Exam Practice Questions And Correct

Mississippi Wastewater Operator Class I Exam Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

1. The primary purpose of a wastewater treatment plant is to:

• Increase water hardness
• Produce drinking water
• Remove contaminants from wastewater
• Generate electricity

Rationale: The main goal of a wastewater treatment plant is to

remove pollutants and protect public health and the environment.

• Which of the following is considered a physical treatment process?
• Chlorination
• Biological digestion 1 / 4

• Sedimentation
• Nitrification

Rationale: Sedimentation removes suspended solids by gravity,

which is a physical process.

• What does BOD stand for?
• Biological Oxidation Demand
• Biochemical Oxygen Demand
• Basic Oxygen Depletion
• Bacterial Oxidation Detection

Rationale: BOD measures the amount of oxygen required by

microorganisms to decompose organic matter in water.

4. The first step in wastewater treatment is usually:

• Aeration
• Screening
• Chlorination
• Filtration

Rationale: Screening removes large debris and solids from incoming

wastewater to protect equipment downstream.

• Which of the following is a chemical method of disinfection?
• UV light
• Filtration
• Chlorination
• Sedimentation 2 / 4

Rationale: Chlorination uses chemicals to kill pathogens in

wastewater.

6. Sludge digestion primarily occurs in:

• Aeration tanks
• Sedimentation tanks
• Anaerobic digesters
• Trickling filters

Rationale: Anaerobic digesters break down sludge using

microorganisms in the absence of oxygen.

7. A lagoon system is an example of:

• Physical treatment
• Chemical treatment
• Biological treatment
• Advanced oxidation

Rationale: Lagoons use natural biological processes to treat

wastewater over time.

8. pH is a measure of:

• Dissolved oxygen
• Acidity or alkalinity
• Turbidity
• Temperature

Rationale: pH indicates the hydrogen ion concentration and whether

the water is acidic, neutral, or basic. 3 / 4

9. Nitrification is the conversion of:

• Nitrite to nitrogen gas
• Ammonia to nitrate
• Nitrate to ammonia
• Nitrogen gas to ammonia

Rationale: Nitrifying bacteria convert ammonia into nitrite and then

nitrate in aerobic conditions.

• The minimum dissolved oxygen concentration required for

aerobic bacteria in secondary treatment is typically:

• 0.5 mg/L
• 2 mg/L
• 5 mg/L
• 8 mg/L

Rationale: Maintaining at least 2 mg/L DO ensures effective

biological treatment in aerobic systems.

• A stormwater inflow during wet weather that enters the

collection system is called:

• Effluent
• Infiltration/Inflow (I/I)
• Biosolids
• Leachate

Rationale: I/I refers to water from rain or groundwater that enters

the sewer system, increasing flow.

• / 4