WASTEWATER OPERATOR CLASS 1 & 2
PRACTICE TEST QUESTIONS WITH DETAILED
VERIFIED AND 100% ACCURATE ANSWERS
WASTEWATER OPERATOR CLASS 1 & 2
Practice Examination – 100 Questions with Verified Answers
SECTION 1: WASTEWATER CHARACTERISTICS AND BASIC PRINCIPLES
Question 1
What is the primary purpose of a wastewater treatment plant?
A. Produce drinking water
B. Generate electricity
C. Remove contaminants from wastewater before discharge
D. Manufacture chemicals
Answer: C
Explanation: Wastewater treatment plants remove physical, chemical, and
biological contaminants to protect public health and the environment before
treated water is released.
Question 2
What does BOD measure in wastewater?
,A. Chlorine demand
B. Water hardness
C. Biodegradable organic pollution
D. Metal concentration
Answer: C
Explanation: Biochemical Oxygen Demand (BOD) measures the oxygen required
by microorganisms to decompose biodegradable organic matter in wastewater.
Question 3
High BOD in receiving waters can result in:
A. Increased oxygen
B. Lower temperatures
C. Oxygen depletion
D. Higher alkalinity
Answer: C
Explanation: Organic decomposition consumes dissolved oxygen, potentially
harming aquatic life and leading to oxygen depletion in receiving waters.
Question 4
What is the approximate BOD contribution per person per day in domestic
wastewater?
A. 0.17 lbs/day/person
B. 0.50 lbs/day/person
C. 1.0 lbs/day/person
D. 2.0 lbs/day/person
Answer: A
Explanation: The standard design criteria for BOD5 is 0.17 lbs per capita per day.
,Question 5
A wastewater sample with a pH of 3 is considered:
A. Neutral
B. Alkaline
C. Acidic
D. Basic
Answer: C
Explanation: A pH below 7 is acidic; a pH of 3 is strongly acidic and can be harmful
to biological treatment processes.
Question 6
What is the ideal pH range for most biological wastewater treatment?
A. 2–4
B. 4–5
C. 6.5–8.5
D. 10–12
Answer: C
Explanation: Most wastewater microorganisms perform best in a near-neutral pH
range of 6.5–8.5.
Question 7
The majority of dissolved oxygen in raw sewage comes from:
A. Atmospheric diffusion
B. Potable drinking water
C. Bacterial photosynthesis
D. Chemical reactions
, Answer: B
Explanation: The majority of dissolved oxygen in raw sewage comes from the
potable drinking water that enters the collection system.
Question 8
What percent of sewage is solid?
A. 10% solids
B. 1% solids
C. 0.1% solids
D. 0.01% solids
Answer: C
Explanation: Raw sewage typically contains approximately 0.1% solids by weight,
with 99.9% being water.
Question 9
Which of the following is NOT considered a type of preliminary treatment?
A. Screening and Grit Removal
B. Odor Control
C. Flow Equalization
D. Aeration
Answer: D
Explanation: Aeration is a secondary treatment process, not preliminary
treatment. Preliminary treatment includes screening, grit removal, odor control,
and flow equalization.
PRACTICE TEST QUESTIONS WITH DETAILED
VERIFIED AND 100% ACCURATE ANSWERS
WASTEWATER OPERATOR CLASS 1 & 2
Practice Examination – 100 Questions with Verified Answers
SECTION 1: WASTEWATER CHARACTERISTICS AND BASIC PRINCIPLES
Question 1
What is the primary purpose of a wastewater treatment plant?
A. Produce drinking water
B. Generate electricity
C. Remove contaminants from wastewater before discharge
D. Manufacture chemicals
Answer: C
Explanation: Wastewater treatment plants remove physical, chemical, and
biological contaminants to protect public health and the environment before
treated water is released.
Question 2
What does BOD measure in wastewater?
,A. Chlorine demand
B. Water hardness
C. Biodegradable organic pollution
D. Metal concentration
Answer: C
Explanation: Biochemical Oxygen Demand (BOD) measures the oxygen required
by microorganisms to decompose biodegradable organic matter in wastewater.
Question 3
High BOD in receiving waters can result in:
A. Increased oxygen
B. Lower temperatures
C. Oxygen depletion
D. Higher alkalinity
Answer: C
Explanation: Organic decomposition consumes dissolved oxygen, potentially
harming aquatic life and leading to oxygen depletion in receiving waters.
Question 4
What is the approximate BOD contribution per person per day in domestic
wastewater?
A. 0.17 lbs/day/person
B. 0.50 lbs/day/person
C. 1.0 lbs/day/person
D. 2.0 lbs/day/person
Answer: A
Explanation: The standard design criteria for BOD5 is 0.17 lbs per capita per day.
,Question 5
A wastewater sample with a pH of 3 is considered:
A. Neutral
B. Alkaline
C. Acidic
D. Basic
Answer: C
Explanation: A pH below 7 is acidic; a pH of 3 is strongly acidic and can be harmful
to biological treatment processes.
Question 6
What is the ideal pH range for most biological wastewater treatment?
A. 2–4
B. 4–5
C. 6.5–8.5
D. 10–12
Answer: C
Explanation: Most wastewater microorganisms perform best in a near-neutral pH
range of 6.5–8.5.
Question 7
The majority of dissolved oxygen in raw sewage comes from:
A. Atmospheric diffusion
B. Potable drinking water
C. Bacterial photosynthesis
D. Chemical reactions
, Answer: B
Explanation: The majority of dissolved oxygen in raw sewage comes from the
potable drinking water that enters the collection system.
Question 8
What percent of sewage is solid?
A. 10% solids
B. 1% solids
C. 0.1% solids
D. 0.01% solids
Answer: C
Explanation: Raw sewage typically contains approximately 0.1% solids by weight,
with 99.9% being water.
Question 9
Which of the following is NOT considered a type of preliminary treatment?
A. Screening and Grit Removal
B. Odor Control
C. Flow Equalization
D. Aeration
Answer: D
Explanation: Aeration is a secondary treatment process, not preliminary
treatment. Preliminary treatment includes screening, grit removal, odor control,
and flow equalization.
