ChloraminationOn-Line Chloramination Monitoring

and Control

Scott Kahle, ASA/ChemScan

What are Chloramines?Chemicals that are formed when chlorine and ammonia are combined

in water.Monochloramine (NH2Cl)

Dichloramine (NHCl2)

Trichloramine (NCl3)

Benefits of Chloramine (compared to chlorine)

More StableLess Reactive (reduced THM formation)Longer Lived ResidualsEffective Secondary DisinfectantMinimizes Objectionable Taste and Odors

Monochloramine is the Desired Form of Chloramine

Most StableLeast Reactive (Reduced THM Formation)Least Taste and Odor

Chloramination Breakpoint Curve

Optimal Chloramination Control Range

Chloramination Control ChallengesMaintain Adequate Disinfectant Concentration to Ensure

Safe WaterFeed Enough Ammonia to Prevent Di and Trichloramine

Formation and Prevent Drop in Chlorine ResidualPrevent Over Feed of Ammonia to Minimize the Potential

of Nitrification in the Reservoirs and Distribution SystemOn-Line Analysis Provides the Information Required to

Control the Chloramination Process

Breakpoint as Measured by Free and Total Chlorine Analyzers

A Total Chlorine result has 3 possible locations on the breakpoint curve Free Chlorine reacts with Monochloramine giving a false reading until beyond the Breakpoint First Indication of Free Chlorine is AFTER Dichloramine Formation

Break-point Curve as Read on ChemScan On-Line Analyzer

At ratios below 5:1, Total Chlorine and Monochloramine values are equivalent

Between the ratios of 5:1 and 8:1, Total Chlorine is greater than Monochloramine as Dichloramine is formed

At ratio greater than 8:1, Free Chlorine is present

At ratios below 5:1, Total Ammonia remains constant as Free Ammonia decreases until reaching 5:1

At ratios greater than 5:1, Total Ammonia decreases and free ammonia is near zero

Fixed NH3-N 0.6 mg/l With Increasing Cl2

-0.5

0

0.5

1

1.5

2

2.5

3

3.5

0 1.67 3.33 4.17 5 5.83 6.67 8.33 10

Actual Cl2:N Ratio

mg

/l

Mono + Free Cl2 Total Cl2 Free NH3Total NH3 Calc. Dichloramine

0

0.2

0.4

0.6

0.8

1

1.2

0

0.5

1

1.5

2

2.5

3

3.5

0 1.9 3.9 4.8 5.8 6.7 7.7 8.8

NH

3 m

g/l

Cl2

mg

/l

Actual Cl2:N Ratio

Fixed Cl2 3.0 mg/l Varying NH3

Mono Cl2 Total Cl2DI Cl2 Free NH3Total N

Breakpoint with Fixed Cl2

Chloramination Control StrategiesRatiometric control

Cl2 : NH3-N ratio between 3:1 and 5:1Measures total chlorine from all forms and total ammonia

from all forms (free and combined)Residual control

Maintain small free ammonia residualMaintain target monochloramine

ChemScan Chloramination Analyzer Advantages

Multiple Parameter AnalysisMultiple Sample LineFast Analysis Time Benign Waste StreamNon-Clogging Sample SystemAuto Zeroing and Clean

Benign Reagents

Sodium Hydroxide (NSF Std 60 Certified)

Sodium Hypochlorite (NSF Std 60 Certified)

Sulfuric Acid (NSF Std 60 Certified)

Potassium Iodide (NSF Approved)

Hydrochloric Acid (NSF Std 60 Certified)

Chloramines are Effective DisinfectantsMonochloramine has Least Odor and TasteChloramination can be Difficult to Control

Too little ammonia cause di and trichloramine formation and loss of chlorine residual

Too much ammonia can cause nitrification in reservoirs and distribution system

Effective On-Line Analysis Equipment will Aid in the Control of the Chloramination Process

Summary

Chloramination Installations Toronto, Ontario Airport Road WTP

La Mesa, CA Alvarado WTP Zefferhills, FL Pasco County S.E. WTPHouston, TX Bilma WTPHayward, CA Skywest Pump StationBlacksburg, VA Blacksburg WTPHillsborough, FL Hillsborough WTPOakland, CA East Bay MUDHudson, FL Pasco County Autumn Oaks WTPLADWP, CA Stone Canyon WTPHouston, TX HC Mud286LADWP, CA Santa Ynez WTPBlanton, FL Pasco County Blanton WTPHouston, TX Malcomson Rd. WTPSan Francisco, CA Hecht-Hetchy Sunol WTPLADWP, CA Green Verdego I WTPWashington, DC Dale Carila WTPHouston, TX Heatherlock WTPCoalinga, CA Coalinga WTPHillsborough, FL WTP/Blend StationsFremont, CA Alameda County Water Dist.Elsinore Valley, CA Inland Valley Pump StationLADWP, CA Stone MountainHouston, TX HC Mud52Holiday, FL Pasco County S.W. WTPColncord, CA Contracosta WTPOntario, Canada Union Water Treatment PlantWashington, DC TP WTPPasco County, FL Pasco County WTPInglewood, CA Inglewood WTPLehigh Acres, FL Lehigh Acres WTPHouston, TX Kleinwood WTPArcadia, FL Arcadia WTPMiami, FL Miami Dade WTPWausau, WI Water Works Houston, TX Bridgestone WTPCharlotte Co. FL Burntstore WTPPomona, CA Well 7 & 8Palm Beach Co. FL Palm Beach WTPWest Lake, CA West Lake WTPLouisville, KY Louisville WTPMilwaukee, WI Howard Avenue WTPNewport Richey, FL Pasco County Little Road WTPSignal Hill, CA Signal Hill WTPSt. Joe Beach, FL St. Joe Beach WTPOakland, CA East Bay MUDHouston, TX HC Mud16LADWP, CA Green Verdego III WTPHouston, TX HC Mud191Alameda County, CA Plant and DistributionHouston, TX HC Mud286Charleston, SC Hanahan WTPDallas, TX Harpool WTPManchester, IA Manchester WTPFlorida City, FL FKAALADWP, CA Green Verdego II WTPHillsborough, FL Fawn Ridge WTPHayward Hesperian, CA Hesperian Booster Pump Station WTPHillsborough, FL Lake Park WTPSan Francisco, CA Hecht-Hetchy Pulgas WTPHillsborough, FL Lithia WTPHouston, TX HC Mud200Hillsborough, FL Central WTPLADWP, CA Eagle Rock WTP Dade City, FL Pasco 1LADWP, CA Santa Ynez WTPLehigh, FL Lehigh WTP

ASA Analytics ChloraminationPresentation