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16 Questions

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Sludge Thickening Process

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Questions and Answers

What is the purpose of sludge thickening prior to the sludge stabilization process?

To increase the ability to mix and pump the sludge

To reduce the volume of sludge (correct)

To improve digester performance

To decrease the solids content of the sludge

What is the upper limit of solids concentration that can be effectively treated in digesters?

10% - 12%

7% - 9% (correct)

5% - 7%

3% - 5%

If a 5000 mg/l (0.5%) sludge is thickened to 5% solids concentration, by how much will it reduce the volume of sludge?

50%

70%

90% (correct)

60%

Which type of sludge is more suitable for a gravity thickener?

Primary sludge Signup and view all the answers

What are the principles of gravity thickener operations based on?

Gravity and settling Signup and view all the answers

What are the advantages of sludge thickening?

Cost savings associated with less digester volume requirements Signup and view all the answers

What is the purpose of the picket fence-like mechanism attached to the bottom sludge rake arms?

To release entrapped gases Signup and view all the answers

Why are the sludge rake arms rotated at a very slow speed in a gravity thickener?

To prevent turbulence causing the sludge to rise Signup and view all the answers

What is the purpose of the scum removal mechanism in a gravity thickener?

To remove scum from the top Signup and view all the answers

What does SVR (Sludge Volume Ratio) provide a means of regulating in a gravity thickener?

The detention time of sludge within the blanket Signup and view all the answers

Why is primary sludge not generally suitable for thickening using Dissolved Air Floatation Thickener (DAFT)?

Its solids are heavier and do not float easily Signup and view all the answers

What is the typical range for Sludge Volume Ratios (SVRs) for primary sludge in a gravity thickener?

0.5 - 2 days Signup and view all the answers

What is the primary principle difference between a gravity thickener and a Dissolved Air Floatation Thickener (DAFT)?

The location of the thickened sludge blanket Signup and view all the answers

What is the typical purpose of utilizing chemical additives in a gravity thickener?

To enhance settling and control odors Signup and view all the answers

What is the typical solids loading rate of a gravity thickener used for thickening primary sludge?

20-30 lbs TS/day-ft2 Signup and view all the answers

What is the typical purpose of maintaining the sludge blanket depth in a gravity thickener?

To ensure that the sludge does not turn septic and the effluent is relatively clear and free of solids. Signup and view all the answers