Oregon Wastewater Treatment Operator Le
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vel I Practice Exam Questions And Correct An
d d d d d d d
swers (Verified Answers) Plus Rationales 20
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26 Q&A | Instant Download Pdf
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1. Which of the following best describes the primary purpose of a
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wastewater treatment plant? d d
A. To produce drinking water
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B. To remove pollutants from wastewater before discharge
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C. To increase water hardness
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D. To add chemicals for industrial use
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Rationale: The main goal of wastewater treatment is to remove contam
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inants and pollutants to protect public health and the environment.
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2. BOD stands for:
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A. Biological Oxidation Demand d d
, B. Biochemical Oxygen Demand d d
C. Basic Oxygen Detergent
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D. Bacterial Oxidation Demand d d
Rationale: BOD measures the amount of oxygen required by microorga
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nisms to decompose organic matter in water.
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3. The first step in most wastewater treatment plants is:
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A. Disinfection
B. Screening and grit removal d d d
C. Biological treatment d
D. Sludge dewatering d
Rationale: Screening removes large solids and grit removal prevents da
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mage to equipment.
d d
4. Which type of bacteria is primarily responsible for breaking down
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organic matter in activated sludge systems?
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A. Nitrifying bacteria d
B. Heterotrophic bacteria d
C. Sulfate-reducing bacteria d
D. Methanogens
Rationale: Heterotrophic bacteria consume organic carbon, reducing BO
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D.
5. Sludge settling occurs in which part of the treatment process?
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A. Aeration basin d
B. Secondary clarifier d
, C. Primary screen d
D. Disinfection chamber d
Rationale: Clarifiers allow solids to settle from the liquid after biological
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treatment.
6. Which of the following is a common method for sludge disposal?
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A. Deep well injection d d
B. Land application d
C. Ocean dumping d
D. Open burning d
Rationale: Land application recycles nutrients and is an environmentall
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y safe method of sludge disposal.
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7. The process of removing nitrogen from wastewater is called:
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A. Chlorination
B. Nitrification-denitrification
C. Sedimentation
D. Flocculation
Rationale: Nitrogen is removed biologically through nitrification follow
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ed by denitrification.
d d
8. A wastewater flow of 1 million gallons per day (MGD) is equal to how
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many gallons per minute (GPM)?
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A. 694
B. 694.44
C. 1,000
, D. 1,440
Rationale: 1 MGD ÷ 1,440 minutes/day = 694.44 GPM.
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9. Which chemical is commonly used for disinfection of wastewater?
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A. Ammonia
B. Chlorine
C. Sulfate
D. Fluoride
Rationale: Chlorine effectively kills pathogenic microorganisms in waste
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water.
10. The primary purpose of aeration in an activated sludge process i
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s to:
d
A. Remove solids d
B. Provide oxygen for microorganisms
d d d
C. Adjust pHd
D. Disinfect water d
Rationale: Oxygen supports the growth and activity of aerobic bacteria.
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11. Which of the following pH levels is considered neutral?
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A. 0
B. 7
C. 7
D. 14
Rationale: A pH of 7 is neutral; below 7 is acidic and above 7 is basic.
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d d d d
vel I Practice Exam Questions And Correct An
d d d d d d d
swers (Verified Answers) Plus Rationales 20
d d d d d
26 Q&A | Instant Download Pdf
d d d d d
1. Which of the following best describes the primary purpose of a
d d d d d d d d d d d d
wastewater treatment plant? d d
A. To produce drinking water
d d d
B. To remove pollutants from wastewater before discharge
d d d d d d
C. To increase water hardness
d d d
D. To add chemicals for industrial use
d d d d d
Rationale: The main goal of wastewater treatment is to remove contam
d d d d d d d d d d
inants and pollutants to protect public health and the environment.
d d d d d d d d d
2. BOD stands for:
d d
A. Biological Oxidation Demand d d
, B. Biochemical Oxygen Demand d d
C. Basic Oxygen Detergent
d d
D. Bacterial Oxidation Demand d d
Rationale: BOD measures the amount of oxygen required by microorga
d d d d d d d d d
nisms to decompose organic matter in water.
d d d d d d
3. The first step in most wastewater treatment plants is:
d d d d d d d d
A. Disinfection
B. Screening and grit removal d d d
C. Biological treatment d
D. Sludge dewatering d
Rationale: Screening removes large solids and grit removal prevents da
d d d d d d d d d
mage to equipment.
d d
4. Which type of bacteria is primarily responsible for breaking down
d d d d d d d d d d
organic matter in activated sludge systems?
d d d d d
A. Nitrifying bacteria d
B. Heterotrophic bacteria d
C. Sulfate-reducing bacteria d
D. Methanogens
Rationale: Heterotrophic bacteria consume organic carbon, reducing BO
d d d d d d d
D.
5. Sludge settling occurs in which part of the treatment process?
d d d d d d d d d
A. Aeration basin d
B. Secondary clarifier d
, C. Primary screen d
D. Disinfection chamber d
Rationale: Clarifiers allow solids to settle from the liquid after biological
d d d d d d d d d d d
treatment.
6. Which of the following is a common method for sludge disposal?
d d d d d d d d d d
A. Deep well injection d d
B. Land application d
C. Ocean dumping d
D. Open burning d
Rationale: Land application recycles nutrients and is an environmentall
d d d d d d d d
y safe method of sludge disposal.
d d d d d
7. The process of removing nitrogen from wastewater is called:
d d d d d d d d
A. Chlorination
B. Nitrification-denitrification
C. Sedimentation
D. Flocculation
Rationale: Nitrogen is removed biologically through nitrification follow
d d d d d d d
ed by denitrification.
d d
8. A wastewater flow of 1 million gallons per day (MGD) is equal to how
d d d d d d d d d d d d d d
many gallons per minute (GPM)?
d d d d
A. 694
B. 694.44
C. 1,000
, D. 1,440
Rationale: 1 MGD ÷ 1,440 minutes/day = 694.44 GPM.
d d d d d d d d
9. Which chemical is commonly used for disinfection of wastewater?
d d d d d d d d
A. Ammonia
B. Chlorine
C. Sulfate
D. Fluoride
Rationale: Chlorine effectively kills pathogenic microorganisms in waste
d d d d d d d
water.
10. The primary purpose of aeration in an activated sludge process i
d d d d d d d d d d
s to:
d
A. Remove solids d
B. Provide oxygen for microorganisms
d d d
C. Adjust pHd
D. Disinfect water d
Rationale: Oxygen supports the growth and activity of aerobic bacteria.
d d d d d d d d d
11. Which of the following pH levels is considered neutral?
d d d d d d d d
A. 0
B. 7
C. 7
D. 14
Rationale: A pH of 7 is neutral; below 7 is acidic and above 7 is basic.
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