CA Grade 2 Wastewater Treatment Operator Practice Exam 4
– 2026 Latest Questions and Answers for Certification Prep
CA Grade 2 Wastewater Treatment Operator Practice Exam –
1. 1 mg/L is the same as 1 part per billion.
Answer: False ✅
Rationale: 1 mg/L is equivalent to 1 part per million (ppm), not part per billion.
2. A SCADA system is capable of monitoring and controlling equipment from where?
Answer: Remote location ✅
Rationale: SCADA (Supervisory Control and Data Acquisition) allows operators to monitor and
control equipment remotely.
3. A Discharge Monitoring Report is typically submitted to the regulatory agency on a
daily basis.
Answer: False ✅ – It is typically submitted monthly.
Rationale: Most regulatory agencies require monthly reports unless specified otherwise.
4. A mechanical seal is used to prevent leaks between where?
Answer: Between the pump casing and shaft ✅
Rationale: Mechanical seals prevent leakage of fluid along the rotating shaft of a pump.
5. Alkalinity is the capacity of a liquid to neutralize a base.
Answer: False ✅ – Alkalinity neutralizes acids.
Rationale: Alkalinity measures the ability of water to resist changes in pH by neutralizing acids.
, 6. Typical mixed liquor suspended solids (MLSS) concentration is?
Answer: 1,000 to 4,500 mg/L ✅
Rationale: Standard MLSS levels for conventional activated sludge processes.
7. Turbidity is caused by…
Answer: Suspended matter ✅
Rationale: Particles suspended in water scatter light, causing turbidity.
8. Algae is not essential to the successful operation of both aerobic and facultative ponds.
Answer: False ✅ – Algae supply most of the oxygen to the supernatant.
Rationale: Algae photosynthesis provides oxygen needed by aerobic bacteria.
9. The addition of acid and CO₂ will do what to wastewater?
Answer: Lower the pH of wastewater ✅
Rationale: Acids decrease pH by increasing hydrogen ion concentration.
10. Hydrogen sulfide will deteriorate what kind of structures?
Answer: Concrete structures ✅
Rationale: H₂S reacts with moisture to form sulfuric acid, which corrodes concrete.
11. The higher the pH, the better the disinfection.
Answer: False ✅
Rationale: Chlorine disinfection is most effective at lower pH values.
12. Maintain a dissolved oxygen concentration of 12 to 14 mg/L in the aeration tank.
Answer: False ✅
Rationale: Typical DO in aeration tanks is 2–4 mg/L; 12–14 mg/L is excessive.
13. What happens when the velocity of the wastewater in a clarifier is greater in some
sections than others?
– 2026 Latest Questions and Answers for Certification Prep
CA Grade 2 Wastewater Treatment Operator Practice Exam –
1. 1 mg/L is the same as 1 part per billion.
Answer: False ✅
Rationale: 1 mg/L is equivalent to 1 part per million (ppm), not part per billion.
2. A SCADA system is capable of monitoring and controlling equipment from where?
Answer: Remote location ✅
Rationale: SCADA (Supervisory Control and Data Acquisition) allows operators to monitor and
control equipment remotely.
3. A Discharge Monitoring Report is typically submitted to the regulatory agency on a
daily basis.
Answer: False ✅ – It is typically submitted monthly.
Rationale: Most regulatory agencies require monthly reports unless specified otherwise.
4. A mechanical seal is used to prevent leaks between where?
Answer: Between the pump casing and shaft ✅
Rationale: Mechanical seals prevent leakage of fluid along the rotating shaft of a pump.
5. Alkalinity is the capacity of a liquid to neutralize a base.
Answer: False ✅ – Alkalinity neutralizes acids.
Rationale: Alkalinity measures the ability of water to resist changes in pH by neutralizing acids.
, 6. Typical mixed liquor suspended solids (MLSS) concentration is?
Answer: 1,000 to 4,500 mg/L ✅
Rationale: Standard MLSS levels for conventional activated sludge processes.
7. Turbidity is caused by…
Answer: Suspended matter ✅
Rationale: Particles suspended in water scatter light, causing turbidity.
8. Algae is not essential to the successful operation of both aerobic and facultative ponds.
Answer: False ✅ – Algae supply most of the oxygen to the supernatant.
Rationale: Algae photosynthesis provides oxygen needed by aerobic bacteria.
9. The addition of acid and CO₂ will do what to wastewater?
Answer: Lower the pH of wastewater ✅
Rationale: Acids decrease pH by increasing hydrogen ion concentration.
10. Hydrogen sulfide will deteriorate what kind of structures?
Answer: Concrete structures ✅
Rationale: H₂S reacts with moisture to form sulfuric acid, which corrodes concrete.
11. The higher the pH, the better the disinfection.
Answer: False ✅
Rationale: Chlorine disinfection is most effective at lower pH values.
12. Maintain a dissolved oxygen concentration of 12 to 14 mg/L in the aeration tank.
Answer: False ✅
Rationale: Typical DO in aeration tanks is 2–4 mg/L; 12–14 mg/L is excessive.
13. What happens when the velocity of the wastewater in a clarifier is greater in some
sections than others?
