Hawaii Wastewater Treatment Operator
Grade 1 Practice Exam Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download
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1. The primary purpose of a wastewater treatment plant is to:
A. Generate electricity
B. Protect public health and the environment by treating wastewater
C. Increase water hardness
D. Store rainwater
Rationale: Wastewater treatment plants are designed to remove
pollutants from sewage to prevent environmental contamination and
protect public health.
2. Which of the following is considered physical treatment?
A. Biological digestion
, B. Chemical precipitation
C. Screening and sedimentation
D. Chlorination
Rationale: Physical treatment involves removing solids from wastewater
by screening, grit removal, and sedimentation.
3. What is the main purpose of primary clarification?
A. Remove dissolved nutrients
B. Remove settleable solids and floating material
C. Kill bacteria
D. Reduce pH
Rationale: Primary clarification allows solids to settle and scum to float,
reducing the load on secondary treatment processes.
4. BOD stands for:
A. Biological Oxidation Demand
B. Biochemical Oxidation Data
C. Biochemical Oxygen Demand
D. Basic Oxygen Design
Rationale: BOD measures the amount of oxygen required by
microorganisms to decompose organic matter in water.
5. Suspended solids in wastewater are primarily removed by:
A. Filtration
B. Sedimentation
, C. Aeration
D. Chlorination
Rationale: Sedimentation allows suspended solids to settle by gravity
before further treatment.
6. Which device is used to remove large objects like rags and sticks from
influent wastewater?
A. Clarifier
B. Aerator
C. Screen
D. Sludge digester
Rationale: Screens are used at the headworks to prevent debris from
damaging downstream equipment.
7. What is grit composed of in wastewater treatment?
A. Soluble organic matter
B. Microorganisms
C. Sand, gravel, and other heavy inorganic materials
D. Oils and grease
Rationale: Grit consists of heavy, inorganic particles that settle quickly in a
grit chamber.
8. The purpose of aeration in secondary treatment is to:
A. Remove grit
B. Settle solids
, C. Provide oxygen to microorganisms for biological treatment
D. Reduce temperature
Rationale: Aeration provides oxygen necessary for aerobic bacteria to
break down organic matter.
9. Nitrification is a process that converts:
A. Ammonia to nitrogen gas
B. Ammonia to nitrate
C. Nitrate to ammonia
D. Nitrite to phosphate
Rationale: Nitrification is an aerobic process in which bacteria convert
ammonia to nitrite and then nitrate.
10. Which of the following is an indicator of the organic strength of
wastewater?
A. pH
B. BOD
C. TSS
D. Temperature
Rationale: BOD measures the amount of biodegradable organic material in
wastewater.
11. Chlorination is primarily used for:
A. Removing solids
B. Aerating wastewater
Grade 1 Practice Exam Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download
1. The primary purpose of a wastewater treatment plant is to:
A. Generate electricity
B. Protect public health and the environment by treating wastewater
C. Increase water hardness
D. Store rainwater
Rationale: Wastewater treatment plants are designed to remove
pollutants from sewage to prevent environmental contamination and
protect public health.
2. Which of the following is considered physical treatment?
A. Biological digestion
, B. Chemical precipitation
C. Screening and sedimentation
D. Chlorination
Rationale: Physical treatment involves removing solids from wastewater
by screening, grit removal, and sedimentation.
3. What is the main purpose of primary clarification?
A. Remove dissolved nutrients
B. Remove settleable solids and floating material
C. Kill bacteria
D. Reduce pH
Rationale: Primary clarification allows solids to settle and scum to float,
reducing the load on secondary treatment processes.
4. BOD stands for:
A. Biological Oxidation Demand
B. Biochemical Oxidation Data
C. Biochemical Oxygen Demand
D. Basic Oxygen Design
Rationale: BOD measures the amount of oxygen required by
microorganisms to decompose organic matter in water.
5. Suspended solids in wastewater are primarily removed by:
A. Filtration
B. Sedimentation
, C. Aeration
D. Chlorination
Rationale: Sedimentation allows suspended solids to settle by gravity
before further treatment.
6. Which device is used to remove large objects like rags and sticks from
influent wastewater?
A. Clarifier
B. Aerator
C. Screen
D. Sludge digester
Rationale: Screens are used at the headworks to prevent debris from
damaging downstream equipment.
7. What is grit composed of in wastewater treatment?
A. Soluble organic matter
B. Microorganisms
C. Sand, gravel, and other heavy inorganic materials
D. Oils and grease
Rationale: Grit consists of heavy, inorganic particles that settle quickly in a
grit chamber.
8. The purpose of aeration in secondary treatment is to:
A. Remove grit
B. Settle solids
, C. Provide oxygen to microorganisms for biological treatment
D. Reduce temperature
Rationale: Aeration provides oxygen necessary for aerobic bacteria to
break down organic matter.
9. Nitrification is a process that converts:
A. Ammonia to nitrogen gas
B. Ammonia to nitrate
C. Nitrate to ammonia
D. Nitrite to phosphate
Rationale: Nitrification is an aerobic process in which bacteria convert
ammonia to nitrite and then nitrate.
10. Which of the following is an indicator of the organic strength of
wastewater?
A. pH
B. BOD
C. TSS
D. Temperature
Rationale: BOD measures the amount of biodegradable organic material in
wastewater.
11. Chlorination is primarily used for:
A. Removing solids
B. Aerating wastewater
