Coagulation & Flocculation Which of the following chemical compounds is most commonly used as a primary coagulant in a conventional water treatment plant? A. Al2(SO4)3 ≅ 14H2O (Aluminum Sulfate) B. FeSO4 ≅ 7H2O (Ferrous Sulfate) C. Fe(SO4)3 ≅ 9H2O (Ferric Sulfate) D. FeCl3 ≅ 6H2O (Ferric Chloride)

A. Al2(SO4)3 ≅ 14H2O (Aluminum Sulfate)

C1 Ops & Maint - B. Coagulation & Flocculation Flashcards by Steven Jensen

Coagulation & Flocculation

Which of the following chemical compounds is most commonly used as a primary coagulant in a conventional water treatment plant?

A. Al₂(SO₄)₃ ≅ 14H₂O (Aluminum Sulfate)

B. FeSO₄ ≅ 7H₂O (Ferrous Sulfate)

C. Fe(SO₄)₃≅ 9H₂O (Ferric Sulfate)

D. FeCl₃ ≅ 6H₂O (Ferric Chloride)

A. Al₂(SO₄)₃≅ 14H₂O (Aluminum Sulfate)

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Coagulation & Flocculation

When using alum, what is the preferred pH range for coagulation?

A. 2.5 - 6.0

B. 7.5 - 12.5

C. 6.0 - 7.5

D. 8.0 - 12.0

C. 6.0 - 7.5

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Coagulation & Flocculation

When alum is added to water, a chemical reaction occurs in which dissolved sulfate _________, alkalinity _________, and pH ________.

A. increases, increases, increases

B. increases. decreases, decreases

C. decreases, decreases, decreases

D. explodes, turns laterally, sinks

B. increases. decreases, decreases

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Coagulation & Flocculation

Particles in water usually carry a negative electrical charge. In water treatment, this natural repelling electrical force is called ____ _________. The force is strong enough hold the very small, colloidal perticles apart and keep them in suspension.

A. Zeta Potential

B. Oxidation

C. Chlorination

D. van der waal

A. Zeta Potential

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Coagulation & Flocculation

What is the opposide of Zeta Potential?

van der waal

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Coagulation & Flocculation

What is the primary purpose of flash mixing?

A. To rapidly mix and distribute coagulant chemicals.

B. To cause particles in water to agglomerate together.

C. To vaporize organic compounds into smaller molecules.

D. The cause a chemical reaction in which a compound is converted into another compound.

A. To rapidly mix and distribute coagulant chemicals.

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Coagulation & Flocculation

Which of the following will affect the coagulation/flocculation process?

A. Type of coagulent, THM’s, pH, amount of coagulant used.

B. Raw water quality, hardness, zeta potential, temperature.

C. Amount of coagulant used, type and length of flash mixing, type and length of flocculation, type of coagulant used.

D. Reservoir level, other chemicals used, alkalinity, pH and color.

C. Amount of coagulant used, type and length of flash mixing, type and length of flocculation, type of coagulant used.

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Coagulation & Flocculation

Coagulation is a physical and chemical reaction that occurs between the coagulant added and the __________ of the water.

A. Turbidity

B. Residual

C. Alkalinity

D. Both A & C

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Coagulation & Flocculation

What laboratory test is performed to indicate the optimum chemical dosage for coagulation?

A. DPD Test

B. Jar Test

C. Marble Test

D. DO Test

B. Jar Test

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Coagulation & Flocculation

Even though flash mixing cannot be directly observed, which of the following is an indicator of inadequate mixing?

A. Fish eyes

B. Very small floc

C. Frequent backwashing

D. All of the above

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Coagulation & Flocculation

Floc that remains suspended longer than __ to __ _______ in a jar test will probably not settle out in the sedimentation basin, and will increase the load of the filter.

A. 5 to 10 seconds

B. 1 to 2 minutes

C. 15 to 20 minutes

D. 5 to 10 hours

C. 15 to 20 minutes

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Coagulation & Flocculation

What is flocculation?

A. The slow stirring process that caused the gathering together of small particles into larger particles.

B. The destabilization process where charges on particles are neutralized and become separated from each other.

C. A treatment process where a tank is filled and a chemical solution is prepared.

D. A process in which solid particles settle out of solution to the bottom of the basin.

A. The slow stirring process that caused the gathering together of small particles into larger particles.

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Coagulation & Flocculation

What is the most important consideration for controlling the coagulaiton and flocculation process?

A. pH adjusment.

B. Selection of the type and amount of coagulant chemical to be applied.

C. Good recordkeeping to comply with drinking water regulation.

D. Visual observations of the flocculation and sedimentation process.

B. Selection of the type and amount of coagulant chemical to be applied.

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Coagulation & Flocculation

Which of the following are common laboratory tests used to monitor the coagulation and flocculation process?

A. Chlorine demand

B. pH

C. Alkalinity

D. Temperature

E. Turbidity

F. All of the above

E. Turbidity (Primary Answer)

F. All of the above

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Coagulation & Flocculation

Why do treatment plants need to monitor for pH and tribidity?

A. To calculate the removal rate of trihalomethanes.

B. To know when the Langlier index needs adjusting.

C. To calculate filter loading rates.

D. Changes in raw water quality.

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Coagulation & Flocculation

Which chemical compound is used to increase the alkalinity and pH i n water treatment to improve the coagulation process?

A. Lime

B. Alum

C, Potassium permaganate

D. Calicium oxide

A. Lime

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Coagulation & Flocculation

What is a coagulant aid?

A. A chemical used to improve the performance of a coagulant.

B. A chemical that will boost the molecular density of a coagulant.

C. A chemical used to fight infection in a coagulant.

D A chemical that will determine the amount of coagulant to use.

A. A chemical used to improve the performance of a coagulant.

Coagulation & Flocculation

Which of the following chemicals is NOT commonly used to raise the alkalinity of water and thereby improve coagulation?

A. Lime

B. Soda ash

C. Caustic soda

D. Polymer

Coagulation & Flocculation

The turbidity of your raw water changes from 50 to 300 NTU’s.

What step should you take?

A. Increase the detention time

B. Increase alum feed rate

C. Increase filter run length time

D. Increase chlorination

B. Increase alum feed rate

Coagulation & Flocculation

TRUE or FALSE

The colder the water the faster chemicals will react.

FALSE

Coagulation & Flocculation

TRUE or FALSE

Temperture, pH, alkalinity and turbidity all have an effect on the coagulation process.

TRUE

Coagulation & Flocculation

TRUE or FALSE

The amount of chemical used during the coagulation process in a conventional water treatment filtration plant has not effect on the filtration process.

FALSE

Coagulation & Flocculation

TRUE or FALSE

Coagulation and flocculation may remove materials causing tastes and odors from water by adsorption and/or trapping of materials within the floc.

TRUE

Coagulation & Flocculation

TRUE or FALSE

One of the most important advantages of ferric chloride (iron salts), over alum is that iron salts will coagulate over a broader pH range.

FALSE

# Coagulation & Flocculation TRUE or FALSE Polyelectrolytes (compounds with long-chain molecules) are used effectively as coagulants, coagulant aids and filter aids.

TRUE

# Coagulation & Flocculation Of the three-polyelectrolyte classifications, which one produces positively charged ions? ## Footnote A. Anionic B. Cationic C. Nonionic D. Floc

B. Cationic

# Coagulation & Flocculation Which polyeletrolyte produces a negatively charged ion? ## Footnote A. Anionic B. Cationic C. Nonionic D. Floc

A. Anionic

# Coagulation & Flocculation Which of the following chemicals, if added at higher rates than needed or over dosed, would most likely increase the headloss on a filter? ## Footnote A. Anionic polymer B. Chorline dioxide C. Caustic soda D. Potassium permanganate

A. Anionic polymer

# Coagulation & Flocculation Duraing coagulation/flocculation process, floc that is too small may be caused by: ## Footnote A. High turbidity B. Low flow conditions C. Improper coagulation dosage D. High levels of organice material

C. Improper coagulation dosage

# Coagulation & Flocculation What is the advantage of optimizing chemical coagulant doses? ## Footnote A. Excissive sludge produces. B. Short filter runs C. Reduced chemical costs. D. Poor disinfection.

C. Reduced chemical costs.

# Coagulation & Flocculation What happenes when a paddle wheel flocculator is operated at a speed lower than desirable? ## Footnote A. Floc settles out prematurely B. Floc particles break-up C. Decrease in the height of the sludge blanket D. Formation of floc particles

A. Floc settles out prematurely

# Coagulation & Flocculation The flocculation compartments are separated by baffles to prevent \_\_\_\_\_-\_\_\_\_\_\_\_\_\_. ## Footnote A. Sedimentation B. Short-circuting C. Headloss D. Sludge

B. Short-circuting

# Coagulation & Flocculation What causes floc that is too small? ## Footnote A. Colder water temperatures B. Flow surges through the plant C. Excessive calcium corbonate compounds D. High levels of aluminum sulfate

A. Colder water temperatures

# Pathogenic What is a disease causing organism including viruses, protozoan and or bacteria?

Pathogenic

# Pathogenic Pathogenics casue diseases causing this such as \_\_\_\_\_\_\_, _______ and \_\_\_\_\_\_\_\_. ## Footnote A. Typhoid, Scabies, Polio B. Typhoid, Cholera, Dysentary C. Dysentary, Typhoid, Polio D. Virus Infection, Bacterial Infection, Mental illness

B. Typhoid, Cholera, Dysentary

# Pathogenic An organism that does not cause a disease is called a \_\_\_-\_\_\_\_\_\_\_\_\_\_.

Non-Pathogenic

# System Monitoring To ensure that drinkning water is safe, monitor for: ## Footnote A. Bacteria B. Turbidity C. Chlorine residual D. All of the above

D. All of the above

# Coliform A group of bacteria foudn in the intestines of warm blooded animals & also plants, soil, air and water is called \_\_\_\_\_\_\_\_.

Coliform

# Coliform When Coliform Bacteria is present and able to be measured in a water system, that is called _____ \_\_\_\_\_\_\_\_.

Total Coliform

# Coagulation & Flocculation If a sample of coliform is posistive and generally from animal intestines it is called _____ \_\_\_\_\_\_\_ and a _____ \_\_\_\_\_\_\_ test is performed.

Fecal Caliform, Fecal Caliform