Disinfection and Supply Changes to Improve Quality

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Disinfection and Supply Changes to Improve
Quality Quantity In Kentucky Americans
Northern Division

• Joint Water Professionals Conference
  KY-TN AWWA WEF
• Covington, Kentucky, September 13, 2005
• By
• Jan Routt, Jan Routt Associates, LLC
• Richard Svindland, American Water Southeast
  Region
• David Shehee, Kentucky American Water
• adapted from original presentationphotos and
  other content omitted for file size reasons.

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Presentation Overview

• Will describe decision making for changes for
  multiple objectives
• Provide adequate supply
• Maintain disinfection and over all water quality
• Disinfection byproduct control
• . Using multiple sources of supply with
  different disinfectants (chloramines and free
  chlorine) in a hydraulically challenging area
• Nitrification control, detection and remediation

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Studies to characterize Source water quality
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Step one (enhancing coagulation at lower pH)
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• KMnO4 demand dosing
• caustic feed
• enhanced alum ferric
• No pre-lime

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Consecutive Systems joint responsibility for
DBP formation and control

• THM/HAA compliance average of four sites per
  joint (or combined) system

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Step two treatment changes Intermediate
chlorination
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• Intermediate chlorination
• State approval
• With substantial monitoring

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Month Source Water Source Water Source SUVA Trt Water TOC (mg/L) Actual TOC Rem (mg/L) (A) TOC Rem (B) Req TOC Rem Basis for Req Rem (C) Rem Ratio (A/B) (D)b Qtr Avg Ratio (E)c RAA Ratio (Last 4 Qtr)
Month Alk (mg/L) TOC (mg/L) Source SUVA Trt Water TOC (mg/L) Actual TOC Rem (mg/L) (A) TOC Rem (B) Req TOC Rem Basis for Req Rem (C) Rem Ratio (A/B) (D)b Qtr Avg Ratio (E)c RAA Ratio (Last 4 Qtr)
JAN 163 6.05 2.93 2.50 3.55 59 25 Step 1 2.35    
FEB 176 5.73 2.80 2.48 3.25 57 25 Step 1 2.27    
MAR 172 4.66 2.74 2.10 2.56 55 25 Step 1 2.20 2.27 1.79
APR 176 5.13 2.52 2.32 2.81 55 25 Step 1 2.19    
MAY 175 5.68 2.55 2.49 3.19 56 25 Step 1 2.25    
JUN 140 6.80 2.86 3.18 3.62 53 25 Step 1 2.13 2.19 1.97
JUL 136 7.16 2.73 3.27 3.89 54 25 Step 1 2.17    
AUG 118 6.70 2.70 3.30 3.40 51 25 Step 1 2.03    
SEP 111 6.26 2.63 2.68 3.58 57 25 Step 1 2.29 2.16 2.09
OCT 128 5.82 2.34 2.65 3.17 54 25 Step 1 2.18    
NOV 126 6.44 2.32 3.29 3.15 49 25 Step 1 1.96    
DEC 121 7.27 2.74 3.06 4.21 58 25 Step 1 2.32 2.15 2.19
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THMS 1stQ/04 2ndQ/04 3rdQ/04 4th Q/04 1stQ/05 2ndQ/05 LRAA
Owenton (Mar) (May) (Aug/Sep) (Nov) (Jan) (Apr)  
Site 1 0.041 0.069 0.087 0.051 0.038 0.040 0.062
Site 2 0.035 0.072 0.091 0.052 0.033 0.037 0.063
Site 3 0.042 0.073 0.097 0.064 0.044 0.039 0.069
Qtr Avg 0.039 0.072 0.092 0.056 0.038 0.038  
4QRAA 0.056 0.060 0.064 0.065 0.064 0.056  
Owenton 73 69 65 53 44 63  
TriVillage Max 0.054 0.103 0.142 0.106 0.087 0.061 0.101
Joint Qtr Avg 0.043 0.080 0.104 0.068 0.050 0.044  
Joint 4QRAA 0.064 0.068 0.072 0.074 0.076 0.067  
HAAS 1stQ/04 2ndQ/04 3rdQ/04 4th Q/04 1stQ/05 2ndQ/05 LRAA
Owenton (Mar) (May) (Aug/Sep) (Nov) (Jan) (Apr)  
Site 1 0.031 0.033 0.037 0.038 0.033 0.031 0.035
Site 2 0.031 0.037 0.058 0.040 0.032 0.033 0.041
Site 3 0.037 0.035 0.057 0.045 0.046 0.037 0.043
Qtr Avg 0.033 0.035 0.051 0.041 0.037 0.034  
4QRAA 0.033 0.034 0.040 0.040 0.041 0.041  
Owenton 68 52 89 46 51 65  
TriVillage Max 0.048 0.068 0.057 0.090 0.073 0.052 0.066
Joint Qtr Avg 0.037 0.043 0.052 0.053 0.046 0.038  
Joint 4QRAA 0.037 0.040 0.044 0.046 0.049 0.047  
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Decision to convert to chloramines a phased
approach over several months/years -- with
conversion to chloramines as the last step

• Profile Disinfection, DBP formation and precursor
  removal through plant and systemState
  approvals-- and lots of testing to confirm water
  quality-- all along the way!
• Optimized preoxidation (KMnO4reliable feed,
  dosed for source demand) Written SOPs/testing.
  Added post pH adjustment (caustic) for corrosion
  control, enhanced coagulation with alum/ferric at
  lower treated pH (no more lime in pre-treatment).
  Written SOPs/testing
• 25 ? gt50 TOC removal, THMs reduced by 15
• Move chlorination point from rapid mix to pre
  filterstwo feed points just before and after
  filters. Written SOPs/Testing
• THMs HAAs reduced to half the previous level
• Optimize distribution operations!

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Compliance is tenuous at bestSurveillance
testing and operations controls critical
Limits

• Reductions in THMs and HAAs to this point have
  been a result of plant modifications.
  Distribution system optimization and future plant
  changes will help us meet future regulations
  while maintaining an ample supply of water.

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Kentucky American TriVillage working to improve
water quality lower DBPs, maintain current
supplies and increase supplies to underserved
areas.

• Due to expanding water supply needs, the
  team/project has grown to include new suppliers
  Georgetown (and suppliers Frankfort, KAW Central)
  and Gallatin Co/Warsaw and Carroll Co.

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Purchaser KAW Northern TriVillage water
purchased rechlorinated
Suppliers Gallatin Co (Warsaw) Carroll Co GW
free chlorine
Supplier Owenton SW free chlorine
Georgetown/Frankfort/KAW Lex SW chloramines
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Poor Turnover when using Chloramines Leads to
Water Quality Problems in the Distribution System
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Nitrification- a microbial biofilm process where
ammonia is the nutrient

• Ammonia is released as chloramines degrade
  (autodecomposition)
• NH2Cl H2O? HOCL NH3 Hydrolysis
• 2NH2Cl H ? NH4 NH2Cl Lower pH speeds up
  autodecomposition
• 3NH2Cl ? N2 NH3 3HCL Net decay reaction
  via autodecomposition
• Ammonia Nitrosomonas? Nitrite Nitrobacter?
  Nitrate
• Nitrite Chloramine ? faster decomposition ?
  more ammonia..

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Decision making processes, studies, design and
operations in converting chloraminated water to
free chlorinated with distribution booster
chlorination

• Operations plan to
• define low flow areas
• minimize water age, degradation and disinfection
  byproducts
• optimize flushing and blow off locations and
  volumes
• Need to blend or alternate water supplies to
  supplement flows from Owenton source in drought
  conditions (will also be helpful when current
  Owenton intake is being modified)
• Georgetown does not annually convert to free
  chlorine for nitrification control and supplies
  higher chloramine residual at master meter. KAW
  water about 1.0 ppm less total chlorine greater
  water age of different general quality alk, TOC,
  and pH
• Need to maintain chlorine residual to ends of
  system from either source so sited chlorine
  booster at master meter

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Comparing waters at the potential interconnection
point
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Breakpoint Chlorination

• The presence of organic nitrogen compounds also
  will increase the chlorine demand and increase
  the Cl2NH3-N ratio at breakpoint. Therefore,
  while the theoretical chlorine dose required to
  reach breakpoint can be estimated, competing side
  reactions and the presence of nitrite and/or
  organic nitrogen compounds, such as proteins and
  amino acids, make calculation of the actual
  breakpoint of an individual water difficult. It
  is recommended that bench-scale studies be
  performed when it is necessary to know the actual
  chlorine dose required to reach breakpoint in a
  specific water to be treated. Optimizing
  Chloramine Treatment, 2nd Edition.

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DBP FP Studies at Interconnection Point
tedious, time-intensive
SITE or Test No Time/ Temp prior to Cl dosing Added Cl Dose Holding Time/ Temp Free Cl Resid THM mg/L HAA mg/L Ammonia (mg/L NH3-N) after dosing Nitrite (mg/L as N) after dosing Turb (NTU) after dosing Alk (mg/L) after dosing
Owenton 48hrs / 4C 0mg 3days/ 25C 0.1 0.132 0.105 0.01 lt0.010 1.600 100
Gtown 48hrs / 4C 0mg 3days/ 25C lt0.01 0.047 0.001 0.01 lt0.010 0.404 129
50/50 split 1A 48hrs / 4C 0mg 3days/ 25C lt0.01 0.088 0.053 0.03 lt0.010 1.410 113
50/50 split 2A 48hrs / 4C 2mg 3days/ 25C 1.5 0.114 0.076 0.04 lt0.010 1.210 114
50/50 split 3A 48hrs / 4C 4mg 3days/ 25C 3.5 0.098 0.101 0.02 lt0.010 1.480 110
50/50 split 4A 48hrs / 4C 8mg 3days/ 25C 7.0 0.096 0.138 0.03 lt0.010 1.020 113
50/50 split NA 0mg 5 days / 25C lt0.01 0.081 0.022 0.04 lt0.010 0.500 119
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DBP FP at Master Meter
SITE or Test No. Total Cl Res (mg/L) Ammonia (mg/L NH3-N) Nitrite (mg/L as N) Time/ Temp prior to CL dosing Added Cl Dose Holding Time/ Temp Free Cl Res after Holding THM mg/L HAA mg/L
MM 1.5 0.400 0.008 NA NA NA NA 0.0435 0.0452
MM -1A       24 hrs/4C 6mg/L 48 hrs/25C 1.3 0.0794 0.0940
MM -1B       24 hrs/4C 8mg/L 48 hrs/25C 3.0 0.0803 0.0832
MM -2A       24 hrs/4C 6mg/L 72 hrs/25C 1.4 0.0825 0.1109
MM -2B       24 hrs/4C 8 mg/L 72 hrs/25C 2.8 0.0912 0.1189
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Breakpoint Studies
SITE Free Chlorine Residual (mg/L) Total Chlorine Residual (mg/L) Time agitated (min.) Concentration of stock solution (ppm) Amount stock soln added (mL) Comments
GT-RD Conn. Time collected 1050 0.0 2.1 NA NA NA  
GT-RD Conn. Ratio 2.1x existing Cl2 res. 3.4 5.9 NA 2300 0.191  
GT-RD Conn. Ratio 2.1x existing Cl2 res. 3.1 4.1 2 2300 0.191  
GT-RD Conn. Ratio 2.1x existing Cl2 res. 2.1 2.8 5 2300 0.191  
GT-RD Conn. Ratio 2.4x existing Cl2 res. 2.7 3.0 5 2300 0.217 Strong chlorine odor present after dosing
GT-RD Conn. Ratio 2.4x existing Cl2 res. 2.6 2.8 8 2300 0.217 Strong chlorine odor present after dosing
GT-RD Conn. Ratio 2.1x existing Cl2 res. 1.6 1.9 12 2300 0.191  
GT-RD Conn. Ratio 2.1x existing Cl2 res. 2.1 2.5 14 2300 0.191  
Note All samples stored and analyses conducted at room temperature. Sample agitated on stir plate with medium setting. Note All samples stored and analyses conducted at room temperature. Sample agitated on stir plate with medium setting. Note All samples stored and analyses conducted at room temperature. Sample agitated on stir plate with medium setting. Note All samples stored and analyses conducted at room temperature. Sample agitated on stir plate with medium setting. Note All samples stored and analyses conducted at room temperature. Sample agitated on stir plate with medium setting. Note All samples stored and analyses conducted at room temperature. Sample agitated on stir plate with medium setting. Note All samples stored and analyses conducted at room temperature. Sample agitated on stir plate with medium setting.
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Zone for potential variable supply if chlorine
same
Free Chlorine Groundwaters Very low TOC
DBPFP Higher hardness
Chloramines Plentiful Surface Water Lower TOC
DBPFP Nitrification Booster Chlorine feed for
free Chlorine
Free Chlorine Limited Surface Water Higher TOC
DBPFP
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Acknowledgements
The authors acknowledge the field sampling and
analysis work of Kentucky American Lab Analyst,
Shana Carr, in the nitrification, disinfection
byproduct formation potential, and breakpoint
chlorination studies presented here, as well as
the hard work of all Kentucky American and
Owenton staff involved in diligently,
comprehensively monitored operations over the
last five years. Support and technical
assistance from Kentucky American and American
Engineering, and Kentucky Division of Water have
been key to success, along with ongoing
cooperation of all local officials in Owenton and
Owen and surrounding counties.