Class II Practice Exam Questions And

Industrial Waste Treatment Operator Class II Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• The main purpose of equalization in an industrial waste treatment plant is

to:

• Increase flow velocity
• Reduce fluctuations in flow and pollutant concentration
• Improve sedimentation rate
• Neutralize acidic waste

Rationale: Equalization tanks balance flow and load variations, improving

downstream process stability.

• The most common type of pH adjustment chemical used for acidic

wastewater is: 1 / 4

• Sulfuric acid
• Ferric chloride
• Sodium hydroxide
• Alum

Rationale: Caustic soda (NaOH) neutralizes acidic wastes effectively and is

widely available.

• Which parameter is most directly reduced by air stripping?
• Total suspended solids (TSS)
• Biological oxygen demand (BOD)
• Volatile organics
• Heavy metals

Rationale: Air stripping removes volatile contaminants such as ammonia and

solvents.

4. The efficiency of a clarifier is primarily determined by:

• Mixing rate
• Depth
• Surface overflow rate
• Tank color

Rationale: Clarifier performance depends on the surface area and flow rate,

expressed as surface overflow rate. 2 / 4

• Which type of bacteria predominates in activated sludge?
• Anaerobic
• Aerobic heterotrophic
• Autotrophic nitrifiers
• Facultative

Rationale: Activated sludge systems rely on aerobic heterotrophic bacteria

to oxidize organic matter.

6. The main byproduct of anaerobic digestion is:

• Nitrogen
• Methane
• Oxygen
• Ammonia

Rationale: Anaerobic microorganisms convert organics into biogas rich in

methane.

7. The sludge volume index (SVI) measures:

• Chlorine demand
• Sludge density
• Settling characteristics of sludge
• Dissolved oxygen 3 / 4

Rationale: SVI indicates the settleability of mixed liquor suspended solids in

activated sludge systems.

8. A high F/M ratio generally indicates:

• Starved microorganisms
• Overloaded biological system
• Efficient treatment
• Low BOD removal

Rationale: High food-to-microorganism ratios cause poor settling and high

effluent BOD.

• Which laboratory test best measures the organic load on a treatment

system?

A. TSS

B. TDS

C. BOD

• pH

Rationale: BOD quantifies the amount of biodegradable organic material

present.

10. In chemical precipitation, metal hydroxides are formed by:

• Oxidation
• / 4