“Identifying Best Practices For 

Decreasing Bacteria To Acceptable 

Levels For Reuse In Hydraulic 

Fracturing”

Shale Play Water Management - 2014 1
Real Time Water Quality Testing

Benefits

• Bacteria Disinfection Monitoring

• Test Influent/Effluent

• Test Working Tanks

• Monitor Water Quality Changes

• Make Live Adjustment When 

Needed

• Pre-Frac Planning

• Determine Water Quality Baseline

• Determine Bacteria Level Baseline

• Allows for Pre- Treatment Planning

• Treatment Requirements

• Treatment Flow rate

• Blend rate

Shale Play Water Management - 2014 2
Bacteria Testing

Methods Used

• Real Time Bacteria via modified 

ATP

• Adenosine Triphosphate

• Found in all living cells, used 

for energy transfer

• Most Probable Number (MPN)

• Uses statistical formula to 

estimate bacteria counts 

• Bug Bottles

• Estimates bacteria counts in 

the form of ranges

Shale Play Water Management - 2014 3
Bacteria Testing

Preservative ? Sterilized Bottles ?

• Sterilized Bottles/Gloves

• Required for accurate tests

• Preservatives

• Negates effect of residual 

disinfection.

• Give result of bacteria at that time

• Shipping and testing delay will over 

estimate the disinfection 

Shale Play Water Management - 2014 4
Bacteria Sampling

Preservative ? Sterilized Bottles ?

• Sterilized 

Bottles/Gloves

• Required for 

accurate tests

• This is NOT proper 

sampling for bacteria

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Bacteria Testing

How do I confirm disinfection ?

• Influent/Effluent Testing

• MPN

• Bug Bottles

• Residual Disinfection / Working Tanks

• Working tanks are typically dirty

• Good disinfection can be 

compromised by dirty working 

tanks

• Monitoring working tanks is critical 

to ensure disinfection

• Flowback Monitoring

• Insures good overall disinfection

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Residual Testing

What Methods ?

• Test Strips

• Convenient 

• Inaccurate

• Colorimetric

• Direct Read , Color Wheel, Color 

Change

• Can be Reliable

• Accuracy can be an issue

• Titrations

• Most Accurate

• Require more time and skill

• May require dilutions to avoid 

interference

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Residual Testing

Chloride Dioxide Test Methods

Shale Play Water Management - 2014

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Direct Reading Testing Strip Color Disc DPD Method

C (ppm)

• 1.8 ppm standard solution was used for all the tests.

• Four testing methods were evaluated.

• Testing strip was not able to detect any chlorine dioxide at this level.

• Accuracy: Colorimetry > Direct Reading > Color Disc > Testing Strip.

• Repeatability: Colorimetry > Color Disc > Direct Reading > Testing Strip.

8
Residual Testing

Free Chlorine Test Methods ?

Shale Play Water Management -

2014

0

10

20

30

40

50

60

70

Colorimetry - HR Colorimetry - MR Titration Strip - Company 1 Strip - Company 2

C (ppm)

• Water sample with unknown free chlorine level was used for all the tests.

• Five testing methods were evaluated.

• Little agreement was observed between different testing methods.

• Testing strips provided by different companies gave quite different results.

• Not considering the strips, the precision: Colorimetry - MR > Colorimetry – HR > Titration.

9
Comparisons of ClO2

, Total Chlorine and Free Chlorine 

Tests in Different % of Produced Water

• Water samples were adjusted by standard solution to approximately 25 ppm of ClO2, 12.0 ppm of total chlorine and 12.0 ppm of 

free chlorine. The reducers in the produced water were oxidized before the adjustment to eliminate further oxidant consumption.

• Colorimetry methods were used for all three tests.

• Discrepancies were observed between the test results and the actual concentrations of the three chemicals. The higher the % of 

produced water, the larger the discrepancy. 

0

5

10

15

20

25

30

10% 30% 50% 80% 100% Actual

c (ppm)

% of Produced Water

ClO2 Total Chlorine Free Chlorine

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Comparisons of ClO2 Test in Different % of Produced 

Water

• The water samples supposed to have same level of ClO2.

• The reading by colorimetry method is different from the reading by testing strip. 

• In most of the cases, the colorimetry method has a higher reading than the testing strip method.

• Huge difference was observed for the 100% produced water, as the colorimetry reading was only half of the 

testing strip reading.

0

5

10

15

20

25

10% 30% 50% 80% 100%

c (ppm)

% of Produced Water

Colorimetry Testing Strip

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Comparisons of Total Chlorine Test in Different % of 

Produced Water

• The water samples have same level of total chlorine.

• Huge differences were observed for different testing methods. The three different types of strips were provided by three different companies.

• When compared within the same testing method, the readings at different percent of produced water are also different. Other species or the 

physical properties of the produced water could have lead to the interferences for the testing.

• It appears that the readings by different testing methods are with the trend of: titration > colorimetry > strip 3 > strip 1 > strip 2.

0

5

10

15

20

25

10% 30% 50% 80% 100%

c (ppm)

% of Produced Water

Colorimetry Titration Strip-1 Strip-2 Strip-3

Shale Play Water Management - 2014 12
Comparisons of Free Chlorine Test in Different % of 

Produced Water

• The water samples supposed to have same level of free chlorine.

• The readings by different testing methods are different from each other. 

• The readings with the same testing method but at different percent of produced water are also different, which indicates the 

different level of interferences.

• Generally, the readings by different testing methods are with the trend of: titration > colorimetry > strip 1 > strip 2.

0

2

4

6

8

10

12

14

16

18

10% 30% 50% 80% 100%

c (ppm)

% of Produced Water

Colorimetry Titration Strip - 1 Strip - 2

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Bacteria Testing

Where do I Sample ?

• Influent/Effluent of 

Treatment System

• MPN

• ATP

• Continuous Testing

• Residual Disinfection / 

Working Tanks

• ATP

• Continuous Testing

• Source Water

• ATP

• MPN

• Baseline Testing

Influent 

& Effluent

Source 

Water 

Testing

Working 

Tank 

Monitoring

Shale Play Water Management - 2014 14
MPN Testing: Frac Fluid Treatment in W. Texas

Slide 1 of 2

• Permian Basin

• Frac Fluid Treatment

• Multi-stage slickwater frac

• Rig up: treating 80/20 fresh water 

flowback mixture at 80 bpm

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MPN Testing: Frac Fluid Treatment in W. Texas

Slide 2 of 2

0

50,000

100,000

150,000

200,000

250,000

300,000

3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11

# of Cells Per Milliliter

Stage Number

Bacteria Treatment Results

Influent

Effluent

99.98%

REDUCTION

Shale Play Water Management - 2014 16
Real Time Testing: Residual Disinfection 

Residual Disinfection - Free Chlorine and ATP

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0

100

200

300

400

500

600

0 1 2 3 4 5 6 7 8

Free Chlorine, mg/L

ATP, pg/mL

Time after treatment, hr

ATP, pg/mL

Free Chlorine

Tests were conducted at Bold Johnson 56-T1-34 #1H

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MPN Testing: Residual Disinfection 

Residual Disinfection – Flowback Testing

BRL: Below Reporting Limits

A: Permian – Pecos, TX; B&C: Permian – Midland, TX; D: Permian – Barnhart, TX; E&F: Marcellus – WV

BRL

BRL

BRL

BRL

BRL

23

46

BRL

4

4

4

2400

46000

1100

2400

150

2400

BRL

BRL

BRL

BRL

BRL

9

BRL

BRL

BRL

BRL

BRL

2400

24000

1100

150

4

43

1 10 100 1000 10000 100000

E-Flowback

D-Flowback

C-Flowback

B-Flowback

A-Flowback

F-Treated

E-Treated

D-Treated

C-Treated

B-Treated

A-Treated

F-Untreated

E-Untreated

D-Untreated

C-Untreated

B-Untreated

A-Untreated

MPN/ml

SRB APB

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Residual Disinfection: Working Tank Monitoring 

Residual Disinfection - Free Chlorine and ATP

0

100

200

300

400

500

600

700

0 2 4 6 8 10 12 14

ATP, pg/ml

Time after Samples Were Taken, hr 

ATP Levels in the Treated Water

Working Tanks Clean Buckets

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Working Tank Monitoring 

Biocide vs. Hydrozonix

1452

1932 1822

5147

2996

1466 1529

436

158

0

1000

2000

3000

4000

5000

6000

Water Delivered Day 1 Day 2 Day 3 Biocide -15 min Biocide - 2 hr Biocide - 24 hr Hydrozonix-Day1 Hydrozonix-Day2

ATP, pg/ml

ATP Level in the Working Tanks 

 Untreated impaired was delivered to the working tanks, the initial ATP level was around 1,452 pg/ml.

 Bacteria level increased as the water was stagnant in the tanks, after 3 days, the ATP level went up to 5,147 pg/ml.

 0.5 gpt of biocide was dosed into the working tanks, this brought the ATP level down to 2,996 pg/ml 15 min after the 

dosing.

 The ATP level stabilized to be around 1,500 pg/ml 24 hr after the dosing, which indicated that the bacteria level in the 

biocide treated water was still high.

 After treated water form Hydrozonix treatment system sent to the working tank for one stage, the ATP level went down 

to 436 pg/ml. This was further reduced to be at 158 pg/ml after the treatment had continued for another day.

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Working Tank Monitoring 

Chlorine Dioxide vs. Hydrozonix

0

100

200

300

400

500

600

HZO Chlorine Dioxide

pg/ml

Treatment Technology

HZO vs. ClO2

Untreated Treated Tanks (2 days)

• 30% blend of produced 

water and fresh

• Both treatment systems 

used side by side

• Baseline untreated at 

508 pg/ml ATP

• Working tanks sampled 

after two days to 

determine overall 

disinfection and residual 

disinfection

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Disinfection vs. Compatibility

Disinfection

Compatibility

Oxidant Oxidation 

Potential, V

Hydroxyl 

Radicals

2.8

Ozone 2.3

Hydrogen

Peroxide

1.8

Chlorine

Dioxide

1.5

Chlorine 1.4

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Disinfection vs. Compatibility

Slickwater: HZO vs. Biocide vs. Chlorine Dioxide 

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

2012/10/18 2012/12/7 2013/1/26 2013/3/17 2013/5/6 2013/6/25 2013/8/14 2013/10/3 2013/11/22

Friction Reducer Concentration, % in mass

Fracturing Date

Hydrozonix

Biocide

ClO2

Water Treatment Technology # of Wells FR Concentration, % in mass

Biocide 22 0.0123

ClO2 9 0.0146

Hydrozonix 27 0.0042

Shale Play Water Management -

2014 23
Flash

Reactor

Mixing Vane

Venturi Reactor

Effluent Static Mixers

Static Mixers

1

2

3

4

5

5 Points 

of 

Mixing

Shale Play Water Management - 2014 24
www.hydrozonix.com

Questions ?

Shale Play Water Management - 2014

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