Operator Class 1 Exam Practice

Maryland Wastewater Treatment Operator Class 1 Exam Practice 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 before discharge
• Generate electricity
• Produce sludge only

B The main goal is to remove harmful pollutants to protect public health and the environment.

• The first step in wastewater treatment is typically: 1 / 4

• Secondary treatment
• Disinfection
• Preliminary treatment
• Tertiary filtration

C Preliminary treatment removes large debris to protect downstream equipment.

3. A bar screen is used to remove:

• Dissolved solids
• Grit
• Large debris
• Pathogens

C Screens capture rags, sticks, and coarse solids.

4. Grit chambers remove:

• Organic solids
• Heavy inorganic particles
• Oils
• Pathogens

B Grit chambers settle dense particles like sand and gravel.

5. Primary clarifiers remove mainly: 2 / 4

• Dissolved solids
• Floatable oils
• Settleable solids
• Pathogens

C Primary clarification targets settleable and floatable solids.

• In activated sludge, microorganisms that break down organic matter are

called:

• Viruses
• Protozoa
• Bacteria
• Fungi

C Bacteria perform most biochemical degradation of organic pollutants.

7. The measure of oxygen needed to stabilize organic matter is:

A. TSS

• pH

C. BOD

• Alkalinity

C Biochemical Oxygen Demand (BOD) indicates organic strength of wastewater. 3 / 4

• What is DO in wastewater treatment?
• Dust output
• Dissolved oxygen
• Dissolved organics
• Distributed oxygen

B DO indicates the oxygen available for biological processes.

9. Low DO in an aeration tank usually indicates:

• Excess aeration
• Poor mixing
• Too much oxygen
• High chlorine

B Insufficient aeration or mixing causes low DO.

10. The activated sludge process relies on:

• Chemical reactions
• Biological oxidation
• Incineration
• Filtration only

B Microorganisms oxidize organic pollutants biologically.

• Sludge that settles poorly and is fluffy is called:
• / 4