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AWWOA Practice Exams > WW Treatment > Flashcards

WW Treatment Flashcards

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1
Q

Which one of the following is a list of the main purposes of wastewater treatment?
A. Remove pathogens through sterilization, meet all approval requirements, protect downstream users.
B. Meet or exceed Canadian Drinking Water Standards, preserve the environment, minimize costs.
C. Protection of the public from communicable disease, preserve aquatic life, protection of the environment.
D. Remove the trihalomethanes, protect water quality, preserve the ecosystem.

A

C. Protection of the public from communicable disease, preserve aquatic life, protection of the environment.

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2
Q

Which of the following lists two sources of wastewater?
A. Industrial, domestic
B. Commercial, deep wells
C. Institutional, precipitation
D. Infiltration, springs

A

A. Industrial, domestic

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3
Q

What is the approximate percentage of solids contained in domestic wastewater?
A. 20%
B. 5%
C. 1%
D. 0.1%

A

D. 0.1%

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4
Q

Which one of the following lists three main types of sewers by wastewater type?
A. Domestic, trunk, C60 series
B. Industrial, interceptor, reduced pressure
C. Chemical, backwash, inverted siphon
D. Sanitary, combined, storm

A

D. Sanitary, combined, storm

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5
Q

What are two reasons why a wastewater collection lift station may be required?
A. When it is no longer economical to construct a gravity system; when the treatment facility is at a lower elevation.
B. If wastewater must be moved to a higher elevation; if wastewater must be pumped to a remote location for treatment.
C. When a community is located at a low area; when inadequate groundwater is available.
D. If the community is located in a high (elevation) location; if the water table is high.

A

B. If wastewater must be moved to a higher elevation; if wastewater must be pumped to a remote location for treatment.

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6
Q

What are two types of Class I wastewater treatment facilities?
A. Aerated Lagoons, oxidation ditch.
B. Wastewater lagoons, aerated lagoons.
C. Activated sludge, slow sand filters.
D. Slow sand filters, deep shaft technology.

A

B. Wastewater lagoons, aerated lagoons.

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7
Q

Which of the following is TRUE?
A. Large communities use wastewater stabilization ponds mainly because of their low cost and ease of operation.
B. Mechanical treatment plants discharge effluent at predefined intervals.
C. Larger communities seldom use stabilization ponds because of the high cost of the necessary land.
D. The process of screening removes heavy inorganic material from a mechanical treatment plant.

A

C. Larger communities seldom use stabilization ponds because of the high cost of the necessary land.

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8
Q

Which of the following wastewater treatment plant processes is incorrectly matched to its description?
A. Grit Removal: Removes larger debris - rags, sticks, cans.
B. Primary Treatment: Removes solids easily settled out by gravity, and floating material.
C. Secondary Treatment: Converts dissolved and very finely divided material into a settleable form.
D. Disinfection: Destroys pathogenic (disease causing) microorganisms.

A

A. Grit Removal: Removes larger debris - rags, sticks, cans.

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9
Q

What are two types of mechanical secondary treatment systems?
A. Rotating biological contactors, activated sludge
B. Anaerobic lagoons, contact stabilization
C. Extended aeration, slow sand filters
D. Facultative stabilization ponds, oxidation ditch

A

A. Rotating biological contactors, activated sludge

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10
Q

What is the function of a secondary clarifier?
A. Physically remove inorganic settleable material from the incoming wastewater flow.
B. Filter out all remaining material prior to discharge.
C. Disinfect the effluent to remove any pathogenic organisms.
D. Remove settleable solids formed by biological conversion of dissolved and finely divided matter.

A

D. Remove settleable solids formed by biological conversion of dissolved and finely divided matter.

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11
Q

What are the three main classifications of bacteria that are active in wastewater stabilization ponds?
A. Aerobic, silicates, and filamentous
B. Autotrophic, aerobic and diatoms
C. Aerobic, facultative and anaerobic
D. Rotifers, filamentous and anaerobic

A

C. Aerobic, facultative and anaerobic

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12
Q

Which of the following statements best applies to stabilization ponds?
A. Algae feed on organic matter in wastewater for cell growth and reproduction.
B. The main purpose of a stabilization pond is to store the wastewater until conditions are suitable for discharge.
C. The main purpose of a stabilization pond is to settle solid matter out of wastewater.
D. Organic matter in wastewater is stabilized by the action of natural bacteria.

A

D. Organic matter in wastewater is stabilized by the action of natural bacteria.

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13
Q

Which of the following are disadvantages of wastewater stabilization ponds?
A. Odour problems can occur, large land area is required, effluent may have high suspended solids levels due to algae.
B. Treatment efficiency is dependent on climate, capital cost is usually lower, usually good effluent quality.
C. Possibility of groundwater contamination, regular backwash is required; treatment efficiency is dependent on climate.
D. Discharge is continuous, very little process control is necessary.

A

A. Odour problems can occur, large land area is required, effluent may have high suspended solids levels due to algae.

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14
Q

Which of the following is a list of advantages of wastewater stabilization ponds over mechanical treatment plants?
A. Usually good effluent quality, no maintenance or operation is required, discharge is continuous.
B. Very little mechanical equipment needed, all bacteria are removed, backwash requirements are minimal.
C. Able to assimilate loading fluctuations, low energy requirement, minimal operating needs.
D. Odour problems are limited to spring and fall, effluent meets Canadian Drinking Water Standard, process control is minimal.

A

C. Able to assimilate loading fluctuations, low energy requirement, minimal operating needs.

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15
Q

Which of the following statements is false?
A. Algae can consume carbon dioxide and release oxygen.
B. Algae can consume oxygen and release carbon dioxide.
C. Dissolved oxygen concentration in an aerobic pond is usually higher on sunny days than on cloudy days.
D. Dissolved oxygen in a pond is usually higher in winter than it is in summer, because the solubility of gases increases as the temperature of the water decreases.

A

D. Dissolved oxygen in a pond is usually higher in winter than it is in summer, because the solubility of gases increases as the temperature of the water decreases.

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16
Q

Design of stabilization ponds depends on the serviced population. A pond system contains two anaerobic ponds, (2 to 5 days retention), followed by an aerobic or facultative pond (60 days retention) and a final storage pond (12 months retention). Which population size(s) is this pond designed to serve?
A. Less than 300
B. 300 to 800.
C. More than 800
D. Any population size

A

B. 300 to 800.

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17
Q

Which of the following is false?
A. Algae require inorganic substances such as phosphorus and nitrogen to grow and reproduce.
B. In the absence of sunlight, algae release carbon dioxide into the wastewater, which tends to lower the pH.
C. In the presence of sunlight, algae consume carbon dioxide from the wastewater, which tends to increase the pH.
D. Algae have no effect on the operation of a wastewater stabilization pond.

A

D. Algae have no effect on the operation of a wastewater stabilization pond.

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18
Q

Which of the following most correctly describes a facultative pond?
A. Less than three feet deep, dissolved oxygen present throughout.
B. Ten to fifteen feet deep, artificially aerated, continuous flow.
C. Five to eight feet deep, with top aerobic layer and bottom anaerobic layer, two to twelve months retention time.
D. Ten to twelve feet deep, short retention time, no dissolved oxygen present.

A

C. Five to eight feet deep, with top aerobic layer and bottom anaerobic layer, two to twelve months retention time.

19
Q

Which of the following most correctly describes an aerobic pond?
A. Less than three feet deep, dissolved oxygen present throughout.
B. Shallow depth, up to three-year retention, no discharge.
C. Five to eight feet deep, about one year retention time.
D. Ten to fifteen feet deep, artificially aerated, continuous flow.

A

A. Less than three feet deep, dissolved oxygen present throughout.

20
Q

Which of the following is not true?
A. Clay liners are usually 3 to 5 feet thick.
B. The width of the top of a pond embankment is usually 10 to 12 feet wide, to allow vehicle access.
C. Embankment slopes are usually about 3:1.
D. A freeboard (distance from water level to top of embankment) of at least 2 to 3 feet should maintained, to avoid the possibility of wastewater overflowing and erosion because of wave action.

A

A. Clay liners are usually 3 to 5 feet thick.

21
Q

What must be provided to prevent animals or the public from entering a stabilization pond facility?
A. Warning signs, regular security patrols, entry alarm systems.
B. Adequate fencing, lockable gates, warning signs.
C. Lockable gates, closed circuit monitoring, composite sampling systems.
D. Motion detectors, adequate fencing, 24-hour flow monitoring.

A

B. Adequate fencing, lockable gates, warning signs.

22
Q

What are three devices used to control levels or flows in stabilization ponds?
A. Sluice gates, parshall flumes, totalizers.
B. Flow splitters, adjustable weirs, valves.
C. Removable pipes, PLCs, reduced pressure black flow prevention devices.
D. Stop logs, sandbags, hydraulic jacking.

A

B. Flow splitters, adjustable weirs, valves.

23
Q

Which one of the following lists the possible function of a lagoon inlet structure?
A. Mixing of wastewater, flow direction control provide primary treatment.
B. Regulation of wastewater levels, provide grit and scum removal.
C. Provide an air gap to prevent back siphoning, provide a site for wastewater disinfection.
D. Flow measurement, chemical addition, sample collection.

A

D. Flow measurement, chemical addition, sample collection.

24
Q

Why is a multiple pond lagoon facility advantageous over a single large cell?
A. Ponds can be isolated for maintenance and operation mode can be series or parallel, depending on need.
B. A large single cell will give better treatment and is less susceptible to wave erosion.
C. A multiple pond installation is less costly to construct and requires less operation.
D. A single large cell is less susceptible to leakage and will give better treatment.

A

A. Ponds can be isolated for maintenance and operation mode can be series or parallel, depending on need.

25
Q

Excessive sludge accumulation can cause the following problems:
A. Odour problems, shock loading.
B. Short circuiting, organic under loading.
C. Clogged structures and piping, solids carryover.
D. Inadequate detention time, inefficient disinfection.

A

C. Clogged structures and piping, solids carryover.

26
Q

Which of the following is not true?
A. In winter the rate of wastewater decomposition is much slower than in summer.
B. Facultative ponds should be at their lowest possible operating depths at the start of winter.
C. Anaerobic conditions often develop over winter because the ice cover prevents oxygen and sunlight from reaching the wastewater.
D. Release of hydrogen sulfide or other gases often causes odour problems when the ice cover breaks up in the spring.

A

B. Facultative ponds should be at their lowest possible operating depths at the start of winter.

27
Q

What percentage of BOD will a properly designed and operated stabilization pond system normally remove?
A. 40 – 60%
B. 60 – 70%
C. 70 – 80%
D. 80 – 90%

A

D. 80 – 90%

28
Q

In a lagoon system, what is thermal turnover?
A. Wastewater is mechanically mixed in a lagoon to inhibit stratification.
B. Temperature changes cause the denser upper layer of water to sink, displacing the bottom layer.
C. During periods of ice cover, iron and manganese re-dissolve into the water from the sediment.
D. Caused during sludge recycling to maximize food to microorganism relationship.

A

B. Temperature changes cause the denser upper layer of water to sink, displacing the bottom layer.

29
Q

How can hydraulic overloading of a lagoon facility be minimized or reduced?
A. Install water meters to discourage excessive water use, construct new facilities.
B. Obtain seed microorganisms from a nearby source, install reduced pressure backflow prevention devices.
C. Eliminate storm water entry into sanitary sewers, dewater the area around the berms by drilling wells.
D. Switch the parallel operating regime, store excess flows in tanker trucks during high flow periods.

A

A. Install water meters to discourage excessive water use, construct new facilities.

30
Q

The normal color of a properly operating facultative stabilization pond in summer is:
A. Colourless
B. Green
C. Brown
D. Grey

A

B. Green

31
Q

Which of the following is true?
A. Ponds should be discharged continuously.
B. Ponds should not be discharged unless the volume of wastewater expected to enter the pond before the next opportune discharge is less than the capacity remaining in the pond.
C. It is not necessary to sample the discharge if it looks reasonably clear.
D. The Environmental Regulatory Agency must be notified when a pond is discharged.

A

D. The Environmental Regulatory Agency must be notified when a pond is discharged.

32
Q

If the projected yearly flow is 13.5 million liters and the current available storage in a 7 month storage pond is 3.4 million liters, what is the remaining volume of wastewater that should be discharged?
A. 4.48 ML
B. 10.1 ML
C. 1.92 ML
D. 7.88 ML

A

A. 4.48 ML

33
Q

What is the surface area of the pond after discharge?
A. 12084 m2
B. 12233 m2
C. 16735 m2
D. 17291 m2

A

B. 12233 m2

34
Q

Use the average area/depth method to calculate the volume of wastewater discharged from this pond.
A. 8645 m3
B. 10042 m3
C. 11579 m3
D. 13356 m3

A

C. 11579 m3

35
Q

How can odours be controlled at a lagoon facility?
A. Eliminate the organic portion of the influent, minimize sludge accumulation.
B. Recirculation, install pH-controlled scrubbers.
C. Aeration, install a pond liner.
D. Chemical (lime) addition, removal of excess sludge and floating material.

A

D. Chemical (lime) addition, removal of excess sludge and floating material.

36
Q

Embankment vegetation may best be controlled by:
A. Regular mowing
B. Application of herbicides.
C. Burning, if approved by the Environmental Regulatory Agency & local Fire Authority.
D. Any of the above.

A

A. Regular mowing

37
Q

What control methods may be used, on rodents such as muskrats, at a lagoon facility?
A. Dynamite or trapping with a permit.
B. Relocating the lagoon facility, removing all ground cover
C. Trapping with a permit or frequently altering pond levels.
D. Declare the facility a “protected area”, or discontinue use of the lagoon.

A

C. Trapping with a permit or frequently altering pond levels.

38
Q

What is the main advantage of aerated ponds over standard stabilization ponds?
A. Less land is required.
B. Maintenance is considerably simpler.
C. Less electrical energy is required so operating cost is reduced.
D. Process control requirements are less.

A

A. Less land is required.

39
Q

Aerated ponds normally consist of two types of ponds in series. These types of ponds are:
A. Complete mix pond, anaerobic pond.
B. Anoxic pond, aerated pond.
C. Storage pond, aerobic pond.
D. Aerated pond, settling pond.

A

D. Aerated pond, settling pond.

40
Q

Which flow measuring device is best suited to measure high flows at a Stabilization Pond?
A. Rectangular Weir
B. V-notch Weir
C. Parshall Flume
D. Palmer-Bowles Flume

A

A. Rectangular Weir

41
Q

Driving along a country road, you spot a stabilization pond. It measures two meters deep and has a medium surface area. Of the following choices, the pond is most likely:
A. Anaerobic
B. Aerobic
C. Facultative
D. Evaporative

A

C. Facultative

42
Q

The chemical composition of industrial process wastes may have several undesirable effects on stabilization pond biology. Which of the following is not one of them?
A. Fungicides or disinfectants may inhibit biotic processes.
B. Reduce effectiveness by excessively raising or lowering pH levels.
C. Nutrient deficiencies reduce the rate of decomposition.
D. Variations in temperature may cause pond upset.

A

D. Variations in temperature may cause pond upset.

43
Q

Which group of bacteria obtains oxygen from inorganic compounds?
A. Heterotrophic
B. Anaerobic
C. Facultative
D. Autotrophic

A

B. Anaerobic

44
Q

Which of the following statements is correct regarding BOD?
A. It is an indirect indication of organic contamination in wastewater.
B. BOD is defined as the quantity of oxygen utilized by organisms in aerobic oxidation at 20oC.
C. BOD can range from 50 to 3,000 mg/L, depending on the source of the effluent.
D. All of the above.

A

D. All of the above.

AWWOA Practice Exams (5 decks)

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