Design of a Mobile Treatment System for Hydraulic Fracturing Waste

Chevron Group

April 19, 2013

1 | P a g e

Design of a Mobile Wastewater

Treatment System for 

Hydraulic Fracturing Waste

Marc Panu

Matthew Claussen

Faiz Talib

April 19, 2013
Design of a Mobile Treatment System for Hydraulic Fracturing Waste

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April 19, 2013

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Table of Contents

Abstract...............................................................................................................................................................................................4

Introduction and Project Charter.............................................................................................................................................4

Technology Readiness Assessment.........................................................................................................................................5

Section I: Concept Stage...............................................................................................................................................................6

Part 1: Market and Competitive Analysis ........................................................................................................................6

Part 2: Customer Requirements ..........................................................................................................................................6

Part 3: Preliminary Process Synthesis ..............................................................................................................................7

Part 4: Assembly of Database ...............................................................................................................................................8

Section II: Feasibility, Development, and Manufacturing ...........................................................................................12

Part 1: Process Flow Diagram, Stream Table, and Simulation of Process.......................................................12

Part 2: Process Description ................................................................................................................................................14

Part 3: Energy Balance and Utility Requirements.....................................................................................................17

Part 4: Equipment List and Unit Descriptions ............................................................................................................19

Part 5: Specification Sheets ...............................................................................................................................................22

Part 6: Equipment Cost Summary....................................................................................................................................29

Part 7: Fixed Capital Investment Summary .................................................................................................................29

Part 8: Other Important Considerations .......................................................................................................................30

Environmental problems and methods used to eliminate them....................................................................30

Safety and health concerns - Hazard and Operability Study (HAZOP)........................................................30

Process controllability and instrumentation..........................................................................................................33

Startup, including additional equipment .................................................................................................................33

Plant (trailer) layout.........................................................................................................................................................33

Part 9: Operating Cost and Economic Analysis ..........................................................................................................34

Section III: Conclusions and Recommendations.............................................................................................................36

Acknowledgements.....................................................................................................................................................................37

Bibliography ..................................................................................................................................................................................38

Appendix .........................................................................................................................................................................................40

Appendix 1: Glossary of Terms .........................................................................................................................................40

Appendix 2: Design Procedures and Calculations.....................................................................................................41

Section 1: Holding Pond ..................................................................................................................................................41

Section 2: Costing Data ....................................................................................................................................................41

Section 3: DAF compressor pressure sample calculation .................................................................................44
Design of a Mobile Treatment System for Hydraulic Fracturing Waste

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April 19, 2013

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Section 5: Relevant tabulated GE data.......................................................................................................................46

Appendix 3: Computer programs developed..............................................................................................................49

Section 1: MATLAB............................................................................................................................................................49

Section 2: SuperPro Designer .......................................................................................................................................53

Section 3: Microsoft Excel Calculator.........................................................................................................................53

Section 4: Pertinent printed material........................................................................................................................53
Design of a Mobile Treatment System for Hydraulic Fracturing Waste

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April 19, 2013

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Abstract

Our team designed a system to treat the contaminated water produced by hydraulic fracturing 

of shale rock for natural gas. We did so by combining and optimizing several current treatment 

technologies to produce a mobile-scale process that can treat the flowback at the well site for reuse at 

other nearby well sites. The process features an electrochemical oxidation/electrocoagulation unit 

(EC) that destabilizes small organics, a dissolved air flotation unit (DAF) that removes suspended 

solids, and a reverse osmosis (RO) unit that treats the dissolved solids. 

Introduction and Project Charter

Hydraulic fracturing (also referred to as hydrofracking or just fracking) is an important 

technology that has contributed significantly to the boom in domestic production of natural gas that 

the United States has seen over the past two decades. Since 1990, the number of actively producing 

natural gas wells in the United States has more than doubled to over 500,0001. The vast majority of 

these new wells are stimulated using hydraulic fracturing, a technique in which fluid containing mostly 

water and fine sand is pumped into a well under extreme pressure. This pressurized fluid flows out 

from the well bore into the gas-containing formation, causing the formation of small fractures. When 

the fluid is depressurized, the sand acts as a proppant, keeping the fractures open, and gas can flow 

into the wellbore through the fractures in the formation1. This unconventional extraction technique is 

essential for producing most new natural gas wells in an economically efficient way, as most of the 

natural gas deposits attainable via conventional strategies have been depleted. 

However, hydraulic fracturing is controversial due to growing concerns over the 

environmental impacts of treating the fluid that returns to the surface once fracturing is complete. 

Rising regulation of the disposal of this fluid, commonly called flowback, has forced fracturing 

operators to ship flowback from well sites to stationary water treatment plants. However, most active 

drilling sites are located far away from a stationary wastewater treatment plant, meaning the well 

owner must invest in transporting the spent fluid long distances for treatment. This in turn has led to a 

demand for a mobile treatment solution that could be deployed to treat flowback at well sites.

The goal of our project was to design a mobile treatment solution geared specifically to 

treatment of fracking wastewater at a well site. Several potential technologies and engineering 

strategies were considered to achieve this goal. The scope of the project consisted of a detailed 

conceptual design of the treatment process, an economic analysis of operating and capital costs, and an 

estimation of the expected return on investment. The design work was completed over a one semester 

period with progress reports generated on a weekly basis. Throughout the design process, our team 

developed simulation tools and other programs to generate custom models and calculators that would 

be useful for planning deployments to individual wells. The process design goals emphasized safety, 

effectiveness of the treatment, and economic benefit to both our company and our clients.
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Technology Readiness Assessment 

Our treatment scheme relies on three core technologies to effectively remove contaminants 

from the flowback. The first process unit is an electrochemical oxidation reactor used to flocculate 

suspended solids and organic species found in the flowback. The next unit is a dissolved air flotation 

chamber which removes the flocculated suspended solids and organics. Finally, a reverse osmosis unit 

removes the dissolved solids in the flowback, rendering the water clean enough to be re-used to 

fracture another well.

Electrocoagulation/Electrochemical Oxidation is a new and emerging technology that has been 

extensively researched on a lab scale. There are some EC units being used in industrial settings, so we 

know it can be done. However, the details of these operations are scarce. Implementing this technology 

on an industrial level will require further research2. Specifically, studies will need to be conducted to 

fine tune the electrode material and specifications and determine if there is a need for any additional 

chemicals to adjust the pH and electrical conductivity. If a business were to be launched based on our 

design, a significant amount of money would need to be invested in research and development of the 

EC unit.

Dissolved air flotation is a widely used technology in many process industries for removing 

suspended solids from solutions where sedimentation is slow or does not occur at all in the case of 

suspended emulsions 3. Because it is a well understood and widely used technology, there will be few 

barriers in the R & D stage of building the required DAF unit. Based on DAF design equations and 

normal operating parameter ranges, our DAF unit could be scaled to a mobile size 4. Additionally, 

several companies such as Ecologix have already begun using mobile DAF units to treat fracking 

flowback, indicating that dissolved air flotation could readily be adapted to the intended application of 

removing suspended solids from flowback 5. 

Reverse osmosis is also widely used in the wastewater processing industry for desalination 

operations similar to the one we intend to perform. The main technological obstacle to the use of an 

RO unit in our design is the selection of an appropriate membrane. However, many companies 

manufacture and sell membrane materials by area. We believe the most effective membrane for our 

process will be an asymmetric cellulose acetate based membrane, but further R & D will be required to 

select a specific type and vendor6. Companies such as GE Wastewater are already using mobile scale 

reverse osmosis systems to treat flowback for re-use, so it is reasonable to expect a reverse osmosis 

unit could be scaled to meet our needs for the process7.
Design of a Mobile Treatment System for Hydraulic Fracturing Waste

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Section I: Concept Stage

Part 1: Market and Competitive Analysis

There are approximately 35,000 wells actively being fracked for natural gas in the United 

States. Typical wells take between 3 and 9 million gallons of water to frack, and on average, about one 

third of that water returns to the surface as flowback. This means that most wells have 1 to 3 million 

gallons of water return to the surface as flowback1. Right now, the majority of wells either have to 

dispose of the flowback (usually through deep well injection or evaporation ponds), or ship the water 

to a remote water treatment facility. Neither of these are particularly good options. Environmentalists 

are also putting pressure on frackers to treat the flowback more stringently. Both deep well injection 

and evaporation ponds are liabilities to the environment. Shipping water to stationary treatment 

facilities is more environmentally friendly, but this method is expensive. Additionally, the high volume 

of flowback being produced is pushing these stationary water treatment facilities to their maximum 

capacity. Once this water is treated, it can either be reintroduced to the environment, or reused in 

other fracking wells.

A mobile treatment option will mitigate all of these concerns if executed properly. First, a 

mobile treatment option will reduce the concern from environmentalists because it can reduce the 

amount of waste water by more than 80%. A mobile treatment system will also significantly reduce 

costs for frackers. Due to the huge volume of water that comes back from the well, a large part of the 

cost is transportation. If the water is treated on site, that will save the well the cost of transporting the 

water to a treatment facility. It will also likely reduce costs due to the fact that most of the water 

reservoirs are far from the wells, while transporting water from one well to another in close proximity 

is much cheaper. 

Part 2: Customer Requirements

Frackers are actively seeking more economically efficient and environmentally friendly ways 

to handle the flowback from fracking operations. Thus, essentially the only customer requirements are 

that we offer an economical and environmentally friendly mobile system that does not have major 

barriers to entry. One key requirement of the mobile process is that it treats flowback to the 

acceptable standards for re-use of the flowback for further fracturing. While these standards vary 

widely depending on the deployment region and the operator conducting the fracturing job, table 1 

shows the most widely used specifications that our product reusable water must meet8.

Table 1. Treatment Specifications for Reusable Flowback8

Parameter Units Re-use specification

TDS mg/L 20,000

Alkilinity mg/L 600
Design of a Mobile Treatment System for Hydraulic Fracturing Waste

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April 19, 2013

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Part 3: Preliminary Process Synthesis

Figure 1 shows the first process flow diagram we generated during the preliminary design 

phase.

Figure 1. Preliminary process flow diagram for SuperPro simulation

In general, the main components of the flowback that we have to remove are organics, 

suspended solids, and dissolved solids. Suspended solids can be removed using either a sedimentation 

tank or a flotation tank. However, a sedimentation tank would require a longer residence time and 

thus a large tank, which is not suitable for a mobile treatment system. This led us to the conclusion that 

dissolved air flotation is the best technology to separate the suspended solids from the water.

Total dissolved solids (TDS) is a term used for the combination of all ions present in the water. 

Dissolved solids could be removed either using reverse osmosis (RO) or an evaporator. The main 

advantage of using RO is that it can handle high throughput, but its economic efficiency decreases 

rapidly as the concentration of TDS increases to above 45,000 ppm. The main advantage of an 

evaporator is its ability to operate on a wide range of TDS concentrations. However, an evaporator can 

only handle low throughput in order to be mobile. 

Hardness as CaCO3 mg/L 2,000

TSS mg/L 50

Chloride mg/L 12,500

Iron mg/L 10

Oil and soluble organics mg/L 50

Sulfate mg/L 25

pH range 6.5-8.5
Design of a Mobile Treatment System for Hydraulic Fracturing Waste

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April 19, 2013

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Based on GE data7, flowback from the well typically has a high flowrate with low concentration 

of TDS during the first few days and this phase is followed by a low flowrate with high concentration of 

TDS. In order to optimize the treatment process, we separated the process into two phases: 1) using 

RO to treat high volumetric flow of wastewater with low TDS concentration; 2) using evaporator to 

treat low volumetric flow of wastewater with high TDS concentration. The process would start by 

removing the organics using activated carbon. DAF would then be used to remove suspended solids. 

Finally, the RO or evaporator would be used to remove dissolved solids, depending on TDS level.

For the first phase of the process, we used RO to remove TDS because RO can handle high 

throughput but has an economically imposed TDS concentration limit (below 45,000 ppm) that it can 

operate on6. Inlet flowrate was set to be at 100 gal/min with TDS concentration at 40,000 ppm. When 

TDS concentration increases to be above 45,000 ppm, we would switch to the second phase of the 

process where the evaporator is used to remove TDS. For the evaporator, inlet flowrate was set to be 

at 10 gal/min with TDS concentration at 100,000 ppm. 

However, several changes were made to this preliminary process based on further research 

results. We discovered that using activated carbon to remove the organics would not be very effective 

due to the fact that most of the organics are either long chain polymers which could not penetrate the 

porous surface of the activated carbon or have a high solubility in water, rendering activated carbon 

ineffective for absorbing them.

Additionaly, the results from the MATLAB simulation based on the GE data7 as shown in 

Figures 2 through 4 revealed that the highest TDS concentration that could be reached is 70,000 ppm. 

We thus decided to eliminate the use of the evaporator in order to reduce the capital cost of 

purchasing the equipment and operating cost due to the evaporator’s high energy demand. We are 

able to reduce the TDS concentration to be below 45,000 ppm by recycling some of the clean water to 

dilute the effluent coming out of the DAF.

Part 4: Assembly of Database 

One early challenge we faced in our design project was a lack of data concerning the 

composition of flowback. Many articles mentioned general ranges and variances based on the shale 

region, but few provided hard data. Eventually we discovered a data set collected by GE Wastewater 

that showed time variance of the flowback composition, density, and flowrate over time (See Appendix 

2, section 5 for relevant tabulated data)

7. Figures 2, 3, and 4 show the GE database information in 

graphical form.
Design of a Mobile Treatment System for Hydraulic Fracturing Waste

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Figure 2. Flowback flow rate from well is initially high, then sharply declines after a few days7

Figure 3. Flowback density increases steadily as the flowback period elapses7

0

50

100

150

200

250

300

0 5 10 15 20 25 30 35

Flowback Flow Rate 

(thousand gpd)

Time (days)

8.2

8.4

8.6

8.8

9

9.2

9.4

9.6

0 5 10 15 20 25 30 35

Flowback Density (lbs/gal)

Time (days)
Design of a Mobile Treatment System for Hydraulic Fracturing Waste

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Figure 4. TDS concentration in the flowback increases steadily as the flowback period elapses7

From the database, we concluded that our process would not be able to handle the wide range 

of flow rates coming from the well directly and thus decided to have the operators pump the flowback 

into a holding pond before we begin treatment 1 day after flowback commences. Figure 5 shows a 

scheme of this setup, along with differential material balances on the total flowback mass and on the 

total dissolved solids.

Figure 5. Flowback flows from the well to a holding pond, where it is stored until treatment. Notation: All 

F variables are flowrates in gpm, all ρ are densities in lbs/gal, and all x are TDS concentrations in lbs/gal. 

The w subscripts indicate that variable refers to the well, and the p subscripts refer to the pond. Vp(t) 

refers to the volume of flowback stored in the pond at time t.

0

20

40

60

80

100

120

140

160

180

Flowback TDS Concentration 

0 5 10 15 20 25 30 35

(thousand ppm)

Time (days)
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Using figure 5, we derived the shown material balances. To simplify the system of differential 

mass balances to a point where both could be solved as ODE’s, we made the simplifying assumption 

that the pond’s density, ρp, was a constant 8.49 lbs/gal. While the density of the flowback from the well 

did increase significantly late in the flowback period, the effects of this increase on the overall pond 

density were negligible owing to the sharply decreasing flowrate from the well after a few days. 

To solve the system of ODE’s, we turned to MATLAB’s ode45 differential equation simulator. 

We created a MATLAB file based on the GE data to represent the system of differential equations. The 

file uses the GE data in a piecewise manner to select values for the well outlet density, flowrate, and 

TDS concentration (See Appendix 3, section 1 for ODE file). We set the Fp, or the flowrate from the 

pond to the unit at approximately 45 gpm in order to simulate the process withdrawing the very last of 

the water from the pond. This allowed us to approximate the highest TDS concentration we would 

observe. Figure 6 shows how the volume of flowback stored in the pond varies over the treatment 

period, while figure 7 shows the variation of TDS concentration.

Figure 6. The volume of flowback stored in the pond increases rapidly for several days until the flowrate 

from the well drops off and the process intake flowrate begins to dominate

0

200

400

600

800

1000

1200

1400

0 5 10 15 20 25 30 35

Flowback Volume in Pond 

(thousand gal)

Time (days)
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Figure 7. The TDS concentration in the pond steadily increases, levels off near 40,000 ppm, and then 

spikes as the pond volume reaches zero

The simulation results led to the very important finding that even though the last portions of flowback 

have TDS concentrations well over 100,000 ppm, the maximum concentration we would ever treat is 

closer to 70,000 ppm due to the dilution effects of the pond’s large volume. This finding lead us to 

remove the evaporator unit we had previously considered to treat high TDS content portions. We 

instead implemented a recycle stream around the RO unit that allowed us to keep the TDS 

concentration in the stream entering it below the economics influenced limit of 45,000 ppm for 

reverse osmosis. 

It should also be noted that the ODE file has been developed so that with minimal modification, 

it can be used to calculate the above plots for any well site. All that would be required is a data set 

similar to the one this simulation was developed from. We expect this data to be readily available from 

operators in the deployment area, as fracturing flowback has been monitored in virtually every region 

fracking occurs.

Section II: Feasibility, Development, and Manufacturing

Part 1: Process Flow Diagram, Stream Table, and Simulation of Process

One key step in moving from a conceptual to a more detailed process design was to use a 

process simulation tool to help determine actual operating conditions and the feasibility of using our 

selected technologies in a mobile setting. Because our design dealt with wastewater treatment, we 

chose to use SuperPro for our simulation. SuperPro’s focus on wastewater processing allowed us to 

more easily simulate the reverse osmosis and dissolved air flotation processes than would have been 

possible using Aspen. Figure 8 shows a simplified process flow diagram drawn in SuperPro and used 

to simulate the process.

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

0 5 10 15 20 25 30 35

TDS Concentration (ppm)

Time (days)
Design of a Mobile Treatment System for Hydraulic Fracturing Waste

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Figure 8. Final process flow diagram for SuperPro simulation

Due to the lack of a process model and usable design data for the EC unit, all design of the 

electrocoagulation unit was done manually based on data acquired from a report describing the 

operation of a comparably sized EC unit being used by a company in Australia9. SuperPro was used to 

solve the material and energy balances for the DAF and RO units, allowing a more rigorous design of 

these units. The TDS in the flowback was modeled using NaCl and CaCl2, and the TSS was modeled 

using octane (SuperPro allows the user to specify whether a component is a dissolved or suspended 

solid). The SuperPro simulation is available as an electronic file. See Appendix 3, Section 2 for more 

information. The stream table shown in table 2 gives the results of the SuperPro simulation.
Design of a Mobile Treatment System for Hydraulic Fracturing Waste

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Table 2. SuperPro simulation stream table for mobile treatment process

Time 

Ref: min

Post EC Suspende

d Waste

Post 

DAF

Recycl

e RO

Pre RO Post RO Treate

d 

Water

Dissolve

d Waste

Type Raw 

Material

Total 

Flow

kg

253.654 3.543

250.11

1

161.16

2

411.27

4 322.325 161.162 88.959

Temp. °C 25 25 25 26.61 25.64 26.61 26.61 26.61

Pressur

e

bar

1.013 1.013 1.013 1.013 1.013 1.013 1.013 1.013

Liq/Sol 

Flow

kg

253.6545 3.5431

250.11

1 161.16 411.27 322.325 161.16 88.9597

Liq/Sol 

Vol Flow

gal

65 0.9247

64.075

3 42.744 106.81 85.488 42.744 21.3717

Total 

Content

s

mas

s 

frac 1 1 1 1 1 1 1 1

CaChlori

de 0.0135 0.013 0.0135 0.0019 0.009 0.0019 0.0019 0.0346

Octane 0.0006 0.0395 0 0.0001 0.0001 0.0001 0.0001 0

Sodium 

Chloride 0.0565 0.0543 0.0565 0.0017 0.035 0.0017 0.0017 0.1558

Water 0.9294 0.8932 0.9299 0.9963 0.9559 0.9963 0.9963 0.8096

Part 2: Process Description 

By chaining the EC, DAF, and RO units together, we were able to design an overall process that 

can address each of the main pollutants in the flowback to the accepted reuse standards. At the 

conceptual level, we also carefully considered the sequencing of the units to achieve the most efficient 

solution, eliminating unnecessary maintenance. Figure 9 shows a conceptual block diagram of the 

process.

Electrocoagulation 

(EC)

Dissolved Air 

Flotation (DAF)

Reverse Osmosis 

(RO)
Design of a Mobile Treatment System for Hydraulic Fracturing Waste

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Figure 9. Conceptual block diagram of the treatment process

Two important steps occur in the EC unit. The first is the electrochemical oxidation of small 

organics from the flowback, typically measured as chemical oxygen demand (COD). While the presence 

of organics in the flowback is not necessarily a major concern in further reuse of the flowback, the 

reverse osmosis unit employed to remove dissolved solids will become easily fouled if exposed to 

these small organics. Thus, to reduce membrane replacement costs to an acceptable level, we need to 

remove the COD from the feed. Electrochemical oxidation allows for the effective removal of organics.

In the electrochemical oxidation reaction, a current is passed through the wastewater using 

two iron electrodes. The anode acts as a sacrificial electrode, degrading overtime as the current causes 

it to dissolve into positively charged iron ions. These ions are strong oxidizers, and react with the small 

organics in solution to oxidize them to CO2 gas and other compounds which do not inhibit reuse or 

further processing of the water10. 

The second major step that happens in the EC unit is the electrocoagulation of suspended 

solids in the flowback. One of the main suspended solids in the flowback is emulsified oil and grease11. 

While dissolved air flotation can remove the emulsified oil, the efficiency of the removal is vastly 

increased if the emulsion is first broken and the suspended solids coagulated. A side effect of the 

current that passes through the EC is that it destabilizes the charges that hold the oil in the emulsion 

state. The charge destabilization causes both the normal suspended solids and the emulsified oil to 

flocculate into much larger grouped particles, commonly called flocs12. The reaction also causes the 

formation of hydrogen gas bubbles, which serve to further increase the efficiency of the DAF unit. For 

further information on the specifications of the EC, see page 17.

After passing through the EC, the flowback enters a dissolved air flotation (DAF) unit. The DAF 

functions to remove suspended solids from the flowback. In the dissolved air flotation unit, the

flowback enters a flotation tank open to the air. A recycle stream exits the other end of the tank and reenters it at the same end as the influent wastewater. Air bubbles are dissolved in the recycle stream of 

the process water at high pressure by a compressor. The pressure is then reduced with a valve at the 

point where the recycle stream enters the flotation tank. When the pressure decreases, the solubility of 

air rapidly falls, causing the formation of micron sized bubbles4. These tiny bubbles attach to the 

flocculated suspended solids in the effluent from the EC, and cause the flocs to float to the surface, 
Design of a Mobile Treatment System for Hydraulic Fracturing Waste

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where the sludge can be removed using a mechanical skimmer. For further information on the 

specifications of the DAF, see page 18.

Once the DAF has removed the suspended solids, the wastewater stream’s main remaining 

contaminants are dissolved solids, mostly CaCl2, NaCl, and other chloride salts. The third and final 

main unit of our process is a reverse osmosis unit that uses a polymer membrane to reject salt and 

produce clean, reusable frack water. The reverse osmosis unit is placed last in the separation train 

because of its fouling sensitivity to organic chemicals and suspended solids. Osmosis is the process by 

which molecules of a solvent will naturally diffuse across a semipermeable membrane towards an area 

of high solute concentration from an area of low solute concentration6. In our RO unit, we apply 

pressure on the high concentration solution side of the membrane using a pump, allowing us to 

reverse the osmosis process. The pressure applied to the wastewater forces clean water through the 

membrane, which rejects the salt ions present in the pre-treated flowback. The resulting exiting 

streams are (1) a concentrated waste stream that can be disposed of by deep well injection, and (2) a 

stream of treated flowback that can be shipped to a new well site to be reused on the next fracking job.

For further information on the specifications of the RO unit, see page 19.
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Figure 10 presents a more detailed flow sheet that shows intermediate processing including 

pumps and compressors.

Figure 10. Detailed process flow diagram for mobile treatment unit

Part 3: Energy Balance and Utility Requirements

Finding a way to power a large scale operation in a remote area was one of the important 

considerations for our process. Most fracking well sites will have a power converter that has the 

capability to convert natural gas to electricity. Each of our units will be powered by electricity 

generated on site. Usually these operations are typically between 40-60% Efficient in converting 

natural gas energy into electrical energy, so we calculated our costs based on 50% efficiency13. Electric 

motors also have a drop off in energy efficiency (78.8% for <5 hp and 90.2% for 50-99 hp motors)13. 

Considering these factors, we were able to estimate the power usage and cost of electricity for the 

motors. Based on the EC unit’s design, the expected electricity requirements of the EC unit will be 

about 0.006 KWh/gallon of water treated. Sample calculations to demonstrate the precise derivation 

can be found in Appendix 2, Section 2.
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Table 3 shows a summary of the energy requirements of each unit.

Table 3. Equipment electricity requirement summary

Operation Time 720 hours

Water Treated 2.83E+06 Gallons

Power Source

(Natural Gas) $ 0.0123 $/KWh

Usage Units

Usage 

(KW)

Usage 

(KWh)

Cost 

($/KWh) Cost ($)

Unit Operations

EC 0.006

KWh/gallo

n 17,000 $ 0.0246 $ 417.84 

Pump-motors

1 1.30 hp 0.969 698 $ 0.0312 $ 21.78 

2 1.30 hp 0.969 698 $ 0.0312 $ 21.78 

3 1.30 hp 0.969 698 $ 0.0312 $ 21.78 

4 85.38 hp 63.667 45,840 $ 0.0273 $ 1,250.20 

5 1.30 hp 0.969 698 $ 0.0312 $ 21.78 

6 0.94 hp 0.700 504 $ 0.0312 $ 15.73 

7 0.58 hp 0.433 312 $ 0.0312 $ 9.74 

Compressor

8 4.25 hp 3.169 2,281 $ 0.0312 $ 71.24 

TOTAL $1,851.86 

TOTAL (per gallon) $ 0.0006542 
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Part 4: Equipment List and Unit Descriptions 

Electrocoagulation (V-100):

As previously mentioned, we were unable to simulate the electrocoagulation reactor due to the 

lack of a process model and usable design data. Thus, the design was done manually based on data 

acquired from a report describing the operation of a similar EC unit being used by a company in 

Australia9. The electrodes used in the unit will be made of Iron metal. Despite the higher cost of 

replacement for Iron electrodes, they are more efficient than aluminum electrodes for natural gasbased wastewaters14. The influent total COD of the wastewater is approximately 742 ppm, and based 

on several sources, it appears that we could reasonably assume a 95% oxidation of the organics in the 

flowback10, 11. This results in the EC unit effectively treating the COD to below acceptable standards. 

The electricity requirements for the EC are estimated to be 0.006 kwh/gal treated, and the costs for 

replacement electrodes are estimated as $0.00015/gal treated9. The EC reactor chamber itself will be 

constructed from stainless steel to provide resistance to corrosive components of the flowback.

Dissolved Air Flotation (V-101, P-101, C-100)

The DAF unit and associated equipment (recycle pump and compressor) were simulated in 

SuperPro. SuperPro allowed us to manipulate several input parameters to the DAF process model, 

which allowed for a rigorous design of the unit. The DAF will be operated with a solids loading of 1 

gal/ft2-min, a typical value for many small DAF units. The first parameter we sought to optimize for the 

operation was the air-to-solids ratio. Given our desired total suspended solids effluent concentration 

of <50 mg/L, we used the optimization chart presented figure 11 to select an air-to-solids ratio of 0.02 

mL/mg.

Figure 11. Air-to-solids optimization chart for the DAF unit 3

Desired Effluent TSS concentration (mg/L)
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After selecting the air to solids ratio, the last critical parameter to be optimized was the recycle ratio. 

This optimization was done on a total capital cost basis. A lower recycle ratio reduces the required cost 

of the pump and the flotation tank, but increases the required air pressure from the compressor. This 

lead to a need to balance the competing effects of the recycle ratio on capital cost. The required air 

compressor pressure was calculated using the DAF design equation4:

 

 

 

 

 

 

 

(1)

Where R is recycle ratio, Sout is concentration of dissolved air in outgoing wastewater (20.36 mg/L),

f accounts for non-saturation of air in water (65%), P is the required air pressure in atm, and X0 is the 

TSS concentration in the influent (608.5 mg/L). This pressure was calculated for each recycle ratio we 

simulated (see appendix 2, section 3 for sample calculation). Once the compressor pressure and 

recycle flow rate were known, the total capital cost for all three pieces of equipment included in the 

DAF analysis (flotation tank V-101, compressor C-100, and pump P-101) were calculated for each 

recycle ratio. The results of these calculations are graphed in figure 12. 

Figure 12. Total capital costs of the DAF system passes through a minimum with a recycle ratio of 0.8

The results of this optimization led us to select a recycle ratio of 0.8 or 80%, which resulted in an 

estimated total capital cost of about $420,000 for the three components of the DAF system. The DAF 

$0

$100,000

$200,000

$300,000

$400,000

$500,000

$600,000

$700,000

0 0.5 1 1.5 2

Capital Costs (USD)

Recycle Ratio

Air Compressor

Flotation Tank and

Recycle Pump

Total DAF Capital

Cost
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tank will be constructed from stainless steel to provide resistance to corrosive components of the 

flowback.

Reverse Osmosis (V-102):

Reverse Osmosis (RO) is used to remove dissolved solid from the flowback. The operating 

pressure is calculated to be about 1000 psi, which is approximately twice the osmotic pressure of the 

45,000 ppm dissolved solid flowback solution (See Appendix 2, section 4)

15. Increasing operating 

pressure would increase percent recovery and rejection coefficient. The operating temperature is 

determined to be at 25oC. Increasing operating temperature would increase percent recovery but 

decrease rejection coefficient16. A membrane with rejection coefficient of 0.99 and 0.95 for NaCl and 

CaCl2, respectively and percent recovery of 80%16 are required for the process. The size of a RO 

module is determined to be about 40 inch in length and 16 inch in diameter which can hold up to 

160m2 of membrane17.

Pumps

Each of our material streams will be pushed through the system by electric powered 

centrifugal pumps. The pumps used for the simulation are constructed from stainless steel because 

there will be copious amounts of dissolved solids passing though. The flow rates they will handle range 

from 30 to 65 gallons per minute, and they are rated to handle head loss up to 45 feet.
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Part 5: Specification Sheets
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Part 6: Equipment Cost Summary

Table 4. Equipment cost breakdown

Equipment Cost

Electric Motors $ 29,448.52 

Centrifugal Pumps $ 154,206.36 

Compressors $ 36,849.74 

DAF $ 311,817.63 

RO (housing) $ 380,800.00 

RO (membrane) $ 15,000.00 

Electrocoagulation $ 155,000.00 

Recycle Tank $ 5,000.00 

Truck $ 50,000.00 

TOTAL EQUIPMENT COST $ 1,123,122.25 

*See Appendix 2, Section 2 for complete derivation of each cost

Part 7: Fixed Capital Investment Summary

Costing for each unit was conducted using the process equipment cost equations presented in Chapter 

22 of Product and Process Design Principles13. These equations allowed us to estimate the expected 

capital cost of process equipment based on a sizing factor related to the unit’s size or throughput. Once 

the capital cost was calculated and adjusted to 2013 dollars using the CE Index, we had a reasonably 

good approximation of the capital cost of each unit. Where appropriate, construction material 

correction factors were used to adjust the cost based on a non-standard material of construction 

(stainless steel flotation tank, pumps, etc.). Sample calculations of the capital cost for some units are 

shown in Appendix 2, section 2. Table 5 gives the sizing parameter and its units used to calculate cost 

of each piece of process equipment.

Table 5. Equipment cost equation parameters and construction material factors13

Equipment Cost Eqn. Parameter 

[units]

Material Material factor

Electric Motors Pc [hp] N/A N/A

Centrifugal Pumps S = Q(H)0.5

[(gpm)*(ft0.5)]

Stainless steel 2.00
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Compressors Pc [hp] Stainless steel 2.5

DAF Q [gpm] N/A N/A

RO (housing) Q [gpm] Cast iron 1.0

RO (membrane) A [ft2] N/A N/A

Electrocoagulation N/A (estimated from 

analysis of similar unit)

N/A N/A

Recycle Tank V (gal) N/A N/A

Truck N/A (estimated from 

typical estimates for 

mobile process trucks)

Part 8: Other Important Considerations

Environmental problems and methods used to eliminate them

The goal of this system is to minimize the effect that fracking has on the environment by 

treating the noxious wastewater so that it can be reused in other wells and not be 

reintroduced directly into the environment. However, there will still be an environmental 

impact. The treatment process will reduce the waste from the well to about 15% of the 

original volume. In the case of most wells, this will still result in tens of thousands of 

gallons of concentrated waste. This sludge is typically taken to a landfill or injected deep 

underground into a well that is no longer active. This does pose a slight risk to the 

environment, but it is greatly reduced from the risk that is present without a treatment 

system.

Safety and health concerns - Hazard and Operability Study (HAZOP)

Node: Pump

Intention: Flows 

Guide 

Word

Parameter Cause Consequence Action

NO FLOW Line is blocked Pump could break due 

to overheat of electric 

motor.

Check for 

bends/blocks

Line is leaking Visual inspection
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No power to pump Have backup power 

source

MORE FLOW Pump spinning too fast Overflow of flowback 

and membrane could be 

damaged

Monitor pump speed 

regularly

Error in pump setting Monitor pump 

setting regularly

Node: Compressor

Intention: Provides compressed air to the Dissolved Air Floatation (DAF)

Guide 

Word

Parameter Cause Consequence Action

NO PRESSURE Line is blocked Tank could be 

overflown due to 

presence of excessive 

solid in the DAF

Check for bends/blocks

Line is leaking Line inspection using 

soap water

No power Have backup power 

source

MORE PRESSURE Error in 

compressor setting

Pipe could burst Monitor compressor 

setting regularly
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Node: Electrocoagulation (EC)

Intention: Destabilizes the organics and suspended solid

Guide 

Word

Parameter Cause Consequence Action

NO CURRENT No power More suspended solid 

and organics get 

through to cause 

membrane fouling

Have backup power 

source

Electrode depleted Monitor electrode 

regularly

MORE CURRENT Error in EC setting Possible electrocution Monitor EC setting 

regularly

Node: Dissolved Air Flotation (DAF)

Intention: Separates organics and suspended solid from water

Guide 

Word

Parameter Cause Consequence Action

NO FLOW Line is blocked Compressed air 

released to 

atmosphere directly

Check for bends/blocks

Line is leaking Visual inspection

MORE FLOW Pump spinning too 

fast

Tank could be 

overflown which 

causes spill of 

flowback

Monitor pump speed 

regularly

Error in pump 

setting

Monitor pump setting 

regularly

Node: Reverse Osmosis

Intention: Separated dissolved solid from water

Guide 

Word

Parameter Cause Consequence Action

NO PRESSURE Pump is broken Minimal or no 

separation occurs

Troubleshoot pump 

regularly

Line is leaking Visual inspection

MORE PRESSURE Pump spinning 

too fast

Membrane could be 

damaged and module 

could burst which 

causes spill of 

Monitor pump speed 

regularly

Error in pump 

setting

Monitor pump setting 

regularly
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Narrow line being 

used

flowback Line inspection

MORE COMPOSITION Error in sensor 

reading

Membrane could be 

fouled and inefficient 

separation

Online and offline 

measurement

Error in control 

action

Monitor control process

Process controllability and instrumentation

Since there are no major effects from changes in flow rates, we will use direct acting 

feedback controllers to control all our valves. There are no heating or cooling elements in 

the process, so there will not be any heat control equipment necessary. We will also have to 

monitor the COD and control the valves accordingly.

Startup, including additional equipment

This process is designed as a mobile service for frackers. Inherent in this design is the 

minimization of startup barriers for the on-site operations. The entire process will fit on a 

standard 8.5’x48’ trailer. This is so that the startup for the system is limited to setting up 

pipes and a pump that drain the holding pond. There will also be additional costs to the 

frackers, as they will need to dig a second well so that the clean water can be stored 

somewhere before being transported to the next fracking location. The majority of our 

startup costs will be related to the assembly of the unit operations as well as mounting 

everything onto our trailer. 

Plant (trailer) layout

Figure 13. Schematic showing proposed physical arrangement of process on truck
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Part 9: Operating Cost and Economic Analysis

Table 6. ROI summary for us

US

EQUIPMENT COST

(1 time cost)

$ 1,126303.58

OPERATING COST

(per well)

$ 102,532.35 

Revenue

(per well)

$ 297,467.65 

Revenue

(per year)

$ 1,665,818.84 

Payback period 3 years

Return on Investment 326.5%
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Table 7. ROI summary for frackers

Frackers

TOTAL COST

(per well)

$ 400,000.00 

TOTAL SAVINGS

(per well)

$ 483,282.72 

Return on Investment 

(%savings)

21%

Cost per Gallon Treated $ 0.14 

The full cost sheet is available as an electronic file. See Appendix 3, Section 3 for more information. We 

have an unrealistically high ROI and this is based on the way we calculated the savings to the well. The 

savings that we considered were 1) treated water that can be used at a nearby well without having to 

draw fresh water and 2) the cost of disposal of dirty water. We have a reliable source indicating that

$0.12 /gal is the average cost to draw and transport fresh water to a well site18. Since we were unable 

to accurately estimate the cost to transport treated water to a nearby well, we assumed these costs to 

be much lower than the cost of transporting fresh water to the well site, and based our calculations on

the $0.12/gal rate for clean water. However, if we bring this number to $0.00 (implying that it would 

cost the same to transport our treated water to a nearby well as it would to draw and transport the 

same amount of clean water from a remote source), we will still have a profitable operation.

Table 8. ROI summary for us, savings from fresh water ignored

US

EQUIPMENT COST

(1 time cost)

$ 1,126,303.58 

OPERATING COST

(per well)

$ 102,532.35 

Revenue

(per well)

$ 82,467.65 

Revenue

(per year)

$ 461,818.84 

Payback period 3 years
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Return on Investment 18.2%

Table 9. ROI summary for frackers, savings from fresh water ignored

Frackers

TOTAL COST

(per well)

$ 185,000.00 

TOTAL SAVINGS

(per well)

$ 198,162.72 

Return on Investment 

(%savings)

7.1%

Cost per Gallon Treated $ 0.065/gal

Section III: Conclusions and Recommendations

Hydraulic fracturing is a growing industry, and will almost certainly be a key part of the energy 

market for the foreseeable future. The rising environmental regulations of fracturing’s impacts are a 

challenge to the development of the technology, but also provide an opportunity for chemical 

engineering companies to design novel solutions for the problem of flowback management. The 

market for a mobile treatment solution for flowback is very large, and is only projected to grow. Based 

on our study, we concluded that a mobile system to treat the flowback at well sites is a viable business 

development opportunity. The key to our process design’s success lies in the synergy between the 

electrocoagulator, the dissolved air flotation unit, and the reverse osmosis modules. By correctly 

sequencing these units, we were able to design an overall process capable of treating the most 

problematic contaminants from fracking flowback. 

Our design centered on creating a safe, functional, and economic method for reusing flowback, 

a goal which we achieved. The high return on investment for both our company and the well operators 

indicates that with our process, operators can realize a significant savings over current disposal

methods in the Marcellus Shale and that our company also stands to profit significantly from this 

operation. In addition to the economic benefits, our mobile treatment process will address several 

environmental issues surrounding fracturing. By reusing flowback, operators avoid withdrawing extra 

water from rivers and lakes. The mobile aspect of the design also significantly reduces greenhouse gas 

emissions from trucking the flowback to deep well injection sites. 

During the design process, our team designed the process for a single specific well in the 

Marcellus Shale region. However, as our design evolved, we developed simulation tools, designed 

calculators, and gathered data that would allow us to generalize our solution to a wide range of well 

sites. The versatility offered by these tools will provide a competitive advantage in allowing us to 

optimize the operation for each well site based on its unique chemistry and flow profile. We 
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recommend that our company engage in further R & D to further explore the potential benefits of this 

design.

Acknowledgements

We would like to thank Dr. Russell F. Dunn, Dr. Kenneth A. Debelak and Dr. John Roth from the 

Vanderbilt University Chemical Engineering Department for their advice throughout the entirety of the 

design process. We would also like to thank Dr. Alan Bowers from the Vanderbilt University Civil 

Engineering Department for his comments and recommendations. And finally, we would like to thank

Vanderbilt University for the financial support and provisions of computer software.
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Bibliography

1. Sourcewatch. “Fracking” Sourcewatch.org. Web. 12 February 2013. 

<http://www.sourcewatch.org/index.php/Fracking>.

2. Sequiera, C. et. Al. “Mediated and non-mediated electrochemical oxidation of isopropanol” 

Applied Surface Science. Web. 13 April 2013. 

<http://www.sciencedirect.com/science/article/pii/S0169433205015680>.

3. GE Water & Process Technologies. “Wastewater Solids Flotation Techniques” World Water 

Tour. Web. 5 February 2013. 

<http://www.gewater.com/pdf/watertour/wwtchi/breakout_session/Flotation_Technology.p

df>.

4. Armenante, Piero M. “Flotation”; Web. March 17, 2013. 

<http://cpe.njit.edu/dlnotes/CHE685/Cls05-1.pdf>.

5. Ecologix Environmental Systems. “Integrated Treatment System for Fracking Flowback” 

Ecologix Wastewater Treatment Solutions. Web. 15 April 2013. 

<http://www.ecologixsystems.com/system-its.php>.

6. Water Quality Association. “Technical Briefs: Reverse Osmosis” Web. April 16, 2013. 

<http://www.wqa.org/sitelogic.cfm?ID=872>.

7. Wilson, Mark “Flowback and Produced Water Treatment Overview” GE Water & Process 

Technologies. Web. February 16, 2013. <http://www.makingwaterconnections.com/wpcontent/uploads/2012/05/Wilson_Flowback-and-Produced-Water-Treatment-Overview.pdf>.

8. Acharya, Harish R. “Cost Effective Recovery of Low-TDS Frac Flowback Water for Re-use” GE 

Water & Process Technologies. Web. February 27, 2013. 

<http://www.gwpc.org/sites/default/files/event-sessions/3Acharya_Haris.pdf>.

9. Tetreault, Alena “Electrocoagulation Process for Wastewater Treatment.” Web. April 8, 2013. < 

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CD8QFjAB&ur

l=http%3A%2F%2Fwww.redmeatinnovation.com.au%2Fproject-reports%2Freportcategories%2Fenvironment%2Felectrocoagulation-process-for-wastewatertreatment%2Fmla-report-prenv011-

1&ei=zQljUaHhLJLW8gTi2ID4Bg&usg=AFQjCNHfIBMws2DnYRvkjhoD19l0Yjazrw&sig2=Nd9M

gRk2iIcO6Hhetqat6Q&bvm=bv.44770516,d.eWU>. 

10. Hardik, Shah. “Electrochemical Oxidation of Organic Pollutants” Sarvajanik College of 

Engineering and Technology. Web. April 16, 2013. 

<http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDoQFjAB&u

rl=http%3A%2F%2Fwww.environmentalexpert.com%2FFiles%2F0%2Farticles%2F2980%2Farticle1363.doc&ei=cVhtUd7VMYS28wT

W7IGgAw&usg=AFQjCNEPzkKIPmy0hETeykLjs7UhLEEgg&sig2=l_ZnyeLndRB5UbMDRExWiQ&bvm=bv.45175338,d.eWU>.

11. Wolford, Robert. “Characterization of Organics in the Marcellus Shale Flowback and Produced 

Waters” Pennsylvania State Library. Web. March 3, 2013. 

<https://etda.libraries.psu.edu/paper/12343/7626>.

12. Holt, Peter et. Al. “Electrocoagulation as a wastewater Treatment” Australian Environmental 

Engineering Research. Web. April 2, 2013. 

<http://www.isf.uts.edu.au/publications/PH_GP_CM_1999.pdf>.
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13. Seider, Warren et. Al. Product and Process Design Principles. Third Ed. John Wiley and Sons: 

Hoboken, NJ. 2009.

14. Vepsäläinen, Mikko. “Electrocoagulation in the treatment of industrial waters and 

wastewaters” VTT Science 19. Web. April 7, 2013. 

<http://www.vtt.fi/inf/pdf/science/2012/S19.pdf>.

15. Applied Membranes. “Reverse Osmosis RO Systems” Water Treatment Guide. Web. April 10, 

2013. <http://www.appliedmembranes.com/Reverse_Osmosis_Systems.htm>.

16. Applied Membranes. “Factors Affecting RO Membrane Performance” Water Treatment Guide. 

April 9, 2013. 

<http://www.watertreatmentguide.com/factors_affecting_membrane_performance.htm>.

17. Johnson, Jon and Busch, Markus. “Engineering Aspects of Reverse Osmosis Module Design.” 

Dow Water & Process Solutions. Web. March 27, 2013. < http://gwriic.technion.ac.il/pdf/IDS/380.pdf>.

18. Sider, Alison. “Drillers Begin Reusing Frac Water” Wall Street Journal. Web. April 8, 2013. 

<http://online.wsj.com/article/SB10001424052970203937004578077183112409260.html>.
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Appendix

Appendix 1: Glossary of Terms 

 – mass flow rate of the water leaving the well 

 – density of the water leaving the well

 – concentration of TDS in the water leaving the well

 – volume of the water in the holding pond

 – density of the water in the holding pond

 – concentration of the water in the pond

 – mass flow rate of the water leaving the pond

 – density of the water in the pond

 – concentration of the water in the pond
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Appendix 2: Design Procedures and Calculations

Section 1: Holding Pond

Component Balance (TDS):

 

 

 

 

 

 

Overall Material Balance:

 

 

 

 

 

 

 

Section 2: Costing Data

CE = 550 

Motors:

Define Q (gpm), P (psi), H (ft), (lb/gal)

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 (table 22.22)

 

 

 

 

 
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Pumps:

Define Q (GPM) and H (feet) 

 (table 22.20 in design book) 

 (table 22.21) (stainless steel)

 

 

 

 

 

 

 

 

 

 

Compressor:

 

 

 (based on an electric powered motor)

 (based on a stainless steel compressor)

 

 

 

 

 

Utilities:

 Natural Gas:

Heating value (approximated as methane)
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Cost of energy from natural gas

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Cost of electricity 

 On site turbines will harness approximately half of the energy in the natural gas as usable

 electricity

 

 

 

 

 

Cost of powering a motor

 Motors will convert approximately 80-95% of the electricity to usable power

 For this example 90.2% (50-99 hp motor minimum efficiency)13

 

 

 

 

 

 

 For a 85.38 hp motor, operating for 720 hours (30 days)

 

 

 

 

 

 

 

DAF:

Q = 117 gpm

CBM = 14,800*Q0.64 = $311,817
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RO:

Q = 144,000 gpd

CBM = 2.7*Q = $388,800

EC: capital cost was assumed to be comparable to cost of Australian unit9, which is $155,000. Nonrigorous design prevented a more accurate estimation.

Section 3: DAF compressor pressure sample calculation

For a recycle ratio of 0.8 (the designed value), the required compression pressure was calculated as4:

 

 

 

 

 

 

 

 

 

 

= 13.03 atm = 191.5 psi

Section 4: TDS model and operating pressure calculation

TDS was modeled by combination of sodium chloride (NaCl) and calcium chloride (CaCl2) which are 

significant components based on GE data7 where 80.7% of TDS was modeled by NaCl and 19.3% of 

TDS was modeled by CaCl3.

Osmotic pressure of NaCl and CaCl2 were calculated to be 413.9 psi and 71.1 psi, respectively from 

known data15:

For NaCl:

 

 

 

 

For CaCl2:

 

 

 

 
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Thus, the osmotic pressure of the solution is 486.1 psi. Operating pressure of a reverse osmosis is 

usually doubled the osmotic pressure17, in our case it would be 972.1 psi which is approximately close 

to 1000 psi.
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Section 5: Relevant tabulated GE data

Table S5.1. Flowback composition

Day Density 

(lbs/gal)

TDS 

(mg/L)

TDS ppm Ca (mg/L) Mg (mg/L) TH (CaCO3) 

(mg/L)

Na (mg/L) K 

(mg/L)

Fe 

(mg/L)

Ba 

(mg/L)

Sr (mg/L)

1 8.36 559 558 40 4 118 137 6 39 0 3

1.5 8.39 6438 6405 380 31 1171 1900 104 27 11 74

2 8.42 12773 12658 935 77 2899 4639 264 16 26 196

3 8.49 23818 23419 1313 102 4087 5943 284 8 38 315

4 8.58 40803 39690 2447 191 7817 11040 457 22 106 734

5 8.60 45759 44381 2680 209 8590 12122 481 28 126 821

12 8.68 59634 57337 4395 381 13644 15740 546 47 210 818

15 8.78 78682 74789 4462 372 14402 19562 713 15 240 1351

21 9.20 156570 142071 10528 872 33122 40017 1750 67 336 2599

25 9.27 170014 153021 12085 1013 38039 41390 1926 39 385 2959

31 9.36 185729 165673
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Table S5.2. Flowback flowrate

Day Percent of 

Fracture

Barrels gallons/day gal/min

1 7.56% 6124 257208 178.62

2 7.56% 6119 256998 178.47

3 7.50% 6071.4 254998.8 177.08

4 7.44% 6023.8 252999.6 175.69

5 7.26% 5881 247002 171.53

6 4.56% 3690.5 155001 107.64

7 2.88% 2333.3 97998.6 68.05

8 1.21% 976.2 41000.4 28.47

9 0.88% 714.3 30000.6 20.83

10 0.65% 523.8 21999.6 15.28

11 0.44% 357.1 14998.2 10.42

12 0.35% 285.7 11999.4 8.33

13 0.26% 214.3 9000.6 6.25

14 0.18% 142.9 6001.8 4.17

15 0.12% 95.2 3998.4 2.78

16 0.07% 57.1 2398.2 1.67

17 0.04% 28.6 1201.2 0.83

18 0.04% 33.3 1398.6 0.97

19 0.03% 23.8 999.6 0.69

20 0.03% 26.2 1100.4 0.76

21 0.04% 28.6 1201.2 0.83

22 0.04% 29.8 1251.6 0.87
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23 0.03% 27.4 1150.8 0.80

24 0.03% 27.1 1138.2 0.79

25 0.04% 30.5 1281 0.89

26 0.04% 28.6 1201.2 0.83

27 0.04% 33.3 1398.6 0.97

28 0.03% 23.8 999.6 0.69

29 0.08% 61.9 2599.8 1.81

30 0.04% 28.6 1201.2 0.83

31 0.04% 29.8 1251.6 0.87
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Appendix 3: Computer programs developed

Section 1: MATLAB

MATLAB ODE file:

Can be used to model or predict incoming TDS concentration at a particular well site by solving 

differential balances on holding pond 

function xdot = Flowback_Blending_Simulator( t,x)

% INPUTS

% t = time in days

% x(1) = Vp (volume in pond, gal)

% x(2) = Xp (TDS concentration in pond, lbs/gal)

% PARAMETERS

% rhoP = density of flowback in pond (lbs/gal)

% rhoW = density of flowback coming out of the well (lbs/gal)

% Fw = volumetric flowrate from well (gal/day)

% Xw = TDS concentration in flowback coming out of well (lbs/gal)

% Fout = volumetric flow rate from pond to seperation units (gal/day)

% OUTPUTS

% xdot(1) = d(Vp)dt (gal/min)

% xdot(2) = d(Xp)dt (lbs/gal * min)

% xdot(3) = can be used to plot TDS concentration in ppm format instead of

% lbs/gal

% Vp= x(1) (gal)

% Xp= x(2) (lbs/gal)

%rhoP
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rhoP = 8.49; % assume constant, weighted average of the well flow density 

measurements from GE data

%rhoW

if (t <= 1)

 rhoW = 8.362;

elseif (t<= 1.5)

 rhoW = 8.387;

elseif (t<= 2)

 rhoW = 8.421;

elseif (t<= 3)

 rhoW = 8.487;

elseif (t<= 4)

 rhoW = 8.579;

elseif (t<= 5)

 rhoW = 8.604;

elseif (t<= 12)

 rhoW = 8.679;

elseif (t<= 15)

 rhoW = 8.779;

elseif (t<= 21)

 rhoW = 9.197;

elseif (t<= 25)

 rhoW = 9.272;

else

 rhoW = 9.355;

end

%Fw 
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Fvals = [257208 256998 254998.8 252999.6 247002 155001 97998.6 41000.4 

30000.6 21999.6 14998.2 11999.4 9000.6 6001.8 3998.4 2398.2 1201.2 1398.6 

999.6 1100.4 1201.2 1251.6 1150.8 1138.2 1281 1201.2 1398.6 999.6 

2599.8 1201.2 1251.6];

tpicked = floor(t);

Fw = Fvals(tpicked);

%Xw

if (t <= 1)

 Xw = .0046;

elseif (t<= 1.5)

 Xw = .053;

elseif (t<= 2)

 Xw = .1065;

elseif (t<= 3)

 Xw = .1987;

elseif (t<= 4)

 Xw = .3405;

elseif (t<= 5)

 Xw = .3819;

elseif (t<= 12)

 Xw = .4976;

elseif (t<= 15)

 Xw = .6565;

elseif (t<= 21)

 Xw = 1.3065;

elseif (t<= 25)
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 Xw = 1.4187;

else

 Xw = 1.5499;

end

Fp= 44.7997*24*60; % Fp chosen to bring simulation to near completion, volume 

is very close to zero

xdot(1)= (Fw*rhoW)/rhoP - Fp;

xdot(2)= (Fw*Xw - Fp*x(2) - x(2)*xdot(1))/x(1);

xdot(3)= (xdot(2)/rhoP) * 1000000; 

xdot=[xdot(1);xdot(2);xdot(3)];

% to Run the simulation at the Matlab Prompt:

%trange = [1 31]

%ic = [257208, .00467, 557.94];

%[t,y]=ode45('Flowback_Blending_Simulator',trange,ic);

%to Plot

% plot(t,y(:,1)) %Vp(t)

% plot(t,y(:,2)) %Xp(t) in lbs/gal

% plot(t,y(:,3)) %Xp(t) in ppm

end
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Section 2: SuperPro Designer

SuperPro Process Simulation: 

An easy to edit process simulation was created in SuperPro. The file can be easily applied to 

design custom units for different regions or well sizes. This file is available as an electronic file 

(contact Matthew Claussen at matthew.w.claussen@vanderbilt.edu for access).

Section 3: Microsoft Excel Calculator

Process Costing and Pricing Calculator: 

An easy to edit economics calculator was created in Microsoft excel. This extensive spreadsheet 

allows for easy addition or modification of process costs, and calculates expected return on 

investment for the design. Due to its large size, the file will not be included here. This file is 

available as an electronic file (contact Marc Panu at marc-daniel.m.panu@vanderbilt.edu for 

access).

Section 4: Pertinent printed material

See design notebook