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NEW JERSEY WATER TREATMENT
OPERATOR EXAM T4 PRACTICE EXAM –
40 QUESTIONS WITH VERIFIED ANSWERS
& COMPLETE RATIONALES
## SECTION 1: GENERAL TREATMENT PRINCIPLES
**1. What is the main purpose of coagulation in water
treatment?**
A. Kill pathogenic bacteria
B. Remove dissolved solids
C. Destabilize particles for removal
D. Increase pH
**Correct answer:** Destabilize particles for removal
**Rationale:** Coagulation neutralizes the electrical charges of
suspended particles, causing them to aggregate into larger
flocs that can be removed by sedimentation and filtration.
Coagulation does not kill bacteria; that is disinfection .
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**2. What chemical is most commonly used as a primary
coagulant in water treatment?**
A. Chlorine
B. Alum (aluminum sulfate)
C. Lime
D. Fluoride
**Correct answer:** Alum (aluminum sulfate)
**Rationale:** Aluminum sulfate (alum) is the most widely used
coagulant in water treatment due to its effectiveness and cost.
Lime is used for pH adjustment, chlorine for disinfection, and
fluoride for dental health .
---
**3. Sedimentation primarily removes what?**
A. Dissolved gases
B. Heavy metals
C. Settled floc particles
D. Bacteria only
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**Correct answer:** Settled floc particles
**Rationale:** Sedimentation allows gravity to settle floc
particles that have been formed during coagulation and
flocculation. It does not remove dissolved gases, heavy metals,
or bacteria that remain in suspension .
---
**4. Filtration removes particles mainly by:**
A. Evaporation
B. Physical straining
C. Freezing
D. Oxidation
**Correct answer:** Physical straining
**Rationale:** Filters physically trap particles as water passes
through the filter media. While some adsorption occurs, the
primary mechanism is physical straining .
---
**5. Chlorination is used primarily for:**
NEW JERSEY WATER TREATMENT
OPERATOR EXAM T4 PRACTICE EXAM –
40 QUESTIONS WITH VERIFIED ANSWERS
& COMPLETE RATIONALES
## SECTION 1: GENERAL TREATMENT PRINCIPLES
**1. What is the main purpose of coagulation in water
treatment?**
A. Kill pathogenic bacteria
B. Remove dissolved solids
C. Destabilize particles for removal
D. Increase pH
**Correct answer:** Destabilize particles for removal
**Rationale:** Coagulation neutralizes the electrical charges of
suspended particles, causing them to aggregate into larger
flocs that can be removed by sedimentation and filtration.
Coagulation does not kill bacteria; that is disinfection .
---
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**2. What chemical is most commonly used as a primary
coagulant in water treatment?**
A. Chlorine
B. Alum (aluminum sulfate)
C. Lime
D. Fluoride
**Correct answer:** Alum (aluminum sulfate)
**Rationale:** Aluminum sulfate (alum) is the most widely used
coagulant in water treatment due to its effectiveness and cost.
Lime is used for pH adjustment, chlorine for disinfection, and
fluoride for dental health .
---
**3. Sedimentation primarily removes what?**
A. Dissolved gases
B. Heavy metals
C. Settled floc particles
D. Bacteria only
, 3 | Page
**Correct answer:** Settled floc particles
**Rationale:** Sedimentation allows gravity to settle floc
particles that have been formed during coagulation and
flocculation. It does not remove dissolved gases, heavy metals,
or bacteria that remain in suspension .
---
**4. Filtration removes particles mainly by:**
A. Evaporation
B. Physical straining
C. Freezing
D. Oxidation
**Correct answer:** Physical straining
**Rationale:** Filters physically trap particles as water passes
through the filter media. While some adsorption occurs, the
primary mechanism is physical straining .
---
**5. Chlorination is used primarily for:**
