Wyoming Wastewater Treatment Operator Level I Practice
Exam Questions And Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. What is the primary purpose of a wastewater treatment plant?
a. Produce drinking water
b. Remove pollutants from wastewater before discharge
c. Generate electricity
d. Store sewage for future use
Rationale: The main purpose of wastewater treatment is to remove
pollutants and protect public health and the environment.
2. Which of the following is a physical method of wastewater treatment?
a. Screening
b. Activated sludge
c. Trickling filter
, d. Chlorination
Rationale: Screening is a physical process used to remove large solids
from wastewater.
3. What is the typical pH range of influent wastewater?
a. 2.0–4.0
b. 6.5–8.5
c. 9.0–11.0
d. 12.0–14.0
Rationale: Most municipal wastewater has a pH between 6.5 and
8.5.
4. Which process uses microorganisms to break down organic matter in
wastewater?
a. Filtration
b. Biological treatment
c. Sedimentation
d. Chlorination
Rationale: Biological treatment relies on microorganisms to degrade
organic pollutants.
5. The term BOD stands for:
a. Biochemical Oxidation Demand
b. Biochemical Oxygen Demand
c. Basic Oxygen Determination
d. Biological Oxidation Degree
, Rationale: BOD measures the amount of dissolved oxygen required
by microorganisms to decompose organic material in water.
6. A high BOD in wastewater indicates:
a. Low organic pollution
b. High organic pollution
c. High dissolved oxygen
d. Low microbial activity
Rationale: BOD reflects the organic load; higher BOD means more
organic matter present.
7. Which unit process is used to remove settleable solids from
wastewater?
a. Aeration
b. Sedimentation
c. Filtration
d. Chlorination
Rationale: Sedimentation allows heavier solids to settle out by
gravity.
8. What is the main purpose of chlorination in wastewater treatment?
a. Remove solids
b. Reduce BOD
c. Disinfect wastewater
d. Neutralize pH
Rationale: Chlorination kills or inactivates pathogenic organisms.
, 9. Which of the following is a typical characteristic of primary sludge?
a. High solids content
b. High oxygen demand
c. High nitrates
d. High alkalinity
Rationale: Primary sludge is composed of settled solids, which are
concentrated and have a high solids content.
10. The process of removing nitrogen from wastewater biologically
is called:
a. Sedimentation
b. Nitrification-denitrification
c. Coagulation
d. Chlorination
Rationale: Biological nitrogen removal occurs through nitrification
(ammonia to nitrate) and denitrification (nitrate to nitrogen gas).
11. Which safety equipment is required when handling chlorine gas?
a. Earplugs
b. Safety goggles only
c. Respirator and full protective clothing
d. Hard hat only
Rationale: Chlorine gas is toxic; proper PPE includes respirators and
protective clothing.
Exam Questions And Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. What is the primary purpose of a wastewater treatment plant?
a. Produce drinking water
b. Remove pollutants from wastewater before discharge
c. Generate electricity
d. Store sewage for future use
Rationale: The main purpose of wastewater treatment is to remove
pollutants and protect public health and the environment.
2. Which of the following is a physical method of wastewater treatment?
a. Screening
b. Activated sludge
c. Trickling filter
, d. Chlorination
Rationale: Screening is a physical process used to remove large solids
from wastewater.
3. What is the typical pH range of influent wastewater?
a. 2.0–4.0
b. 6.5–8.5
c. 9.0–11.0
d. 12.0–14.0
Rationale: Most municipal wastewater has a pH between 6.5 and
8.5.
4. Which process uses microorganisms to break down organic matter in
wastewater?
a. Filtration
b. Biological treatment
c. Sedimentation
d. Chlorination
Rationale: Biological treatment relies on microorganisms to degrade
organic pollutants.
5. The term BOD stands for:
a. Biochemical Oxidation Demand
b. Biochemical Oxygen Demand
c. Basic Oxygen Determination
d. Biological Oxidation Degree
, Rationale: BOD measures the amount of dissolved oxygen required
by microorganisms to decompose organic material in water.
6. A high BOD in wastewater indicates:
a. Low organic pollution
b. High organic pollution
c. High dissolved oxygen
d. Low microbial activity
Rationale: BOD reflects the organic load; higher BOD means more
organic matter present.
7. Which unit process is used to remove settleable solids from
wastewater?
a. Aeration
b. Sedimentation
c. Filtration
d. Chlorination
Rationale: Sedimentation allows heavier solids to settle out by
gravity.
8. What is the main purpose of chlorination in wastewater treatment?
a. Remove solids
b. Reduce BOD
c. Disinfect wastewater
d. Neutralize pH
Rationale: Chlorination kills or inactivates pathogenic organisms.
, 9. Which of the following is a typical characteristic of primary sludge?
a. High solids content
b. High oxygen demand
c. High nitrates
d. High alkalinity
Rationale: Primary sludge is composed of settled solids, which are
concentrated and have a high solids content.
10. The process of removing nitrogen from wastewater biologically
is called:
a. Sedimentation
b. Nitrification-denitrification
c. Coagulation
d. Chlorination
Rationale: Biological nitrogen removal occurs through nitrification
(ammonia to nitrate) and denitrification (nitrate to nitrogen gas).
11. Which safety equipment is required when handling chlorine gas?
a. Earplugs
b. Safety goggles only
c. Respirator and full protective clothing
d. Hard hat only
Rationale: Chlorine gas is toxic; proper PPE includes respirators and
protective clothing.
