Wastewater Operator Class C Exam

South Carolina Physical/Chemical Wastewater Operator Class C Exam Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary purpose of coagulation in wastewater treatment?
• To disinfect the water
• To remove suspended solids by chemical aggregation
• To increase pH
• To aerate the water

Coagulation adds chemicals that cause fine particles to clump together, making them easier to remove in subsequent sedimentation steps.

• What is the most commonly used coagulant in municipal wastewater

treatment? 1 / 4

• Sodium hydroxide
• Aluminum sulfate (alum)
• Calcium carbonate
• Ferric chloride

Alum is widely used due to its effectiveness in destabilizing colloidal particles.

3. The purpose of sedimentation in physical/chemical treatment is to:

• Increase dissolved oxygen
• Reduce nitrogen content
• Remove suspended solids by allowing them to settle
• Adjust pH

Sedimentation allows heavier particles to settle out under gravity.

• What factor does NOT significantly affect coagulation efficiency?
• Water temperature
• pH
• Color of water
• Mixing intensity

While water color may indicate organic content, it does not directly affect the chemical reactions in coagulation.

5. Flocculation is the process of:

• Gently mixing water to promote particle aggregation after

coagulation

• Removing bacteria 2 / 4

• Increasing water hardness
• Adjusting pH

Flocculation encourages formation of larger flocs that can settle in sedimentation basins.

• What is the main purpose of filtration in wastewater treatment?
• Remove remaining suspended solids
• Add nutrients to the water
• Remove dissolved oxygen
• Lower pH

Filters physically remove particles that were not removed during sedimentation.

• Which type of filter is commonly used in physical/chemical

wastewater treatment?

• Reverse osmosis
• Activated carbon only
• Rapid sand filter
• Ultraviolet filter

Rapid sand filters are commonly used for polishing water after sedimentation.

8. The term “turbidity” refers to:

• pH
• Temperature
• Cloudiness caused by suspended solids 3 / 4

• Color

Turbidity is a measure of water clarity affected by particles in suspension.

9. A typical coagulant aid used in physical/chemical treatment is:

• Chlorine
• Polymers (synthetic flocculants)
• Ozone
• Lime

Polymers enhance floc formation and improve settling.

• What is the main chemical used for pH adjustment in

wastewater treatment?

• Chlorine
• Lime (Ca(OH)₂)
• Alum
• Fluoride

Lime raises pH and helps with chemical precipitation of metals and phosphorus.

11. In chemical precipitation, phosphorus is typically removed using:

• Chlorine
• Ozone
• Alum or ferric salts
• Sodium hydroxide only
• / 4