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5 Cards in this Set

  • Front
  • Back
1. Denitrification in an activated sludge plant involves:
(a)
The oxidation of ammonia to nitrates
(b)
High concentrations of DO in the mixed liquor as it settles in the secondary clarifier
(c ) The biological oxidation of nitrates to nitric oxide
(d)
The biological reduction of nitrates to nitrogen gas
(e)
Poor compaction of the mixed liquor as it settles in the secondary clarifier
2. A strategy for controlling filamentous bulking, used with increasing frequency in recent years, has been
(a)
The use of an anoxic selector
(b)
The use ofa DAF thickener to selectively float the undesirable filaments so that they may be removed from the mixed liquor.
(c ) The application of 50% hydrogen peroxide solution to the surface of the aeration tank in order to destroy the undesirable filaments
(d)
The application of a I % aqueous solution of "bluestone"
(e)
The application of granular HTH to the surface of the aeration tank
3. Which one of the following statement is true regarding activated sludge wastewater treatment?
(a)
A hydraulic detention time of 0.5 to 1.0 hrs is appropriate in the contact tank in the contact-stabilization process.
(b)
F to M ratios of 0.0 I to 0.1 are appropriate for the complete-mix activated sludge process.
(c)
Oxidation ditches often use platform aerators so that good mixing can be achieved.
(d)
Nocardia are desirable organisms in extended aeration activated sludge plants
(e)
SVI measures the rate at which mixed liquor suspended solids settle.
4. Which of the following statements is true regarding activated sludge wastewater treatment?
(a)
Many modifications of the activated sludge process work well at F to M ratios of 0.5 to 1.5.
(b)
Ifan operator reduces the activated sludge wasting rate, F/M wil increase
(c)
1/SVI = SDI
(d)
If a wastewater operates well at an F to
5. Which one of the following statement is true regarding activated sludge wastewater treatment?
(a)
The white, thick billowing foam common during the startup of an activated sludge plant results from too Iowan F to M ratio.
(b)
SVI measures the rate at which activated sludge mixed liquor settles.
(c)
The "solids balance approach" as applied to the calculation ofQr makes the assumption that the amount of new growth is equal to the amount of solids wasted.
(d)
F to M ratios of 0.2 to 0.5 are appropriate in the operation of extended aeration activated sludge.
(e)
Denitrification in the secondary clarifier of an activated sludge plant often occurs because the concentration of the nitrate ion is too low.