Npdes Oil & Grease Discharge
Compliance Exam Practice Questions
And Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A | Instant
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1. What is the primary regulatory purpose of oil and grease monitoring
under NPDES permits?
A) To measure dissolved oxygen
B) To control hydrocarbon pollution in wastewater
C) To regulate nitrogen levels
D) To measure pH fluctuations
Answer: B
Rationale: Oil and grease monitoring is used to control and limit
hydrocarbon and fatty waste discharges into receiving waters.
2. Which parameter is commonly used to measure oil and grease in
wastewater?
A) BOD
, B) TSS
C) Hexane Extractable Material (HEM)
D) COD
Answer: C
Rationale: Oil and grease are typically measured as hexane
extractable material using solvent extraction methods.
3. Which EPA method is most commonly used for oil and grease analysis?
A) Method 200.7
B) Method 8260
C) Method 1664
D) Method 300.0
Answer: C
Rationale: EPA Method 1664 is the standard method for measuring
oil and grease using n-hexane extraction.
4. What is the preferred sample container for oil and grease analysis?
A) Plastic bottle
B) Metal container
C) Glass bottle
D) Polyethylene bag
Answer: C
Rationale: Glass containers are used because plastics can absorb or
leach hydrocarbons.
,5. What is the required sample preservation for oil and grease?
A) Freeze immediately
B) Acidify to pH < 2 and refrigerate at 4°C
C) Add chlorine
D) Heat to 60°C
Answer: B
Rationale: Samples must be acidified and refrigerated to prevent
biodegradation and volatilization.
6. What is the typical holding time for oil and grease samples?
A) 7 days
B) 14 days
C) 28 days
D) 48 hours
Answer: C
Rationale: EPA allows up to 28 days holding time when properly
preserved.
7. Which process best separates oil from wastewater?
A) Filtration
B) Sedimentation
C) Skimming
D) Chlorination
Answer: C
, Rationale: Skimming physically removes floating oil from water
surfaces.
8. What type of oil is most likely to float on water?
A) Emulsified oil
B) Dissolved oil
C) Free oil
D) Heavy tar oil
Answer: C
Rationale: Free oil is less dense than water and rises to the surface.
9. Which device is commonly used in industrial oil-water separation?
A) UV reactor
B) API separator
C) Aeration tank
D) Sand filter
Answer: B
Rationale: API separators are designed to remove oil based on
gravity separation.
10. What is a major source of oil and grease in industrial
wastewater?
A) Cooling towers
B) Domestic toilets
C) Food processing and petroleum operations
D) Rainwater
Compliance Exam Practice Questions
And Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A | Instant
Download Pdf
1. What is the primary regulatory purpose of oil and grease monitoring
under NPDES permits?
A) To measure dissolved oxygen
B) To control hydrocarbon pollution in wastewater
C) To regulate nitrogen levels
D) To measure pH fluctuations
Answer: B
Rationale: Oil and grease monitoring is used to control and limit
hydrocarbon and fatty waste discharges into receiving waters.
2. Which parameter is commonly used to measure oil and grease in
wastewater?
A) BOD
, B) TSS
C) Hexane Extractable Material (HEM)
D) COD
Answer: C
Rationale: Oil and grease are typically measured as hexane
extractable material using solvent extraction methods.
3. Which EPA method is most commonly used for oil and grease analysis?
A) Method 200.7
B) Method 8260
C) Method 1664
D) Method 300.0
Answer: C
Rationale: EPA Method 1664 is the standard method for measuring
oil and grease using n-hexane extraction.
4. What is the preferred sample container for oil and grease analysis?
A) Plastic bottle
B) Metal container
C) Glass bottle
D) Polyethylene bag
Answer: C
Rationale: Glass containers are used because plastics can absorb or
leach hydrocarbons.
,5. What is the required sample preservation for oil and grease?
A) Freeze immediately
B) Acidify to pH < 2 and refrigerate at 4°C
C) Add chlorine
D) Heat to 60°C
Answer: B
Rationale: Samples must be acidified and refrigerated to prevent
biodegradation and volatilization.
6. What is the typical holding time for oil and grease samples?
A) 7 days
B) 14 days
C) 28 days
D) 48 hours
Answer: C
Rationale: EPA allows up to 28 days holding time when properly
preserved.
7. Which process best separates oil from wastewater?
A) Filtration
B) Sedimentation
C) Skimming
D) Chlorination
Answer: C
, Rationale: Skimming physically removes floating oil from water
surfaces.
8. What type of oil is most likely to float on water?
A) Emulsified oil
B) Dissolved oil
C) Free oil
D) Heavy tar oil
Answer: C
Rationale: Free oil is less dense than water and rises to the surface.
9. Which device is commonly used in industrial oil-water separation?
A) UV reactor
B) API separator
C) Aeration tank
D) Sand filter
Answer: B
Rationale: API separators are designed to remove oil based on
gravity separation.
10. What is a major source of oil and grease in industrial
wastewater?
A) Cooling towers
B) Domestic toilets
C) Food processing and petroleum operations
D) Rainwater
