Chlorination in Waterworks Operation Waterworks Operations I WQT 111 Chlorination

Chlorination in Waterworks Operation

Chlorination in Waterworks Operation

Waterworks Operations IWQT 111

Chlorination

Waterworks Operations IWQT 111

Chlorination

http://www.c3.org/chlorine_knowledge_center/history.html

http://www.wrb.state.ri.us/programs/eo/historydrinkingwater.htm

http://ewr.cee.vt.edu/environmental/teach/wtprimer/chlorine/chlorine.html

http://web.deu.edu.tr/atiksu/toprak/ani4101.html

Week Objectives Week Objectives

1. Comprehend “the basics” of chlorine chemistry

2. Understand the advantages and disadvantages of chlorine

3. Understand the history of chlorine via a timeline

4. Understand Breakpoint Chlorination Curve

5. Calculate C•T values

1. Comprehend “the basics” of chlorine chemistry

2. Understand the advantages and disadvantages of chlorine

3. Understand the history of chlorine via a timeline

4. Understand Breakpoint Chlorination Curve

5. Calculate C•T values

Reading assignment: Water Treatment , Chapter 7: DisinfectionReading assignment: Water Treatment , Chapter 7: Disinfection

Key WordsKey WordsChlorine Residual- Measurable chlorine remaining after the

demand is satisfied.

Chlorine Demand- The amount of chlorine destroyed by reaction with Fe, Mn, turbidity, organics, and microorganisms in the water.

Free Chlorine Residual- point past breakpoint where

HOCl (hypochlorous acid) and OCL- (hypochlorite ion) form.

25 times more powerful than combined chlorine for disinfection

Combined residual chlorine: chlorine combined with organics or ammonia.

• NH2Cl (monochloramine) and

• NH(Cl)2 (dichloramine)

• N(Cl)3 (nitrogen trichloride)

Chlorine Residual- Measurable chlorine remaining after the demand is satisfied.

Chlorine Demand- The amount of chlorine destroyed by reaction with Fe, Mn, turbidity, organics, and microorganisms in the water.

Free Chlorine Residual- point past breakpoint where

HOCl (hypochlorous acid) and OCL- (hypochlorite ion) form.

25 times more powerful than combined chlorine for disinfection

Combined residual chlorine: chlorine combined with organics or ammonia.

• NH2Cl (monochloramine) and

• NH(Cl)2 (dichloramine)

• N(Cl)3 (nitrogen trichloride)

Key WordsKey WordsBreakpoint chlorination: The point at which near complete

oxidation of nitrogen compounds are reached . Any point beyond breakpoint is mostly free chlorine (HOCL and OCL-)

C•T (concentration and contact time): Effectiveness of chlorination is dependant on chlorine concentration and contact time.

Sterilization: The destruction of all living things in a sample

Disinfection: The removal or inactivation of disease causing (pathogenic) organisms

Chlorine Demand= Chlorine Dose- Chlorine Residual

Breakpoint chlorination: The point at which near complete oxidation of nitrogen compounds are reached . Any point beyond breakpoint is mostly free chlorine (HOCL and OCL-)

C•T (concentration and contact time): Effectiveness of chlorination is dependant on chlorine concentration and contact time.

Sterilization: The destruction of all living things in a sample

Disinfection: The removal or inactivation of disease causing (pathogenic) organisms

Chlorine Demand= Chlorine Dose- Chlorine Residual

The destruction of the larger portion of microorganisms with

the probability that all pathogens are killed is called

The destruction of the larger portion of microorganisms with

the probability that all pathogens are killed is called

Dig

estio

n

Dis

infe

ctio

n

Dilu

tion

Ste

riliz

atio

n

Dis

posal

0%

79%

0%

21%

0%

1. Digestion

2. Disinfection

3. Dilution

4. Sterilization

5. Disposal

1. Digestion

2. Disinfection

3. Dilution

4. Sterilization

5. Disposal

Proper disinfection kills all organisms?

Proper disinfection kills all organisms?

Tru

e

Fal

se

91%

9%

1. True

2. False

1. True

2. False

Chlorine applied minus ____ equals chlorine residual

Chlorine applied minus ____ equals chlorine residual

Chlo

rine

dose

Chlo

rine

dem

an...

Com

bined

chlo

r...

Fre

e ch

lorin

e

Tota

l chlo

rine

6%

88%

6%0%0%

1. Chlorine dose

2. Chlorine demand

3. Combined chlorine

4. Free chlorine

5. Total chlorine

1. Chlorine dose

2. Chlorine demand

3. Combined chlorine

4. Free chlorine

5. Total chlorine

CL2 Demand= Cl2 Dose- Cl2 Residual?CL2 Demand= Cl2 Dose- Cl2 Residual?

Tru

e

Fal

se

7%

93%

1. True

2. False

1. True

2. False

A low chlorine dose w/ longer the contact time can have the same

disinfecting power as a high chlorine dose with a short detention time?

A low chlorine dose w/ longer the contact time can have the same

disinfecting power as a high chlorine dose with a short detention time?

Tru

e

Fal

se

0%

100%

1. True

2. False

1. True

2. False

The amount of chlorine destroyed by reaction with Fe, Mn, turbidity,

organics, and microorganisms in the water?

The amount of chlorine destroyed by reaction with Fe, Mn, turbidity,

organics, and microorganisms in the water?

Fre

e Chlo

rine

Resid

ual

Chlo

rine

Deman

d

Chlo

rine

Resid

ual

11% 6%

83%1. Free Chlorine Residual

2. Chlorine Demand

3. Chlorine Residual

1. Free Chlorine Residual

2. Chlorine Demand


Measurable chlorine remaining after the demand is

satisfied.

Measurable chlorine remaining after the demand is

satisfied.

Chlo

rine

Deman

d

Chlo

rine

Resid

ual

100%

0%

1. Chlorine Demand


1. Chlorine Demand


HOCL?HOCL?

Hyp

ochlo

rous

acid

Hyp

ochlo

rite

ion

Dic

hlora

min

e

89%

0%11%

1. Hypochlorous acid

2. Hypochlorite ion

3. Dichloramine


2. Hypochlorite ion

3. Dichloramine

HOCL?HOCL?

Com

mon a

t pH <

6

Most

power

ful/e

ffect

...

All

of the

above

0%

95%

5%

1. Common at pH < 6

2. Most powerful/effective disinfectant

3. All of the above

1. Common at pH < 6

2. Most powerful/effective disinfectant

3. All of the above

NH2ClNH2Cl

Mono

chlo

ram

ine

Com

bined

Res

idua

l ...

Not a

s ef

fect

ive

as a

...

All

of the

above

6%

89%

6%0%

1. Monochloramine

2. Combined Residual Chlorine

3. Not as effective as a disinfectant as hypochlorus acid

4. All of the above

1. Monochloramine

2. Combined Residual Chlorine

3. Not as effective as a disinfectant as hypochlorus acid

4. All of the above

Sterilization only removes pathogenic organism from a

water sample?

Sterilization only removes pathogenic organism from a

water sample?

Tru

e

Fal

se

100%

0%

1. True

2. False

1. True

2. False

Chlorine AdvantagesChlorine Advantages1.Chlorine provides a strong residual in the

distribution system.

2.Chlorine can be easily converted to chloramines which also provide a strong residual and do not produce by-products.

3.Chlorine is easy to apply. Can use it in liquid, solid, or gas form

4.Chlorine is a relatively inexpensive disinfecting agent.

5.Chlorine is effective at low concentrations.

1.Chlorine provides a strong residual in the distribution system.

2.Chlorine can be easily converted to chloramines which also provide a strong residual and do not produce by-products.

3.Chlorine is easy to apply. Can use it in liquid, solid, or gas form

4.Chlorine is a relatively inexpensive disinfecting agent.

5.Chlorine is effective at low concentrations.

Chlorine DisadvantagesChlorine Disadvantages1.When chlorine reacts with organic material its'

concentration is reduced and trihalomethanes(THM's), haloacetic acids (HAA5), chlorite (when chlorine dioxide is used) and bromate (when ozone is used) are disinfection-by-products (DBP's). These compounds are carcinogenic.

2.Chlorine provides poor Cryptosporidium and Giardia control.

3.Effectiveness varies depending on turbidity, [ammonia], pH, etc.

4.Chlorine is a dangerous and potentially fatal chemical if used improperly

1.When chlorine reacts with organic material its' concentration is reduced and trihalomethanes(THM's), haloacetic acids (HAA5), chlorite (when chlorine dioxide is used) and bromate (when ozone is used) are disinfection-by-products (DBP's). These compounds are carcinogenic.

2.Chlorine provides poor Cryptosporidium and Giardia control.

3.Effectiveness varies depending on turbidity, [ammonia], pH, etc.

4.Chlorine is a dangerous and potentially fatal chemical if used improperly

According to the Stage 1 Disinfectant/Disinfection

Byproducts Rule which of the following are considered

haloacetic acids (HAA5) DPBs disinfectant byproducts?

According to the Stage 1 Disinfectant/Disinfection

Byproducts Rule which of the following are considered

haloacetic acids (HAA5) DPBs disinfectant byproducts?

Mono

chlo

roac

et...

Dic

hloro

acet

ic...

Mono

brom

oacet

i...

All

of the

abo...

0%

92%

4%4%

1. Monochloroacetic acid

2. Dichloroacetic acid

3. Monobromoacetic acid

4. All of the above

1. Monochloroacetic acid

2. Dichloroacetic acid

3. Monobromoacetic acid

4. All of the above

An advantage of chlorine is that it can be a liquid, solid, or a

gas?

An advantage of chlorine is that it can be a liquid, solid, or a

gas?

Tru

e

Fal

se

0%

100%1. True

2. False

1. True

2. False

Chlorine can completely remove Giardia and Cryptosporidium

from water?

Chlorine can completely remove Giardia and Cryptosporidium

from water?

Tru

e

Fal

se

100%

0%

1. True

2. False

1. True

2. False

Chlorine Disinfection TimelineChlorine Disinfection Timeline500 BC- Boiling of water recommended by Hippocrates

1879- Chlorine was applied as a disinfectant for the first time (England).

1893-First time chlorine applied on a plant scale basis (Hamburg, Germany).

1903- First time chlorine gas was used as a disinfectant in drinking water (Middlekerke, Belgium).

1908- The first full scale chlorine installation at a drinking water plant in the United States was initiated in this year.

(Bubbly Creek Filter Plant in Chicago)

500 BC- Boiling of water recommended by Hippocrates

1879- Chlorine was applied as a disinfectant for the first time (England).

1893-First time chlorine applied on a plant scale basis (Hamburg, Germany).

1903- First time chlorine gas was used as a disinfectant in drinking water (Middlekerke, Belgium).

1908- The first full scale chlorine installation at a drinking water plant in the United States was initiated in this year.

(Bubbly Creek Filter Plant in Chicago)

Chlorine Chemistry TimelineChlorine Chemistry Timeline1744- S.W. Scheele, a Swedish chemist, discovers chlorine.

1810-Chlorine was identified as a chemical element by Davey and called Chlorine (chlorous) due to its pale yellow/green color

1909 Liquid chlorine bleach becomes available after the Niagara Starch Co. in NY develops a production method.

1914-Wallace and Tiernan develop chlorine gas feed equipment

1914 CR Cox describes experiments with chlorine that are called “double chlorination” (Discovered breakpoint)

1928 The Olin Corporation begins production of High Test Hypochlorite dubbed “HTH”

1744- S.W. Scheele, a Swedish chemist, discovers chlorine.

1810-Chlorine was identified as a chemical element by Davey and called Chlorine (chlorous) due to its pale yellow/green color

1909 Liquid chlorine bleach becomes available after the Niagara Starch Co. in NY develops a production method.

1914-Wallace and Tiernan develop chlorine gas feed equipment

1914 CR Cox describes experiments with chlorine that are called “double chlorination” (Discovered breakpoint)

1928 The Olin Corporation begins production of High Test Hypochlorite dubbed “HTH”

http://ewr.cee.vt.edu/environmental/teach/wtprimer/chlorine/chlorine.html#History

Chlorination Methods TimelineChlorination Methods Timeline1939- A.E. Griffin explains “Breakpoint Chlorination”1942-Henry Marks invents the amperometric chlorine residual analyzer.

1973-JJ Rook discovers chloroform (trtihalomethane) in drinking water in New Orleans and Corvallis.

1974- the SDWA is passed into law by congress.

1986 -The Surface Water Treatment Rule requires disinfection of all surface water and groundwater under the influence of surface water (GWUISW)

1986- USEPA approves four methods of drinking water disinfection. Disinfection C•T requirements for each disinfectant are established to insure inactivation of Giardia and viruses

-Chlorination, Chloramines, Ozone, UV light

2003- USEPA approves UV disinfection for Crypto

1939- A.E. Griffin explains “Breakpoint Chlorination”1942-Henry Marks invents the amperometric chlorine residual analyzer.

1973-JJ Rook discovers chloroform (trtihalomethane) in drinking water in New Orleans and Corvallis.

1974- the SDWA is passed into law by congress.

1986 -The Surface Water Treatment Rule requires disinfection of all surface water and groundwater under the influence of surface water (GWUISW)

1986- USEPA approves four methods of drinking water disinfection. Disinfection C•T requirements for each disinfectant are established to insure inactivation of Giardia and viruses

-Chlorination, Chloramines, Ozone, UV light

2003- USEPA approves UV disinfection for Crypto

http://ewr.cee.vt.edu/environmental/teach/wtprimer/chlorine/chlorine.html#History

SDWA AmendmentsSDWA AmendmentsDecember 16,1998 promulgatedDisinfection Byproduct Rule (DBPR): Stage 1 DBPR **Stage 2 in the works!**• MCLs for trihalomethanes, haloacetic acids, bromate, and chlorite. • Maximum residual disinfectant level goals (MRDLs) were also finalized for

chlorine, chloramines, and chlorine dioxide.

“Community water systems and non-transient non-community systems, including those serving fewer than 10,000 people, that add a disinfectant to the drinking water during any part of the treatment process.”

MRDLGs for chlorine (4 mg/L), chloramines (4 mg/L), and chlorine dioxide (0.8 mg/L);

• MCLs for total trihalomethanes - a sum of the four listed above (0.080 mg/L), haloacetic acids (HAA5) (0.060 mg/L)- a sum of the two listed above plus monochloroacetic acid and mono- and dibromoacetic acids), and two inorganic disinfection byproducts (chlorite (1.0 mg/L)) and bromate (0.010 mg/L));

December 16,1998 promulgatedDisinfection Byproduct Rule (DBPR): Stage 1 DBPR **Stage 2 in the works!**• MCLs for trihalomethanes, haloacetic acids, bromate, and chlorite. • Maximum residual disinfectant level goals (MRDLs) were also finalized for

chlorine, chloramines, and chlorine dioxide.

“Community water systems and non-transient non-community systems, including those serving fewer than 10,000 people, that add a disinfectant to the drinking water during any part of the treatment process.”

MRDLGs for chlorine (4 mg/L), chloramines (4 mg/L), and chlorine dioxide (0.8 mg/L);

• MCLs for total trihalomethanes - a sum of the four listed above (0.080 mg/L), haloacetic acids (HAA5) (0.060 mg/L)- a sum of the two listed above plus monochloroacetic acid and mono- and dibromoacetic acids), and two inorganic disinfection byproducts (chlorite (1.0 mg/L)) and bromate (0.010 mg/L));

SDWA AmendmentsSDWA Amendments• May 1996- Information Collection Rule (ICR), occurrence data

for DBPs and precursors, microbials, water quality parameters, and treatment plant parameters.

Used to develop the Stage 2 DBPR and the Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR).

• May 1996- Information Collection Rule (ICR), occurrence data for DBPs and precursors, microbials, water quality parameters, and treatment plant parameters.

Used to develop the Stage 2 DBPR and the Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR).

Interim Enhanced Surface Water Treatment Rule -Applies to systems serving 10,000 or more people

Long Term 1 Enhanced Surface Water Treatment Rule -strengthen microbial controls for small systems (i.e., those systems serving fewer than 10,000 people.)

January 2002

SDWA AmendmentsSDWA AmendmentsJanuary 5, 2006 Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR).

All public water systems with surface water or groundwater under the influence of surface water.LT2 rule reduce illness linked with the contaminant Cryptosporidium and other disease-causing microorganisms in drinking water. Targets Cryptosporidium treatment requirements to higher risk systems.

•Targeting additional Cryptosporidium treatment requirements to higher risk systems •Requiring provisions to reduce risks from uncovered finished water storage facilities •Providing provisions to ensure that systems maintain microbial protection as they take steps to reduce the formation of disinfection byproduct

Chlorine was first used as a disinfectant in Europe in the late

1800s?

Chlorine was first used as a disinfectant in Europe in the late

1800s?

Tru

e

Fal

se

0%

100%

1. True

2. False

1. True

2. False

Ozone, UV light, Chlorination, and Chloramines are 4 EPA

approved disinfection methods?

Ozone, UV light, Chlorination, and Chloramines are 4 EPA

approved disinfection methods?

Tru

e

Fal

se

0%

100%1. True

2. False

1. True

2. False

Chlorine (Cl2)Chlorine (Cl2)• Widely distributed element• Most important use is bleach• Toxic, noncombustible, yellow-green gas with a

pungent, irritating odor and strong oxidizing effects• 2.5 times as dense as air!• Slightly soluble in water

– Combines with water to form hypochlorous acid (HOCl) and hydrochloric acid (HCl)

• Highly corrosive causes injury when the gas reacts with moisture in the body

• Widely distributed element• Most important use is bleach• Toxic, noncombustible, yellow-green gas with a

pungent, irritating odor and strong oxidizing effects• 2.5 times as dense as air!• Slightly soluble in water

– Combines with water to form hypochlorous acid (HOCl) and hydrochloric acid (HCl)

• Highly corrosive causes injury when the gas reacts with moisture in the body

Chlorine - ToxicityChlorine - Toxicity

• Major route of toxicity is inhalation

• Solutions that generate chlorine can be highly corrosive to skin or GI tract

• Strong oxidizing capability – Produce major tissue damage

• Major route of toxicity is inhalation

• Solutions that generate chlorine can be highly corrosive to skin or GI tract

• Strong oxidizing capability – Produce major tissue damage

Chlorine - ToxicityChlorine - Toxicity• Hypochlorous acid

– Penetrates cells and react with cytoplasmic proteins, enzymes

– Form N-chloro derivatives that destroy cell structure

– Can alter DNA replication of viruses

• Estimated lowest lethal concentration – 30-min exposure is 430 ppm -- 1000 ppm – Fatal within minutes

• Hypochlorous acid – Penetrates cells and react with

cytoplasmic proteins, enzymes– Form N-chloro derivatives that destroy

cell structure– Can alter DNA replication of viruses

• Estimated lowest lethal concentration – 30-min exposure is 430 ppm -- 1000 ppm – Fatal within minutes

Chlorine is a toxic, corrosive, gas?

Chlorine is a toxic, corrosive, gas?

Tru

e

Fal

se

0%

100%1. True

2. False

1. True

2. False

Which of the following is a correct set of characteristics for chlorine as used in disinfection?

Which of the following is a correct set of characteristics for chlorine as used in disinfection?

Chlo

rine

gas

i...

Chlo

rine

gas

i...

Chlo

rine

gas

i...

Chlo

rine

gas

i...

Chlo

rine

gas

i...

0% 0%

96%

0%4%

1. Chlorine gas is colorless, flammable, and heavier than air

2. Chlorine gas is colorless, flammable, and lighter than air

3. Chlorine gas is greenish-yellow (amber) in color, flammable, and lighter than air

4. Chlorine gas in greenish-yellow (amber) in color, toxic, lighter than air, and noncorrosive

5. Chlorine gas is toxic, corrosive, and heavier than air

1. Chlorine gas is colorless, flammable, and heavier than air

2. Chlorine gas is colorless, flammable, and lighter than air

3. Chlorine gas is greenish-yellow (amber) in color, flammable, and lighter than air

4. Chlorine gas in greenish-yellow (amber) in color, toxic, lighter than air, and noncorrosive

5. Chlorine gas is toxic, corrosive, and heavier than air

Protective EquipmentProtective Equipment

• Variety of rubber and plastic materials resist chlorine

• Wear protective clothing appropriate to the type and degree of contamination

• Use air-purifying or supplied-air respiratory equipment

• Chlorine-resistant plastic sheeting and disposable bags useful in preventing spread of contamination

• Variety of rubber and plastic materials resist chlorine

• Wear protective clothing appropriate to the type and degree of contamination

• Use air-purifying or supplied-air respiratory equipment

• Chlorine-resistant plastic sheeting and disposable bags useful in preventing spread of contamination

Protective EquipmentProtective Equipment

Chlorine ChemistryChlorine Chemistry• Chlorine Atom:

Atomic Number 17Atomic Weight 35.45 g

– Molecular Chlorine: Cl2• Yellow-green gas (above 100 ppm)• Chemical Classification

-"Oxidizer“, "Reactive“

********Two SMCL's apply to chlorine: 4 mg/l for Cl2, and 250mg/l for Cl-**New MCL under consideration

• Chlorine Atom:Atomic Number 17Atomic Weight 35.45 g

– Molecular Chlorine: Cl2• Yellow-green gas (above 100 ppm)• Chemical Classification

-"Oxidizer“, "Reactive“

********Two SMCL's apply to chlorine: 4 mg/l for Cl2, and 250mg/l for Cl-**New MCL under consideration

Chlorine Chemistry PropertiesChlorine Chemistry PropertiesDry liquid: 100% gas• Powder: Calcium Hypochlorite- 30, 65, 70% chlorine• Liquid: Sodium Hypochlorite: 5-15% chlorine

Density = 2.5 times as heavy as air, Irritant• Boiling point -29.9 oF• Freezing point -149.76 oF • 1 part of liquid will produce 450 parts of gas

Maximum solubility: 1% at 49.2 oF• Slightly soluble in water• Temperatures below 49.2 will result in chlorine ice• Insoluble in water at 212oF.

Dry liquid: 100% gas• Powder: Calcium Hypochlorite- 30, 65, 70% chlorine• Liquid: Sodium Hypochlorite: 5-15% chlorine

Density = 2.5 times as heavy as air, Irritant• Boiling point -29.9 oF• Freezing point -149.76 oF • 1 part of liquid will produce 450 parts of gas

Maximum solubility: 1% at 49.2 oF• Slightly soluble in water• Temperatures below 49.2 will result in chlorine ice• Insoluble in water at 212oF.

Where should sodium hypochlorite (liquid bleach) be

stored?

Where should sodium hypochlorite (liquid bleach) be

stored?

Away

from

flam

...

Aw

ay fr

om e

qu...

clo

sed

cont

ai...

Nea

r the

chem

i...

6%0%0%

94%1. Away from flammable objects, as it is a fire hazard

2. Away from equipment that is susceptible to corrosion

3. closed containers at room temperature for no longer than 6 months

4. Near the chemical feed pump day tank, to lessen operator handling risks

1. Away from flammable objects, as it is a fire hazard

2. Away from equipment that is susceptible to corrosion

3. closed containers at room temperature for no longer than 6 months

4. Near the chemical feed pump day tank, to lessen operator handling risks

Chlorine as a powder can have purities of 30, 65, and 70%?

Chlorine as a powder can have purities of 30, 65, and 70%?

Tru

e

Fal

se

11%

89%1. True

2. False

1. True

2. False

Sodium hypochlorite is manufactured by the reaction of gaseous or liquid chlorine with a solution of _________ _________

to produce a liquid containing NaOCl.

Sodium hypochlorite is manufactured by the reaction of gaseous or liquid chlorine with a solution of _________ _________

to produce a liquid containing NaOCl.

Sodiu

m h

ydro

xi...

Pota

ssiu

m h

ydr..

.

Pota

ssiu

m b

isu...

Sodiu

m a

zide

86%

0%0%

14%

1. Sodium hydroxide

2. Potassium hydroxide

3. Potassium bisulfite

4. Sodium azide

1. Sodium hydroxide

2. Potassium hydroxide

3. Potassium bisulfite

4. Sodium azide

Which form of hypochlorite is the most dangerous to handle? Which form of hypochlorite is

the most dangerous to handle?

Sodiu

m

Flu

oride

Cal

cium

Chlo

rine

36%

23%

27%

14%

1. Sodium

2. Fluoride

3. Calcium

4. Chlorine

1. Sodium

2. Fluoride

3. Calcium

4. Chlorine

Chlorine gas is _____ times heavier than air

Chlorine gas is _____ times heavier than air

2.5 2. 3.

51.

5

96%

0%0%4%

1. 2.5

2. 2.0

3. 3.5

4. 1.5

1. 2.5

2. 2.0

3. 3.5

4. 1.5

Chlorine ChemistryChlorine ChemistryWhen Cl combines with water it produces hypochlorous acid (HOCl) and hydrochloric acid (HCl).

Cl2 + H2O HOCl + HCl

When Cl combines with water it produces hypochlorous acid (HOCl) and hydrochloric acid (HCl).

Cl2 + H2O HOCl + HCl

hypochlorous acid and hypochlorite (OCL-) ion vary with pH.

Both HOCl and OCl are good disinfecting agents, but un-ionized hypochlorous acid (HOCl) is 100 times more effective than hypochlorite (OCl-)

HOCL is stable below pH 6

hypochlorous acid and hypochlorite (OCL-) ion vary with pH.

Both HOCl and OCl are good disinfecting agents, but un-ionized hypochlorous acid (HOCl) is 100 times more effective than hypochlorite (OCl-)

HOCL is stable below pH 6


Hypochlorous acid is the most powerful disinfectant associated

with chlorine?

Hypochlorous acid is the most powerful disinfectant associated

with chlorine?

Tru

e

Fal

se

0%

100%1. True

2. False

1. True

2. False

pH Impact on Free ChlorinepH Impact on Free Chlorine


What compound is first formed when chlorine is applied to

water?

What compound is first formed when chlorine is applied to

water?

Hyp

ochlo

rous

a...

Hyd

roch

loric

a...

Chlo

ram

ines

Fre

e ch

lorin

e ...

75%

4%

17%

4%


2. Hydrochloric acid

3. Chloramines

4. Free chlorine ions


2. Hydrochloric acid

3. Chloramines

4. Free chlorine ions

Chlorine will destroy bacteria most rapidly at what pH?

Chlorine will destroy bacteria most rapidly at what pH?

7.5

8.5

9.5

10.5

100%

0%0%0%

1. 7.5

2. 8.5

3. 9.5

4. 10.5

1. 7.5

2. 8.5

3. 9.5

4. 10.5

Chlorine Chemistry in WaterChlorine Chemistry in Water

1. Start with chlorine gas Cl2 + H2O HOCl + HCl

2. If the pH of the water is greater than 8, the hypochlorus acid (HOCl-) will dissociate (break) to yield hypochlorite ion.

HOCl H+ + OCl– @pH>8

3. pH is less than 7, HOCl will not dissociate.

1. Start with chlorine gas Cl2 + H2O HOCl + HCl

2. If the pH of the water is greater than 8, the hypochlorus acid (HOCl-) will dissociate (break) to yield hypochlorite ion.

HOCl H+ + OCl– @pH>8

3. pH is less than 7, HOCl will not dissociate.


HOClHOClHOClHOCl @pH<7@pH<7

Free residual hypochlorous acid (HOCl) is more 1000 times more effective than combined residual monochloramine

Free residual hypochlorous acid (HOCl) is more 1000 times more effective than combined residual monochloramine

Which of the following is true about chlorine chemistry?

Which of the following is true about chlorine chemistry?

pH <

7 fa

vors

hyp

oc...

pH >

8 hyp

ochlo

rite

i...

HOCL is

100

tim

es m

o..

All

of the

above

100%

0%0%0%

1. pH < 7 favors hypochlorous acid

2. pH >8 hypochlorite ions form which can still disinfectant

3. HOCL is 100 times more powerful then OCL-

4. All of the above

1. pH < 7 favors hypochlorous acid

2. pH >8 hypochlorite ions form which can still disinfectant

3. HOCL is 100 times more powerful then OCL-

4. All of the above

HOCL is 1,000 times more powerful then monochloramine?

HOCL is 1,000 times more powerful then monochloramine?

Tru

e

Fal

se

6%

94%

1. True

2. False

1. True

2. False

Basic Chlorine CompoundsBasic Chlorine Compounds

Chlorine Demand: chlorine reacted with – Clay, silt, iron, manganese, bacteria

Combined Chlorine ResidualsChloramines: chlorine reacted with

– Inorganic ammonia compounds (NH3)– Organic nitrogen proteins (amino acids)– Less DBP– Weak against virus and protozoa

Chlorine Demand: chlorine reacted with – Clay, silt, iron, manganese, bacteria

Combined Chlorine ResidualsChloramines: chlorine reacted with

– Inorganic ammonia compounds (NH3)– Organic nitrogen proteins (amino acids)– Less DBP– Weak against virus and protozoa

Chlorine demand is satisfied at the point when

Chlorine demand is satisfied at the point when

The

reac

tion

o...

Fre

e ch

lorin

e ...

An o

dor o

f chl

...

Chlo

rine

reac

h...

96%

0%0%4%

1. The reaction of chlorine with organic and inorganic materials stops

2. Free chlorine residuals reach 2.5 mg/L

3. An odor of chlorine is present

4. Chlorine reaches the last tap

1. The reaction of chlorine with organic and inorganic materials stops

2. Free chlorine residuals reach 2.5 mg/L

3. An odor of chlorine is present

4. Chlorine reaches the last tap

Cl:NH3 and pH Impact in WaterCl:NH3 and pH Impact in Water


1. If ammonia (NH3) is present in water, the hypochlorus acid (HOCL) will react to form one kind of chloramine depending on the pH, temperature, and reaction time.

1. If ammonia (NH3) is present in water, the hypochlorus acid (HOCL) will react to form one kind of chloramine depending on the pH, temperature, and reaction time.

2. Monochloramine and dichloramine are formed at pH 4.5 - 8.5

3. Monochloramine is most common @pH>7.5; Cl2:NH3 <5:1

4. pH 4-5-7.5, Cl:NH3 > 5:1 -Monochloramine converts to dichloramines

5. pH < 4.5, Cl2:NH3 ~15:1 -Trichloramine which produces a very foul odor.

2. Monochloramine and dichloramine are formed at pH 4.5 - 8.5

3. Monochloramine is most common @pH>7.5; Cl2:NH3 <5:1

4. pH 4-5-7.5, Cl:NH3 > 5:1 -Monochloramine converts to dichloramines

5. pH < 4.5, Cl2:NH3 ~15:1 -Trichloramine which produces a very foul odor.

Chlorine-Ammonia (chloramines)Chlorine-Ammonia (chloramines)


1. Rates of formation of mono and dichloramine.2. pH3. Temperature4. Time5. Cl:NH3 ratio

Fact: High Cl:NH3 ratio, low temp & pH favor dichloramine

Combined Available Chlorine- chlorine existing in the water in chemical combination with ammonia-nitrogen or organic nitrogen

1. Rates of formation of mono and dichloramine.2. pH3. Temperature4. Time5. Cl:NH3 ratio

Fact: High Cl:NH3 ratio, low temp & pH favor dichloramine

Combined Available Chlorine- chlorine existing in the water in chemical combination with ammonia-nitrogen or organic nitrogen

Chlorine- Ammonia reactions are governed by:Chlorine- Ammonia reactions are governed by:

Chloramines in WaterChloramines in Water


3. pH 4.5-8.5; pH 8.0-8.5 Monochloramine: NH3 + HOCl NH2Cl + H2O

2. pH 4.5-8.5; pH 4.5-8.0 Dichloramine: NH2Cl + 2HOCl NHCl2 + 2H2O

4. pH <4.5Trichloramine: NHCl2 + 3HOCl NHCl3 + 3H2O

3. pH 4.5-8.5; pH 8.0-8.5 Monochloramine: NH3 + HOCl NH2Cl + H2O

2. pH 4.5-8.5; pH 4.5-8.0 Dichloramine: NH2Cl + 2HOCl NHCl2 + 2H2O

4. pH <4.5Trichloramine: NHCl2 + 3HOCl NHCl3 + 3H2O

•Chloramines are an effective disinfectant against bacteria but not against viruses.

•Add more chlorine to the wastewater to prevent the formation of chloramines and form stronger disinfectants.

•Chloramines are an effective disinfectant against bacteria but not against viruses.

•Add more chlorine to the wastewater to prevent the formation of chloramines and form stronger disinfectants.

ChloraminesChloramines

Add the Extra Free Chlorine (HOCL)

Add the Extra Free Chlorine (HOCL)


5. Additional free chlorine (HOCL or OCL-) reacts with chloramine to produce hydrogen ion, water , and nitrogen gas which will come out of solution.

In the case of the monochloramine, the following reaction occurs:

2NH2Cl + HOCl N2 + 6HCl + H2O

Added free chlorine reduces the concentration of chloramines in the disinfection process. Instead the chlorine that is added is allowed to form the stronger disinfectant, hypochlorus acid.

5. Additional free chlorine (HOCL or OCL-) reacts with chloramine to produce hydrogen ion, water , and nitrogen gas which will come out of solution.

In the case of the monochloramine, the following reaction occurs:

2NH2Cl + HOCl N2 + 6HCl + H2O

Added free chlorine reduces the concentration of chloramines in the disinfection process. Instead the chlorine that is added is allowed to form the stronger disinfectant, hypochlorus acid.

If abundant (15 times) Cl is around and the pH < 4.5

Trichloramine is the most likely chloramine to form?

If abundant (15 times) Cl is around and the pH < 4.5

Trichloramine is the most likely chloramine to form?

Tru

e

Fal

se

10%

90%1. True

2. False

1. True

2. False

Which of the following impact chloramine disinfection?

Which of the following impact chloramine disinfection?

pH

Tem

perat

ure

Tim

e

All

of the

above

0%

100%

0%0%

1. pH

2. Temperature

3. Time

4. All of the above

1. pH

2. Temperature

3. Time

4. All of the above

Ammonium nitrogen and chlorine

Ammonium nitrogen and chlorine

Taste and Odor ProblemsTaste and Odor Problems

• Free (HOCL) 20 mg/L

• Monochloramine 5 mg/L

• Dichloramine .8 mg/L

• Trichloramine .02 mg/L

• Free (HOCL) 20 mg/L

• Monochloramine 5 mg/L

• Dichloramine .8 mg/L

• Trichloramine .02 mg/L

Chlorine Chemistry SummaryChlorine Chemistry SummaryCl2 + H2O HCl + HOClChlorine Hydrochloric Hypochlorous

Ca(OCl)2 (aqueous) Ca2+ +2 OCl-

Calcium Hypochlorite Hypochlorite

NaOCl2 (aqueous) Na+ + OCl-

Sodium Hypochlorite Hypochlorite

HOCl H+ + OCl-

Hypochlorous Hypochlorite

HOCl + NH3 NH2Cl + H2OHypochlorous Ammonia Chloramine

Cl2 + H2O HCl + HOClChlorine Hydrochloric Hypochlorous

Ca(OCl)2 (aqueous) Ca2+ +2 OCl-

Calcium Hypochlorite Hypochlorite

NaOCl2 (aqueous) Na+ + OCl-

Sodium Hypochlorite Hypochlorite

HOCl H+ + OCl-

Hypochlorous Hypochlorite

HOCl + NH3 NH2Cl + H2OHypochlorous Ammonia Chloramine

Chlorine Residual AnalysisChlorine Residual Analysis• Starch Iodide Titration: common in wastewater

• Amperometric Titration: common in wastewater with cloudy or turbidity problems

• DPD colorometric- common in water and wastewater. Measures free residual or combined residual.

• Starch Iodide Titration: common in wastewater

• Amperometric Titration: common in wastewater with cloudy or turbidity problems

• DPD colorometric- common in water and wastewater. Measures free residual or combined residual.

Chlorine residual may be determined using the reagent:

Chlorine residual may be determined using the reagent:

Die

thyl

-p-p

hen...

Eth

ylen

e dia

mi..

.

Poly

chlo

rinat

e...

Sodiu

m th

iosu

l...

100%

0%0%0%

1. Diethyl-p-phenylene diamine

2. Ethylene diamine tetraacetic acid

3. Polychlorinated biphenyls

4. Sodium thiosulfate

1. Diethyl-p-phenylene diamine

2. Ethylene diamine tetraacetic acid

3. Polychlorinated biphenyls

4. Sodium thiosulfate

Which of the following methods is not used to determine chlorine

residual?

Which of the following methods is not used to determine chlorine

residual?

Photo

met

ric

Iodo

met

ric

Titr

imet

ric

Am

perom

etric

70%

25%

5%0%

1. Photometric

2. Iodometric

3. Titrimetric

4. Amperometric

1. Photometric

2. Iodometric

3. Titrimetric

4. Amperometric

A chlorine demand test will show the:

A chlorine demand test will show the:

Saf

e am

ount o

f...

Num

ber o

f lbs

...

Am

ount of c

hlo...

Am

ount of c

hlo...

0% 0%

100%

0%

1. Safe amount of chlorine that may be fed without killing people

2. Number of lbs required to kill 100% of coliforms

3. Amount of chlorine required to give a desired residual after a given time

4. Amount of chlorine required to satisfy the biochemical oxygen demand

1. Safe amount of chlorine that may be fed without killing people

2. Number of lbs required to kill 100% of coliforms

3. Amount of chlorine required to give a desired residual after a given time

4. Amount of chlorine required to satisfy the biochemical oxygen demand

Breakpoint ChlorinationBreakpoint ChlorinationBreakpoint chlorination: The point at which near complete oxidation of nitrogen

compounds are reached . Any point beyond breakpoint is mostly free chlorine (HOCL and OCL-)

A. Amount of chlorine required

Theory: 7.6 to 15 times the ammonia nitrogen content of the water

Practice: up to 25 times the ammonia nitrogen content

B. Beyond breakpoint

90% free residual chlorine (HOCL and OCL-)

10% combined chlorine

C. Why must breakpoint chlorination be reached?• Necessary for the production of free residual chlorine (HOCL and OCL -)• Reduces taste and odors• Reduces chloramines

Breakpoint chlorination: The point at which near complete oxidation of nitrogen compounds are reached . Any point beyond breakpoint is mostly free chlorine (HOCL and OCL-)

A. Amount of chlorine required

Theory: 7.6 to 15 times the ammonia nitrogen content of the water

Practice: up to 25 times the ammonia nitrogen content

B. Beyond breakpoint

90% free residual chlorine (HOCL and OCL-)

10% combined chlorine

C. Why must breakpoint chlorination be reached?• Necessary for the production of free residual chlorine (HOCL and OCL -)• Reduces taste and odors• Reduces chloramines

What is the process of adding chlorine to water until the chlorine demand has been

satisfied called?

What is the process of adding chlorine to water until the chlorine demand has been

satisfied called?

Conta

ct ti

me

Rel

ique

fact

ion

Hyp

ochlo

rinat

i...

Bre

akpoi

nt chl..

.

0%

100%

0%0%

1. Contact time

2. Reliquefaction

3. Hypochlorination

4. Breakpoint chlorination

1. Contact time

2. Reliquefaction

3. Hypochlorination

4. Breakpoint chlorination

Breakpoint ChlorinationBreakpoint ChlorinationZone I: Chlorine is destroyed by reducing agents such as iron,

manganese, clay and silt. Chlorine reduced to chloride

Zone II: Chlorine comes into contact with organics and ammonia. Chloroorganics and chloramines are formed.

Zone III: Chloroorganics and chloramines are partially destroyed. Chloramines are broken down and converted to nitrogen gas which leaves the system

Zone IV: Breakpoint. Beyond this point, free available residual is formed. Some chloroorganics still remain as combined residual.

Chlorine demand is difference between applied chlorine and the free chlorine residual at any two points on the breakpoint curve.

Zone I: Chlorine is destroyed by reducing agents such as iron, manganese, clay and silt. Chlorine reduced to chloride

Zone II: Chlorine comes into contact with organics and ammonia. Chloroorganics and chloramines are formed.

Zone III: Chloroorganics and chloramines are partially destroyed. Chloramines are broken down and converted to nitrogen gas which leaves the system

Zone IV: Breakpoint. Beyond this point, free available residual is formed. Some chloroorganics still remain as combined residual.

Chlorine demand is difference between applied chlorine and the free chlorine residual at any two points on the breakpoint curve.

In Zone 1 most of the chlorine dose gets used by chlorine

demand ?

In Zone 1 most of the chlorine dose gets used by chlorine

demand ?

Tru

e

Fal

se

0%

100%1. True

2. False

1. True

2. False

In Zone II chlorine reacts with ammonia to form combined

chlorine ?

In Zone II chlorine reacts with ammonia to form combined

chlorine ?

Tru

e

Fal

se

22%

78%1. True

2. False

1. True

2. False

In Zone III some combined chlorine gets broken down to

nitrogen gas ?

In Zone III some combined chlorine gets broken down to

nitrogen gas ?

Tru

e

Fal

se

0%

100%1. True

2. False

1. True

2. False

At Breakpoint chlorine added becomes free available chlorine?

At Breakpoint chlorine added becomes free available chlorine?

Tru

e

Fal

se

0%

100%1. True

2. False

1. True

2. False

Disinfection with chlorine may cause the formation of these

compounds. They are a result of chlorine binding to naturally

occurring organic matter.

Disinfection with chlorine may cause the formation of these

compounds. They are a result of chlorine binding to naturally

occurring organic matter.

Trih

alom

ethan

e...

Tric

hlora

min

es

CFCs

Chlo

roal

kali

s...

54%

0%0%

46%

1. Trihalomethanes

2. Trichloramines

3. CFCs

4. Chloroalkali salts

1. Trihalomethanes

2. Trichloramines

3. CFCs

4. Chloroalkali salts

DPB (TRIHALOMETHANES)DPB (TRIHALOMETHANES)• THM: Carcinogenic byproduct of a reaction with chlorine. Form when

free chlorine comes into contact with organic compounds. ID by EPA in 1974.

A. Four most common THMs MCLS• Chloroform 0 mg/L• Bromodichloromethane 0 mg/L• Dibromochloromethane 0.06 mg/L• Bromoform 0 mg/L

C. DPB• Trihalomethanes, haloacetonitriles, chlorinated acetic acids,

chlorophenolds,

• THM: Carcinogenic byproduct of a reaction with chlorine. Form when free chlorine comes into contact with organic compounds. ID by EPA in 1974.

A. Four most common THMs MCLS• Chloroform 0 mg/L• Bromodichloromethane 0 mg/L• Dibromochloromethane 0.06 mg/L• Bromoform 0 mg/L

C. DPB• Trihalomethanes, haloacetonitriles, chlorinated acetic acids,

chlorophenolds,

Bromoform is a type of trihalomethane?

Bromoform is a type of trihalomethane?

Tru

e

Fal

se

0%

100%1. True

2. False

1. True

2. False

TRIHALOMETHANESTRIHALOMETHANES

•Chloroform•Bromodichloromethane•Bromoform

•MCL=0.08 mg/L

•Chloroform•Bromodichloromethane•Bromoform

•MCL=0.08 mg/L CC

XX

XX

XX

HH

X= Cl, Br, or I X= Cl, Br, or I

HCX3HCX3

DPB (TRIHALOMETHANES)DPB (TRIHALOMETHANES)D. Water treatment processes that can be used to control THMs.• Aeration• Feed oxidation chemicals instead of pre chlorination • Coagulation, flocculation, sedimentation, and filtration• Water softening processes (Ion exchange)• Powdered activated carbon.

E. Substitute Oxidants for Pre-chlorinations

• Ozone O3 Potassium permangante KMnO4

• Hydrogen peroxide H2O2 hypochlorous acid HOCl

• Hypobromous Acid HOBr Bromine Br

• Hypoiodous acid HOIChlorine Dioxide ClO2

• Iodine I2 Oxygen O2

D. Water treatment processes that can be used to control THMs.• Aeration• Feed oxidation chemicals instead of pre chlorination • Coagulation, flocculation, sedimentation, and filtration• Water softening processes (Ion exchange)• Powdered activated carbon.

E. Substitute Oxidants for Pre-chlorinations

• Ozone O3 Potassium permangante KMnO4

• Hydrogen peroxide H2O2 hypochlorous acid HOCl

• Hypobromous Acid HOBr Bromine Br

• Hypoiodous acid HOIChlorine Dioxide ClO2

• Iodine I2 Oxygen O2

You can aerate or add oxygen to water before chlorination to cut

THMS?

You can aerate or add oxygen to water before chlorination to cut

THMS?

Tru

e

Fal

se

6%

94%

1. True

2. False

1. True

2. False

Chlorine EffectivenessChlorine EffectivenessThese are all important:

1.pH

2.Temperature

3.Chlorine Demand:

4.suspended solids/nitrite/organics/

reduced chemicals

5. Contact time

6. Concentration

7. Mixing Intensity

8. Type of residual

These are all important:

1.pH

2.Temperature

3.Chlorine Demand:

4.suspended solids/nitrite/organics/

reduced chemicals

5. Contact time

6. Concentration

7. Mixing Intensity

8. Type of residual

Chlorine EffectivenessChlorine Effectiveness1. pH (low pH =better disinfection) • want pH < 7.5=more hypochlorus acid

2. Temperature (warm temp=better disinfect)• chlorine disinfection power doubles every 10 degrees.

3. Chlorine Demand (Low Chlorine demand=better disinfect)

• Fe+3, Mn+4, HS and turbidity cause chlorine demand

4. Suspended solids/nitrite/organics/

reduced chemicals

1. pH (low pH =better disinfection) • want pH < 7.5=more hypochlorus acid

2. Temperature (warm temp=better disinfect)• chlorine disinfection power doubles every 10 degrees.

3. Chlorine Demand (Low Chlorine demand=better disinfect)

• Fe+3, Mn+4, HS and turbidity cause chlorine demand

4. Suspended solids/nitrite/organics/

reduced chemicals

As water temperatures decrease, the disinfecting action of

chlorine

As water temperatures decrease, the disinfecting action of

chlorine

Dec

reas

es

Incr

ease

s

Rem

ains

the

sam

e

94%

0%6%

1. Decreases

2. Increases

3. Remains the same

1. Decreases

2. Increases

3. Remains the same

In the application of chlorine for disinfection, which of the

following is not normally an operational consideration?

In the application of chlorine for disinfection, which of the

following is not normally an operational consideration?

Mix

ing

Conta

ct ti

me

Dis

solv

ed o

xyg...

pH

None

of the

se ..

.

14%

0%

32%

0%

55%

1. Mixing

2. Contact time

3. Dissolved oxygen

4. pH

5. None of these answers are correct

1. Mixing

2. Contact time

3. Dissolved oxygen

4. pH

5. None of these answers are correct

pH > 8 favors hypochlorite ion which is a more powerful

disinfectant than hypochlorous acid?

pH > 8 favors hypochlorite ion which is a more powerful

disinfectant than hypochlorous acid?

Tru

e

Fal

se

93%

7%

1. True

2. False

1. True

2. False

Chlorine disinfection power doubles every 10 degrees?Chlorine disinfection power doubles every 10 degrees?

Tru

e

Fal

se

7%

93%

1. True

2. False

1. True

2. False

Low chlorine demand is better for disinfection?

Low chlorine demand is better for disinfection?

Tru

e

Fal

se

0%

100%1. True

2. False

1. True

2. False

Chlorine EffectivenessChlorine Effectiveness5. Contact time (longer contact = better disinfection)• Varies depending on tank dimensions

6. Concentration (higher concentration=better disinfection)• OPTIMIZE THE DISINFECTION PROCESS

7. Mixing Intensity (Rapid Mixing=better disinfection)• Rapidly disperse chlorine better kill rate

8. Disinfection CT (higher actual CT=better disinfection)• As disinfection CT increases by 50, effective kill

increases 10 times (EPA set guidelines)

5. Contact time (longer contact = better disinfection)• Varies depending on tank dimensions

6. Concentration (higher concentration=better disinfection)• OPTIMIZE THE DISINFECTION PROCESS

7. Mixing Intensity (Rapid Mixing=better disinfection)• Rapidly disperse chlorine better kill rate

8. Disinfection CT (higher actual CT=better disinfection)• As disinfection CT increases by 50, effective kill

increases 10 times (EPA set guidelines)

Longer contact time is better for disinfection?

Longer contact time is better for disinfection?

Tru

e

Fal

se

0%

100%1. True

2. False

1. True

2. False

In general high dose concentrations = better

disinfection?

In general high dose concentrations = better

disinfection?

Tru

e

Fal

se

13%

87%1. True

2. False

1. True

2. False

Slow mixing favors better disinfection?

Slow mixing favors better disinfection?

Tru

e

Fal

se

85%

15%

1. True

2. False

1. True

2. False

SDWASDWA

99.9% removal of Giardia Lamblia cysts

99.99% removal of Enteric Viruses

Disinfection CTs have been established

Free chlorine

Chloramine

Chlorine dioxide

Ozone

99.9% removal of Giardia Lamblia cysts

99.99% removal of Enteric Viruses

Disinfection CTs have been established

Free chlorine

Chloramine

Chlorine dioxide

Ozone

LogLogUnderstanding “log removal” requirements of the Long Term 1 Enhanced Surface Water Treatment RuleFirst a definition and some examples:Logarithm10: The exponent of the power to which 10 must be raised to equal a given number.

Examples:• 102 is equal to 100, the log10 of 100 is 2• 103 is equal to 1000, the log10 of 1000 is 3• 102.65 is equal to 446.7, the log10 of 446.7 is 2.65

Log inactivation: A simplified method for expressing the degreeto which microorganisms are removed from water. The removalpercentage is expressed as the log to the base 10.

Examples:If 100 Giardia cysts are inactivated so that only 1 remains, what is the percent removal of the microorganism?(100 - 1) x 100 = 99% or 2 log inactivation100

Understanding “log removal” requirements of the Long Term 1 Enhanced Surface Water Treatment RuleFirst a definition and some examples:Logarithm10: The exponent of the power to which 10 must be raised to equal a given number.

Examples:• 102 is equal to 100, the log10 of 100 is 2• 103 is equal to 1000, the log10 of 1000 is 3• 102.65 is equal to 446.7, the log10 of 446.7 is 2.65

Log inactivation: A simplified method for expressing the degreeto which microorganisms are removed from water. The removalpercentage is expressed as the log to the base 10.

Examples:If 100 Giardia cysts are inactivated so that only 1 remains, what is the percent removal of the microorganism?(100 - 1) x 100 = 99% or 2 log inactivation100

Inactivation of Waterborne Pathogens By DisinfectionThe EPA has approved 4 chemical oxidizers for drinking

water

Disinfection:1. Free Chlorine, (HOCl and OCl-)2. Chloramine, (NH2Cl)3. Chlorine dioxide, (ClO2)4. Ozone (O3)

Each of these disinfectants has a proven capability to kill orinactivate waterborne pathogens, including viruses and

protozoa cysts. The disinfection power of these chemicals is dramatically different.

Inactivation of Waterborne Pathogens By DisinfectionThe EPA has approved 4 chemical oxidizers for drinking

water

Disinfection:1. Free Chlorine, (HOCl and OCl-)2. Chloramine, (NH2Cl)3. Chlorine dioxide, (ClO2)4. Ozone (O3)

Each of these disinfectants has a proven capability to kill orinactivate waterborne pathogens, including viruses and

protozoa cysts. The disinfection power of these chemicals is dramatically different. Disinfection C•TDisinfection C•T

EPA APPROVED METHODSEPA APPROVED METHODS

Four EPA Approved disinfectant chemicals are Free Chlorine, (HOCl and OCl-)

Chloramine, (NH2Cl)Chlorine dioxide, (ClO2)

Ozone (O3)?

Four EPA Approved disinfectant chemicals are Free Chlorine, (HOCl and OCl-)

Chloramine, (NH2Cl)Chlorine dioxide, (ClO2)

Ozone (O3)?

Tru

e

Fal

se

0%

100%

1. True

2. False

1. True

2. False

Disinfection C•T Requirements Disinfection C•T Requirements

Chlorine residual concentrations (mg/L)

Contact Time (min)

Water Temperature

Water pH

Disinfection power= [residual chlorine] • time of its contact

Chlorine residual concentrations (mg/L)

Contact Time (min)

Water Temperature

Water pH

Disinfection power= [residual chlorine] • time of its contact

Disinfection C•T CalculationDisinfection C•T CalculationC•T= [disinfection concentration mg/L] • contact time (min)

C•T units= mg/L• min or mg •min/L

Required C•TCTrequired is # established by EPA to provide log inactivation. Based on Giardia

cysts. Look up in charts

Actual C•TCTactual is # established by multiplying actual chlorine residual by hydraulic

detention time and baffle factor.

C•T= [disinfection concentration mg/L] • contact time (min)

C•T units= mg/L• min or mg •min/L

Required C•TCTrequired is # established by EPA to provide log inactivation. Based on Giardia

cysts. Look up in charts

Actual C•TCTactual is # established by multiplying actual chlorine residual by hydraulic

detention time and baffle factor.

Disinfection C•T CalculationDisinfection C•T Calculation

C•T actual =[Residual chlorine]•hydraulic detention time•baffle factor (table)

Hydraulic detention time = volume/flow rate

C•Tact/ CTreq= ratio must be > or = to 1.

C•Tact/ CTreq>1.0

C•T actual =[Residual chlorine]•hydraulic detention time•baffle factor (table)

Hydraulic detention time = volume/flow rate

C•Tact/ CTreq= ratio must be > or = to 1.

C•Tact/ CTreq>1.0

Disinfection C•T RulesDisinfection C•T Rules1.Chlorine residuals used for C•T

calculations are measured after contact, but before first customer.

2. Contact times are determined by calculating the hydraulic detention time (HDT) as water flows through pipes and tanks. Based on highest flow of day.

1.Chlorine residuals used for C•T calculations are measured after contact, but before first customer.

2. Contact times are determined by calculating the hydraulic detention time (HDT) as water flows through pipes and tanks. Based on highest flow of day.

Disinfection C•T RulesDisinfection C•T Rules

3. Water flowing through pipes provides contact times that are equal to the calculated HDT. Circular or rectangular tanks used for contact time are given only partial credit due to short circuiting.

3. Water flowing through pipes provides contact times that are equal to the calculated HDT. Circular or rectangular tanks used for contact time are given only partial credit due to short circuiting.

The objective stated in the syllabus to have an overview of chlorine

chemistry and the chlorination process, were met ?

The objective stated in the syllabus to have an overview of chlorine

chemistry and the chlorination process, were met ?

Stro

ngly A

gree

Agre

e

Dis

agre

e

Stro

ngly D

isag

ree

0% 0%0%0%

1. Strongly Agree

2. Agree

3. Disagree

4. Strongly Disagree

1. Strongly Agree

2. Agree

3. Disagree

4. Strongly Disagree

Documents

Chlorination in Waterworks Operation Waterworks Operations I WQT 111 Chlorination