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Treatment 1 > Secondary Treatment > Flashcards

Secondary Treatment Flashcards

1
Q

A recirculation rate of 1:1 means which of the following:

a) 50% dilution in the BOD test
b) Total flow to the trickling filter is 2.0 ML/day
c) Total flow to the trickling filter is twice that of incoming flow
d) Total flow is unchanged

A

c) Total flow to the trickling filter is twice that of incoming flow

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2
Q 
A trickling filter receiving a flow of 9.6 m3
/m2/day would be classified as a:
a) Low-rate filter
b) Polishing filter
c) High-rate filter
d) Second-stage filter
A

c) High-rate filter

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3
Q

The slime growth on the media of a trickling filter is sometimes called the:

a) Bio-matt
b) Zoogleal film
c) Sloughing layer
d) Autotrophic zone

A

b) Zoogleal film

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4
Q

The flow of air through a trickling filter in winter conditions is:

a) Downward
b) Low
c) Upward
d) Accelerated

A

c) Upward

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5
Q

The effect of a primary sedimentation tank sludge pumping cycle that was too short on a trickling filter would be:

a) Waste stream to filter turns dark
b) Septic odour develops
c) Filter media turns black
d) All of the above

A

d) All of the above

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6
Q

Rotating biological contactors are a fixed film process. What is a fixed film?

a) A thin sheet of plastic covering the biological treatment system to prevent algae growth
b) A viscous jellylike slime containing living organisms such as bacteria, protozoa, algae and fungi
c) A viscous film made up of algae only
d) A jellylike film of glucose, organic polymers and worms

A

b) A viscous jellylike slime containing living organisms such as bacteria, protozoa, algae and fungi

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7
Q

Fixed film systems are affected by variations in which of the following?

a) pH, alkalinity, BOD5 and temperature
b) pH, total suspended solids and grit
c) Alkalinity, total Kjeldahl nitrogen, total nitrogen and nitrate
d) Transmittance, BOD5 and total phosphate

A

a) pH, alkalinity, BOD5 and temperature

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8
Q

Rotating biological contactors do not require which of the following?

a) Oxygen
b) Nutrients
c) Cleaning of the discs
d) Equipment to waste sludge

A

c) Cleaning of the discs

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9
Q

The lower regions of a trickling filter are normally anaerobic because of reduced air flow.

a) True
b) False

A

b) False

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10
Q

Reddish brown patches on an RBC disk are indications of the presence of Beggiatoa and Thiothrix.

a) True
b) False

A

b) False

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11
Q

Which of the following is not a biological process in lagoons?

a) Stabilization
b) Polishing
c) Oxidation
d) Grit removal

A

a) Stabilization

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12
Q

Which of the following actions should an operator take if he finds the dissolved oxygen in the mixed zone of an aerated lagoon is 2.0 mg/L?

a) Increase the aeration rate to raise the dissolved oxygen concentration to 8 mg/L
b) Shut off the aerators for 48 hours and retest
c) Maintain the present aeration rate
d) Check that the lagoons are being operated in series

A

c) Maintain the present aeration rate

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13
Q

Given the following information, determine the lagoon organic loading: influent flow 120 m3/ day. Influent BOD 169 mg/L, lagoon dimensions 60 m by 60 m by 2.75 m

a) 5.8 kg/day/ha
b) 360 kg/day/ha
c) 56.3 kg/day/ha
d) 515 kg/day/ha

A

c) 56.3 kg/day/ha

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14
Q

Photosynthesis is the conversion of to by algae using sunlight for energy.

a) Carbon dioxide to water
b) Carbon dioxide to methane
c) Carbon dioxide to oxygen
d) Carbon dioxide to ammonia

A

c) Carbon dioxide to oxygen

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15
Q

Freeboard is provided for a lagoon for which of the following reasons?

a) To provide extra capacity for rainfall events
b) For dike stability and room for ice accumulation
c) To protect inlet structures and prevent short-circuiting
d) To permit lowering of water levels and control depths

A

b) For dike stability and room for ice accumulation

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16
Q

The average influent flow to a pond is 1,892 L/min. The pond is 91 cm deep and designed for a 30 day detention time. What is the volume of the pond?

a) 50.5 ML
b) 72.3 ML
c) 81.7 ML
d) 101.0 ML

A

c) 81.7 ML

17
Q

Which of the following forms of plant life is necessary for the proper functioning of a stabilization or oxidation pond?

a) Algae
b) Cattails
c) Water lilies
d) Weeds

A

a) Algae

18
Q

Which of the following materials may be used to prevent seepage from a lagoon?

a) Bentonite clay
b) Polyethylene
c) Vinyl
d) All of the above

A

d) All of the above

19
Q

Surface aerators may be added to a lagoon to produce better effluent when

a) The lagoon is hydraulically overloaded
b) High levels of BOD are carried in the influent
c) Influent contains high levels of non-volatile suspended solids
d) The lagoon is covered by algal mats

A

b) High levels of BOD are carried in the influent

20
Q

Most lagoons are facultative.

a) True
b) False

A

a) True

21
Q

Pond systems with multiple cells whose effluent requirements demand a high degree of treatment are best run in parallel to reduce the organic loading to the units.

a) True
b) False

A

b) False

22
Q

The heaviest oxygen demand on an aerated lagoon is during the day at peak flow.

a) True
b) False

A

a) True

23
Q

The amount of active biomass in an aeration tank may be best estimated using which test?

a) Settleable solids
b) Mixed liquor suspended solids
c) Mixed liquor volatile suspended solids
d) Total dissolved solids

A

c) Mixed liquor volatile suspended solids

24
Q

The conventional activated sludge process:

a) Is a chemical-physical process
b) Requires no oxygen
c) Utilizes a living community of microorganisms
d) Is a suspended-growth process, predominantly anoxic, that maintains a high microorganism population by means of solids recycling from the secondary clarifier

A

c) Utilizes a living community of microorganisms

25
Q

Which of the following processes is eliminated in a sequencing batch reactor activated sludge process?

a) Mixing
b) Aeration
c) Waste activated sludge
d) Return activated sludge

A

d) Return activated sludge

26
Q

Mixed liquor solids are waste from the biological reactor, Effluent solids are negligible. The volume of the activated sludge reactor is 34,977 cubic meters. 9,993 cubic meters of mixed liquor are wasted per day. What is the system’s retention time?

a) 1.5 days
b) 3.5 days
c) 4 days
d) 2.3 days

A

b) 3.5 days

27
Q

Under which one of the following circumstances should sludge wasting normally be increased?

a) Mixed liquor settles too slowly
b) Large quantities of white billowy foam forming on the surface of the aeration tank
c) Both of the above
d) None of the above

A

a) Mixed liquor settles too slowly

28
Q

Which of the following practices is not a method of controlling filamentous organisms

a) Increase RAS rate
b) Add hydrogen peroxide to the RAS at a concentration of up to 100 mg/L
c) Add copper sulfate to the RAS at a concentration of up to 7 mg/L
d) Decreased RAS rate

A

a) Increase RAS rate

29
Q

A dark greasy foam in an aeration tank may be controlled by:

a) Decreasing the F/M ratio
b) Increasing the SRT
c) Increasing the F/M ratio
d) Increasing the sludge wasting rate

A

a) Decreasing the F/M ratio

30
Q

Which of the following is a probable cause for filamentous sludge bulking?

a) Insufficient nutrients
b) Uniform organic loading
c) Low influent sulfide concentrations
d) High DO concentrations in biological reactors

A

a) Insufficient nutrients

31
Q

Nitrification removes ammonia from wastewater as nitrogen gas

a) True
b) False

A

b) False

32
Q

In an activated sludge system, particulate matter is referred to as mixed liquor volatile suspended solids

a) True
b) False

A

b) False

33
Q

If an activated sludge is not settling or compacting well and the SVI is greater than 150 mL/g, there may be excessive growth of filamentous organisms

a) True
b) False

A

a) True

34
Q

High rate activated sludge processes typically have a MCRT of 5 to 15 days

a) True
b) False

A

b) False

35
Q

Adsorption is the taking or soaking up of one substance into the body of another by molecular or chemical action

a) True
b) False

A

b) False

36
Q

An extended aeration package plant typically operates at a low SRT and high F:M

a) True
b) False

A

b) False

Treatment 1 (8 decks)

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