The major advantage a GBT has over a centrifuge, in the thickening of activated sludge, is that a GBT does not require polymer in its operation.

1.   ?    True
2.   ?    False

Which basically describes a GBT?

1.   ?    The bottom half of a belt filter press
2.   ?    The top half of a belt filter press
3.   ?    A machine that does not resemble a belt filter press
4.   ?    A machine that stabilizes WAS

What is the main purpose for the chicanes on the GBT?

1.   ?    To mix polymer and sludge feed
2.   ?    To break-up scum
3.   ?    To turn-over sludge and release free water
4.   ?    To dewater sludge by squeezing out bound water

What is a typical percent solids in the product of a GBT system?

1.   ?    1% to 2%
2.   ?    10% to 15%
3.   ?    20% to 25%
4.   ?    4% to 8%

What device is used to blend polymer and sludge feed?

1.   ?    Retention vessel
2.   ?    Venturi mixer
3.   ?    Chicanes
4.   ?    Drive unit

What is the purpose for the washwater nozzles on a GBT?

1.   ?    To clean the chicanes
2.   ?    To clean the venturi mixer
3.   ?    To clean the belts
4.   ?    To backflush the hydraulic pump

What items should be evaluated, and what actions should be performed, if the gravity belt floods during operation?
Select only one answer

1.   ?    Polymer dose rate
2.   ?    Mixing energy
3.   ?    Sludge feed rate
4.   ?    Belt speed
5.   ?    All of the Above

What are the major effects of polymer conditioning? Select only one answer

1.   ?    Promote rapid desorption
2.   ?    Neutralize sludge particle charge
3.   ?    Conglomerate small particles through bridging
4.   ?    Unbinding of surface water
5.   ?    All of the Above

Acceptable quality filtrate (on a GBT) should have a TSS level about:

1.   ?    5 to 15 ppm
2.   ?    50 to 100 ppm
3.   ?    500 to 1,000 ppm
4.   ?    1.0% TS

If the hydraulic system reservoir level drops, will the hydraulic system temperature increase or decrease? What problems may result?

1.   ?    Increase
2.   ?    Decrease

What action should be performed if there are streaks of sludge on the belt of a GBT?

1.   ?    Increase the sludge feed rate
2.   ?    Increase the polymer feed rate
3.   ?    Reduce the belt speed
4.   ?    Clean the washbox nozzles

What 15 minute test will help to identify the GBT thickened sludge concentration?

1.   ?    Laboratory TSS
2.   ?    Centrifuge spindown
3.   ?    Settleometer
4.   ?    Filter press

What adjustment should be considered if the feed sludge floc is too large entering the top feed chute of a GBT?

1.   ?    Increase the opening of the venturi mixer
2.   ?    Increase the belt speed
3.   ?    Increase the polymer feed rate
4.   ?    Decrease the opening of the venturi mixer

What causes the sludge to float to the surface in the DAF process?

1.   ?    Wasting sludge at a fast rate
2.   ?    Withdrawing bottom sludge
3.   ?    The addition of air-saturated recycle water
4.   ?    The addition of polymer

Will sludge be more likely to sink or float when its specific gravity is less than 1.0?

1.   ?    Sink
2.   ?    Float
3.   ?    Stay in suspension
4.   ?    Specific gravity has no affect on flotation

What is the top blanket of thickened sludge called in the DAF process?

1.   ?    Float sludge
2.   ?    Bottom sludge
3.   ?    Subnatant
4.   ?    George

What is the typical total solids concentration range for thickened sludge in a properly operated DAF process?

1.   ?    6% to 8%
2.   ?    7% to 10%
3.   ?    1% to 2%
4.   ?    3% to 5%

Where does the DAF pressurized water stream originally come from?

1.   ?    Thickener liquid effluent
2.   ?    Waste sludge flow
3.   ?    Potable water system
4.   ?    Reuse water system

Where does the DAF pressurized water stream directly come from?

1.   ?    Thickener liquid effluent
2.   ?    Waste sludge flow
3.   ?    Potable water system
4.   ?    Reuse water system

Increasing the air saturation into the recycle stream of a DAF can be accomplished two ways. What is one of the methods?

1.   ?    Increasing the polymer dosage
2.   ?    Decreasing the skimmer speed/frequency
3.   ?    Shutting off the pressurization pump
4.   ?    Increasing the amount of air into the pressurization tank

What is another method of increasing the air saturation into the recycle stream in a DAF?

1.   ?    Decreasing the waste sludge rate
2.   ?    Increasing the volume of recycle water through the system
3.   ?    Increasing the bottom sludge withdrawal rate
4.   ?    Decreasing the volume of recycle water through the system

What does the rise rate test tell you?

1.   ?    Bottom sludge level
2.   ?    Waste sludge rate
3.   ?    Volume of recycle water
4.   ?    Amount of air in the recycle water

What does it mean when there is a slow floc time accompanied with a normal rise time?

1.   ?    Too much polymer and not enough air
2.   ?    Not enough polymer and the proper amount of air
3.   ?    Not enough polymer and not enough air
4.   ?    The air compressor has been off for several hours