I Certification Practice Exam Questions And

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

• The primary purpose of preliminary treatment in industrial wastewater is

to:

• Remove nutrients
• Reduce biochemical oxygen demand
• Remove large solids and grit
• Disinfect effluent

Rationale: Preliminary treatment screens out debris and grit to protect

downstream equipment.

2. The main function of a bar screen is to:

• Measure flow
• Remove large floating debris
• Reduce BOD 1 / 3

• Aerate wastewater

Rationale: Bar screens trap large solids like rags and plastics to prevent

damage to pumps.

3. The pH scale measures:

• Turbidity
• Hardness
• Acidity or alkalinity
• Solids concentration

Rationale: pH quantifies hydrogen ion concentration, indicating acidic or

basic nature.

4. The most common method to neutralize acidic wastewater is:

• Adding sulfuric acid
• Adding lime or sodium hydroxide
• Aeration
• Chlorination

Rationale: Caustic compounds raise pH by neutralizing excess hydrogen ions.

5. The unit mg/L is equivalent to:

• Grams per liter
• Parts per million (ppm)
• Kilograms per cubic meter
• Percent concentration

Rationale: At water’s density, 1 mg/L equals 1 ppm. 2 / 3

6. The biological treatment process primarily removes:

• Heavy metals
• Organic matter
• Grit and grease
• Suspended solids

Rationale: Microorganisms consume organic matter, lowering BOD.

7. Activated sludge relies on:

• Chemical oxidation
• Sedimentation only
• Aerobic microorganisms
• Anaerobic digestion

Rationale: Oxygen supports aerobic bacteria that break down organics.

8. The MLSS in an aeration tank represents:

• Flow rate
• Dissolved oxygen
• Concentration of suspended solids
• pH

Rationale: MLSS quantifies biomass in the mixed liquor.

9. The main source of nitrogen in industrial wastewater is:

• Silica
• Sulfate
• Ammonia or organic nitrogen
• Chloride
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