PAC 1 EXAM QUESTIONS WITH VERIFIED ANSWERS
Which of the following is used for sludge dewatering
A. sludge digesters
B. sludge settling tanks
C. twin belt press
D. media filter - Answers - C. twin belt press
If incoming sludge is highly variable or operator attention is minimal, it is desired to have
a product with a wide operating window. Which flocculant would you choose? - Answers
- The one with the largest operating window
When treating sludge with a flocculant, which of the following impacts the flocculant
performance?
A. polymer-sludge mixing energy
B. sludge solids consistency and sludge ratio
C. temperature and pH
D. aging of polymer after activation
E. all of the above - Answers - E. all of the above
The primary purpose of a "gravity drainage zone" is
A. mechanical pressure promoting drainage
B. belt changes direction and gravity causes the filter cake to drop free
C. free water drainage from solids
D. chemical is mixed with sludge to form "drainable" floc - Answers - C. free water
drainage from solids
Increasing the speed of a belt on a twin belt press while leaving the sludge and polymer
flow dosage unchanged will typically result in
A. decreased throughput
B. increase belt life
C. Decreased cake dryness
D. increased throughput - Answers - C. Decreased cake dryness
After running a gravity filter test to determine the best flocculant for a dewatering
application, a graph is generated. Sludge disposal costs greatly outweigh chemical
treatment cost and the customer want to get the driest cake possible. Which flocculant
should be chosen? - Answers - The flocculant that provides the most drainage, which
would result in the driest cake
Which of the following devices is NOT used for sludge dewatering?
A, Centrifuge
, B. Belt Filter Press
C. Up-flow clarifiers
D. Plate and frame press - Answers - C. Up-flow clarifiers
When selecting a flocculant for sludge dewatering it is best to use which test method?
A. sludge solids test
B. drainage test
C. Jar test
D. micro-particle test - Answers - B. drainage test
Recirculated sludge aids in clarification by:
A. preventing carryover of floc particles
B. keeping fluid and not plugging the blowdown line
C. providing alkalinity to the process
D. "sweeping" coagulated particles out of the water - Answers - D. "sweeping"
coagulated particles out of the water
Temperatures near freezing have no effect on clarifier operations.
True
False - Answers - False
When evaluating common causes of floc carryover from a clarifier, you must consider:
A. short circuiting
B. excessive rise rate
C. air entrainment
D. Flow surges due to rapid flow changes
E. All of the above - Answers - E. All of the above
Clarification removes which of the following:
A. Emulsified oils
B. Sodium, potassium, chloride and sulfate
C. Suspended solids
D. Colloidal solids - Answers - D. Colloidal solids
The source of color in most surface waters is:
A. micro-organism growth
B. Dissolved mineral salts
C. Lignins and Tannins
D. industrial waste - Answers - C. Lignins and Tannins
The purpose of sludge or solids in a solids contact clarifier is to:
A. add density to the blowdown
B. reduce water velocity through the clarifier
C. contact fine coagulated particles to form larger particles
D. prevent untreated water from passing through the clarifier
Which of the following is used for sludge dewatering
A. sludge digesters
B. sludge settling tanks
C. twin belt press
D. media filter - Answers - C. twin belt press
If incoming sludge is highly variable or operator attention is minimal, it is desired to have
a product with a wide operating window. Which flocculant would you choose? - Answers
- The one with the largest operating window
When treating sludge with a flocculant, which of the following impacts the flocculant
performance?
A. polymer-sludge mixing energy
B. sludge solids consistency and sludge ratio
C. temperature and pH
D. aging of polymer after activation
E. all of the above - Answers - E. all of the above
The primary purpose of a "gravity drainage zone" is
A. mechanical pressure promoting drainage
B. belt changes direction and gravity causes the filter cake to drop free
C. free water drainage from solids
D. chemical is mixed with sludge to form "drainable" floc - Answers - C. free water
drainage from solids
Increasing the speed of a belt on a twin belt press while leaving the sludge and polymer
flow dosage unchanged will typically result in
A. decreased throughput
B. increase belt life
C. Decreased cake dryness
D. increased throughput - Answers - C. Decreased cake dryness
After running a gravity filter test to determine the best flocculant for a dewatering
application, a graph is generated. Sludge disposal costs greatly outweigh chemical
treatment cost and the customer want to get the driest cake possible. Which flocculant
should be chosen? - Answers - The flocculant that provides the most drainage, which
would result in the driest cake
Which of the following devices is NOT used for sludge dewatering?
A, Centrifuge
, B. Belt Filter Press
C. Up-flow clarifiers
D. Plate and frame press - Answers - C. Up-flow clarifiers
When selecting a flocculant for sludge dewatering it is best to use which test method?
A. sludge solids test
B. drainage test
C. Jar test
D. micro-particle test - Answers - B. drainage test
Recirculated sludge aids in clarification by:
A. preventing carryover of floc particles
B. keeping fluid and not plugging the blowdown line
C. providing alkalinity to the process
D. "sweeping" coagulated particles out of the water - Answers - D. "sweeping"
coagulated particles out of the water
Temperatures near freezing have no effect on clarifier operations.
True
False - Answers - False
When evaluating common causes of floc carryover from a clarifier, you must consider:
A. short circuiting
B. excessive rise rate
C. air entrainment
D. Flow surges due to rapid flow changes
E. All of the above - Answers - E. All of the above
Clarification removes which of the following:
A. Emulsified oils
B. Sodium, potassium, chloride and sulfate
C. Suspended solids
D. Colloidal solids - Answers - D. Colloidal solids
The source of color in most surface waters is:
A. micro-organism growth
B. Dissolved mineral salts
C. Lignins and Tannins
D. industrial waste - Answers - C. Lignins and Tannins
The purpose of sludge or solids in a solids contact clarifier is to:
A. add density to the blowdown
B. reduce water velocity through the clarifier
C. contact fine coagulated particles to form larger particles
D. prevent untreated water from passing through the clarifier
