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AN INNOVATION-‐DRIVEN APPROACH TO DISTRIBUTION SYSTEM MONITORING
Gary Visser Regional Sales Manager Hach Company [email protected]
PPA ANALYTICAL METHODS
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1. The challenge: op=mizing chloramina=on 2. Parallel analysis: a new portable measurement paradigm 3. Technical Overview of the System 4. Method Valida=on and Comparison 5. Field Studies and Method Automa=on 6. USEPA Method Approval
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Max Mono
FREE CHLORINE RESIDUAL
COMBINED RESIDUAL
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SID
UA
L C
HLO
RIN
E (
mg
/L)
CHLORINE DOSE (mg/L)
TYPICAL CHLORINE DOSE-RESIDUAL CURVE
INCREASING DOSE- INCREASING RESIDUAL
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FREE AVAILABLE CHLORINE RESIDUAL
BREAKPOINT CHLORINE
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INCREASING DOSE- DECREASING RESIDUAL
DI & TRI CL
ammonia ammonia chlorine
I’m pretty comfy right here
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MAXIMUM
FREE CHLORINE RESIDUAL
COMBINED RESIDUAL (PRIMARILY MONOCHLORAMINE)
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SID
UA
L C
HLO
RIN
E &
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MO
NIA
-NIT
RO
GE
N (
mg
/L)
CHLORINE DOSE (mg/L)
TYPICAL CHLORAMINATION DOSE-RESIDUAL CURVE
2.5
BREAKPOINT
0
Free Ammonia “break-point” is a lot like the Free Chlorine “break-point”, just “backwards”.
Free Ammonia
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MAXIMUM
FREE CHLORINE RESIDUAL
COMBINED RESIDUAL (PRIMARILY MONOCHLORAMINE)
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SID
UA
L C
HLO
RIN
E &
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MO
NIA
-NIT
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N (
mg
/L)
CHLORINE DOSE (mg/L)
TYPICAL CHLORAMINATION DOSE-RESIDUAL CURVE
2.5
BREAKPOINT
0
Free Ammonia
You know this Breakpoint.
..is the same as breakpoint CL,
Flipped over backwards!
A CHLORAMINE & NITRIFICATION PRIMER
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• More stable than free chlorine (long distribu=on systems), but not as effec=ve
• Generally do not produce DBP • Free ammonia is present in distribu=on system -‐ Released from monochloramine forma=on as the disinfectant aWacks bacteria or reacts with organics
• Issue: Free ammonia oxidizes to nitrite, then nitrate • Over 2/3 of DW systems report experiencing issues with nitrifica=on, and all systems have poten=al for issues
Conversion of ammonia to nitrites and nitrates – Nitrosomonas Nitrosococcus, and Nitrosospira – NH3 + O2 NO2
-‐+ 3H+ + 2e-‐
Conversion of nitrite to nitrate – Nitrobacter Nitrospina, Nitrococcus, and Nitrospira – NO2
-‐ + H2O NO3-‐ + 2H+ +2e-‐
NITRIFICATION IN THE DISTRIBUTION SYSTEM
NH3/NH4+ + NO2
-‐ + NO3-‐ NH2Cl +
Disinf ▼ f-‐NH3 ▲
pH ▼ DO ▼ NO2
-‐ ▲ Alk ▼
pH ▼ DO ▼ NO3
-‐ ▲ Alk ▼
Circular Problem
Sloughing of biofilm causes Turbidity ▲ Flow ▼
HPC ▲
Customer Complaints ▲
Distribu>on System
A CHLORAMINE & NITRIFICATION PRIMER
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Nitrifica>on is Costly & Disrup>ve to U>li>es • Compliance Risk -‐ Nega=ve health effects of nitrite/nitrate -‐ Rapid loss of disinfec=on residual and possible microbiological contaminant growth
-‐ Reduc=on in alkalinity & pH à corrosion, Lead & Copper Rule issues, & reduced effec=veness of disinfectant
• Wasted water and labor cost of flushing lines • Taste & Odor Complaints -‐ Nitrifica=on events themselves -‐ Free chlorine “burn” used to resolve the event
Controlling Nitrifica>on • Nitrifica=on can be avoided by taking ac=on once leading indicators are iden=fied in the distribu=on system
• Key Indicators: ü Presence of Free Ammonia ü Loss of Monochloramine Residual ü Decrease in pH ü Increase in Nitrite
pH
Free ammonia
Water age
Chloramine residual
Light
TOC
Tank Mixing
DESIRE FOR MONITORING AND CONTROL
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Common Procedural Errors Future State Correc>on
Scratched sample cells Sample cells eliminated Improper reac=on =me All reac=on =me automated/standardized Different mixing method Mixing automated/standardized Different mixing =me Mixing automated/standardized
Improper/lack of zeroing Mul=ple "Blanks" processed automa=cally Sample degrada=on Ability to test on site (reduc=on of lab samples)
Improper sample volume Sample volume automated/standardized Improper reagent amount (spill) Reagent amount automated/standardized
Incorrect program selected Barcode allows for automa=c method selec=on Improper sample temperature Individual slot heaters compensate for temperature
Single readings (outlier) 10+ readings per test, average taken, outliers discarded Transcrip=on errors USB port allows for easy data transfer
• Tes=ng capacity can be a limita=on -‐ Not enough =me for addi=onal parameters in field -‐ Too complex in field environment and/or field tech skill set
• Gap between data in the lab and ac=on in the field
WHAT YOU MIGHT SEE
INTRODUCTION TO PORTABLE PARALLEL ANALYSIS
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• Analyst and operator desire for a streamlined measurement process
• Parallel analysis = capability for 6 channel, simultaneous measurement – Designed for portable measurement/distribu=on monitoring – Colorimetry and electrochemistry
Analyte Method Range
Free Chlorine 0.12 mg/L -‐ 4.6 mg/L Total Chlorine 0.12 mg/L -‐ 4.6 mg/L
Monochloramine 0.12 mg/L -‐ 4.6 mg/L Nitrite 0.005 mg/L -‐ 0.600 mg/L Copper 0.06 mg/L -‐ 5.75 mg/L
Free Ammonia 0.05 mg/L -‐ 0.5 mg/L Total Ammonia 0.05 mg/L -‐ 1.5 mg/L
INTRODUCTION TO PORTABLE PARALLEL ANALYSIS
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• Planar cuveWes developed for Free and Total Chlorine, Monochloramine, Free and Total Ammonia, Nitrite, and Copper – All chemicals and processes are en=rely contained inside the planar
cuveWe
• Method reac=on and measurement =mes fully automated • Meso-‐fluidic channel colorimetry
– 30 to 50 μL sample volume – Op=cal Path length: 11 mm – Wavelengths: 427, 510, 655 and 890 nm
PRINCIPLE OF OPERATION
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1
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PRINCIPLE OF OPERATION
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Disposable Planar CuveWes (Chemkeys™)
CuveWes include buffers, reagents, and act as the sample cell
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CHEMKEY REAGENTS
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Parameter Range Free CL 0.12 mg/L -‐ 4.6 mg/L ~ EPA Approved Total CL 0.12 mg/L -‐ 4.6 mg/L ~ EPA Approved
Monochloramine 0.12 mg/L -‐ 4.6 mg/L Nitrite 0.005 mg/L -‐ 0.600 mg/L Copper 0.06 mg/L -‐ 5.75 mg/L
Free Ammonia 0.05 mg/L -‐ 0.5 mg/L Total Ammonia 0.05 mg/L -‐ 1.5 mg/L
CONFIDENTIAL
Chemkeys sold in boxes of 25. Free/Total CL will be offered in a KTO of 300 keys
METHOD 10260 VALIDATION
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Mul>ple Lab Valida>on Study – Pooled Data, Drinking Water Matrices
Valida>on Study – Mul>ple GW and SW Sample Matrices
Method performance compared to SM 4500-‐Cl G (DPD) shows that performance is equivalent across several matrix types and pH ranges
Key Key Key Key
VALIDATION IN THE FIELD
Residual Disinfectants in Finished Drinking Water
• Method automa=on and elimina=on of procedural errors improves quality of field data
• Nitrifica=on: Reduc=on in flushing =me and water loss
Total Chlorine Monochloramine Free Ammonia SL1000 Colorimeter SL1000 Colorimeter SL1000 Colorimeter
Sample 1 4.21 3.86 4.10 4.13 0.03 0.00 Sample 2 4.20 3.89 4.16 4.44 0.03 0.00 Sample 3 4.40 3.89 4.27 4.27 0.01 0.01 Sample 4 4.29 3.65 4.28 4.37 0.00 0.13 Sample 5 4.20 3.75 4.23 4.33 0.02 0.01 Sample 6 4.35 3.73 4.30 4.24 0.00 0.06 Sample 7 4.22 3.87 4.13 4.25 0.03 0.13
mean 4.27 3.81 4.21 4.29 0.02 0.05 RSD 1.9% 2.5% 1.9% 2.3%
VALIDATION IN THE FIELD
Parallel analysis solving u>lity and environmental challenges • Reduc=on of analysis =me via automa=on:
1.5 hours saved on a 4 hour route
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colorimeter parallel analyzer
On-‐site Analysis Time avg =me (min)
VALIDATION IN ROCKY MOUNTAIN REGION
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Town of Castle Rock, CO • Switched to monochloramine as primary disinfectant in 2013 • Monitors residuals and water chemistry daily in tanks and pump sta=ons
Treatment and Monitoring Goals • Understand baselines in distribu=on
system • Maintain Free ammonia < 0.1 mg/L • Improve quality of analysis and data
gathered • Maintain safe environment while
sampling storage tanks
Thanks to Tim Lambert and John Ferguson at the u5lity for contribu5ng to this study
VALIDATION IN ROCKY MOUNTAIN REGION
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Evalua>on Results • Found that water quality was being maintained and
treatment strategy was working • Time in the field reduced and safe working environment could
be maintained, even in cold/snowy months • Operator to operator results improved – consistency of data
was no=ceable • Side by side tes=ng with current instruments confirmed
accuracy of new system – confident in field measurements
METHOD APPROVAL STATUS
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• Method 10260 “Determina=on of Chlorinated Oxidants (Free and Total) in Water using Disposable Planar Reagent-‐Filled CuveWes and Mesofluidic Channel Colorimetry”
• Alternate test procedure to Standard Method 4500-‐Cl G • Method published in 40 CFR Part 141 Appendix A to Subpart C, Alterna=ve
Test Methods. Promulgated June 19, 2014 in the Federal Register.
“Hach Method 10260 is equally as effec5ve as Standard Method 4500-‐Cl G for the colorimetric determina5on of free and total chlorine in drinking water. The basis for this determina<on is discussed in Smith and Wendelken (2013b). EPA is thus approving Hach Method 10260 as an alternate method to Standard Method 4500-‐Cl G for the analysis of free and total chlorine in drinking water.”
