Texas Wastewater Operator Exam With
Actual Questions & Verified Answers, Plus
Explained Rationales/Expert Verified For
Guaranteed 100% Pass 2026/Latest
Update/Instant Download Pdf
1. The primary purpose of wastewater treatment is to
A. Reduce water hardness
B. Remove color and odor only
C. Protect public health and the environment
D. Increase water availability
Answer: C
Rationale: Wastewater treatment removes contaminants that could
harm human health and ecosystems before discharge or reuse.
2. Which process removes large solids at the headworks of a
treatment plant?
A. Sedimentation
B. Aeration
C. Screening
D. Filtration
Answer: C
Rationale: Screening physically removes large debris such as rags,
plastics, and sticks before further treatment.
, 3. Grit chambers are designed to remove
A. Organic solids
B. Grease
C. Inorganic particles such as sand and gravel
D. Dissolved oxygen
Answer: C
Rationale: Grit chambers protect downstream equipment by removing
heavy inorganic materials that settle quickly.
4. Primary clarification primarily removes
A. Dissolved solids
B. Pathogens
C. Settleable and floatable solids
D. Nutrients
Answer: C
Rationale: Primary clarifiers allow heavier solids to settle and lighter
materials to float for removal.
5. Biological treatment processes rely on
A. Chemicals
B. Heat
C. Microorganisms
D. Ultraviolet light
Answer: C
Rationale: Microorganisms metabolize organic matter during
secondary treatment.
, 6. Activated sludge systems require adequate
A. Chlorine
B. pH adjustment
C. Dissolved oxygen
D. Coagulation
Answer: C
Rationale: Aerobic bacteria in activated sludge need sufficient oxygen
to break down organic waste.
7. The food-to-microorganism (F/M) ratio represents
A. Sludge age
B. Oxygen efficiency
C. Organic load compared to biomass
D. Settling velocity
Answer: C
Rationale: F/M ratio compares incoming organic material to the
amount of microorganisms available to treat it.
8. Sludge age is also known as
A. Hydraulic retention time
B. Mean cell residence time (MCRT)
C. Detention time
D. Contact time
Answer: B
Rationale: MCRT measures how long microorganisms remain in the
system.
, 9. A low dissolved oxygen level in an aeration basin can cause
A. Improved settling
B. Increased nitrification
C. Odors and poor treatment efficiency
D. Higher chlorine demand
Answer: C
Rationale: Insufficient oxygen leads to anaerobic conditions and
reduced biological activity.
10. Secondary clarifiers are used to
A. Add oxygen
B. Kill bacteria
C. Separate biomass from treated effluent
D. Remove grit
Answer: C
Rationale: Secondary clarifiers allow activated sludge to settle so clear
effluent can be discharged.
11. Return activated sludge (RAS) is sent
A. To disposal
B. To disinfection
C. Back to the aeration basin
D. To the grit chamber
Answer: C
Rationale: RAS maintains an adequate microbial population in the
aeration basin.
Actual Questions & Verified Answers, Plus
Explained Rationales/Expert Verified For
Guaranteed 100% Pass 2026/Latest
Update/Instant Download Pdf
1. The primary purpose of wastewater treatment is to
A. Reduce water hardness
B. Remove color and odor only
C. Protect public health and the environment
D. Increase water availability
Answer: C
Rationale: Wastewater treatment removes contaminants that could
harm human health and ecosystems before discharge or reuse.
2. Which process removes large solids at the headworks of a
treatment plant?
A. Sedimentation
B. Aeration
C. Screening
D. Filtration
Answer: C
Rationale: Screening physically removes large debris such as rags,
plastics, and sticks before further treatment.
, 3. Grit chambers are designed to remove
A. Organic solids
B. Grease
C. Inorganic particles such as sand and gravel
D. Dissolved oxygen
Answer: C
Rationale: Grit chambers protect downstream equipment by removing
heavy inorganic materials that settle quickly.
4. Primary clarification primarily removes
A. Dissolved solids
B. Pathogens
C. Settleable and floatable solids
D. Nutrients
Answer: C
Rationale: Primary clarifiers allow heavier solids to settle and lighter
materials to float for removal.
5. Biological treatment processes rely on
A. Chemicals
B. Heat
C. Microorganisms
D. Ultraviolet light
Answer: C
Rationale: Microorganisms metabolize organic matter during
secondary treatment.
, 6. Activated sludge systems require adequate
A. Chlorine
B. pH adjustment
C. Dissolved oxygen
D. Coagulation
Answer: C
Rationale: Aerobic bacteria in activated sludge need sufficient oxygen
to break down organic waste.
7. The food-to-microorganism (F/M) ratio represents
A. Sludge age
B. Oxygen efficiency
C. Organic load compared to biomass
D. Settling velocity
Answer: C
Rationale: F/M ratio compares incoming organic material to the
amount of microorganisms available to treat it.
8. Sludge age is also known as
A. Hydraulic retention time
B. Mean cell residence time (MCRT)
C. Detention time
D. Contact time
Answer: B
Rationale: MCRT measures how long microorganisms remain in the
system.
, 9. A low dissolved oxygen level in an aeration basin can cause
A. Improved settling
B. Increased nitrification
C. Odors and poor treatment efficiency
D. Higher chlorine demand
Answer: C
Rationale: Insufficient oxygen leads to anaerobic conditions and
reduced biological activity.
10. Secondary clarifiers are used to
A. Add oxygen
B. Kill bacteria
C. Separate biomass from treated effluent
D. Remove grit
Answer: C
Rationale: Secondary clarifiers allow activated sludge to settle so clear
effluent can be discharged.
11. Return activated sludge (RAS) is sent
A. To disposal
B. To disinfection
C. Back to the aeration basin
D. To the grit chamber
Answer: C
Rationale: RAS maintains an adequate microbial population in the
aeration basin.
