1

Review of the Production Review of the Production and Control of Disinfection and Control of Disinfection

By-Products (DBP’s)By-Products (DBP’s)

2

Goals of DBP ReviewGoals of DBP Review

Review Disinfection By-Product MCL’sReview Disinfection By-Product MCL’s Review How DBPs are FormedReview How DBPs are Formed Review Water Sources and ID Conditions Review Water Sources and ID Conditions

that Contribute to a DBP Problemthat Contribute to a DBP Problem Identify Measuring Parameters Identify Measuring Parameters

Associated with NOM and TOCAssociated with NOM and TOC Identify DBP Best Management PracticesIdentify DBP Best Management Practices Review DBP Troubleshooting GuideReview DBP Troubleshooting Guide Conduct Interactive Role Playing Exercise Conduct Interactive Role Playing Exercise

3

DEP MCL Requirements for DEP MCL Requirements for DBP’s DBP’s

TTHM, HAA5, Chlorite and TTHM, HAA5, Chlorite and BromateBromate

– TTHMTTHM .080 mg/l .080 mg/l– HAA5HAA5 .060 mg/l .060 mg/l– ChloriteChlorite 1.0 mg/l* 1.0 mg/l*– Bromate 0.010 mg/l **Bromate 0.010 mg/l **

* * associated with the use of Chlorine Dioxideassociated with the use of Chlorine Dioxide** naturally occurring precursor in systems near ** naturally occurring precursor in systems near

saltwater, associated with use of Ozonesaltwater, associated with use of Ozone

4

Disinfection Byproducts Disinfection Byproducts FormationFormation

Disinfection Byproducts (DBP) are produced by the Disinfection Byproducts (DBP) are produced by the reaction of free chlorine with natural organic reaction of free chlorine with natural organic material (NOM) found in source waters.material (NOM) found in source waters.

The amount of organic materials (NOM) can be The amount of organic materials (NOM) can be approximated by the amount of Total Organic approximated by the amount of Total Organic Carbon (TOC) present. Carbon (TOC) present.

The portion of the NOM that forms the DBP’s is The portion of the NOM that forms the DBP’s is generally the dissolved portion (DOC is that part of generally the dissolved portion (DOC is that part of the TOC that can be identified by first removing the the TOC that can be identified by first removing the NOM that is retained on a 45 micron filter)NOM that is retained on a 45 micron filter)

NOM + Cl2 THMs + HAAs + Other DBP CompoundsNOM + Cl2 THMs + HAAs + Other DBP Compounds

5

Sources of Natural Organic Sources of Natural Organic Material (NOM) in Surface WaterMaterial (NOM) in Surface Water

Rain Events wash organic matter into receiving body. Rain Events wash organic matter into receiving body. Flooding reverses flow gradients in upper aquifersFlooding reverses flow gradients in upper aquifers Cavities and Fissures in Karst Conditions allow surface Cavities and Fissures in Karst Conditions allow surface

intrusionintrusion Poor Sanitary Conditions, i.e., broken seals, abandoned Poor Sanitary Conditions, i.e., broken seals, abandoned

wells, poor locations, result in intrusionwells, poor locations, result in intrusion Ground Water that has high NOM content is indicative Ground Water that has high NOM content is indicative

of the intrusion from Surface Waterof the intrusion from Surface Water Sedimentation, biogrowth or poor flushing practices in Sedimentation, biogrowth or poor flushing practices in

distribution systems increase organics concentration. distribution systems increase organics concentration.

6

Use of Different Carbon Use of Different Carbon SurrogatesSurrogates

  

NOM SpeciesNOM Species

  

DescriptionDescription

  

SignificanceSignificance

TOCTOC

Total amount of all forms Total amount of all forms of Organic Carbon of Organic Carbon PresentPresent

Good overall indicator of Good overall indicator of potential DBP problemspotential DBP problems

DOCDOC

The TOC passing through The TOC passing through a 0.45 micron filter is a 0.45 micron filter is dissolveddissolved

Better indicator of the Better indicator of the reactive portion of the reactive portion of the TOCTOC

UVUV254254

Used to identify light Used to identify light absorption of reactive absorption of reactive humic componentshumic components

Identifies the reactive Identifies the reactive potion of the DOCpotion of the DOC

SUVASUVA Ratio of UVRatio of UV254 254 to DOCto DOC

Best indicator of reactive Best indicator of reactive portion of the TOCportion of the TOC

7

Raw Water ConsiderationsRaw Water Considerations

DBP Problem analysis always starts with a well DBP Problem analysis always starts with a well investigation!investigation!

Generally surface waters or ground waters under the Generally surface waters or ground waters under the direct influence of surface water (UDI) will have higher direct influence of surface water (UDI) will have higher levels of organic materials (TOC.) levels of organic materials (TOC.)

Surface waters have higher treatable humic content than Surface waters have higher treatable humic content than GW GW

If Surface water mixes with ground water, each well may If Surface water mixes with ground water, each well may experience different levels of TOCs. experience different levels of TOCs.

The humic content can be approximated by using SUVA. The humic content can be approximated by using SUVA.

8

Organic Carbon (TOC) or Organic Carbon (TOC) or Precursors in Natural Waters Precursors in Natural Waters

mg/lmg/l

.1 .2 .5 1.0 2 5 10 20 50 100 200 500 1000

Sea Water

Ground Water

Surface Water Swamp

Wastewater

Wastewater Effluent

Mean Surface Water 3.5

9

Typical Values of TOC for Typical Values of TOC for Various WatersVarious Waters

Type of Type of WaterWater

Range in Range in mg C/l mg C/l

Sea WaterSea Water 0.5 – 5.00.5 – 5.0

Most Ground Most Ground WaterWater

0.1 – 5.00.1 – 5.0

Surface Surface WaterWater

1.0 – 201.0 – 20

Swamp Swamp WaterWater

75 – 30075 – 300

Effluents Effluents BiotreatmenBiotreatmentt

8.0 – 208.0 – 20

WastewaterWastewater 50 – 100050 – 1000

WMD WMD

Inter-Inter-MediatMediatee

MedianMedian

FloridaFloridann

MedianMedianmg C/lmg C/l

NWFWMNWFWMDD

6.16.1 <1.0<1.0

SRWMDSRWMD <1.0<1.0 2.02.0

SJRWMDSJRWMD 5.55.5 3.33.3

SWFWMSWFWMDD

9.89.8 16.816.8

SFWMDSFWMD 6.36.3 1.91.9

STATESTATE 4.84.8 2.22.2

10

Thickness and Extent of Thickness and Extent of Intermediate Aquifer Intermediate Aquifer

ConfinementConfinement

The Confining Unit restricts The Confining Unit restricts flow of groundwater between flow of groundwater between the Surficial Aquifer and the Surficial Aquifer and Floridan Aquifer when present.Floridan Aquifer when present.

Protects underlying Floridan Protects underlying Floridan Aquifer, Florida’s primary Aquifer, Florida’s primary source of drinking water, from source of drinking water, from potential contaminationpotential contamination

NN

11

Karst FeaturesKarst Features

Karst is a type of Karst is a type of topography that is topography that is characterized by characterized by depressions caused depressions caused by the dissolution of by the dissolution of limestone.limestone.

These features include These features include caves, sinkholes, caves, sinkholes, springs, and other springs, and other openings.openings.

In karst areas, In karst areas, interactions between interactions between surface water and surface water and groundwater are groundwater are extensive and extensive and groundwater quality groundwater quality can degrade quickly.can degrade quickly.

N

Light areas indicate Karst features

12

Reducing the Production Reducing the Production of Disinfection By-Productsof Disinfection By-Products

Eliminating Sources of Surface Water into Production Eliminating Sources of Surface Water into Production WellsWells

Selecting Well Blends with Lower DBPsSelecting Well Blends with Lower DBPs Removing Precursor Material within treatment process Removing Precursor Material within treatment process Changing the Point(s) of Chlorine ApplicationChanging the Point(s) of Chlorine Application Lowering the Chlorine Dose and/or ResidualLowering the Chlorine Dose and/or Residual Using Alternate Disinfection Strategies Using Alternate Disinfection Strategies Ensuring the WTP processes are absent of organic growth Ensuring the WTP processes are absent of organic growth

(ie. Ion Exchange and Activated Carbon Systems)(ie. Ion Exchange and Activated Carbon Systems) Ensuring Water Tank TurnoverEnsuring Water Tank Turnover Reducing Distribution System Water Age Reducing Distribution System Water Age Flushing water in slow moving areas and at dead-endsFlushing water in slow moving areas and at dead-ends Removing sediment that creates chlorine demand Removing sediment that creates chlorine demand Removing biofilm that converts inorganic to organic Removing biofilm that converts inorganic to organic

materials materials

13

Coagulation to Remove TOCCoagulation to Remove TOC

TOCTOC Alkalinity (CaCO3)Alkalinity (CaCO3)

Mg C/L 0-60 60-120 >120Mg C/L 0-60 60-120 >120

2.0 to 4.02.0 to 4.0 35% 25% 15% 35% 25% 15%

4.0 to 8.0 45% 35% 25%4.0 to 8.0 45% 35% 25%

>8.0 50% 40% 30%>8.0 50% 40% 30%

TOC Removal using TOC Removal using Enhanced Coagulation for Surface Water Plants (TT)Enhanced Coagulation for Surface Water Plants (TT)

Typically Alum is used and requires sedimentation/filtration Typically Alum is used and requires sedimentation/filtration Lime can also be used but has less ability due to high pHLime can also be used but has less ability due to high pH

Florida Source WatersFlorida Source Waters

14

Other Means to Remove Other Means to Remove TOCTOC

PermanganatePermanganate Long Used for Taste and OdorLong Used for Taste and Odor Removes color forming Removes color forming

substances which are the same substances which are the same constituents that cause DBP constituents that cause DBP formationformation

Range of dosage vary on water Range of dosage vary on water quality with .25 mg/l to 20 mg/l.quality with .25 mg/l to 20 mg/l.

Average dosage is 2 to 4 mg/l Average dosage is 2 to 4 mg/l with 30% TOC removal with 30% TOC removal efficiencies reportedefficiencies reported

Limitation is that can not be Limitation is that can not be used in systems with High used in systems with High Sulfide Levels or with changing Sulfide Levels or with changing conditions conditions

Activated Carbon Activated Carbon FilterFilter

With Source Water TOC With Source Water TOC from 2 to 4 mg C/L from 2 to 4 mg C/L Activated Carbon Systems Activated Carbon Systems typically remove >50% typically remove >50%

Activated Carbon comes in Activated Carbon comes in two forms:two forms:

Powdered Activated Powdered Activated Carbon (PAC)Carbon (PAC)

Granular Activated Granular Activated Carbon (GAC)Carbon (GAC)

Removal mechanisms are Removal mechanisms are the samethe same

15

Factors Affecting Factors Affecting Disinfection By-Product Disinfection By-Product

Production w/ ClProduction w/ Cl22

Turbidity and the type of NOM presentTurbidity and the type of NOM present Concentration of Chlorine added and how Concentration of Chlorine added and how

well it is mixedwell it is mixed Bromide Ion Concentration Bromide Ion Concentration Presence of HPresence of H22S, Iron and NHS, Iron and NH33

Age of Water System (amt of CI pipeline)Age of Water System (amt of CI pipeline) Warmer TemperaturesWarmer Temperatures Longer Contact Times (MRT)Longer Contact Times (MRT) Presence of Sediment in TanksPresence of Sediment in Tanks

16

Breakpoint Chlorination Curve

DBP Production

DBPs Remain

Chloramines

Oxidation/Reduction Only

17

Steps in the Formation of DBPs Steps in the Formation of DBPs

with Free Chlorinewith Free Chlorine 1.1. Inorganic reducing constituents such as HInorganic reducing constituents such as H22S, Fe & Mn S, Fe & Mn

and NHand NH33 compounds react first (oxidation reduction compounds react first (oxidation reduction reaction). reaction).

2.2. When Iron, Sulfide or NHWhen Iron, Sulfide or NH33 are present, they exert the are present, they exert the major Chlorine Demand major Chlorine Demand

3.3. Iron concentrations are required in the Secondary Iron concentrations are required in the Secondary Standard submittal but Sulfide or NHStandard submittal but Sulfide or NH33 are not. are not.

4.4. If there are products of Biological Metabolism such as If there are products of Biological Metabolism such as Nitrite this will also react. (Important in Nitrification)Nitrite this will also react. (Important in Nitrification)

5.5. Any readily soluble Organic Materials in the water (TOC) Any readily soluble Organic Materials in the water (TOC) will then react forming DBPs.will then react forming DBPs.

6.6. Further Free Chlorine addition will not destroy DBPs.Further Free Chlorine addition will not destroy DBPs.7.7. Disinfection “jar test” can be used to identify reducing Disinfection “jar test” can be used to identify reducing

constituents but will not identify by specific constituent.constituents but will not identify by specific constituent.

18

Example of Calculating CLExample of Calculating CL22 DemandDemand

Water Water QualityQuality

actual mg/lactual mg/l

CL2 CL2 MultiplierMultiplier

Total CL2Total CL2

Demand Demand

Fe = 0.3Fe = 0.3 0.64*0.64* 0.190.19

Mn = 0.06Mn = 0.06 1.31.3 0.070.07

H2S = 0.2H2S = 0.2 2.1* 2.1* 0.420.42

NO2 = 0.1NO2 = 0.1 55 0.500.50

NH3 = 0.1NH3 = 0.1 10 to 1210 to 12 1.201.20

Org-N = 0.05Org-N = 0.05 11 0.050.05

TOC = 1.0TOC = 1.0 0.10.1 0.100.10

Chlorine DemandChlorine Demand 2.53 2.53

* Note: Actual amount of oxidant must be about 15% – 20% higher * Note: Actual amount of oxidant must be about 15% – 20% higher

19

DEP HDEP H22S Treatment S Treatment RequirementsRequirements

Potential ImpactPotential Impact Water Quality RangesWater Quality Ranges Water Water TreatmentTreatment

LowLow Total Sulfide < 0.3 mg/lTotal Sulfide < 0.3 mg/l Direct Direct ChlorinationChlorination

Moderate pH < Moderate pH < 7.2 7.2

pH > pH > 7.27.2

Total Sulfide < 0.6 mg/lTotal Sulfide < 0.6 mg/l

Total Sulfide < 0.6 mg/lTotal Sulfide < 0.6 mg/lAeration Aeration Aeration w/ pH Aeration w/ pH adjustmentadjustment

Significant pH < Significant pH < 7.2 7.2

pH > pH > 7.27.2

Total Sulfide < 0.6 mg/lTotal Sulfide < 0.6 mg/l

Total Sulfide < 0.6 mg/lTotal Sulfide < 0.6 mg/lForced DraftForced Draft

Forced Draft w/ Forced Draft w/ pH adjustmentpH adjustment

Very SignificantVery Significant Total Sulfide < 3.0 mg/lTotal Sulfide < 3.0 mg/l Packed Tower Packed Tower w/ pH w/ pH adjustmentadjustment

20

DEP Iron Treatment DEP Iron Treatment RequirementsRequirements

State Secondary Standards require Iron State Secondary Standards require Iron to be < 0.30 mg/l in the finished water to be < 0.30 mg/l in the finished water

Thus water systems with iron Thus water systems with iron concentration greater than 0.3 mg/l concentration greater than 0.3 mg/l would need to install filterswould need to install filters

Iron may be sequestered up to a Iron may be sequestered up to a concentration of 1.0 mg/lconcentration of 1.0 mg/l

In an aeration system Iron is removed by In an aeration system Iron is removed by raising the pH while H2S is removed raising the pH while H2S is removed better at lower pH’sbetter at lower pH’s

Treatment Issues with Treatment Issues with Sulfide and Iron in Unlined Sulfide and Iron in Unlined

CI PipesCI Pipes

Sulfide is remove by Sulfide is remove by lowering pH and filteringlowering pH and filtering

Unreacted Sulfide will Unreacted Sulfide will form “blackwater” with form “blackwater” with unlined CI pipesunlined CI pipes

Sulfate and Colloidal Sulfate and Colloidal Sulfur can be Sulfur can be reconverted to sulfide by reconverted to sulfide by bacteria in water tanks bacteria in water tanks causing odorcausing odor

Iron is removed by raising Iron is removed by raising pH and filtering source pH and filtering source waterwater

Unfiltered Iron will result Unfiltered Iron will result in “red water” complaintsin “red water” complaints

Iron can also be a Iron can also be a corrosion product from corrosion product from unlined CI pipesunlined CI pipes

Iron will result in stainingIron will result in staining

> 0.3 mg/l > 0.3 mg/l Problematic Problematic because of because of

colloidal solidscolloidal solids

22

Chlorine Disinfecting Power Chlorine Disinfecting Power and and

pH Considerations in WaterpH Considerations in Water Chlorine reacts with waterChlorine reacts with water Producing hypochlorous acid (HOCl) and the Producing hypochlorous acid (HOCl) and the

hypochlorite ion (OCl-) hypochlorite ion (OCl-) Chlorine is more reactive at lower pHs.Chlorine is more reactive at lower pHs. Low pH forms > HAA5s, High pH forms > TTHMsLow pH forms > HAA5s, High pH forms > TTHMs

6 7 8 9

%

HOCL

%

OCL-

pH

Hypochlorite (pH Hypochlorite (pH 12.5) raises pH at 12.5) raises pH at high dose levels!high dose levels!

Old Hypochlorite Old Hypochlorite contributes to contributes to DBP formation DBP formation because doses because doses must be higher!must be higher!

23

Sources of Chlorine and Sources of Chlorine and Bromine in DBP Bromine in DBP

CompoundsCompounds

ChlorineChlorine

Free ChlorineFree Chlorine Improper NHImproper NH33

applicationapplication Poor Chemical Poor Chemical

MixingMixing Chloramine Chloramine

BreakdownBreakdown

BromineBromine

Bromide from Bromide from Saltwater or Saltwater or Brackish Water Brackish Water IntrusionIntrusion

Drought Drought ConditionsConditions

Presence of Free Presence of Free ChlorineChlorine

24

Effect of the Addition of Effect of the Addition of FreeFree

CL at MCLCL at MCL++ Level with TOC Level with TOC

CL at 4.3 PPM

Note that TTHM growth is Note that TTHM growth is directly proportional to the directly proportional to the excess amount of chlorine excess amount of chlorine present (in concentrations above present (in concentrations above 1 mg/l) and the excess TOC that 1 mg/l) and the excess TOC that is available for reaction.is available for reaction.

This relationship is steady as Cl This relationship is steady as Cl residuals approach 1.5 mg/l.residuals approach 1.5 mg/l.

Note the 300% increase in the Note the 300% increase in the amount of TTHM made when amount of TTHM made when chlorine and TOC are increased chlorine and TOC are increased by 50%. by 50%.

Florida Source Water often apporach 4 mg/l TOCFlorida Source Water often apporach 4 mg/l TOC

Chlorine Detention Time Small Chlorine Detention Time Small SystemSystem

Time Paced

Control

Flow Paced Control

Water Systems experience both Water Systems experience both Seasonal and Diurnal Demand Seasonal and Diurnal Demand Changes.Changes.

Colder months require less chlorine Colder months require less chlorine dose.dose.

Wet and hot periods cause longer Wet and hot periods cause longer detention periods.detention periods.

In times when demand exceeds In times when demand exceeds average demand, a time-paced Cl feed average demand, a time-paced Cl feed system overfeeds chlorine.system overfeeds chlorine.

Ave Demand

26

Production of Total Production of Total Trihalomethanes (TTHMs)Trihalomethanes (TTHMs)

Trihalomethanes (TTHMS) are produced by the reaction of Trihalomethanes (TTHMS) are produced by the reaction of chlorine with organic constituents found in natural waters. chlorine with organic constituents found in natural waters.

The 4 Trihalomethane compounds of concern are:The 4 Trihalomethane compounds of concern are:

Chloroform (typically >70% inland) BromodichloromethaneChloroform (typically >70% inland) BromodichloromethaneBromoform (can be >70% coastal) DibromochloromethaneBromoform (can be >70% coastal) Dibromochloromethane

The sum of the concentrations of these four compounds are Total The sum of the concentrations of these four compounds are Total Trihalomethanes (TTHMs)Trihalomethanes (TTHMs)

However, Chloroform or Bromoform will always constitute the However, Chloroform or Bromoform will always constitute the higher portion of the TTHMs. higher portion of the TTHMs.

Bromoform is produced in coastal areas due to brackish intrusion Bromoform is produced in coastal areas due to brackish intrusion and varies by well. Bromoform is formed by the reaction of Cl on and varies by well. Bromoform is formed by the reaction of Cl on Bromide.Bromide.

Chloroform is present in inland areas and varies by well.Chloroform is present in inland areas and varies by well.

27

Where TTHMs are FormedWhere TTHMs are Formed

High Water Age (MRT)High Water Age (MRT)

Storage Tanks with poor water Storage Tanks with poor water

turnoverturnover

Low Demand AreasLow Demand Areas

Stagnant & Slow Moving Water Stagnant & Slow Moving Water

AreasAreas

Dead Ends Pipelines (MRT)Dead Ends Pipelines (MRT)

Note: Unlined CI Pipe (systems in Note: Unlined CI Pipe (systems in

existence before 1949) require existence before 1949) require

higher residual chlorine levelshigher residual chlorine levels

Unlined CI Pipe Tuberculation with Bacterial Growth producing Organic Precursors

28

Production of Haloacetic Production of Haloacetic AcidsAcids

Like THMs, Haloacetic Acids are produced by the addition Like THMs, Haloacetic Acids are produced by the addition of free chlorine to watersof free chlorine to waters

containing natural organic materials. containing natural organic materials. These 5 compounds are regulated as HAA5s.These 5 compounds are regulated as HAA5s.

Monochloroacetic AcidMonochloroacetic AcidMonobromoacetic Acid Monobromoacetic Acid Dichloroacetic Dichloroacetic

AcidAcidDibromoacetic Acid Dibromoacetic Acid Trichloroacetic AcidTrichloroacetic Acid

These compounds will begin to degrade a few days after These compounds will begin to degrade a few days after formation.formation.

They can not be removed by air stripping.They can not be removed by air stripping.

29

Where HAA5s are FoundWhere HAA5s are Found

Low Demand Areas Low Demand Areas

Toward Middle SystemToward Middle System Areas w/ high Chlorine Areas w/ high Chlorine

concentration and low movementconcentration and low movement

Near High Chlorine Dose and/or Residual Near High Chlorine Dose and/or Residual

LocationsLocations

High Bacterial Growth internal to systemHigh Bacterial Growth internal to system HAA5 will degrade in systems with high water age, HAA5 will degrade in systems with high water age,

thus highest HAA5s are not found at MRTthus highest HAA5s are not found at MRT

30

Ratio of TTHM to HAA5Ratio of TTHM to HAA5 Ratios of TTHM to HAA5 should remain Ratios of TTHM to HAA5 should remain

relatively constantrelatively constant Large variations indicate a change of system Large variations indicate a change of system

conditionsconditions Since HAA5’s decay, an increase in HAA5 Since HAA5’s decay, an increase in HAA5

levels indicates that water age has declinedlevels indicates that water age has declined An increase in both would mean that Cl An increase in both would mean that Cl

residuals are too highresiduals are too high Trending of changes can be very valuable Trending of changes can be very valuable

for troubleshootingfor troubleshooting

31

Chlorine Dose and Its Chlorine Dose and Its Effect on DBP ProductionEffect on DBP Production

Typical Chlorine Doses may range Typical Chlorine Doses may range between 2 mg/l to 4 mg/l with between 2 mg/l to 4 mg/l with Chlorine Residual leaving the plant at Chlorine Residual leaving the plant at an average near 1.5 mg/l.an average near 1.5 mg/l.

Often Chlorine Residual Often Chlorine Residual Concentration can be lowered Concentration can be lowered proving significant reductions in DBP proving significant reductions in DBP production.production.

32

DBP Formation Potential DBP Formation Potential Indicates Significance of DBP Indicates Significance of DBP

ProblemProblem

DBP YieldDBP Yield

%%Formation Formation Potential Potential

SimulatedSimulated

Dist. Sys. Dist. Sys. TestTest

TOX*TOX* 100%100% N/AN/A

TTHM TTHM 23%23% 7%7%

HAA5HAA5 33%33% 11%11%

Other DBPsOther DBPs 44%44% N/AN/A

After Watson and Montgomery AWWA Water Quality and Treatment, 1999

Water Age

* TOX = Total Organic Halides

33

Formation of DBP in a Typical Formation of DBP in a Typical Water Treatment and Water Treatment and Distribution SystemDistribution System

~ 50% ~ 50% DistributionDistribution

~ 50% ~ 50% TreatmentTreatment

34

Identifying the Point of DBP Production Identifying the Point of DBP Production in a Water Systemin a Water System

1.1. DBPs are equally produced DBPs are equally produced in the treatment plant and in the treatment plant and in the WD system.in the WD system.

2.2. It is important to note It is important to note where the DBPs are where the DBPs are produced (extra sampling) produced (extra sampling) to identify effective to identify effective corrective actions.corrective actions.

3.3. Typically DBP problems Typically DBP problems occur at MRT Locations.occur at MRT Locations.

4.4. Proactive DBP Strategies Proactive DBP Strategies should be targeted.should be targeted.

35

Effects of Moving the Point Effects of Moving the Point ofof

DisinfectionDisinfectionMoving the Point of Disinfection Moving the Point of Disinfection

acts in three ways:acts in three ways:

1.1. Decreases significantly the Decreases significantly the time that the highest free time that the highest free chlorine concentration is in chlorine concentration is in contact with organic material.contact with organic material.

2.2. Treatment, especially Treatment, especially coagulation, sed. and filtration coagulation, sed. and filtration removes a portion of the TOC.removes a portion of the TOC.

3.3. In combining 1 & 2 above, the In combining 1 & 2 above, the dose requirement for chlorine dose requirement for chlorine is lower and easier to predictis lower and easier to predict

Surface Water Process Treatment Surface Water Process Treatment provides significant TOC reduction. provides significant TOC reduction. However, any treatment process used However, any treatment process used provides some level of TOC reductionprovides some level of TOC reduction..

36

Effective Chlorination Effective Chlorination System Modification StrategiesSystem Modification Strategies

DisinfectionDisinfectionLocationLocation ActionAction BenefitBenefit

Chlorine FeedChlorine Feed Reduce chlorine feed Reduce chlorine feed rates while maintaining rates while maintaining proper chlorine residualsproper chlorine residuals

Fewer DBPs formed in the water Fewer DBPs formed in the water system. No / little cost for this system. No / little cost for this option.option.

Chlorine Chlorine Injection PointInjection Point

Change point of chlorine Change point of chlorine injection to reduce the injection to reduce the age of chlorinated waterage of chlorinated water

Fewer DBPs formed in the water Fewer DBPs formed in the water system. Small cost for this system. Small cost for this option.option.

Chlorine Chlorine Injection Injection BoostersBoosters

Add chlorine injection Add chlorine injection point(s) to boost Chlorine point(s) to boost Chlorine residuals in the residuals in the distribution system distribution system instead of at the plantinstead of at the plant

Lower total chlorine added at the plant site. Fewer DBPs formed in the distribution system.

Alternate Alternate Disinfection / Disinfection / ApplicationApplication

Use of chloramines in Use of chloramines in distribution systems with distribution systems with long detention times or long detention times or selective use of selective use of preoxidation or oxidant preoxidation or oxidant such as NaMnOsuch as NaMnO4 4

Fewer DBPs formed in the water system. Costs for this option could be significant.

37

Water Age and DBP Water Age and DBP ProductionProduction

Franchi and Hill, 2002

Other than Reducing Cl Other than Reducing Cl dose and residual levels, dose and residual levels, reducing water age is the reducing water age is the most effective method most effective method available for reducing available for reducing TTHM concentrations.TTHM concentrations.

There are two slopes There are two slopes present in TTHM present in TTHM development, The first is development, The first is most significantmost significant and is and is related to related to Cl doseCl dose, the , the second is slower and related second is slower and related to to Cl residualCl residual

CL CL dosedose

CL ResidualCL Residual

38

Typical Distribution Typical Distribution System Water Age (Days)System Water Age (Days)

PopulatioPopulationn

Miles of WMMiles of WM Min RTMin RT MRTMRT

> > 750,000750,000

> 1,000> 1,000 1 day1 day ~ 1 wk ~ 1 wk

< < 100,000100,000

< 400< 400 1 day1 day ~ 2 wks ~ 2 wks

< < 25,00025,000

< 100< 100 1 day1 day ~ 1 mo. ~ 1 mo.

AWWA: Water Age for Ave and Dead End Conditions

39

Flushing Objectives Used in Flushing Objectives Used in Water Distribution SystemsWater Distribution Systems

Unidirectional Flushing

> 2.5 fps velocity that removes solid deposits and biofilm from

pipelines

Conventional Flushing

< 2.5 fps velocity that reduces water age, raises disinfectant residual removes coloration

&

40

Removing Sediment and Biofilm Removing Sediment and Biofilm from Water Mains by Unidirectional from Water Mains by Unidirectional

FlushingFlushing

Sediment deposits and most biofilm can be Sediment deposits and most biofilm can be removed if cleansing velocities can be achievedremoved if cleansing velocities can be achieved

The velocity that needs to be developed is 2.5 to 5 The velocity that needs to be developed is 2.5 to 5 fps; these velocities will cause pressure drops and fps; these velocities will cause pressure drops and movement of sediment including rust to movement of sediment including rust to customer’s plumbingcustomer’s plumbing

To achieve these types of velocities without To achieve these types of velocities without problems, a planned unidirectional approach must problems, a planned unidirectional approach must be used that valves off piping to force water to a be used that valves off piping to force water to a certain locationcertain location

41

Effects of pH on the Production Effects of pH on the Production of DBPs in Distribution Systemof DBPs in Distribution System

pH Note:

HAA5

Amy et al. 1987 Franchi et al. 2002

TTHM and HAA% Formation Potential

42

Problems with Water Problems with Water Turnover and Sediments in Turnover and Sediments in

TanksTanks

Sediments contain significant concentrations of organic nutrients and Sediments contain significant concentrations of organic nutrients and exert a disinfectant demand leading to higher Cl dosesexert a disinfectant demand leading to higher Cl doses

Sediments provide protective layers for biofilms which allow pathogens Sediments provide protective layers for biofilms which allow pathogens to repairto repair

Sediments encourage the growth of slow growing nitrifying bacteria that Sediments encourage the growth of slow growing nitrifying bacteria that lower Cl residuallower Cl residual

Bacteria contribute organics that lead to the formation of DBPsBacteria contribute organics that lead to the formation of DBPs Bacterial growth lead to turbidity, taste and odor problems that require Bacterial growth lead to turbidity, taste and odor problems that require

higher Cl dosehigher Cl dose

Storage Tank Water Movement: 1.) Daily goal of 50% storage volume Storage Tank Water Movement: 1.) Daily goal of 50% storage volume removed, 2.) Minimum of 20% - 30% , and removed, 2.) Minimum of 20% - 30% , and TargetTarget of every 3 days of every 3 days

Increasing Bacterial Growth: 1. ) protection from UV, 2.) moderate high Temp., Increasing Bacterial Growth: 1. ) protection from UV, 2.) moderate high Temp., 3.) mildly alkaline pH (7.4 – 8.4) , 4.) O3.) mildly alkaline pH (7.4 – 8.4) , 4.) O22 present and 5.) substrate for growth present and 5.) substrate for growth

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DEP Flushing Removal DEP Flushing Removal RequirementsRequirements

Flushing Flushing ProgramProgram

SuggestedSuggestedActions/DEP Actions/DEP

RuleRule

Benefits toBenefits toTreatment SystemTreatment System

Written Written Flushing Flushing ProceduresProcedures

Submit a Written Water Main Submit a Written Water Main Flushing Program.Flushing Program.DEP Rule 62-555.350DEP Rule 62-555.350

Sampling is during normal operating Sampling is during normal operating conditions, and is not valid if you conditions, and is not valid if you ONLY flush the day you are ONLY flush the day you are collecting samplescollecting samples

Treatment Treatment Components Components in Contact in Contact With WaterWith Water

Clean & remove biogrowths, Clean & remove biogrowths, calcium or iron / manganese calcium or iron / manganese deposits, & sludgedeposits, & sludge DEP Rule 62-555.350(2)DEP Rule 62-555.350(2)

Improves water quality, reduces Improves water quality, reduces chlorine demand & regrowth in the chlorine demand & regrowth in the water system.water system.

ReservoirsReservoirsand Storage and Storage TanksTanks

Clean & remove biogrowths, Clean & remove biogrowths, Ca or Fe / Mn deposits, & Ca or Fe / Mn deposits, & sludge from storage tanks.sludge from storage tanks.DEP Rule 62-555.350(2) FACDEP Rule 62-555.350(2) FAC

Improves water quality, reduces Improves water quality, reduces chlorine demand & biological chlorine demand & biological regrowth in the water system. regrowth in the water system.

Water Distribution Mains

Begin systematic flushing of Begin systematic flushing of water system from water system from treatment plant to system treatment plant to system extremities.extremities.

Improves water quality, reduces Improves water quality, reduces chlorine demand & biological chlorine demand & biological regrowth in the water system. regrowth in the water system.

Dead-End Dead-End Water MainsWater Mains

Flushing (every other day) Flushing (every other day) or Automatic Flushing.or Automatic Flushing.DEP Rule 62-555.350(2) DEP Rule 62-555.350(2)

Improves water quality,& reduces Improves water quality,& reduces biological regrowth. biological regrowth.

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Use of Disinfectant Use of Disinfectant StrategiesStrategies

Reduce Dosing Concentration of Reduce Dosing Concentration of DisinfectantDisinfectant

Change Points of ApplicationChange Points of Application Change forms of DisinfectantChange forms of Disinfectant Use of Multiple DisinfectantsUse of Multiple Disinfectants Change DisinfectantChange Disinfectant Use of Orthophosphate in WD Use of Orthophosphate in WD

systems that use Unlined CI Pipe systems that use Unlined CI Pipe

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Advantages in the Use of Advantages in the Use of ChloramineChloramine

Chloramines Not As Reactive With Organic Compounds Chloramines Not As Reactive With Organic Compounds so significantly less DBPs will formso significantly less DBPs will form

Chloramine Residual are More Stable & Longer LastingChloramine Residual are More Stable & Longer Lasting Chloramines Provides Better Protection Against Bacterial Chloramines Provides Better Protection Against Bacterial

Regrowth in Systems with Large Storage Tanks & Dead Regrowth in Systems with Large Storage Tanks & Dead End Water Mains when Residuals are MaintainedEnd Water Mains when Residuals are Maintained

Since Chloramines Do Not React With Organic Since Chloramines Do Not React With Organic Compounds; Less Taste & Odor ComplaintsCompounds; Less Taste & Odor Complaints

Chloramines Are InexpensiveChloramines Are Inexpensive Chloramines Easy to MakeChloramines Easy to Make

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Chloramine DisadvantagesChloramine Disadvantages

Not As Strong As Other DisinfectantsNot As Strong As Other Disinfectantseg. Chlorine, Ozone, & Chlorine Dioxideeg. Chlorine, Ozone, & Chlorine Dioxide

Cannot Oxidize Iron, Manganese, & SulfidesCannot Oxidize Iron, Manganese, & Sulfides.. Sometimes Necessary to Periodically Convert to Free Chlorine Sometimes Necessary to Periodically Convert to Free Chlorine

for Biofilm Control in the Water Distribution System (Burn for Biofilm Control in the Water Distribution System (Burn lasting 2 to 3 weeks)lasting 2 to 3 weeks)

Chloramine Less Effective at High pHChloramine Less Effective at High pH Forms of Chloramine such as Dichloramine cause Treatment & Forms of Chloramine such as Dichloramine cause Treatment &

Operating ProblemsOperating Problems Excess Ammonia Leads to NitrificationExcess Ammonia Leads to Nitrification Problems in Maintaining Residual in Dead Ends & Other Problems in Maintaining Residual in Dead Ends & Other

LocationsLocations

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Nitrification Concerns in Water Storage Nitrification Concerns in Water Storage Tanks with the Use of ChloramineTanks with the Use of Chloramine

Nitrification is the conversion of ammonia to nitrite then to Nitrification is the conversion of ammonia to nitrite then to nitrate nitrate

Occurs in dark areas, at pH > 7, with at warm temperatures Occurs in dark areas, at pH > 7, with at warm temperatures and long detentionand long detention

Nitrification problems occur with systems that use Nitrification problems occur with systems that use chloramine which contains excess ammonia that when chloramine which contains excess ammonia that when released can support the nitrification process released can support the nitrification process

Nitrite (intermediate product) will consume free chlorine and Nitrite (intermediate product) will consume free chlorine and chloramine disinfectantschloramine disinfectants

Must ensure that disinfectant residual levels are adequate (> Must ensure that disinfectant residual levels are adequate (> 1.5 ppm chloramine; with 2.0 to 2.5 recm.) 1.5 ppm chloramine; with 2.0 to 2.5 recm.)

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Nitrification Monitoring Nitrification Monitoring IndicatorsIndicators

Higher Water Temperatures andHigher Water Temperatures and Depressed Disinfectant LevelsDepressed Disinfectant Levels Elevated DBPsElevated DBPs Elevated Bacterial Counts (HPC)*Elevated Bacterial Counts (HPC)* Elevated Nitrate/Nitrite Levels for Elevated Nitrate/Nitrite Levels for

Chloramination SystemsChloramination Systems High Corrosion Potential High Corrosion Potential Direct Nitrification Monitoring ineffectiveDirect Nitrification Monitoring ineffective* HPC use organic carbon as food, include total coliform; Not to exceed 500/ml in 95% of samples

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Troubleshooting DBPTroubleshooting DBPProblemsProblems

Quantitative Approach to Quantitative Approach to DPB ReductionDPB Reduction

Interactive Portion of Interactive Portion of PresentationPresentation

Bob’s HandoutsBob’s Handouts