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# Treatment of Flowback – Shale Plays

Mark Galimberti VSep – New Logic Research, State College, PA

ABSTRACT

Customers have had samples of flow-back water resulting from hydro-fracturing of gas wells drilled in the Marcellus Shale in Pennsylvania. They would like to treat the wastewater to a quality suitable for reuse in the fracturing of the next well. This re-use water will likely be diluted with fresh water. The water is currently being hauled off site.

New Logic has conducted many P-Mode VSEP test (pilot mode) to demonstrate the separation ability of VSEP. VSEP is a unique membrane filtration technology that uses vibration to minimize fouling of the filtration media.

OBJECTIVE

The primary objective of the testing was for the VSEP to produce permeate that could be reused as frac water. Maximizing the recovery rate was also an important objective during this test. Maximizing the overall recovery will reduce the volume of waste being hauled and thus reduce operation costs. There is a natural variation in this type of feed material, and the feed conductivity will increase over time. The VSEP needs to produce consistent results despite this variation in feed.



### 3.0 Equipment and Set-Up NLR provided a VSEP membrane filtration unit and periphery equipment. The figure above illustrates the basic set up for a VSEP Series LP. The VSEP pilot unit was tested in P-mode whichhas 16.7 square feet of membrane area. The Punit was installed with a nanofiltration (NF) membrane called NF-270. This membrane was chosen based on previous in house lab testing.

The standard system was run in batch mode in which the feed tank is filled with a limited volume of feed material and the concentrate line is returned to the feed tank. The permeate is allowed to leave the system thus concentrating the feed tank. Batch mode was chosen as the mode of operation for pilot testing in order to handle the high TDS of feed and maintain economical flow rates. The VSEP set up is shown in Figure 1.

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Figure 1: Examples of VSEP Set up



### 4.0 Results

As part of pilot testing, various operating variables were optimized for the best performance and economic balance. The operating pressure was optimized by collecting permeate flux readings at various pressures. The relationship between pressure and flux was found to be linear. There was no increased rate of fouling or flow threshold at higher operating pressures up to 500psi. The operating pressure chosen was 480psi. The results are shown in Figure 2.

0 10 20 30 40

0 50 100 150 200 250 300 350 400 450 500 550 600

Pressure (psi)Instantaneous Flux (GFD) - Temp. Corrected



### Figure 2: Pressure Study

One case showed a total of 8 batch runs of varying feed quality. The first batch was a single pass through the membrane with no concentration and will not be included in the calculations. The end point of each batch was determined by a low permeate flux rate or a low feed level (not enough feed to pump through the system). A chemical pre-treatment of Ferric Chloride and Soda Ash was tested but was not successful in reaching higher recovery or flux rates and actually performed worse than raw feed. The results of the instantaneous flux rates for the batch concentrations are shown in Figure 3 and Tables 1, 2, and 3.

The average performance of the system: 17.2 GFD and 92% recovery at 20 o C and 480psi. The average flux is based on the six batches on raw feed and these values will be used for system sizing calculations. The average flux was calculated by fitting an exponential trend line to the average flux rates for each batch. The equation used for calculating the average flux based on percent recovery is: Ave Flux = 31.465e 0.6574*%Rec



### . The average recovery is based on the arithmetic mean of the six batches. These values will be used for system sizing calculations. The results can be seen in Figure 4 and 5.

0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0

0% 20% 40% 60% 80% 100% % RecoveryInstantaneous Flux - Temp Corr Batch #2 - 136.0mS
Batch #3 - 73mS
Batch #4 - 45mS
Batch #5 - 86mS
Batch #6 - Ferric/Soda Ash
Batch #7 - 67.5mS
Batch #8 - 34.5mS



### Figure 3: Batch Concentration

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y = 31.465e -0.6574x

R 2 = 0.146

0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% % RecoveryAverage Flux - Temp Corr



### Figure 4: Average Flux

Figure 5: VSEP Permeate and Concentrate Table 1: Quantitative Results

* All Flux values are corrected to 20 o C



### Table 2: Analytical Results Batc

h Pressur

e Average Flux %Recovery

2 480psi 13.3 GFD 91%

3 480psi 35.9 GFD 94%

4 480psi 31.4 GFD 80%

5 480psi 27.8 GFD 93%

6 480psi 22.7 GFD 43%

7 480psi 27.5 GFD 96%

8 480psi 11.0 GFD 98%

Batc

h Sample pH Conductivity

2 Feed 6.26 136.0 mS

Permeate 6.99 129.0 mS
Concentrat

e 5.63 173.2 mS

3 Feed 6.27 72.7 mS

Permeate 6.36 67.3 mS
Concentrat

e 6.56 134.3 mS

4 Feed 6.39 44.7 mS

Permeate 6.38 43.9 mS
Concentrat

e 6.75 69.0 mS

5 Feed 6.34 86.4 mS

Permeate 6.25 72.7 mS
Concentrat

e 6.62 136.4 mS

6 Feed 8.52 87.0 mS

Permeate 7.31 71.6 mS
Concentrat

e 7.04 98.1 mS

7 Feed 6.94 65.7 mS

Permeate 7.18 63.8 mS
Concentrat

e 7.02 123.2 mS

8 Feed 6.64 34.5 mS

Permeate 7.74 31.0 mS
Concentrat

e 7.17 71.2 mS

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Table 3: Analytical Results – Batch #8 at 98% Recovery



### 5.0 Cleaning

Chemical cleaning of the membrane is used to restore the flux rate. While VSEP can prevent colloidal fouling of the membrane and can reduce the polarization of rejected materials at the membrane surface, like other membranes, it cannot avoid chemical bonding type fouling that will occur. For this reason, chemical cleaners are used to solubilize the foulants and restore the membrane. During chemical cleaning, cleaners are re-circulated through the membrane system and then flushed out. Multiple cleaning cycles are used.

The cleaning procedure used was a two-part process. The steps in sequence were: NLR 404 acid cleaning followed by NLR 505 caustic cleaning. The procedure was based on previous experience with similar applications. The cleaners were used in a 3% by volume solution. After each batch run, a cleaning was completed and the starting flux on feed was recovered each time. When a new membrane is exposed to feed material, the membrane will take time to be conditioned. Once the membrane is conditioned, a new base line can be used for measuring a successful cleaning. The effectiveness of the cleanings can be seen in Figure 6 and the new base line can be seen around 120 GFD. Cleaning frequency is estimated after each batch with NLR 404 and 505. Hot water will need to be available for fully effective cleaning.

NLR 404 is an acidic liquid cleaner designed to provide superior and rapid mineral scale cleaning of wide range of RO, NF and UF membranes. It removes metallic salts such as iron, aluminum, barium and strontium sulfate, calcium sulfate, calcium carbonate, as well as dyes and polymers.

NLR 505 is a caustic liquid membrane cleaner designed to provide superior and rapid soil removal properties. It contains a combination of ingredients, which provide cleaning actions that include lifting, dispersing, emulsifying, sequestering, dissolving and suspending. It removes biological and organic materials, silt, particulates, colloids, silica and emulsified oil from a wide range of RO, NF, UF and MF membranes.

0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0

New

M e m brane

Hot

W a te r F lush NLR 4 0 4 NL

R 505 Hot W

a ter F lush NLR 4 0 4 NLR 505

Hot W

a ter F lush NLR 40 4 NLR 5 0 5 Hot Water Flush NLR 40 4 NLR 5 0 5 Hot Water Flush

N L R 40 4 NLR 50 5 NLR 4 0 4 NLR 505GFD @ 25oC



### Figure 6: Cleaning Data Parameter Permeate Concentrate
Conductivity 29.44 mS 36.5 mS

Alkalinity 130 mg/L 225 mg/L

TDS 17,806 mg/L 21,286 mg/L

pH 7.35 7.53

Chloride 17,800 mg/L 14,800 mg/L

Barium 194 mg/L 352 mg/L

Calcium 424 mg/L 716 mg/L

Magnesium 32.0 mg/L 70.8 mg/L

Strontium 137 mg/L 215 mg/L

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### 6.0 Summary

Based on the objectives and results presented in this report it can be said that we were successfulin demonstrating the ability of VSEP to treat Fracflow back water. The following is a list of process recommendations/results:

Test Results:

Membrane: NF-270 Mode of Operation: Batch Mode Average Flux Rate: 17.2 GFD Percent Recovery: 92% Pressure: 480psi Temperature: 20oC Cleaner Needed: NLR 404/505 Cleaning Frequency: Every week, Hot water flush every day



### System Sizing Estimates For a process of 28 GPM:

EXAMPLE CALCULATION (92% recovery, 20  C):

28 gal of feed*1440 minutes/day*92% recovery rate = 37,094 gallons of permeate generated per day

37,094 gallons of permeate per day / 17.2 GFD * 24/22 hours (2 hours for cleaning) = 2,353 sf

2,353 * 1.3 (30% over design) = 3,058 sf needed.

Module size = 3,058/1500sf = 2.03, therefore, 2 units needed at 20  C and 92% recovery.

NF-270 92% Recovery Membrane SF 3,058 SF VSEP Modules 2 - 84” 1500 SF units 

### 7.0 System Design Requirements

Stage Type: 2 - 84” 1500 VSEP Elastomers: EPDM

Mode of Operation: Batch Drain Cloth: Polyester

Membrane Type: NF-270 Resin: Epoxy Operating Temperature: 20  C End Plates: Polypropylene

Design Pressure: 480psi (600max) Membrane Trays: 304

Feed Flow Rate: 28 GPM Operation: Automated Recovery Rate: 92% Pre-treatment: None

Design Flux Rate: 17.2 GFD AVE Max Flux After Clean: 140 GFD @ 200psi Cleaning Chemicals: NLR 404/505
Feed Pump Max Flow: 70 GPM @ 480psi Cleaning Frequency: After every week Permeate Destination: Reuse as Frac water Concentrate Destination: Hauled for disposal



### Some Photos of VSEP units used in Flowback Mobile Treatment in Pennsylvania:

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### Mark Galimberti, mgalimberti@vsep.com