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Level II Exam Questions And CorrectAnsw
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ers(Verified Answers) Plus Rationales 202
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6 Q&A | Instant Download Pdf
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1. Which of the following is the primary purpose of a grit chamber in was
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tewater treatment?
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A. Remove organic solids j j
B. Remove inorganic solids j j
C. Reduce biological oxygen demand
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D. Clarify effluent j
Answer: B. Remove inorganic solids
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Rationale: Grit chambers are designed to remove heavy, inorganic particles like s
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and, gravel, and grit to prevent wear on equipment.
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,2. In wastewater treatment, BOD stands for:
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A. Biological Oxidation Demand j j
B. Biochemical Oxygen Demand j j
C. Basic Oxygen Determination
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D. Biochemical Oxidation Density j j
Answer: B. Biochemical Oxygen Demand
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Rationale: BOD measures the amount of dissolved oxygen needed by microorgan
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isms to decompose organic matter over a specified time, indicating wastewater s
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trength.
3. Which of the following is a common source of nitrogen in municipal was
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tewater?
A. Detergents
B. Human waste j
C. Heavy metals j
D. Sand
Answer: B. Human wastej j j
Rationale: Nitrogen primarily comes from urea in urine and proteins in feces, whi
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ch convert to ammonia during treatment.
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4. The main purpose of a primary clarifier is to:
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A. Remove pathogens j
B. Settle suspended solids
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C. Aerate the wastewater j j
D. Remove nutrients j
,Answer: B. Settle suspended solids
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Rationale: Primary clarifiers allow heavier solids to settle out, reducing the load o
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n secondary treatment processes.
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5. In activated sludge systems, return activated sludge (RAS) is:
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A. Wasted sludge sent to disposal j j j j
B. Sludge returned to the aeration tank
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C. Sludge discharged to the river j j j j
D. Settled solids in primary clarifier j j j j
Answer: B. Sludge returned to the aeration tank
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Rationale: RAS maintains a high concentration of microorganisms in the aeratio
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n tank to efficiently treat incoming wastewater.
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6. A characteristic of septic tank effluent is:
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A. High dissolved oxygen j j
B. Low dissolved oxygen and high BOD
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C. Completely pathogen-free j
D. High nutrient removal j j
Answer: B. Low dissolved oxygen and high BOD
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Rationale: Septic tank effluent is partially treated, with organic matter remainin
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g, resulting in low oxygen content.
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7. What is the most common method to disinfect treated wastewater be
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fore discharge?
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A. Filtration
B. Sedimentation
, C. Chlorination
D. Nitrification
Answer: C. Chlorination
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Rationale: Chlorination is widely used to kill pathogens before wastewater is rele
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ased to receiving waters.
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8. Which microorganism is primarily responsible for nitrification?
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A. Escherichia coli j
B. Nitrosomonas and Nitrobacter j j
C. Clostridium
D. Pseudomonas
Answer: B. Nitrosomonas and Nitrobacter
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Rationale: Nitrosomonas oxidizes ammonia to nitrite, and Nitrobacter oxidizes n
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itrite to nitrate in nitrification.
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9. Sludge digestion reduces volume primarily through:
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A. Sedimentation
B. Filtration
C. Biological decomposition j
D. Coagulation
Answer: C. Biological decomposition
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Rationale: Anaerobic or aerobic digestion breaks down organic matter in sludge,
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reducing solids and volume.
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10. Which parameter indicates the strength of wastewater?
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A. Turbidity
Level II Exam Questions And CorrectAnsw
j j j j j j
ers(Verified Answers) Plus Rationales 202
j j j j j
6 Q&A | Instant Download Pdf
j j j j j
1. Which of the following is the primary purpose of a grit chamber in was
j j j j j j j j j j j j j j
tewater treatment?
j
A. Remove organic solids j j
B. Remove inorganic solids j j
C. Reduce biological oxygen demand
j j j
D. Clarify effluent j
Answer: B. Remove inorganic solids
j j j j
Rationale: Grit chambers are designed to remove heavy, inorganic particles like s
j j j j j j j j j j j
and, gravel, and grit to prevent wear on equipment.
j j j j j j j j
,2. In wastewater treatment, BOD stands for:
j j j j j
A. Biological Oxidation Demand j j
B. Biochemical Oxygen Demand j j
C. Basic Oxygen Determination
j j
D. Biochemical Oxidation Density j j
Answer: B. Biochemical Oxygen Demand
j j j j
Rationale: BOD measures the amount of dissolved oxygen needed by microorgan
j j j j j j j j j j
isms to decompose organic matter over a specified time, indicating wastewater s
j j j j j j j j j j j
trength.
3. Which of the following is a common source of nitrogen in municipal was
j j j j j j j j j j j j
tewater?
A. Detergents
B. Human waste j
C. Heavy metals j
D. Sand
Answer: B. Human wastej j j
Rationale: Nitrogen primarily comes from urea in urine and proteins in feces, whi
j j j j j j j j j j j j
ch convert to ammonia during treatment.
j j j j j
4. The main purpose of a primary clarifier is to:
j j j j j j j j
A. Remove pathogens j
B. Settle suspended solids
j j
C. Aerate the wastewater j j
D. Remove nutrients j
,Answer: B. Settle suspended solids
j j j j
Rationale: Primary clarifiers allow heavier solids to settle out, reducing the load o
j j j j j j j j j j j j
n secondary treatment processes.
j j j
5. In activated sludge systems, return activated sludge (RAS) is:
j j j j j j j j
A. Wasted sludge sent to disposal j j j j
B. Sludge returned to the aeration tank
j j j j j
C. Sludge discharged to the river j j j j
D. Settled solids in primary clarifier j j j j
Answer: B. Sludge returned to the aeration tank
j j j j j j j
Rationale: RAS maintains a high concentration of microorganisms in the aeratio
j j j j j j j j j j
n tank to efficiently treat incoming wastewater.
j j j j j j
6. A characteristic of septic tank effluent is:
j j j j j j
A. High dissolved oxygen j j
B. Low dissolved oxygen and high BOD
j j j j j
C. Completely pathogen-free j
D. High nutrient removal j j
Answer: B. Low dissolved oxygen and high BOD
j j j j j j j
Rationale: Septic tank effluent is partially treated, with organic matter remainin
j j j j j j j j j j
g, resulting in low oxygen content.
j j j j j
7. What is the most common method to disinfect treated wastewater be
j j j j j j j j j j
fore discharge?
j
A. Filtration
B. Sedimentation
, C. Chlorination
D. Nitrification
Answer: C. Chlorination
j j
Rationale: Chlorination is widely used to kill pathogens before wastewater is rele
j j j j j j j j j j j
ased to receiving waters.
j j j
8. Which microorganism is primarily responsible for nitrification?
j j j j j j
A. Escherichia coli j
B. Nitrosomonas and Nitrobacter j j
C. Clostridium
D. Pseudomonas
Answer: B. Nitrosomonas and Nitrobacter
j j j j
Rationale: Nitrosomonas oxidizes ammonia to nitrite, and Nitrobacter oxidizes n
j j j j j j j j j
itrite to nitrate in nitrification.
j j j j
9. Sludge digestion reduces volume primarily through:
j j j j j
A. Sedimentation
B. Filtration
C. Biological decomposition j
D. Coagulation
Answer: C. Biological decomposition
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Rationale: Anaerobic or aerobic digestion breaks down organic matter in sludge,
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reducing solids and volume.
j j j
10. Which parameter indicates the strength of wastewater?
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A. Turbidity
