TCEQ Wastewater (Class D) License Prep questions with correct answers
TCEQ
SECTION 1: Safety & General Knowledge
1. What gas is most commonly associated with sewer systems and is deadly at high
concentrations?
A. Methane
B. Hydrogen sulfide
C. Carbon dioxide
D. Chlorine
✅ Answer: B — Hydrogen sulfide (H₂S)
⚠️Smells like rotten eggs, but odor disappears at lethal levels.
2. Which PPE is MOST important when working around open wastewater tanks?
A. Hard hat
B. Steel-toe boots
C. Safety glasses
D. Fall protection
✅ Answer: D — Fall protection
3. Confined spaces must be tested for which THREE hazards?
A. Oxygen, chlorine, methane
B. Oxygen, toxic gases, flammable gases
C. pH, temperature, humidity
D. Carbon monoxide, nitrogen, sulfur
✅ Answer: B
SECTION 2: Basic Math (VERY IMPORTANT)
4. One acre-foot of water equals:
A. 325,851 gallons
B. 43,560 gallons
C. 1 million gallons
D. 7.48 gallons
✅ Answer: A
, 5. If a plant treats 0.5 MGD, how many gallons per day is that?
✅ Answer:
0.5 × 1,000,000 = 500,000 gallons/day
6. Pounds formula used on the Class D exam:
✅ Answer:
lbs/day = MGD × mg/L × 8.34
7. A plant has a flow of 0.75 MGD and influent BOD of 200 mg/L.
How many pounds of BOD per day?
✅ Answer:
0.75 × 200 × 8.34 = 1,251 lbs/day
SECTION 3: Treatment Process Basics
8. What is the PRIMARY purpose of preliminary treatment?
A. Remove dissolved organics
B. Kill bacteria
C. Remove large debris and grit
D. Remove nutrients
✅ Answer: C
9. Which unit removes settleable solids?
A. Aeration basin
B. Primary clarifier
C. Trickling filter
D. Disinfection chamber
✅ Answer: B
10. Activated sludge is best described as:
A. Raw sewage
TCEQ
SECTION 1: Safety & General Knowledge
1. What gas is most commonly associated with sewer systems and is deadly at high
concentrations?
A. Methane
B. Hydrogen sulfide
C. Carbon dioxide
D. Chlorine
✅ Answer: B — Hydrogen sulfide (H₂S)
⚠️Smells like rotten eggs, but odor disappears at lethal levels.
2. Which PPE is MOST important when working around open wastewater tanks?
A. Hard hat
B. Steel-toe boots
C. Safety glasses
D. Fall protection
✅ Answer: D — Fall protection
3. Confined spaces must be tested for which THREE hazards?
A. Oxygen, chlorine, methane
B. Oxygen, toxic gases, flammable gases
C. pH, temperature, humidity
D. Carbon monoxide, nitrogen, sulfur
✅ Answer: B
SECTION 2: Basic Math (VERY IMPORTANT)
4. One acre-foot of water equals:
A. 325,851 gallons
B. 43,560 gallons
C. 1 million gallons
D. 7.48 gallons
✅ Answer: A
, 5. If a plant treats 0.5 MGD, how many gallons per day is that?
✅ Answer:
0.5 × 1,000,000 = 500,000 gallons/day
6. Pounds formula used on the Class D exam:
✅ Answer:
lbs/day = MGD × mg/L × 8.34
7. A plant has a flow of 0.75 MGD and influent BOD of 200 mg/L.
How many pounds of BOD per day?
✅ Answer:
0.75 × 200 × 8.34 = 1,251 lbs/day
SECTION 3: Treatment Process Basics
8. What is the PRIMARY purpose of preliminary treatment?
A. Remove dissolved organics
B. Kill bacteria
C. Remove large debris and grit
D. Remove nutrients
✅ Answer: C
9. Which unit removes settleable solids?
A. Aeration basin
B. Primary clarifier
C. Trickling filter
D. Disinfection chamber
✅ Answer: B
10. Activated sludge is best described as:
A. Raw sewage
