Operator Class I Practice Exam

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

• What is the primary purpose of a wastewater treatment plant?
• Produce drinking water
• Remove pollutants from wastewater
• Generate electricity
• Irrigate crops

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

remove pollutants to protect human health and the environment.

• Which of the following is a typical characteristic of domestic

wastewater?

• High levels of heavy metals 1 / 4

• Contains organic matter and nutrients
• Pure water with no contaminants
• High concentrations of industrial chemicals

Rationale: Domestic wastewater primarily contains organic matter,

nutrients like nitrogen and phosphorus, and pathogens.

• What is BOD?
• Biological Oxygen Demand
• Biochemical Oxygen Demand
• Base Oxygen Demand
• Basic Oxygen Deficiency

Rationale: BOD measures the amount of oxygen microorganisms need

to decompose organic matter in wastewater.

• What is the main purpose of preliminary treatment?
• Reduce nitrogen
• Remove large solids and debris
• Kill pathogens
• Adjust pH

Rationale: Preliminary treatment removes rags, sticks, and grit that

can damage equipment.

• Which process primarily removes suspended solids from wastewater?
• Chlorination
• Sedimentation
• Aeration 2 / 4

• Filtration

Rationale: Sedimentation allows solids to settle out of wastewater by

gravity.

• In activated sludge, what provides the primary mechanism for organic

matter removal?

• Chemicals
• Microorganisms
• Screens
• Filtration

Rationale: Microorganisms consume organic matter, converting it to

more biomass and CO₂.

• What is the primary function of an aeration basin?
• Remove grit
• Supply oxygen to microorganisms
• Chlorinate water
• Filter solids

Rationale: Aeration supplies oxygen so microorganisms can break

down organic pollutants.

• Which of the following is a common method for sludge disposal?
• Bottling
• Land application
• Evaporation only
• Ocean dumping 3 / 4

Rationale: Sludge can be treated and safely applied to land as

fertilizer.

• What is the main goal of secondary treatment?
• Remove large debris
• Reduce BOD and suspended solids
• Disinfect water
• Remove metals

Rationale: Secondary treatment focuses on removing dissolved and

suspended organic matter.

10. Chlorination is primarily used for:

• Removing BOD
• Disinfection
• Filtration
• Aeration

Rationale: Chlorine kills or inactivates pathogenic organisms.

• What does TSS stand for in wastewater treatment?
• Total Salt Solids
• Total Sulfate Substances
• Total Suspended Solids
• Total Standard Salts

Rationale: TSS measures the amount of particles suspended in water.

• Which factor affects the rate of BOD removal in a treatment

system?

• / 4