Page 1 of 117
Hawaii Wastewater Treatment Operator Grade 1 Exam
ACTUAL EXAM COMPLETE QUESTIONS AND CORRECT
ANSWERS LATEST UPDATE THIS YEAR
SUMMARIZED EXAM COVERAGE
The Hawaii Grade 1 Wastewater Operator exam focuses on the fundamental operation of wastewater
treatment systems, including preliminary screening, primary sedimentation, and biological treatment
using activated sludge processes. Candidates are tested on basic plant operations such as sludge
handling, disinfection using chlorine or UV systems, and understanding of microbial activity in treatment
tanks.
The exam also emphasizes basic laboratory testing including BOD, pH, dissolved oxygen, and suspended
solids, along with simple mathematical calculations related to flow, detention time, and percentage
removal efficiency. Operators must understand basic pump operation, valve functions, and flow
measurement techniques.
Safety is a critical component, including confined space awareness, PPE use, and handling of hazardous
gases such as hydrogen sulfide. Regulatory knowledge includes compliance with environmental
discharge standards and Hawaii Department of Health wastewater regulations.
1.
A wastewater operator notices a sudden drop in flow entering the plant during peak hours. What is the
most likely cause?
A. Increased biological activity in aeration tank
B. Infiltration and inflow reduction or upstream sewer blockage
C. Excess chlorine dosage in disinfection stage
D. Improved sludge digestion efficiency
, Page 2 of 117
Answer: B
Rationale: Flow drops are commonly caused by upstream blockages or reduced infiltration/inflow.
2.
A plant operator observes excessive solids passing through the primary clarifier into secondary
treatment. What is the most likely issue?
A. Over-aeration in biological tank
B. Poor sedimentation due to high flow or malfunctioning clarifier
C. Excess chlorine in disinfection system
D. Low sludge production in digestion tank
Answer: B
Rationale: Primary clarifiers remove solids by settling; failure leads to carryover.
3.
A wastewater operator measures low dissolved oxygen levels in an aeration tank. What is the most likely
operational adjustment?
, Page 3 of 117
A. Reduce sludge wasting rate
B. Increase aeration to support microbial activity
C. Decrease influent flow rate
D. Add more chlorine to system
Answer: B
Rationale: Aeration must increase to maintain aerobic conditions for microorganisms.
4.
A plant experiences foul odors near sludge processing areas. What is the most likely cause?
A. Excess oxygen in sludge tank
B. Anaerobic conditions producing hydrogen sulfide gas
C. Over-chlorination of effluent
D. High dissolved oxygen levels
Answer: B
Rationale: Anaerobic decomposition produces H₂S, causing strong odors.
5.
, Page 4 of 117
A wastewater operator finds that effluent turbidity is high after secondary clarification. What is the
likely cause?
A. Excess chlorine dosage
B. Poor floc formation or overloaded clarifier
C. Low influent flow rate
D. High UV disinfection efficiency
Answer: B
Rationale: Poor settling or overloading increases turbidity in effluent.
6.
An operator measures BOD levels that are higher than permitted discharge limits. What does this
indicate?
A. Excess chlorine residual
B. High organic pollution in effluent
C. Low microbial activity in aeration tank
D. Improved treatment efficiency
Hawaii Wastewater Treatment Operator Grade 1 Exam
ACTUAL EXAM COMPLETE QUESTIONS AND CORRECT
ANSWERS LATEST UPDATE THIS YEAR
SUMMARIZED EXAM COVERAGE
The Hawaii Grade 1 Wastewater Operator exam focuses on the fundamental operation of wastewater
treatment systems, including preliminary screening, primary sedimentation, and biological treatment
using activated sludge processes. Candidates are tested on basic plant operations such as sludge
handling, disinfection using chlorine or UV systems, and understanding of microbial activity in treatment
tanks.
The exam also emphasizes basic laboratory testing including BOD, pH, dissolved oxygen, and suspended
solids, along with simple mathematical calculations related to flow, detention time, and percentage
removal efficiency. Operators must understand basic pump operation, valve functions, and flow
measurement techniques.
Safety is a critical component, including confined space awareness, PPE use, and handling of hazardous
gases such as hydrogen sulfide. Regulatory knowledge includes compliance with environmental
discharge standards and Hawaii Department of Health wastewater regulations.
1.
A wastewater operator notices a sudden drop in flow entering the plant during peak hours. What is the
most likely cause?
A. Increased biological activity in aeration tank
B. Infiltration and inflow reduction or upstream sewer blockage
C. Excess chlorine dosage in disinfection stage
D. Improved sludge digestion efficiency
, Page 2 of 117
Answer: B
Rationale: Flow drops are commonly caused by upstream blockages or reduced infiltration/inflow.
2.
A plant operator observes excessive solids passing through the primary clarifier into secondary
treatment. What is the most likely issue?
A. Over-aeration in biological tank
B. Poor sedimentation due to high flow or malfunctioning clarifier
C. Excess chlorine in disinfection system
D. Low sludge production in digestion tank
Answer: B
Rationale: Primary clarifiers remove solids by settling; failure leads to carryover.
3.
A wastewater operator measures low dissolved oxygen levels in an aeration tank. What is the most likely
operational adjustment?
, Page 3 of 117
A. Reduce sludge wasting rate
B. Increase aeration to support microbial activity
C. Decrease influent flow rate
D. Add more chlorine to system
Answer: B
Rationale: Aeration must increase to maintain aerobic conditions for microorganisms.
4.
A plant experiences foul odors near sludge processing areas. What is the most likely cause?
A. Excess oxygen in sludge tank
B. Anaerobic conditions producing hydrogen sulfide gas
C. Over-chlorination of effluent
D. High dissolved oxygen levels
Answer: B
Rationale: Anaerobic decomposition produces H₂S, causing strong odors.
5.
, Page 4 of 117
A wastewater operator finds that effluent turbidity is high after secondary clarification. What is the
likely cause?
A. Excess chlorine dosage
B. Poor floc formation or overloaded clarifier
C. Low influent flow rate
D. High UV disinfection efficiency
Answer: B
Rationale: Poor settling or overloading increases turbidity in effluent.
6.
An operator measures BOD levels that are higher than permitted discharge limits. What does this
indicate?
A. Excess chlorine residual
B. High organic pollution in effluent
C. Low microbial activity in aeration tank
D. Improved treatment efficiency
