CHLORINATION
Chlorination Curve What happens when chlorine is added to water? A chlorination curve will help describe what happens during this process
Chlorination Curve What is a chlorination curve? A graph of the amount of chlorine measured in a solution versus the amount of chlorine added
Chlorination Curve Chlorine Added Chlorine Measured
Chlorination Curve Begin adding chlorine to water Chlorine will first react to exhaust chlorine demand in the system Chlorine added will not be recovered in a chlorine test
Chlorination Curve Chlorine Added Chlorine Measured
Chlorination Curve Continue adding chlorine to the system Once chlorine demand is exhausted, additional chlorine added will be recovered in a chlorine test
Chlorination Curve Chlorine Added Chlorine Measured
Chlorine Testing Chlorine - Free & Total DPD chlorine reagent powder pillows or AccuVacs (EPA approved) Pocket Colorimeter II DR/800 DR/2800 DR/5000
CHLORAMINATION
Chloramines Chloramines are formed when free chlorine reacts with free ammonia present in the water Monochloramine (NH 2 Cl) Dichloramine (NHCl 2 ) Trichloramine (NCl 3 )
Chloramination Curve Chlorine Measured Chlorine Added
Chloramination Curve Begin adding chlorine to a water containing ammonia Initial addition of chlorine reacts to exhaust any chlorine demand present in the water
Chlorination Curve Chlorine Added Chlorine Measured
Chloramination Curve Continue to add chlorine to the water After chlorine demand is exhausted, chlorine reacts with ammonia to form monochloramine HOCl + NH 3 NH 2 Cl + H 2 O
Chlorination Curve Chlorine Measured Chloramination 5:1 Cl 2 :N Ratio I Chlorine Added
Chloramination Curve Continue to add chlorine to the water After complete formation of monochloramine, monochloramine reacts with additional chlorine to form dichloramine and nitrogen trichloride. HOCl + NH 2 Cl NHCl 2 + H 2 O
Chloramination Curve Continue to add chlorine to the water As dichloramine and nitrogen trichloride form, the addition of chlorine continues to oxidize these compounds to nitrogen gases
Chlorination Curve Chlorine Measured Chloramination I 5:1 Cl 2 :N Ratio II Breakpoint 9:1 Cl 2 :N Ratio Chlorine Added
Chloramination Curve Continue to add chlorine to the water After the breakpoint, all chlorine added to the water remains as free chlorine Breakpoint chlorination Cl 2 + H 2 O HOCl + OCl -
Chlorination Curve Chlorine Measured Chloramination I 5:1 Cl 2 :N Ratio II Breakpoint 9:1 Cl 2 :N Ratio Free Chlorination III Chlorine Added
Chloramination Goals Complete formation of monochloramine (stay in section I) 3-5:1 Cl 2 :N optimal feed ratio Avoid dichloramine formation Avoid taste and odor problems Minimize un-reacted ammonia Control biofilm and nitrification
Chloramination Species Chloramination Free Chlorination Chlorine Measured I Total Chlorine Free Ammonia II III Chlorine Added
Chloramination Species Chlorine Measured Chloramination I Total Chlorine Free Ammonia II Monochloramine Free Chlorination III Chlorine Added
Chloramination Species Chlorine Measured Chloramination I Total Chlorine Free Ammonia II Monochloramine Free Chlorination III Free Chlorine Chlorine Added
Chloramination Curve Continue to add chlorine to the water The point at which all dichloramine is converted to nitrogen gas is the breakpoint.
Where Am I When Total Chlorine = 3mg/L? Chloramination Free Chlorination Chlorine Measured I II III Chlorine Added
I Am Here! Chloramination Free Chlorination Chlorine Measured I Mono = Total Cl2 Free Am > 0 II Mono < Total Cl2 Free Am = 0 III Total Cl2 > 0 Mono = 0 Free Am = 0 Chlorine Added
Ammonia/Monochloramine Relationship Measured, mg/l 1.2 1 0.8 0.6 0.4 0.2 t-nh 3 N Results as N NH 2 Cl (N) f-nh 3 N Break-point 0 0 2 4 6 8 10 12 Chlorine Dose, mg/l