the EPA is currently aware of that market the technology fo r UOG extraction wastewater treatment

.

2.3.1 How RO Works

The following subsections describe reverse osmosis operating principles and how the process has been used to treat UOG extraction wastewater.

Principle

In RO, pressurized water is forced through a semi

- pe rmeable membrane to separate the water from dissolved solids. S emi

- permeable membranes allow water but not dissolved solids to flow through (they are permeable to water but impermeable to dissolved solids). Like other filtration technologies, the RO membra ne separates constituents from wastewater based on size differences. However, unlike other filtration technologies, RO membranes also separate constituents based on electrostatic charge. RO membranes will repel most charged particles (ions), but allow neut ral molecules like water to pass through. Because salts, such as sodium (Na + 

### ) and chloride (Cl - 

### ), are ions that are repelled by RO membranes, RO is well suited for desalination (DCN SGE 00166 ).

The name “reverse osmosis” derives from osmosis: the spontaneo us flow of water from a dilute solution to a concentrated solution, which occurs when the two solutions are separated byPart B



### 77 a semi

- permeable membrane (DCN SGE 00166 ). In “reverse” osmosis, water flow s from a concentrated solution to a dilute solution. This is accomplished when a pressure greater than the osmotic pressure is applied to the concentrated water. When the pressure applied to the concentrated water exceeds the osmotic pressure, the osmosis process reverses and the water is driven through the membrane to the dilute solution . The membrane prevents B + 

### ions from passing, leaving a concentrated solution behind (DCN SGE00167 ). Figure B

- 20 illustrates RO when a pressure greater than the osmotic pressure is applied to the concentrated water. Because the applied pressure must be greater than the osmotic pressure, higher concentra tion s require higher applied pres sure (DCN SGE00166 ).

Figure B

- 20 . Flow Diagram of Reverse Osmosis Principle

Process Description

In a typical wastewater treatment RO unit, hydraulic pumps appl y pressure to the influent wastewater. The process requires pressures ranging from 250 to 1,180 psi, depending on the TDS of the influent waste water (DCN SGE 00175 ). The applied pressure pushes the water through the membrane while the membrane blocks the ions and other dissolved material (TDS) from passing. The influent wastewater is separated into two separate streams: treated wastewater and concentrated brine. In the literature, the treated wastewater is referred to as permeate and the concentrated brine is referred to as concentrate (DCN SGE 00264 ).

RO membranes are made from man

- made polymers, such as synthetic cellulose or polyamide (e.g., nylon). All membrane materials have a retention rating, which describes the size of materials retained by the membrane. The reten tion rating can be called the molecular weight cutoff (MWCO), based on the molecular weight of material retained by the membrane. The lower the cutoff, the smaller the molecules that will be retained by the membrane. The MWCO varies between membranes and c an affect the performance of the RO process and operatin g costs (DCN SGE 001 67 ). A typical membrane pore size is between 0.0001 and 0.001 micron s (4 to 40 billionths of an inch) and have treatment rates of 8 to 12 gallons per square foot of membrane perPart B



### 78 day . At these rates, a typical unit will require hundreds to thousands of square feet of membrane to treat typical desired rates of wastewater by the UOG industry. To reduce the space required by membrane systems, the membranes are often rolled into spirals ( DCN SGE 00167 )

.
During RO treatment , the influent wastewater first enters a hydraulic pump where it is pumped to the required pressure. The pressurized wastewater flows into the RO vessel, where the membrane separates the permeate from the concentrate. Figure B

- 21 illustrates how a spiral

wound membrane separates the influent wastewater into permeate and concentrate streams. The pressurized influent wastewater enters one end of the wound membrane, which is wrapped around a permeate collection tube. The high pressure in the influent stream drives the water through the wound membrane and into the permeate collection tube. However, only the water is able to pass through the membrane, leaving the concentrate behind. The two streams exit the membrane device in parallel with the permeate in the collection tube and the concentrate outside.

Figure B

- 21 . Spiral

- Wound Membrane F low Diagram

2.3.2 Capabilities and Limitations

Th is subsection describe s the targeted constituents and effectiveness, design and operation considerations, residuals, and energy use of RO

.
Targeted Constituent

s and Treatment Effectiveness

RO is used to remove di ssolved organic and inorganic constituents, such as ions, acids, sugars, dyes, natural resins, salts, biochemical oxygen demand ( BOD ) , COD, and radioactive elements from wastewater (DCN SGE 00264 ). The typical upper limit of TDS concentration inPart B



### 79 the wastewater for cost

- effective operation is 45,000 to 50,000 mg/L (DCN SGE 00683 ; DCN SGE 00161 ). Higher TDS concentrations increase osmotic pressure to the point where excessive energy is required to generate enough applied pressure to reverse the osmoti c flow, making the process prohibitively expensive. RO can produce effluent TDS concentrations of 200 to 500 mg/L, depending on the composition of the influent wastewater (DCN SGE 00095). Alexander,
2011 (DCN SGE 00161) suggests that RO is the most cost

- effe ctive treatment for UOG extraction wastewater when TDS is less than 30 ,000 mg/L

.

Table B

- 29 shows performance data for RO in UOG extraction wastewater applications

. Th e table includes untreated influent constituent concentrations, effluent constituent concentrations, and the resulting constituent removal efficiencies.

Table B

- 29

. RO Removal Efficiency in UOG Extraction Was tewater Applications

Constituent Typical Influent Range (mg/L) a Typical Effluent

Range (mg/L) a Removal Efficiency (%) b Reference ID

TDS 8,000

– 31,000 41

– 400 > 99 76 ; 127 ; 

### 8 ; 142

Chloride 3,600

– 21,000 18

– 240 > 99 142 ; 127 ; 76 ; 

### 8 ; 77

Sodium 3,300

– 17,000 37

– 220 >98 142 ; 77 ; 

### 8

Metals

Aluminum 0.35

– 1 ND

– 0.2 >80 77

Arsenic 0.037 ND >99 76

Barium 0.15

– 35 ND

– 0.1 32

– >99 76 ; 77 ; 

### 8

Boron 15

– 30 ND

– 8.4 64

– 98 

### 8 ; 127

Cadmium 0.014 ND >99 76

Calcium 37

– 350 5 >97 76 ; 77 ; 

### 8

Chromium 0.068 ND >99 76
Copper 0.068

– 0.13 0.020

– 0.025 70

– 80 76 ; 77

Iron 1

– 13 ND

– 0.5 >92 76 ; 77 ; 

### 8

Lead 0.015 0.003 80 77 Magnesium 25

– 520 ND

– 8.2 80

– 98 76 ; 77 ; 

### 8

Manganese 0.075

– 0.10 0.015

– 0.10 80 77 ; 

### 8

Nickel 0.056

– 0.10 0.025

– 0.10 55 76 ; 

### 8
Phosphorous 1.2 ND >99 76

Potassium 140

– 320 5 96

– 98 77 ; 

### 8

Silver 0.087 0.001 99 76

Strontium 6

– 24 0.1 >98 77 ; 

### 8

Thallium 0.038 ND >99 76Part B



### 80 Table B

- 29

. RO Removal Efficiency in UOG Extraction Was tewater Applications

Constituent Typical Influent Range (mg/L) a Typical Effluent

Range (mg/L) a Removal Efficiency (%) b Reference ID
Organics
Benzene (μg/L) 0.005 ND >99 76
Bis(2

- chloroethyl)ether (μg/L) 0.038 ND >99 76

BTEX (μg/L) 28,000

– 80,000 ND >99 127
Diesel range organics (μg/L) 77,000

– 1,100,000 ND >99 127

Ethylbenzene (μg/L) 0.004 ND >99 76 Gasoline range organics (μg/L) 88,000

– 420,000 ND >99 127

Oil and grease 14

– 2,400 ND

– 1.1 >92 76 ; 127
Phenol (μg/L) 39 ND >99 76

TOC 6

– 65 1

– 3 83

– 95 

### 8 ; 76
Toluene (μg/L) 6 0. 97 83 76 Xylene (μg/L) 24 ND >99 76

Other Alkalinity 330

– 1,000 31

– 81 86

– 97 77 ; 76 ; 

### 8

Ammonia 40

– 53 1.1

– 1.9 >97 76 ; 

### 8

BOD 200 9 95 76

COD 250 2 99 76

Fluoride 2 0 >99 76

Hardness 560

– 1,200 10 98 76 ; 

### 8

Methanol 40

– 1,500 ND >99 127

Silica 14

– 40 0.43

– 5 >87 77 ; 

### 8

Sulfates 10

– 100 ND >99 127 ; 76 ; 

### 8

TSS 18

– 65 ND

– 10 >44

– 97 

### 8 ; 76

Radioactives
Gross Alpha (pCi/L) 270 ND >99 76
Gross Beta (pCi/L) 72 ND >99 76 Radium 226 (pCi/L) 82 ND >99 76
Radium 228 (pCi/L) 7 ND >99 76 Uranium 234 (pCi/L) 1 ND >99 76 Uranium 238 (pCi/L) 1 ND >99 76

ND

— Not detected; mg/L

— milligrams per liter; μg/L

— micrograms per liter; pCi/L

— picocuries per liter; TDS

— total dissolved solids; BTEX

— benzene, toluene, ethylbenzene, and xylenes; TOC

— total organic carbon; BOD

— biochemical oxygen demand; COD

— chemical oxygen demand; TSS

— total suspended solids.

a

— Units are in mg/L unless otherwise specified in the constituent column.Part B



### 81 b

— The EPA calculated all removal efficiencies using paired influent and effluent concentrations reported in literature. Attachment 1 ( DCN SGE00692.A01 ) presents these removal efficiency calculations. The number of data points that these removal efficiencies are based on are also presented in Attachment 1.



### Design and Operation Considerations for UOG Extraction Wastewater

Because RO is only efficient when treating wastewater with TDS concentrations less than 50,000 mg/L, it is generally only used to treat flowback wastewater (which has relatively low TDS), or long

- term produced waters from UOG formations that generate relatively low TDS concentrations (DCN SGE 00331 ).

A number of other limitations must also be considered in the design and operation of RO units. The most challenging problem with RO is that

, without proper pretreat ment, membranes are subject to fouling. 42 

### Constituents that cause fouling include metal hydroxides, colloidal and particulate foulants, precipitates or salts, organic material s (e.g., oil , humic acids ), and biologicals (e.g., microbes, bacteria) (DCN SGE001 61; DCN SGE00264 ). Membrane fouling can lead to reduc ed treatment efficiency and high volumes of concentrate d brine

.
To prevent scaling and reduce membrane fouling, pretreatment and chemical addition are typically required (DCN SGE00264; DCN SGE 00683). Us ua lly, scale control occurs first, and can include pH adjustment or antiscalant addition. After scale control, the wastewater is filtered to remove particulate matter (TSS). Finally, wastewater should also be disinfected to reduce biofouling of the membran e (DCN SGE0016 7 ). Even with proper pretreatment, occasional chemical addition may be needed to clean buildup from the membrane. Cleaning c hemicals include hydrochloric acid and sodium hydroxide (DCN SGE 00264 ). Examples of pretreatment specifically used in UOG applications include AOP, induced gas flotation, filtration, and electrocoagulation.

Residuals

RO generates c oncentrate d brine . At higher influent TDS concentrations, water recovery decreases

, resulting in a larger proportion of concentrate and higher disposal costs (DCN SGE 00095 ; DCN SGE 00264 ; DCN SGE 00109 ). High water recovery (75 to 90 percent) and reduced concentrated brine generation is possible if influent TDS is below approximately 25,000 mg/L (DCN SGE 00095 ). One vendor estimated that water recovery drops to 60 percent when TDS reaches 30,000 m g/L and to 25 percent when TDS reaches 50,000 mg/L (DCN SGE 00161 ). For comparison, flowback from UOG wells typically contain TDS concentrations between 30,000 mg/L and 120,000 mg/L and long

- term produced water from UOG wells may have TDS concentrations as high as nearly 400,000 mg/L (DCN SGE00704) 43



### .

Table B

- 30 shows results of RO water recovery as a function of influent TDS concentration using Woodford shale wastewater. As TDS concentration s increase above

42 Membrane fouling occurs when dissolved and suspended solids deposit onto a membrane surface, degrading overall performance. Specific declines in performance include a decrease in permeate quality and water recovery percentage.

43 The reported flowback range represents the 25 th to 75 th percentiles of TDS concentrations.Part B



### 82 approximately 30,000 mg/L , the percent recovery decreases which results in higher operating costs (e.g., higher pressure requi red, increased brine disposal ) (DCN SGE 00070).

Table B

- 30 . Influent TDS Concentration Versus Water Recovery

Influent TDS to RO (mg/L) Water Recovery Percent (%)

20,000 95

33,000 95

42,000 51

64,000 42

TDS

— total dissolved solids; mg/L

— milligrams per liter.

Source: DCN SGE 00070. 

### The overall performance and treated wastewater recovery is also affected by the desired effluent TDS concentration

. If the lowest TDS concentration possible is desired

, treated

wa stewater recovery will decrease as illustrated in Figure B

- 22

.

Source: DCN SGE 00166

.


### Figure B

- 22 . TDS Concentration Versus Water Recovery Percent

In UOG applications, d isposal methods used for concentrate d brine include evaporation in ponds (DCN SGE 00374 ; DCN SGE 00298.A24 ; DCN SGE 00369 ) and injection to a Class II disposal well (DCN SGE 00298.A24 ; DCN SGE 0 0369 )

.
Energy Use

RO requires electrical energy to run the pumps that pressurize the influent wastewater (DCN SGE 00175 ). A general rule of thumb in industry is that for every 100 mg/L of influent TDS, an additional 1 psi of applied pressure is required (D CN SGE 00161 ). For example, sodium chloride concentration of 13,000 mg/L results in an osmotic pressure of 150 psi

. W hen thePart B



### 83 concentration increases to 35,000 mg/L, then the osmotic pressure increases to 398 psi (DCN SGE 00166 ) . When the required applied pre ssure increases, then energy requirements also increase.

In general, RO pumps are powered by electricity purchased from off

- site gener ation (i.e., the grid). Burnett, 2011 (DCN SGE 00163 ) suggested alternative methods of powering RO units. These methods include microturbines (which require low grade gas), solar panels (if the system has low pressure requirements), and wind turbines. Burnett described a mobile wind turbine unit that is capable of providing enough power for pretreatment operations such as m ed ia filtration

, but not enough to run the high

- pressure hydraulic pumps required for RO.

Table B

- 31 reports energy use per barrel of influent wastewater. Influent an d effluent TDS concentrations are also included with the final water recovery percent. The reported data confirm the general trend that higher influent TDS concentrations result in higher energy requirements. The data also confirm that as influent TDS conc entration increases, water recovery percentage decreases.

Table B

- 31 . RO Energy Use in UOG Extraction Wastewater Applications

Vendor Technology Name Influent TDS concentration (mg/L) Energy Use

(kWh per bbl) Water

Recovery (%) Reference

ID Ecosphere Technologies, Inc. Ozonix TM, includes AOP for pretreatment 14,000 2.2 75 76 ; 57

Not specified N/A, includes filtration for pretreatment 500

– 25,000 0.02

– 0.4 a 60

– 85 57 ; 16

Not specified Mobile unit designed by Chevron, includes electrocoagulation for pretreatment 45,000 1 NR 110

Not specified N/A, includes softening and

filtration for pretreatment 20,000

– 47,000 0.5

– 1.6 30

– 60 57 ; 16

NR

— Not reported ; mg/L

— milligrams per liter; kWh

— kilowatt

- hour; bbl

—

barrel; TDS

— total dissolved solids

.



### 2.3.3 Costs

The major capital costs associated with RO are the RO unit and reliable hydraulic pumps that can withstand the corrosivity of the high TDS in UOG extraction wastewater . The major

oper ating costs associated with RO include membrane replacement, which is expected to occur every three to seven years for oil and gas wastewater applications according to Colorado School of Mines (CSM) (2009). According to Burnett

, 2011 (DCN SGE 00163 ), UOG ex traction

wastewater treatment requires annual membrane replacement. The second major cost is the

e nergy required for the pumps (DCN SGE 00264 ).

Table B

- 32 shows appro ximate RO capital and operating cost s . The reported data show that overall cost of RO units depends on influent wastewater quality. As influent TDS concentrations increase

, the capital and operational costs increase. This is because larger and more robust pumps and vessels are required as the applied pressure increases (with the increasePart B



### 84 of TDS). Table B

- 33 shows approximate costs UOG operators pay CWT facilities to tre at UOG extraction wastewater using RO (including pretreatment)

.

Table B

- 32 . RO Capital and O&M Costs for UOG Extraction Wastewater Applications

Vendor and Technology Name System

Description Influent

TDS (mg/L) Capacity

(MGD) Cost

Basis Capital

Cost ($ per gpd) O&M

Cost ($ per bbl) Rental or Effective Cost ($/bbl) a Reference

ID

General Mobile system

with EC and
DAF ~50,000 0.063 Purchase and Rental 18.00 1.50 4.40 110

Ecosphere Energy Services, Inc. Mobile system 20,000

– 30,000 0.14 NR NR NR 3.50

– 4.00 99

Siemens Mobile system ~30,000 NR Purchase 1

– 4 NR NR 33

General Mobile system

with filtration 20,000

–

47,000 NR Purchase 3.00

– 7.00 0.08 NR 57

NR

— Not reported; mg/L

— milligrams per liter; MGD

— million gallons per day; gpd

— gallons per day; bbl

— barrels; TDS

— total dissolved solids.

a

— Represents rental cost if the cost basis was rental and is inclusive of O&M. Represents total effective cost when cost basis is purchase, which includes amortized capital costs and O&M costs combined. When the cost basis is purchased, total effect cost is only included when a reference reported amortized ca pital costs.



### Table B

- 33 . RO Costs to UOG Operator s at CWT Facilities

CWT Facility
Name Type of

UOG Influent TDS concentration (mg/L) Type of Service Cost to UOG Operator at CWT Facilities ($ per bbl) Reference

ID

Anticline Disposal, LLC Tight gas ~20,000 Discharge treated wastewater to surface water 2.50

– 3.50 24

Red Desert Reclamation, LLC Tight gas ~20,000 Reuse treated wastewater in fracturing and evaporate concentrated brine in ponds 2.00

– 3.00 137

m g/L

— milligrams per liter; bbl

— barrel ; TDS

— total dissolved solids

. Note: Data in this table are as

- reported in literature.



### 2.3.4 Summary of Vendors for UOG Extraction Wastewater

To date, the EPA has found that only CWT facilities are removing TDS from UOG extraction wastewater with reverse osmosis (RO) technology. However, RO has also been pilot

tested by UOG operators for reuse applications. The EPA identified full scale applicat ions of reverse osmosis treatment systems in the Mes aver de and Lance tight gas formations at CWT facilities. 44 

### In addition, the EPA identified several vendors offering mobile RO units that can be used by UOG operators, most of which have been pilot tested for UOG extraction wastewater.

44 Th is area is commonly referred to as the Pinedale field, which includes the Mesaverde and Lance tight gas formation s

.Part B



### 85 Table B

- 34 s ummarizes data gathered from vendors marketing RO units for treating UOG extraction wastewater

.

Table B

- 34

. RO Technology Vendors for UOG Extraction W astewater

Vendor Technology

Name System

Description Surfac e

Footprint (ft 2 ) a Capacity

(bpd) Other Notes Reference
ID

GeoPure Hydrotechnologies NR NR NR 5,000 None 101

M

- I SWACO GPRI

DesignsTM NR NR 5,000 None 103

Veolia Water Solutions & Technologies OPUSTM Mobile or stationary NR 10,000 Includes chemical softening, degasification, and media filtration 112 ; 104

Omni Water Solutions, Inc. HIPPO® Mobile NR 2,500

– 10,000 Includes pretreatment 122

Siemens Water Technologies FracTreat Mobile NR NR Includes pretreatment 33 ; 15

Ecosphere Technologies, Inc. Ozonix TM Mobile 380 7,200 Includes AOP as pretreatment 99 ; 76

NR

— Not reported; ft 2

— square feet; bpd

— barrels per day.

a

— Only includes the primary treatment unit

, not storage for wastewater, chemicals, or sludge ( solid waste )Part C



### 86 

## Part C. P OTENTIAL 

## T ECHNOLOGIES



### In addition to the established technologies described above, the EPA identified the following treatment technologies not currently used to treat UOG extraction wastewater , but which may be applied in the future due to their use for other similar wastewaters, such as drinking water treatment of brackish or sea water :

 Ion Exchange

 E lectrodialysis R eversal (EDR)

 Capacitative Deionization (CDI)

 Membrane Distillation

 Forward Osmosis

Section C contains two parts: Section C.1 is a table documenting the potential of each technolog y for application in UOG extraction wastewater treatment and Section C.2 contains a detailed description of how each technology works.

1 P OTENTIAL 

### T ECHNOLOGIES FOR 

### A PPLICATION IN 

### UOG E XTRACTION 

### W ASTEWATER 

### T REATMENT



### Table C

- 1 presents technologies that the EPA identified as being potentially relevant for the treatment of UOG extraction wastewater. Table C

- 1 presents a summary of each technology, including the capabilities of the treatment technology, design and operation considerations, and residuals

.Part C



### 87 Table C

- 1 . Potential Technologies for Application in UOG Extraction Wastewater Treatment

Treatment Technology Potential Application for

UOG Extraction
Wastewater Treatment Design and Operation Considerations Residuals Reference ID Ion Exchange Removes arsenic, metals,

nitrates, radium, salts, and uranium. Pretreatment to prevent resin fouling by TSS, oil and

grease. Use of scavenger exchange resins to selectively remove organic chemicals which compete with targeted constituents during ion exchange. Concentration of mixed salts in produced water, requiring a two

- stage process. Regenerate containing TDS, metals, hardness, calcium, magnesium, sodium, sulfa te, chloride, nitrates, and radioactive elements. Expected water recovery less than 97 percent. 10 ; 27 ; 36 ; 37 ; 39 ; 45 ; 58 ; 142 ; 176

Electrodialysis Reversal Removes dissolved charged

ions, including: TDS, chloride, sodium, calcium, magnesium, hardness, sulfate, bicarbonate, nitrate, fluoride, barium, potassium, iron, phosphate, total organic carbon ( TOC ) , and
SAR. Pretreatment to reduce membrane fouling, including scaling control, filtration, or disinfection. Membrane life expectancy is about ten years. Cathode membranes have a longer life expectancy than anode membranes. Cathode and anode plates must be replaced every two to three years. Low maintenance r equirements. Concentrated brine stream ranging from 10

- 20 percent of the influent wastewater volume. 10 ; 16 ; 20 ; 38 ; 39 ; 56 ; 57

Capacitative Deionization Removes dissolved charged

ions, including: nitrates, ammonia, perchlorate, arsenic, fluoride, chromium, ion, and organic acids Performance factors include: electrode thickness, spacer geometry, cell design, operational settings. CDI modules operated in series can treat higher TDS concentrations while modules in parallel can do treatment at higher flow rates.
Pretreatment using microfiltration or other appropriate technologies to remove contaminants such as particulates, biological matter, or organic constituents. Long electrode life expectancy with little maintenance. Regeneration time can be lengthy or incomplete with hig h salinity water. Concentrated brine

stream. Expected water recovery of 75

- 90 percent. 188 ; 186 ; 57 ; 111Part C



### 88 Table C

- 1 . Potential Technologies for Application in UOG Extraction Wastewater Treatment

Treatment Technology Potential Application for

UOG Extraction
Wastewater Treatment Design and Operation Considerations Residuals Reference ID
Membrane Distillation Removes non

- volatile

constituents, including: ions, macromolecules, colloids, cells, and metals Performance depends on membrane properties, design of the module, operating temperature and flow rate, and partial pressur e established by condensate stream. Minimal pretreatment is required to remove large particles and surfactants, and reduce membrane fouling. Capable of treating wastewater with TDS > 50,000

- 70,000 mg/L, up to 200,000 mg/L. Flux through the membrane decreases significantly with increasing salinity. Membranes can be cleansed with citric or hydrochloric acid to remove deposits. A decline in maximum flux capacity may result if not properly cleansed. Relatively low energy requir ements. Optimal operating temperature > 68o F. Low capital and maintenance costs, compared with costs for pressure

- driven membrane processes. Volatile organic compounds ( VOCs ) pass through the membrane with water vapor. Expected water recovery rate of 60

- 9 5 percent. 187 ; 57 ; 109 ; 114 ; 115 ; 118 ; 120 ; 130

Forward Osmosis Removes TDS, ammonia,

organic carbon, boron, barium, calcium, iron, magnesium, potassium,

stro ntium, alkalinity, bromine, silica, sodium, sulfates, gross alpha, and gross beta. Requires additional processes to produce a high quality effluent. Requires little oversight, flexible with sensitivity to low and high pH streams, and operates semi

- continuo usly, requiring little downtime for cleaning. Operation at high pressure increases membrane fouling. Operates at ambient temperature, reducing energy requirements and costs. Treatment unit operators must select the draw solution. Highly soluble solutes
min imize scaling. Concentrated brine and dilute draw solution. 57 ; 117 ; 131 ; 136Part C



### 89 2 D ESCRIPTION OF 

### H OW 

### E ACH 

### P OTENTIAL 

### T ECHNOLOGY 

### W ORKS



### 2.1 Ion Exchange

Ion exchange treatment is used to remove ionic species from water using an ion exchange resin. Ion exchange is commonly used in water softening, where calcium (Ca +2 

### ) and magnesium (Mg +2 

### ) are the ions targeted for removal. Ion exchange has also been used to remove sodium (Na + 

### ) and bicarbonate (HCO 3 - 

### ) ions from coalbed methane (CBM) wastewater in the Powder River Basin (PRB)

.

TDS in UOG extraction wastewater contains both cations and anions

, primarily consisting of sodium (Na + 

### ), calcium (Ca +2 

### ), and chloride (Cl - 

### ) (DCN SGE 00704) (see Part A.1 ); therefore, removing TDS from UOG extraction wastewater via ion exchange would require both cationic and anionic exchangers in a two

- step process. Some UOG operators have also discussed removing select ions (e.g., boron) from UOG extraction wastewater using ion exchange (DCN SGE01067).

Ion exchange removes dissolved ions using an ion exchange resin

. Ion exchange resins, also known as cation (positively charged) and anion (negatively charged) exchangers, contain charged and mobile ions (e.g., sodium, hydrogen) on the surface that are available for exchange with other charged ions. Ion exchange resins are chosen based on what ions are targeted for removal; positively or negatively charged ions present in water are replaced with similarly charged ions present in the ion exchange resin. The types of ion exchange resins used depend on the ions targeted for removal and the concentrations o f anions and cations in the wastewater.

Figure C

- 1 illustrates the ion exchange process. Specifically, dissolved ions (B + 

### ) are removed from wastewater by absorption t o the resin surface; in exchange, the mobile ions (A + 

### ) from the resin transfer to the wastewater (see Figure C

- 1 (A)). The concentration of targeted ions differs from the concentration of ions present in the resin, creating a concentration gradient which drives the exchange of ions to and from the resin. This process continues until the concentration of A + 

### is the same in the resin and solution, as shown in Figure C

- 1 (B) (DCN SGE 00166)

.

Figure C

- 1 . Ion Exchange Process Using a Cation Exchange ResinPart C



### 90 As more and more ions are exchanged, the resin eventually requires regeneration through a reverse chemical reaction with a regeneration solution (DCN SGE001 6 7). Cation resin regeneration requires an acidic solution because acids provide free H+ cations. Anion resin regeneration req uires a basic solution because bases provide free OH

- anions (DCN SGE00166 ; DCN SGE 00690 ). Table C

- 2 shows regeneration solutions for different types of resins.

Table C

- 2 . Resin Type and Corresponding Regenerate Solutions

Resin Type Strongly Acidic Cation Exchanger Weakly Acidic Cation Exchanger Strongly Basic Anion Exchanger Weakly Basic Anion Exchanger

Form of resin Strong acid

- H + Weak acid

- H + Strong base

- OH - Weak base

- OH Regenerate HCl or H 2 SO 4 HCl or H 2 SO 4 NaOH NaOH, NH 4 OH, or
Na 2 CO 3 Source: DCN SGE 00166 ; DCN SGE 00690

. 

### Figure C

- 2 illustrates how concentration gradients drive the regeneration process in reverse of the ion exchange process. If a resin with a low concentration of A+ cations is placed in a solution with a high concentration of A+, a driving force is established due to the concentration difference between A+ in the regeneration solution and on the resin and B+ in the solution and on the resin. B+ cations from the resin will exchange places with A+ cations i n the solution, as shown in Figure C

- 2 (A). This process continues until the concentration of A+ is the same in the resin and solution, as shown in Figure C

- 2 (B) (DCN SGE 00166).

Figure C

- 2 . Regeneration Process of a Cation Resin

2.2 Electrodialysis Reversal

E lectrodialysis reversal (EDR) is an electrically driven membrane separation process with alternating stacks of cation and anion membranes that work to remove dissolved ions from the influent wastewater using an electrical current gradient. The current reversal facilitates backwashing, which minimizes scale build

- up on the anion and cation mem branes.Part C



### 91 EDR technologies have been used since the 1960s to generate drinking water by desalinating brackish water 45 

### and seawat er ( DCN SGE00264; DCN SGE00261 ; DCN SGE00175 ). The EPA identified a few instances where EDR was used to treat CBM wastewater (DCN S GE00141), but did not identify any specific instances where EDR was used to treat UOG extraction wastewater.

The principle of EDR builds on the principle of electrodialysis (ED). ED is an electrically driven membrane separation process. Electrical current is applied to a salty solution (e.g., UOG extraction wastewater) between two electrodes with opposite electrical charges (one positive and one negative), the positively

- and negatively

- charged ions in solution migrate to opposite electrodes. Between the positively and negatively charged electrodes lie ED membranes that are semi

- permeable, meaning that they are impermeable to water

, but are permeable to certain ions. Further, ED membranes are selective in what charged ions they allow to pass through. One type of ED membrane (cation membrane) allows only positively charged ions to pass; the second type (anion membrane) allows only negatively charged ions t o pass. These two phenomena: charged electrodes and selective membranes are the basis for ED treatment.

Figure C

- 3 illustrates the principle of ED. The gray

- shaded region in Figure C

- 3 represents a solution with the ionic constituent s A + 

### and B -



### . The water

- tight compartments formed by the selective membranes are called cells. The following steps explain what occurs in ED, as shown in Figure C

- 3 : (1) A positive charge is applied to the anode and a negative charge is applied to the cathode; (2) The negatively charged cathode attracts the A + 

### ions while the positively charged anode repels the A + 

### ions; (3) As the A + 

### ions move in the dir ection of the cathode, they pass through the cation membrane but are blocked by the anion membrane. As a result, the A + 

### ions are trapped in the central cell; (4) The positively charged anode attracts the B 

### ions while the negatively charged cathode repels the B 

### ions (5) As the B 

### ions move toward the anode, they pass through the anion membrane but are blocked by the cation membrane. As a result, the B 

### ions are trapped in the central cell; (6) Ion concentrations decrease in the lower and upper cells, while ion concentrations in the central cell increase.

45 The TDS concentration of brackish water is between freshwater (500 mg/L) and seawater (35,000 mg/L).Part C



### 92 Figure C

- 3 . Flow Diagram of Electrodialysis Principle

ED is effective at separating ions from water in principle, but in practice, operating with the flow of ions always in the same direction can result in membrane fouling. Membrane fouling can be minimized by using EDR, a process that uses the same principle as ED, but reverses the cathode and anode several times per hour. Reversing the cathode and anode ch anges the direction of ion flow, thus removing ions that have built up on the membranes ( DCN SGE00264 ; DCN SGE00175 ).

Figure C

- 4 shows the principle of EDR. Figure C

- 4 (A) shows an ED unit equipped with four selective membranes, forming five cells , through which w astewater enter s the unit . The arrangement of alternative anion and ca tion membranes traps the ions in cells 2 and 4 while treated waste water flows out of cells 1, 3, and 5. Figure C

- 4 (B) shows the charge reversal that occurs during EDR. The charge applied to the electrodes is reversed so that the cathode is on the left and anode is on the right. The process of reversing the electrode charges flushes out the brine cells by pulling away trapped ions from the membranes and preventing ions from building up in any particular cell. Cells 1, 3, and 5 accumulate the concentrated solution and cells 2 and 4 accumulate the dilute solution.Part C



### 93 Figure C

- 4 . Flow Diagram of Electrodialysis Reversal Principle

Figure C

- 5 is a flow diagram of EDR in wastewater treatment application. Electricity is applied to the cathode and a node metal plates, creating opposite charges. Following any necessary pretreatment, the influent wastewater enters a low

- pressure pump. The pressurized wastewater is split into separate streams as it enters the individual cells of the EDR unit. After the t reatment is complete, the treated wastewater and concentrated brine exit the unit.

Figure C

- 5 . Flow Diagram of Electrodialysis Reversal

EDR units can run in either batch or continuous operation. In additi on, multiple EDR units, or EDR “ stacks ”, can be operated in parallel or in series. Operating EDR stacks in parallelPart C



### 94 adds treatment capacity , while o perating stacks in series improves treatment performance ( e.g., TDS removal percent age ). Figure C

- 6 shows a flow diagram of EDR stacks in parallel (see Figure C

- 6 (A) ) and in series (see Figure C

- 6 (B)) . The solid black lines represent wastewater and treated wastewater, while the dotted black lines represent the concentrated brine streams. EDR units require recycling a portion (typically 10 percent) of the concentrate d brine stream to the influent to maintain pressures and equal flow rates on both sides of the membranes.

Figure C

- 6

. Flow Diagram of EDR Units in Parallel and in Series

2.3 Capacitive Deionization

Capacitive deionization (CDI) is an emerging treatment technology used to desalinate brackish water. CDI works by absorbing ions in porous electrodes and later releasing the ions into a concentrated waste stream. CDI has been demonstrated to remove negatively charged ions such as chloride, nitrate, and silica , and positively charged ions such as calcium, magnesium, and sodium ( DCN SGE01082 ). The technology has been pilot tested b y vendors and various research institutions specifically for treatment of UOG extraction wastewaters, but the EPA has not identified its use by UOG operators or CWT facilities.

A capacitor consists of two electric conductors, or electrodes, separated by a n insulating material. In CDI, the electrodes of the capacitor are constructed of a porous carbon or metal and the insulating material is the wastewater to be treated. The basic CDI process consists of two phases: purification and regeneration. In the puri fication phase, a low electrical voltage potential, approximately 0.8 to 1.5 volts (DCN SGE 00681), is applied, and ions move from the waste stream into the electrodes. The charged ions are pulled into electrodes with the opposite charge:Part C



### 95 the positive elect rode (i.e., the anode) attracts particles with negative charges (anions) and the negative electrode (i.e., the cathode) attracts particles with positive charges (cations). After the ions are removed, treated effluent is discharged from the CDI channel.

Ty pically within 20 minutes, the electrodes become saturated with ions and must be regenerated. In the regeneration phase of the CDI process, the electrical voltage potential is reduced or reversed to release the ions from the electrodes (i.e., desorption). Desorption regenerates the absorption capacity of the electrodes to their initial uptake, and generates a waste stream with high ion concentrations ( DCN SGE00673). The concentrated waste stream must be flushed from the cell and disposed of. When the electr ode is completely regenerated, the original voltage potential is restored, and the cell is ready for use. According to the vendor Atlantis Technologies, typical cycle times for their Radial Deionization super capacitor technology platform (RDITM) range from 2 to 40 minutes, with 2 to 20 minutes for purification and 2 to 20 minutes for regeneration (DCN SGE01082)

.
The capacitor’s two electrodes may be protected by a membrane that selectively allows positive or negative ions to pass. Only positive ions can pa ss through the cationic membrane, which protects the cathode, and only negative ions can pass through the anionic membrane, which protects the anode (DCN SGE 01051 ). Coating the electrodes with membranes also increases CDI’s removal efficiency by preventing ions from desorbing from the electrodes during purification and by promoting more complete desorption during regeneration ( DCN SGE01086 ). The removal efficiency of CDI with a membrane is as high as 97%, whereas the removal efficiency of CDI without membra ne is around 60% ( DCN SGE01087 ).

Figure C

- 7 and Figure C

- 8 are process flow diagrams for Atlantis Technologies RDITM, which has a selective membrane coating. Figure C

- 7 shows the purification process and Figure
C

- 8 s hows the regeneration process.

Source: Compiled by the EPA using information from literature ( DCN SGE01082 ).



### Figure C

- 7 . RDI TM 

### Purification Process DiagramPart C



### 96 Source: Compiled by the EPA using information from literature ( DCN SGE01082 )

.


### Figure C

- 8 . RDI TM 

### Regeneration Process Diagram

The porous carbon electrode is a key component in CDI. CDI perfo rmance depends on material properties of the carbon, such as total pore volume, pore size, pore connectivity, electronic conductivity, electrochemical stability and cost (DCN SGE00673 ). Ideal electrode material characteristics include a large ion

- accessibl e surface area, high electro

- chemical stability for the operating pH and voltage range, fast ion mobility within the pore network, high electric conductivity, low contact resistance between the electrode and the current collector, good wetting behavior, lo w costs and scalability, capable of being shaped into film electrodes, and low bio

- fouling (DCN SGE00673 ). Currently, electrodes are most often made from a porous carbon material, such as activated carbon or carbon aerogel.

While CDI and EDR treatment process es are similar , the EPA identified the following differences:

 Constituent s removed from wastewater in CDI collect within the porous electrodes, while constituent s removed from wastewater in EDR collect in brine chambers separated from treated wastew ater chambers by semi permeable ion selective membranes.

 Performance of CDI is highly dependent upon the surface area and adsorption properties of the electrode (DCN SGE 00264). EDR efficiency is highly dependent on membrane performance ( DCN SGE00264).

 CD I operates in cycles of purification and regeneration, generating intermittent streams of treated wastewater and concentrated brine. EDR operates continuously, generating treated wastewater and brine streams (DCN SGE01082).Part C



### 97 2.4 Membrane Distillation

Membrane d istillation (MD) is an emerging technology which uses heat to thermally drive vapor molecules through a hydrophobic porous membrane and into a permeate stream, leaving behind a waste stream concentrated in non

- volatile and solid constituents. The EPA is

no t aware of any pilot scale testing of MD that has been performed for UOG extraction wastewater, but the technology is being developed and evaluated extensively.

MD is based on the principles of vapor pressure and diffusion. In a basic MD unit, the feed st ream (wastewater) is separated from the permeate stream (treated water) by a hydrophobic porous membrane. Vapor molecules diffuse across the membrane as a result of a difference in vapor pressure between the feed stream and the permeate stream. Liquid wate r cannot pass through the hydrophobic membrane’s pores, but water vapor and volatile vapors can. Non

volatile solutes and suspended solids remain in the concentrated waste stream. Depending on the composition of the feed stream and the intended use for the permeate stream, additional treatment (e.g., air stripping) may be required to remove any volatile constituents from the permeate stream.

The vapor pressure of a liquid is directly related to temperature. For MD, the feed stream must be kept warmer than t he permeate stream so that the vapor pressure of the feed stream is higher than that of the permeate stream. In other words, a temperature gradient causes a vapor pressure gradient across the membrane. Ultimately, water vapor and volatile vapors evaporate from the feed stream, diffuse through the membrane pores and condense upon contact with the cold permeate stream. Figure C

- 9 depicts the vapor pressure drop across th e membrane and shows how water vapor would move through a pore.

Source: DCN SGE01083



### Figure C

- 9

. Membrane Distillation Pressure Gradient

The configuration shown in Figure C

- 9 is called Direct Contact Membrane Distillation (DCMD), and it’s the most basic and extensively studied configuration (DCN SGE01084). There are several other configurations, which are variatio ns on DCMD. The following is an overview of a few different MD configurations (DCN SGE01081):

 Direct contact membrane distillation (DCMD)

– The hot feed stream and cold permeate stream are both in direct contact with the membrane surface.Part C



### 98 Condensation take s place at the permeate

- membrane interface. This method is the simplest configuration, but the main disadvantage is conductive heat loss across the membrane.

 Air gap membrane distillation (AGMD)

– The feed stream is in contact with the membrane but the per meate stream is separated from the membrane by a gap filled with stagnant air. The vapor must cross the air gap before reaching the cold permeate stream and condensing. This configuration reduces the amount of heat lost by conduction, but the main disadvan tage is that the air gap reduces mass transfer.

 Sweeping gas membrane distillation (SGMD)

– The feed stream is in contact with the membrane but the permeate stream is separated from the membrane by a gap through which an inert gas flows. The flow, or sweep, of the inert gas carries the vapor out of the unit to an external condenser. The sweeping air reduces the heat lost by conduction, enhances mass transfer, and is useful for removing volatile constituents from the vapor. However, the disadvantage of this configuration is that a large volume of sweep gas is needed to generate a small amount of permeate, so a large condenser is required.

 Vacuum membrane distillation (VMD)

– The feed stream is in contact with the membrane but the permeate stream is separ ated from the membrane by a vacuum, which pulls the vapor out of the unit and into an external condenser. This configuration enhances the vapor pressure gradient across the membrane and the heat lost by conduction is negligible.

 Thermostatic sweeping gas membrane distillation (TSGMD)

– This configuration is the combination of AGMD and SGMD, where there is still a gas sweeping through the gap, but part of the vapor condenses in the permeate stream inside the unit, and the remainder condenses in an external condenser.

The hydrophobic porous membrane is typically constructed of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), or polypropylene (PP), but there is ongoing research investigating the use of novel membrane materials. Some qualities of an ideal membrane material include low resistance to mass transfer, low thermal conductivity, good thermal stability, and high resistance to chemical degradation (DCN SGE01081). The pore sizes usually range from 0.05 to 0.2 μm, but can be as large as 0.3 to 1.1 μm (DCN SGE00678 ). The mean pore size should be large enough to allow sufficient mass transfer, but small enough to prevent liquid penetration. Although the pores are larger than a water molecule, water does not flow through the pores due to its hig h surface tension and the effect of capillary action (DCN SGE 00678). The membrane material and pore size distribution should be selected based on the specific wastewater feed composition and operating conditions.

Figure C

- 10 is a flow diagram showing the process for a vacuum membrane distillation (VMD) module from the startup vendor Refrakt. This system is designed to treat hydraulic fracturing wastewater. In this flow diagram, the wastewater stream is sent through three VMD units in series, and vapor is pulled out of the units and into an external condenser using a vacuum pump. More vapor is transferred from the wastewater feed stream into the permeate stream with

eac h pass through the successive VMD units. The number of VMD units needed depends on the mass transfer efficiency of each unit and the level of treatment required for the operation.Part C



### 99 Source: Compiled by the EPA using information from literature (DCN SGE0108 5).



### Figure C

- 10 . Process Flow Diagram from Refrakt Vacuum Membrane Distillation System

2.5 Forward Osmosis

Forward osmosis (FO) , also referred to as engineered osmosis, is capable of reducing dissolved constituents commonly found in UOG extraction wastewater. FO has been bench and pilot tested for the treatment of UOG extraction wastewater, but there have not been full

- scale applications ( DCN SGE00264; DCN SGE00684 ).

O smos is refers to the spontaneous flow of water from a dilute solution to a concentrated solution, which occurs when the two solutions are separated by a semi

- permeable membrane ( DCN SGE00166 ). FO uses osmotic pressure to draw water from a wastewater feed strea m through a semi

- permeable membrane, without the application of hydraulic pressure. The semi

permeable membrane allows water to flow through while preventing target ions (e.g., B + 

### ) from passing through.

Figure C

- 11 shows a flow diagram of an FO unit consisting of two cells separated by a semi

- permeable membrane. The right cell contains the draw solution, which has a high concentration of ions, and the left cell contain s the influent waste stream, which has a lower concentration of ions than the draw solution. Osmotic pressure causes water to flow from the left cell to the right cell and as a result, the concentration of ions in the left cell increases and the

concentrat ion of ions in the right cell decreases ( DCN SGE00167 ). The transfer of water from the left to right continues until the ion concentrations in the two cells are equal. Suspended solids and dissolved constituents in the influent waste stream remain in the l eft cell and exit the FO unit as a concentrated brine stream ( DCN SGE00264 ).

The FO wastewater treatment process shown in Figure C

- 11 uses the following steps: (1)
W astewater is fed into the FO unit where it contacts the semi

- permeable membrane. (2) ThePart C



### 100 osmotic pressure gradient between the influent wastewater and the concentrated draw solution drives the transport of water molecules through the membrane, resulting in a diluted draw solution and concentrated brine. (3) The concentrated brine stream exits the FO unit for disposal. (4) The diluted draw solution is circulated through a draw solution separation unit (e.g., reverse osmosis) where it is separated from water obtained from the influent wastewater. This separation process results in treated wastewater and a reusable concentrated draw solution. (5) The reconcentrated draw solution is returned to the draw solution chamber to continue to drive the FO process.

Source: Compiled by the EPA using information from literature (DCN SGE00264 ).



### Figure C

- 11 . Flow Diagram of Forward Osmosis

As the ratio of ion concentrations in the draw solution relative to the concentration of ions in the waste stream decreases, the osmotic pressure decreases. When the ion concentrations in the left and right cells are equal, the draw solution needs to be regenerated to restore the osmotic pressure difference and recover the treated water. T he draw solution is circulated out of the FO unit and into an external unit (draw solute separation) where it can be regenerated. Regeneration is typically achieved using reverse osmosis or distillation, but chemical precipitation or thermal methods can al so be used. The regeneration process creates a clean water stream and a regenerated draw solution for recycle in the FO unit. In s ome industrial application s , including UOG extraction wastewater , the dilute draw solution may be reused

, eliminating the need for the secondary draw solute separation process (DCN SGE00684 )

.Part D



### 101 

## Part D. R EFERENCE 

## L IST AND 

## S OURCE 

## F LAGS



### The EPA reviewed existing data sources, including journal articles and technical papers, technical references, industry/vendor telephone queries, and vendor websites to gather information for this report. The EPA identified all of the information described in this report from the sources listed in Table D

- 1 . EPA assigned one of the following data source quality flags to each of the sources referenced:

 Source q uality f

lag “A”: J ournal articles and documents prepared by or for a government agency (e.g., EPA site visit reports, industry meeting notes)

 Source q uality f

lag “B”: Documents prepared by a verified 46 

### source that include citation information (e.g., operator reports, vendor documents, university publications)

 Source q uality f

lag “C”: Documents prepared by a verified source that do not include citation information (e.g., operator reports, vendor documents, conference presentations)

 Source q uality f

lag “D”: Documents prepared b y a source that could not be verified and that do not include citation information

Table D

- 1 . Reference List

ID DCN Source Citation Source Flag a

1 SGE00006.A03 Havics, Andrew, and D. Wright. 2011a. Fracing & Associated Media

Composition in Colorado. Prepared by pH2, LLC and QEPA. Presented at the EPA Technical Workshops for the Hydraulic Fracturing Study

— Fate and Transport, March 28

- 29, 2011. B

2 SGE00007.A18 Alleman, David. 2011. Treatment of Shale Gas Produced Water for Discharge.

Prepared by ALL Consulting, LLC. Presented at the EPA Technical Workshops for the Hydraulic Fracturing Study

— Water Resources Management March 29

- 30, 2011. ( March). D

3 SGE00007.A21 Havi cs, Andrew, and D. Wright. 2011 . Simple Modeling of the Disposition of

Fluids On

- Site in a Pit. Prepared by pH2, LLC, and QEPA. Presented at the EPA Technical Workshops for the Hydraulic Fracturing Study

— Water
Resou rces Management, March 29

- 30, 2011. C

4 SGE00010 U.S. DOE. Office of Fossil Energy NETL. 2009. Modern Shale Gas

Development in the United States: A Primer. Produced with the Ground Water Protection Council. (April). Available online at: http://fossil.energy.gov/programs/oilgas/publications/naturalgas_general/Shale_ Gas_Primer_2009.pdf B

5 SGE00011 Veil, John. 2010. Water Management Technologies Used by Marcellus Shale

Gas Procedures. Prepared by Argonne National Laboratory. Prepared for U.S. DOE NETL. (July). A

46 The EPA considered sources as “verified” if we were able to find information about the author outside of the reference document. The EPA primarily verified information by looking for company/organization websites that confirmed the author’s affiliation wi th the UOG industryPart D



### 102 Table D

- 1 . Reference List

ID DCN Source Citation Source Flag a

6 SGE00046 Abdalla, Charles; Drohan, Joy; Edson, Jessie. 2011. Marcellus Shale

Wastewater Issues in Pennsylvania

— Current and Emerging Treatment and Disposal Technologies. Prepared by The Pennsylvania State University (April). B

7 SGE00068 American Petroleum Institute (API). 2010. Water Management Associated with

Hydraulic Fracturing. (June). B

8 SGE00070 Acharya, Harish; Henderson, Claire; Matis, Hope; Kommepalli, Hareesh;

Moore, Brian; Wang, Hua, 2011. Cost Effective Recovery of Low

- TDS Frac Flowback Water for Re

- use. Prepared by GE Global Research. Prepared for U.S. DOE NETL. (June). A

9 SGE00086 American Petroleum I nstitute (API). 2009. Hydraulic Fracturing Operations

—

Well Construction and Integrity Guidelines. (October). B

10 SGE00095 URS. 2011. Water

- Related Issues Associated with Gas Production in the

Marcellus Shale. Prepared in support of the Supplemental Generic Environmental Impact Statement for Natural Gas Production. (March). B

11 SGE00099 Burnett, David. 2006. Advanced Membrane Filtration Technology for Cost

Effective Recovery of Fresh Water from Oil & Gas Produced Brine. Texas A&M University. Available online at: http://www.netl.doe.gov/KMD/cds/disk23/D

Water%20Management%20Projects/Produced%20Water%5C15427%5C15427 %20Jan

- Mar06%20TXA&M.pdf B

12 SGE00100 Brown, Terry, et al. 2009. Final Report: Produced Water Management and

Beneficial Use. Oil & Natural Gas Technology. (January). B

13 SGE00103 Aqua Technology. An Overview of Deionization Technology, Principles of

Operation for Industrial Deionization Systems. Available online at: http://www.aquatechnology.net/industrial_deionization.html D

14 SGE00105 Papso, John, et al. 2010. Gas Well Treated with 100% Reused Frac Fluid.

Exploration and Production. (August). Available at: http://www.swsi .com/pdf/Cabot_SWSI_reuse.pdf B

15 SGE00108 Siemens, 2011. Total Water Management for the Oil & Gas Industry. Available

online at: http://www.water.siemens.com/SiteCollectionDocuments/Industries/Oil_and_G as/Brochures/SWT

- 021_OG

- CAPABILITIES

- BR

- 0111medres.pdf C

16 SGE00109 Asano, Takashi. 2007. Water Reuse: An Integrated Approach to Managing the

World’s Water Resources. McGraw

- Hill. A

17 SGE00110 Bruff, Matthew. 2011. An Integrated Water Treatment Technology Solution for

Sustainable Water Resource Management in the Marcellus Shale. Altela Inc., Argonne National Laboratory. B

18 SGE00124 Beckman, James R. 2008. Dewvaporation Desalination 5,000

- Gallon

- per

- Day

Pilot Plant. Desalination and Water Purification Research and Develop ment Program Report No. 120. (June). Contract No. 03

- FC

- 81

- 0905. B

19 SGE00125 Provaris. Unknown. Process Water Recycling Technologies. Available online

at: http://www.clearwatergroup.org/provaris%20

- %20process%20water%20recycling%20technologies.pdf C

20 SGE00126 Reed, Joseph. 2002. Application of an Electro

- D ialysis Process to Remediate a

Brine

- Impacted Aquifer. Arcadis G&M, Inc. CPart D



### 103 Table D

- 1 . Reference List

ID DCN Source Citation Source Flag a

21 SGE00127 U.S. EPA. 2000. Wastewater Technology Fact Sheet: Chemical Precipitation.

EPA

- 832

- F

- 00

- 018. (September). A

22 SGE00129 Water Research Foundation (WRF). Unknown. Ion Exchange. Simultaneous

Compliance Tool. D

23 SGE00133 Means, Brent, and Tiff Hilton. 2004. Comparison of Three Methods to Measure

Acidity of Coal

- Mine Drainage. 2004. National Meeting of the American Society of Mining and Reclamation. EPA

- HQ

- OW

- 2006

- 0771

- 0142. A

24 SGE00139 Puder, M.G.; Veil, J.A. 2006. Argonne National Laboratory. Offsite

Commercial Disposal of Oil and Gas Exploration and Production Waste: Availabi lity, Options, and Costs. Prepared for U.S. DOE NETL. (August). Available online: http://www.evs.anl.gov/pub/doc/ANL

- EVS

- R

- 06

- 5.pdf A

25 SGE00140 ALL Consulting. 2011. Water Treatment Technology Fact Sheet:

Crystallization. B

26 SGE00141 ALL Consulting. 2011. Water Treatment Technology Fact Sheet:

Electrodialysis. B

27 SGE00142 ALL Consulting. 2011. Water Treatment Technology Fact Sheet: Ion Exchange. B

28 SGE00144 ALL Consulting. 2011. Water Treatment Technology Fact Sheet: Thermal

Evaporation Distillation. B

29 SGE00145 Veolia Water. 2011. Technology Data Sheet: MULTIFLO TM Technology, a

Transportable Water Treatment Solution for Shal e Gas Exploration. Available online at: http://www.vwsoilandgas.com/lib/vws

oilandgas/brochures/16103,Multiflo_HDlocal

- sm.pdf C

30 SGE00149 INTEVRAS Technologies LLC. 2011. EVRASTM Evaporative Reduction and

Solidification. Available online at: http://www.layneintevras.com/downloads/Evras/technical/EVRAS_Summary_ w__Heat_Rates.pdf C

31 SGE00156 Flottweg. 2011. Flottweg Separation Technology. Available online at:

http://www.flottweg.de/cms/upload/downloads/old/Dril ling_Mud_en.pdf. C

32 SGE00160 Adams, Andy. 2011. Telephone Communication with Andy Adams,

INTEVRAS, and Brent Ruminski, Eastern Research Group Inc. “EVRASTM Evaporation Technology.” (September 26). A

33 SGE00161 Alexander, Jerry. 2011. Telephone Communication with Jerry Alexander,

Siemens, and Sarah Hays, Eastern Research Group, Inc. “Siemens Reverse Osmosis Technology.” (September 29). A

34 SGE00162 Beagle, Douglas. 2011. Telephone Communication with Douglas Beagle, Drake

Water Technologies, and Brent Ruminski, Eastern Research Group, Inc. “Higgins Loop Technology.” (September 28). A

35 SGE00163 Burnett, David. 2011. Telephone Communication with David Burnett, Global

Petroleum Research Institute, and Sarah Hays, Eastern Research Group, Inc. “GPRI Reverse Osmosis Research.” (September 26). A

36 SGE00164 Dennis, Rich. 2011. Telephone Communication with Rich Dennis, Severn

Trent, and Brent Ruminski, Eastern Research Group, Inc. “Severn Trent: Higgins Loop Technology.” (September 28). A

37 SGE00165 Drake, Ron. 2011. Telephone Communic ation with Ron Drake, Drake Water

Technologies, and Brent Ruminski, Eastern Research Group, Inc. “Ionflo Technology.” (September 26). APart D



### 104 Table D

- 1 . Reference List

ID DCN Source Citation Source Flag a

38 SGE00166 Weber, Walter. 1972. Physicochemical Processes for Water Quality Control.

University of Michigan. Wiley

- Interscience. A

39 SGE00167 Metcalf and Eddy, Inc. 2002. Wastewater Engineering: Treatment and Reuse.

Fourth edition. McGraw

- Hill, Inc. A

40 SGE00175 Hayes, Tom. 2004. The Electrodialysis Alternative for Produced Water

Management. Gas Technology Institute. (Summer). A

41 SGE00177 Crittenden, John, et al. 2005. Water Treatment: Principles and Design. John

Wiley & Sons, Inc. 2 nd ed ition. A

42 SGE00178 American Water Works Association (AWWA). 2005. Water Quality &

Treatment: A Handbook of community Water Supplies. McGraw

- Hill. A

43 SGE00189 General Electric (GE). 2011. Chapter 07

— Precipitation Sof tening. GE Power and Process Te chnologies. C

44 SGE00 195 U.S. EPA. 2011. Development Document for the CWT Point Source Category.

Retrieved: http://water.epa.gov/scitech/wastetech/guide/cwt/develop_index.cfm A

45 SGE00197 U.S. EPA. 2004. Technical Support Document for the 2004 Effluent Guidelines

Program Plan. U.S. EPA. A

46 SGE00225 ALL Consulting, LLC. 2011. Shale Gas Produced Water Treatment Catalog.

Available online at: http://www.all

llc.com/projects/produced_water_tool/page.php?14 B

47 SGE00227 Mertz, Barry. 2011. Telephone Communication with Barry Mertz, 212 Resource

Corporation, and Brent Ruminski, Eastern Research Group, Inc. “212 Re sources VACOM Technology.” (October 14). A

48 SGE00228 Roman, Jaime. 2011. Telephone Communication with Jaime Roman, Fountain

Quail, and Brent Ruminski, Eastern Research Group, Inc. “Fountain Quail Nomad Evaporator.” (October 26). A

49 SGE00230 Wilson, Mark. 2011. Telephone Communication with Mark Wilson, General

Electric (GE), and Brent Ruminski, Eastern Research Group, Inc. “GE Power and Water: Wastewater Treatment Technologies.” (November 10). A

50 SGE00234 Silva, James. 2011. NORM Removal From Hydrofracturing. GE Global

Research Center. B

51 SGE00238 Shaw, William. 2011. The Real Cost of zero liquid discharge (ZLD) for Shale

Gas Frac Water in the Marcellus Shale Play. HPD, LLC, a Veolia Water Solutions & Technologies company. (September). C

52 SGE00239 Hefley, William, et al. 20 11. The Economic Impact of the Value Chain of a

Marcellus Shale Well. University of Pittsburgh. (August) B

53 SGE00244 ERG. 2012. Camp, Meghan; Bicknell, Betsy; Ruminski, Brent. Notes on

Conference Call with 212 Resources on 4 January 2012. (January 9) A

54 SGE00245 ERG. 2012. Camp, Meghan et. al. Notes on Conference Call with Reserved

Environmental Services, LLC on 5 January 2012. (February 1) A

55 SGE00252 West Virginia Department of Environmental Protection (WV DEP). 2010. Salt

Brine from Gas Wells Agreement. Division of Highway. (July). A

56 SGE00261 Kiernan, John. 1998. Selection of EDR Desalting Technology Rather Than

MF/RO for th e City of San Diego Water Reclamation Project. General Electric (GE) Water & Process Technologies. (August). BPart D



### 105 Table D

- 1 . Reference List

ID DCN Source Citation Source Flag a

57 SGE00264 Colorado School of Mines (CSM). 2009. An Integrated Framework for

Treatment and Management of Produced Water, 1 st edition. (November). A

58 SGE00265 Hanson, Paul. 2010. Ion Exchange for Produced Water Treatment. PG

Environmental LLC. (August 30). EPA Docket Number: EPA

- HQ

- OW

- 2008

- 0517. A

59 SGE00268 Advanced Resources International, Inc. 2006. The Economics of Powder River

Basin Coalbed Methane Development

- DCN 03444. EPA

- HQ

- OW

- 2004

- 0032

- 2451. B

60 SGE00269 U.S. Geological Survey. 2000. Water co

- produced with coalbed methane in the

Powder River Basin, Wyoming: preliminary compositional data. Open

- File Report 00

- 372 A

61 SGE00271 Drake Water Technologies, LLC. 2007. Drake Process Technology Scope and

Pricing Summary Based on Na+ Removal

- Calendar Year 2007

. C

62 SGE00275 U.S. EPA. 2012. Site Visit Report: Citrus Energy Corporation Marcellus Shale

Gas Operations. (January 22). A

63 SGE00276 U.S. EPA. 2012. Meeting with XTO Energy, Inc. about Unconventional Oil and

Gas Sanitized. A

64 SGE00285 Silva, James. 2012a. Produced Water Pretreatment for Water Recovery and Salt

Production. (January 26). Report 08122

- 36. A

65 SGE00286 Hammer, R. et. al. 2012. In Fracking's Wake: New Rules are Needed to Protect

Our Health and Environment from Contaminated Wastewater. (May). NRDC
D:12

- 05

- A A

66 SGE00298.A21 Ron Pettengill. Innovative Water Management Strategies for Future Marcellus

Development. Epiphany Solar Systems. C

67 SGE00298.A23 Robie Cathey. 2012. Ecosphere. Ecosphere Technologies, LLC. Technical

Presentation at the 2012 Water Management for Shale Plays Conference. B

68 SGE00298.A24 Johan Themaat. 2012. Water Infrastructure Versus Mobile Options for Treating

and Disposing Fracking and Produced Water. High Sierra Water Services. C

69 SGE00299 U.S. EPA. 2012. Site Visit Report: US Gas Field Fluids Management (formerly

Clean Streams) Marcellus Shale Gas Operations. (October 9). A

70 SGE00300 U.S. EPA. 2012. Site Visit Report: Eureka Resources, LLC Marcellus Shale

Gas Operations. (February 25). A

71 SGE00305.A07 Horn, Aaron. 2012. Comparing the Latest Innovations in Treatment Technology

Based on Water Quality and Cost per Barrel. Hydrozonix, LLC. C

72 SGE00306.A04 Silva, James. 2012 . Shale Gas Produced Water Pretreatment for Barium and

Radium Removal. GE Global Research Center. B

73 SGE00306.A06 Keister, Timothy. 2012. Sequential Precipitation

- Fractional Crystallization

Treatment of Marcellus Shale Flowback and Production Wastewaters. ProChemTech International, Inc. B

74 SGE00311.A01 Walter Dale. 2012. Sustainable Development of Completions. Haliburton Water

Solutions. C

75 SGE00331 Ely, John W. 2011. Game Changing Technology for Treating and Recycling

Frac Water. Society of Petroleum Engineering. BPart D



### 106 Table D

- 1 . Reference List

ID DCN Source Citation Source Flag a

76 SGE00333 Horn, Aaron. 2009. Breakthrough Mobile Water Treatment Converts 75% of

Fracturing Flowback Fluid to Fresh Water and Lowers CO2 Emissions. Society of Petroleum Engineering. B

77 SGE00358 Ecolotron Wa ter Recovery Systems. 2011. Treatment of Flow Back and

Produced Water from the Hydraulic Fracturing of Oil

– Shale. B

78 SGE00367 CARES. Unknown. CARES McKean. Available online at:

http://www.caresforwater.com/location/cares

- mckean C

79 SGE00369 Anticline Disposal, LLC.. Unknown. Anticline Disposal, LLC.. Available

online at: http://www.highsierrawater.com/high

- sierra

- water/ C

80 SGE00374 Red De sert. Unknown. Red Desert: Facilities. Available online at:

http://reddesertwater.com/facilities.html C

81 SGE00415 Hayes, Thomas et al. 2012. Evaluation of the Aqua Pure Mechanical Vapor

Recompression System in the Treatment of Shale Gas Flowback Water Report
No. 08122

- 0 5.11. Research Partnership to Secure Energy for America (RPSEA). B

82 SGE00421 Jay Ewing. 2008. Taking a Proactive Approach to Water Recycling in the

Barnett Shale. Devon Energy B

83 SGE00463 Halliburton. 2012. El Paso Corporation completes first natural gas well using all

four CleanSuite technologies. Halliburton. B

84 SGE00478 Kasey, Pam. 2009. Gas Well Drilling Brine Treatment Facility Opens in

Fairmont

- AOP Clearwater LLC is set to be gin operation of its gas well drilling brine recycling facility in Fairmont. The State Journal. D

85 SGE00479 Kadramas, Lee & Jackson, Inc.. 2012. Power Forecast 2012 Williston Basin Oil

and Gas Related Electrical Load Growth Forecast. Kadramas, Lee & Jackson,
Inc.. B

86 SGE00523 Eureka Resources, LLC. 2013. Eureka Resources Announces Plans for New

Wastewater Treatment Plant. ( May 30 ). C

87 SGE00528 Gilmer, Ellen. 2013. Data Show More Marcellus Wastewater, More Injections.

E&E News. (February 22). C

88 SGE00596 ERG. 2015. Analysis of Centralized Waste Treatment Facilities (CWTs)

Accepting UOG Extraction Wastewater. A

89 SGE00601 U.S. EPA. 2001. Small Entity Compliance Guide: CWT Effluent Limitations

Guidelines and Pretreatment Standards (40C.F.R. 437). EPA 821

- B

- 01

- 003. A

90 SGE00613 U.S. EPA. 2013. Meeting Summary: Meeting with Industry Representatives

About the Unconventional Oil and Gas Effluent Guideline Rulemaking. A

91 SGE00616 U.S. EPA. 2013. Summary of the Technical Workshop on Wastewater

Treatment and Related Modeling. (April 18) A

92 SGE00625 U.S. EPA. 201 5 . Site Visit Report: Southwestern Energy (SWN) Fayetteville

Shale Gas Operations Sanitized A

93 SGE00635 US EPA. 2012. Site Visit Report Chesapeake Energy Corporation Marcellus

Shale Gas Operations Sanitized. A

94 SGE00638.A10 Cath, Tzahi. 2013. An Integrated Framework for Treatment and Management of

Produced Water. (Presentation) CPart D



### 107 Table D

- 1 . Reference List

ID DCN Source Citation Source Flag a

95 SGE00638.A11 Dale, Walter. 2013. H2OForward SM Service

– Sustainable Development of

Completions. Halliburton. Technical presentation presented at the 2013 Produced Water Reuse Initiative Conference. (October 30). C

96 SGE00638.A12 Wilkerson, Tommy. 2013. Strategies for Sustainable Water Transport Lessons

Learned in the Marcellus Applied to the Niobrara. Carrizo Oil and Gas, Inc. Technical presentation presented at the 2013 Produced Water Reuse Initiative Conference. (October 30). C

97 SGE00645 ALL Consulting. 2011. Vendor Profile: 212 Resources. C

98 SGE00646 ALL Consulting. 2011. Vendor Profile: AquaTech. C

99 SGE00647 ALL Consulting. 2011. Vendor Profile: Ecosphere Technologies, Inc. C

100 SGE00648 ALL Consulting. 2011. Vendor Profile: FountainQuail. C

101 SGE00649 ALL Consulting. 2011. Vendor Profile: GeoPure Hydrotechnologies. C

102 SGE00650 ALL Consulting. 2011. Vendor Profile: INTEVRAS Technologies, LLC. C

103 SGE00651 ALL Consulting. 2011. Vendor Profile: MISWACO. C

104 SGE00652 ALL Consulting. 2011. Vendor Profile: Veolia. C

105 SGE00653 Ali, Ehsan. 2012. Chapter 11: Electrocoagulation for Treatment of Industrial

Effluents and Hydrogen Production. Available online at: http://www.intec hopen.com/download/get/type/pdfs/id/40138

. A

106 SGE00654 Atlas, Robert. 2006. Purification of Brackish Water using Hybrid CDI

- EDI

Technology. Aqua EWP, LLC. Available online at: http://ipec.utulsa.edu/Conf2007/Papers/Atlas_77a.pdf C

107 SGE00655 Baker Hughes. 2012. H2prO HMS Water Management Service. Available

online at: http://public.bakerhughes.com/atce/presskit/Overviews/H2prO%20HMS%20W ater%20Management%20Services%20overview.pdf

. C

108 SGE00656 Bosque Systems, LLC. 2013. Water Treatment Solutions Using Electro

Coagulation. Available online at: http://www.bosquesystems.com/pdf/INSMWR06

- 13%20

- %20MWRU%20

- %20Bosque.pdf C

109 SGE00657 Brant, Jonathan. , Unknown. Available online at:

http://nex usgroupsolutions.com/TechnicalBrief_Produced%20Waters.pdf B

110 SGE00658 Panu, Marc et al. 2013. Design of a Mobile Wastewater Treatment System for

Hydraulic Fracturing Waste. Chevron Group. (April 19). B

111 SGE00659 Christen, Kris. 2006. Desalination technology could clean up wastewater from

coal

- bed methane production. Environmental Science & Technology. Available online at: http://pubs.acs.org/doi/abs/10.1021/es062630s. A

112 SGE00660 Colorado Department Of Public Health And Environment. 2011. Colorado

Discharge Permit System (Cdps) Fact Sheet To Permit Number Co0048739 Bopco, L.P., Yellow Creek Water Management Facility Rio Blanco County. Water Quality Control Division. A

113 SGE00661 Hause, Jennifer et al. 2010. Zero Discharge Water Management for Horizontal

Shale Gas Well Development. Submitted by West Virginia Water Research Institute to Department of Energy (DOE) National Technology Laboratory (NET L). APart D



### 108 Table D

- 1 . Reference List

ID DCN Source Citation Source Flag a

114 SGE00662 Emis. 2010. Membrane Distillation. Available online at:

http://www.emis.vito.be/techniekfiche/membrane

- distillation?language=en C

115 SGE00663 Gryta, Marek. 2011. Water Desalination by Membrane Distillation. Available

online at: http://www.intechopen.com/download/get/type/pdfs/id/13752 A

116 SGE00664 Heartland Technologies, LLC. 2013. Produced Water Treatment. Available

online at: http://www.heartlandtechnologypartners.com/solutions/produced

water

- treatment/

. C

117 SGE00665 Hickenbottom, Kerri L. et al. 2013. Forward osmosis treatment of drilling mud

and fracturing wastewater from oil and gas operations. Desalination , 312. 60

- 66. A

118 SGE00666 Kmx Corp. 2014. Membrane Distillation

– Contaminated Water. Available

online at: http://www.kmxcorp.com/water_chemical_purification.php?division=Technolo gies&area=Membrane%20Distillation&page=Contaminated%20Water C

119 SGE00667 Lord, LeBas et al. 2013. Development and Use of High

- TDS Recycled

Produced Water for C rosslinked

- Gel

- Based Hydraulic Fracturing. Society of Petroleum Engineers. SPE 163824. B

120 SGE00668 Mendez, Enrique. 2012. Sustainable desalination: Membrane distillation

delivers greener clean water. Available online at: http://www.filtsep.com/view/29567/sustainable

- desalination

- membrane

distillation

- delivers

- greener

- clean

- water/ B

121 SGE00669 Nelson, Cecilia E., and Ghosh, Ashok Kumar. 2011. Membrane Technology for

Produced Water in Lea County. Pre pared by Lea County Government and New Mexico Institute of Mining and Technology. Prepared for U.S. DOE NETL. (September). B

122 SGE00670 Omni Water Solutions. 2014. Frac Water. Treating Flowback and Produced

Water for Re

- Use. C

123 SGE00671 OriginOil. 2013. EWS Petro P160 "Cleav

- Frac: Process and Equipment

Description. Avialable online at: http://www.originoil.com/pdf/OriginOi l

- EWS

Petro

- P160

- Data

- Sheet.pdf

. C

124 SGE00672 OriginOil. 2013. Originoil’s Clean

- Frac: An Overview. (June) C

125 SGE00673 Porada, S. 2013. Review on the science and technology of water desalination by

capacitive deionization. Progress in Materials Science Volume 58, Issue 8, October 2013, Pages 1388

– 1442. Available online at: http://www.sciencedirect.com/science/article/pii/S 0079642513000340 A

126 SGE00674 Purestream. 2011. Welcome to Purestream. (January). Available online at:

http://purestreamtechnology.com/downloads/purestream

- technology

- overview

2011.pdf B

127 SGE00675 Shafer, Lee. 2010. A Working Model for Oil and Gas Produced Water

Treatment. Technical presentation from the Opportunities and Obstacles to Improving the Environmental Footprint of Energy Extraction in the Uintah Basin Workshop. C

128 SGE00676 Shelp, Gene. 2004. The DesEl System

– Capacitive Deionization for the

Removal of Ionic Contaminants from Water. EnPa r Technologies, Inc. Available online at: http://msas.maliwatch.org/msas2004/proceedings/msas2004_pp161

- 167.pdf. CPart D



### 109 Table D

- 1 . Reference List

ID DCN Source Citation Source Flag a

129 SGE00677 Tinto, Joseph. 2012. Water Recovery via Thermal Evaporative Processes for

High Saline Frac Water Flowback. Technical Presentation from the 2012 International Water Conference. C

130 SGE00678 Walton, John. 2004. Solar and Waste Heat Desalination by Membrane

Distillation. Available online at: http://www.usbr.gov/research/AWT/reportpdfs/report081.pdf A

131 SGE00679 Wickramasinghe, Ranil and Jones, Steven. 2013. Treating Hydraulic Fracturing

Flowback Waters: Potential New Membrane Applications Webinar . American Institute of Chemical Engineers and International Society for Water Solutions. December 11, 2013. C

132 SGE00680 Xu, Pei. 2008. Treatment of Brackish Produced Water Using Carbon Aerogel

based Capacitive Deionization Technology. Environmental Science & Engineering Division, Colorado School of Mines, Advanced Water Technology Center (AQWATEC). A

133 SGE00681 Yukon College. 2012. Capacitative Deionization in Mine Water Recycling.

Available online at: http://www.yukoncollege .yk.ca/research/projects/capacitive_deionization. C

134 SGE00682 ALL Consulting. 2011. Vendor Profile: Altela C

135 SGE00683 ALL Consulting. 2011. Water Treatment Technology Fact Sheet: Reverse

Osmosis. B

136 SGE00684 Coday, Bryan D. et al. 2014. The sweet spot of forward osmosis: Treatment of

produced water, drilling wastewater, and other complex and difficult liquid

streams. Desalination , 333. 23

- 25. A

137 SGE00685 Global Water Intelligence (GWI). 2011. Produced Water Recycling Oasis

flourishes in Wyoming. (February). D

138 SGE00686 U.S. EPA. 2011. Proceedings of the Technical Workshops for the Hydraulic

Fracturing Study: Water Resourc es Management. EPA 600/R

- 11/048. (May). A

139 SGE00687 AquaTech International Corporation. 2011 . Mo Treat: Mobile Water Pre

treatment System. Available online at: http://www.aquatech.com/portals/0/MoTreat%20Cut%20Sheet

- 02.pdf C

140 SGE00688 AquaTech International Corporation. 2011 . Mo Vap: Mobile Water Distillation

System. Available online at: http://www.aquatech.com/portals/0/MoVap%20Cut%20Sheet

- 01.pdf C

141 SGE00689 M

- I SWACO. 2009. Frac Water Reclamation System Reduces Operator’s Water

Cost. Available at: http://www.slb.com/~/media/Files/miswaco/case_studies/frac_water_reclamatio n_marcellus_shale.ashx C

142 SGE00690 ALL Consulting, LLC. 2006. A Guide to Practic al Management of Produced

Water from Onshore Oil and Gas Operations in the United States. Interstate Oil and Gas Commission and ALL Consulting. (October). B

143 SGE00691 U.S. EPA. 2013. Summary of the Technical Workshop on Water Acquisition

Modeling: Assessing Impacts Through Modeling and Other Means. (September). A

144 SGE00692.A01 ERG . 2015. UOG WW Treatment Technologies

- Attachment 1: Treatment

Technology Costs Spreadsheet. APart D



### 110 Table D

- 1 . Reference List

ID DCN Source Citation Source Flag a

145 SGE00693 ERG. 2015. Data Compilation Memorandum for the Technical Development

Document (TDD) for Proposed Effluent Limitations Guidelines and Standards for Oil and Gas Extraction. A

146 SGE00704 U.S. EPA. 2015. Technical Development Document for Proposed Effluent

Limitations Guidelines and Standards for Oil and Gas Extraction. A

147 SGE00705 ERG. 2014. Ruminski, Brent. Notes on Call with Hydrozonix, LLC on 7

February 2014. (March 7.) B

148 SGE00706 Ecosphere Energy Services, LLC. 2011. 100 percent Frac Water Recycling

-

Strategy & Focus Ozonix®. (April 13). B

149 SGE00707 Horn, Aaron et al. 2013. Minimum Effective Dose: A Study of Flowback and

Produced Fluid Treatment for Use as Hydraulic Fracturing Fluid. Hydrozonix, LLC (March 18). B

150 SGE00708 Environmental Leader. 2013. Unconventional E&P '$8 Billion of US Water

Services Market'. (November 11). B

151 SGE00709 Natural Gas Europe. 2012. Flowback Water Driving Flurry of Activity in Water

Treatment (May 22). B

152 SGE00710 Slutz, James; Anderson, Jeffrey; Broderick, Richard; Horner, Patrick. 2012. Key

Shale Gas Water Management Strategies: An Economi c Assessment Tool. SPE 157532. Society of Petroleum Engineers. (September 11). B

153 SGE00714 Ziemkiewicz, Paul et al. 2012. Zero Discharge Water Management for

Horizontal Shale Gas Well Development. West Virginia Water Research Institute. Department of Energy (DOE). A

154 SGE00717 U.S. EPA. 2013. Meeting with Purestream Technology about Treatment

Technologies Relevant to the Unconventional Oil and Gas Industry. (November 8). A

155 SGE00722 IHS. 2012. Water Management in Shale Gas Plays. (August ) B

156 SGE00724 ERG. 2015. Unconventional Oil and Gas (UOG) Produced Water Volumes and

Characterization Data Compilation Memorandum

. A

157 SGE00740 ERG. 2015. Unconventional Oil and Gas (UOG) Drilling Wastewater

Memorandum

. A

158 SGE00989 Energy Information Administration (EIA). 2014. Annual Energy Outlook

(AEO) 2014 with Projections to 2040. DOE/EIA

- 0383(2014). A

159 SGE01033 All Consulting. Water Treatment Technology Fact Sheet: UV Light. Available

online a t: http://www.all

- llc.com/publicdownloads/UVLightFactSheet.pdf B

160 SGE01034 Atg UV Technology. 2015. SRB Treatment. Available online at:

http://www.atguv.com/srb

- treatment C

161 SGE01035 Bosque Systems, LLC. 2013. Case Study CSDIO001. C

162 SGE01036 Bosque Systems, LLC. 2013. Water Treatment Solutions Using Chlorine

Dioxide: DIONIX. Available online at: http://www.bosquesystems.com/pdf/INSDIO06

- 13%20

- %20DIONIX%20

- %20Bosque.pdf C

163 SGE01037 PureLine. 2014. About ClO2. Available online at:

http://www.pureline.com/about

- clo2/ C

164 SGE01038 PureLine. 2014. CG Series. Available online at: http://www.pureline.com/clo2

-

generation/cg

- series/ CPart D



### 111 Table D

- 1 . Reference List

ID DCN Source Citation Source Flag a

165 SGE01039 PureLine. 2014. Pure 3 Series. Available online at:

http://www.pureline.com/clo2

- generation/pure

- 3

- series/ C

166 SGE01040 Sabre Energy Services, LLC. 2011.Chlorine Dioxide Generation Equipment.

Available online at: http://www.thesabrecompanies.com/sabreenergyservices/services/equipment.as

px C

167 SGE01041 U.S. EPA. 1999. Wastewater Technology Fact Sheet: Ultraviolet Disinfection.

EPA

- 832

- F

- 99

- 064. (September). Available online at: http://water.epa.gov/scitech/wastetech/upload/2002_06_28_mtb_uv.pdf A

168 SGE01042 Wang, J. et al. 2005. Successfully Sterilizing the Sulfate Bacteria With

Ultraviolet Radiation in Produced

- Water Treatment in Daqing Oilfield. Society of Petroleum Engineers. SPE 93148. A

169 SGE01043 World Health Organization. WHO Seminar Pack for Drinking

- Water Quality.

Disinfectants and Disinfection By

- products. Available online at: http://www.who.int/water_sanitation_health/dwq/S04.pdf?ua=1 B

170 SGE01044 Lee, Douglas et al. 2007. Efficiency of Oil/Water Separation Controlled by Gas

Bubble Size and Fluid Dynamics within the Separation Vessel. Presented at the
17 th Annual Produced Water Society Seminar, League City, TX. Available online at: http://www.exterran.com/Content/Docs/Products/Efficiency

- of

- Oil

Water

- Separation

- English

- A4.pdf B

171 SGE01046.A02 Smith, Daniel. 2014. Determining the Minimum Treatment Levels Required for

Production Efficiency: Stating the Lowest Acceptable Water Quality Levels for Effective Reuse in Fracs. Apache. Technical presentation presented at 5 th Annual Shale Play Water Management 2014

– Southern States Conference. (November 19). C

172 SGE01046.A05 Wrenn, Brian A., 2014. Optimizing the Treatment of Produced Water

and Flowback for Reuse or Disposal. PureLine. Technical Presentation at the 5th Annual Shale Play Water Management Conference

– Southern States. C

173 SGE01047 U.S. EPA. 2015. Site Visit Report Seneca Resources Corporation, Covington,

PA. A

174 SGE01048 Zhou, H and D. Smith 2002. Advanced technologies in water and wastewater

treatment. Journal of Environmental Engineering and Science Volume 1, 2002, Pages 247

- 264. Available online at: http://www.ozomax.com/pdf/Article_O3_treat_for_waste_water.pdf. A

175 SGE01049 NETL. 2011. Produced Water Management Technology Descriptions Fact Sheet

- Ion Exchange. A

176 SGE01050 Kimball, Bob. 2010. High Recovery Reverse Osmosis for Treatment of

Produced Water. B

177 SGE01051 Drewes, Jorg E; et al. 2009. Opportunities, Challenges, and Research Needs for

Beneficial Use of CBM Produced Water. B

178 SGE01054 Atg UV Technology. Unconventional Gas (Fracking). Available online at:

http://www.atguv.com/unconventional

- gas

- fracking C

179 SGE01056 Geiver, Luke. 2013.Water Recycling's New Reality. The Bakken Magazine.

Available online at: http://www.halliburton.com/public/ multichem/contents/Papers_and_Articles/we b/Bakken

- Water

- Recyclings

- New

- Reality

- Dec13.pdf BPart D



### 112 Table D

- 1 . Reference List

ID DCN Source Citation Source Flag a

180 SGE01057 Halliburton Multi

- Chem. 2013. CleanStream® Service Capabilities. Available

online at: http://www.halliburton.com/public/pe/contents/Presentations/CleanStream

Service

- Presentation.pptx C

181 SGE01058 Halliburton Multi

- Chem. 2014. CleanStream® Water Treatment Service

Frequently Asked Questions. Available online at: http://www.halliburton.com/public/multichem/contents/Data_Sheets/web/H011 059

- CleanStream

- Frequently

- Asked

- Questions.pdf C

182 SGE01059 Sabre Energy Services, LLC. 2011. Oil Field Case Study: Disinfecting Water

for Well Fracturing wit h Chlorine Dioxide. Available online at: http://www.thesabrecompanies.com/sabreenergyservices/casestudies/frac2.aspx C

183 SGE01060 Sabre Energy Services, LLC. 2011.Oil Field Case Study: Maximizing Frac

Water Reuse with Chlorine Dioxide. Available online at: http://www.thesabrecompanies.com/sabreenergyservices/casestudies/frac1.aspx C

184 SGE01061 Sabre Oxidation. 2011. DiKlor®

- Sodium Chlorite Solution. Available online

at: http://www.thesabrecompanies.com/sabreoxidation/services/diklor.aspx C

185 SGE01067 ERG. 2015. International Water Conference 2014. A

18 6 SGE01080 Fajt, James. 2012. Capacitive Deionization (CDI). M

- I SWACO, A

Schlumberger Co. (November 11). C

187 SGE01081 Alkhudhiri, Abdullah. 2012. Membrane distillation: A comprehensive review.

Desalination. (August 11). A

188 SGE01082 Atlantis Technologies. 2012. Technical Summary Radial Deionization.

Available online at: http://www.deionizing.com/technology.html. Accessed on November 26, 2014. C

189 SGE01083 Kim, Albert S. 2012. A two

- interface transfport model with pore

- size

distribution for predicting the performance of direct contact membrane distillation (DCMD). Journal of Membrane Science. (October 6). A

190 SGE01084 Shaffer et al. 2013. Desalination and Reuse of High

- Salinity Shale Gas

Produced Water: Drivers, Techn ologies, and Future Directions. Environmental Science & Technology. (July 25). A

191 SGE01085 Refrakt. 2012. Purifying oil and gas produced water with membrane distillation.

Available online at: https://angel.co/refrackt

- 1. Accessed on February 6, 2015. C

192 SGE01086 Biesheuvel, P.M., A. van der Wal. 2010. Membrane capacitive deionization.

Journal of Membrane Science. (September 18). A

193 SGE01087 Li, Haibo, Linda Zou. 2011. Ion

- exchange membrane capacitive deionization: A

new strategy for brackish water desalination. Desalination. (February 11). A

194 SGE01111 Litvak, Anya. 2014. Engineering firm ventures into wastewater, LNG.

Pittsburgh Post

- Gazette. B

195 SGE01116 Halliburton. 2014. CleanStream® System Sterilizes Water, Reduces Chemical

Footprint and Saves ‘Green’ by Going Green. B

196 SGE01118 Tischler, A, et al. 2010. Controlling Bacteria in Recycled Produc tion Water for

Completion and Workover Operations. Society of Petroleum Engineers. A

197 SGE01119 Crane, B, et al. 2011. Improved Process Provides More Effective Ultraviolet

Light Disinfection of Fracturing Fluids. Society of Petroleum Engineers. APart D



### 113 Table D

- 1 . Reference List

ID DCN Source Citation Source Flag a

198 SGE01120 Rodvelt, Gary, et al. 2011. Case History: Challenges Using UV Light to Control

Bacteria in Marcellus Completions. Society of Petroleum Engineers. A

199 SGE01121 McCutchan, Morgan. 2013. Water Management Overview, Chlorine Dioxide,

Detail Case History. Baker Hughes. B

a

— Source Flag A

- Journal articles and documents prepared by or for a government agency (e.g., site visit reports, industry meeting notes); Source Flag B

- Do cuments prepared by a verified source 47 that include citation information (e.g., operator reports, vendor documents, university publications); Source Flag C

- Documents prepared by a verified source that do not include citation information (e.g., operator reports, vendor documents, conference presentations); and Source Flag D

- Documents prepared by a source that could not be verified and that do not include citation information.

47 The EPA considered sources as “verified” if we were able to find information about the author outside of the reference document. The EPA primarily verified information by looking for company/organization websites that confirmed the au thor’s affiliation with the UOG industryPart E



### 114 

## Part E. A

TTACHMENTS

### 115

Attachment 1: UOG Extraction Wastewater Treatment Technology Costs & Performance
Data (DCN SGE00692.A01)