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Flashcards in Residual Disposal Deck (18)
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1
Q

In the precipitative softening plant, which percentage of solids sludge is produced?

a. 1%
b. 5%
c. 10%
d. 30%

A

b. 5%

2
Q

Which sludge disposal method is most economical for lime-soda ash softening plants?

a. Disposal into the sewage system
b. Sand drying beds
c. Lagoons
d. Landfill the sludge

A

c. Lagoons

3
Q

Current regulations require water treatment wastes to be monitored ________.

a. daily.
b. weekly.
c. monthly.
d. quarterly.

A

a. daily.

4
Q

Which process is used to concentrate sludge?

a. Sand bed
b. Solar lagoon
c. Thickener
d. Centrifuge

A

c. Thickener

5
Q

Which process is used to dewater sludge?

a. Wash water basin
b. Sand bed
c. Thickener
d. Reclamation basin

A

b. Sand bed

6
Q

Which is the total concentration of dissolved solids in the wastewater from the regeneration of ion exchange units?

a. 10,000 to 20,000 mg/L
b. 20,000 to 30,000 mg/L
c. 35,000 to 45,000 mg/L
d. 45,000 to 60,000 mg/L

A

c. 35,000 to 45,000 mg/L

7
Q

Which is the usual range of percent sludge solids, if the sludge is allowed to accumulate and compact at the bottom of a sedimentation basin?

a. 2 - 4%
b. 4 - 7%
c. 7 - 12%
d. 12 - 15%

A

a. 2 - 4%

8
Q

Which should be determined first before an in-ground sedimentation tank is drained?

a. The solids content
b. The hazardous metals content
c. Sludge volume and volume of process area to make sure it will be large enough.
d. Water table level

A

d. Water table level

9
Q

Which sludge dewatering process is best for alum sludges (which are difficult to dewater) when the cakes are very dry, filtrate is clear, and solids capture is very high?

a. Centrifuge
b. Vacuum filters
c. Filter press
d. Belt filter press

A

c. Filter Press

10
Q

Which national law regulates underground disposal of wastes in deep wells?

a. The Toxic Substance Control act (TSCA)
b. The Comprehensive Environmental Response Compensation, and Liability Act (Superfund).
c. The Resource Conservation and Recovery Act (RCRA)
d. The Safe Drinking Water Act

A

d. The Safe Drinking Water Act

11
Q

Which is typically the percentage of solid material of alum sludge?

a. 0.1 to 2.0%
b. 2.0 to 5.0%
c. 4.0 to 7.0%
d. 5.0 to 15%

A

a. 0.1% to 2.0%

12
Q

Which is the most troublesome operating problem for sedimentation basins?

a. Algae and slime growths
b. Short-circuiting
c. Density currents
d. Sludge collection and removal

A

d. Sludge collection and removal.

13
Q

Sludge produced by water drawn from sources with relatively low turbidity __________.

a. is high in silt and organic content.
b. is high in liquid content.
c. can be very gelatinous and difficult to handle.
d. handles like clay.

A

c. can be very gelatinous and difficult to handle.

14
Q

Which is the recommended number of solar drying Lagoons?

a. 2
b. 3
c. 4
d. 5

A

b. 3

15
Q

Which sludge dewatering process has a low consumption of energy, is easy to operate, has small land requirements, and can produce a dry filter cake of between 35% and 40% solids?

a. Centrifuge
b. Vacuum filters
c. Filter press
d. Belt filter press

A

d. Belt filter press

16
Q

Which sludge dewatering process has the advantage of varying the density of the sludge cake from a thickened liquid slurry to a dry cake?

a. Centrifuge
b. Vacuum filters
c. Filter press
d. Belt filter press

A

a. Centrifuge

17
Q

Which sludge dewatering process requires a precoat of diatomaceous earth and its use has declined due to other newer methods?

a. Centrifuge
b. Vacuum filters
c. Filter press
d. Belt filter press

A

b. Vacuum Filters

18
Q

The concentration of solids in the lower level of a

sludge blanket in a softening facility’s solid contact

basin should be _________.

A

5% to 15%