Chap 3 Wastewater Treatment Facilties

Question 1

True or false: Waste Material removed by treatment processes goes to solids handling facilities and then to ultimate disposal.

Answer 1

True

Question 2

True or false: A sanitary sewer separately collects all storm runoff from streets, land, and roofs of buildings.

Answer 2

False

Question 3

True or false: To prevent overloading or shock loading of the plant, supernatant from an anaerobic digester should be returned slowly to the plant headworks.

Answer 3

True

Question 4

True or false: A lacy network is formed by activated sludge that captures pollutants.

Answer 4

True

Question 5

True or false: The filtering action in a trickling filter removes solids from the wastewater being treated.

Answer 5

False

Question 6

True or false: Greater solids removal in treatment process results from shorter detention times.

Answer 6

False

Question 7

True or false: The sludge from an anaerobic digester will thicken less readily than aerobic sludge from an aerobic digester

Answer 7

False

Question 8

True or false: Digester gas is extremely explosive when mixed with air in the proper proportion..

Answer 8

True

Question 9

True or false: The application of strong acids is used to accomplish most disinfection in wastewater treatment plants.

Answer 9

False

Question 10

True or false: Other organisms use oxygen produced by algae in ponds.

Answer 10

True

Question 11

Best answer select one: When there are infiltration problems in sewers, how does an operator become aware of them?

1. Being informed by management of the need to increase plant capacity.
2. Communicating with collection system operators.
3. Observing unusually high flows at the plant during periods of stormwater runoff.
4. Receiving recommendations from consulting engineers to seal leaky sewers.

Answer 11

3. Observing unusually high flows at the plant during periods of stormwater runoff.

Question 12

Best answer select one: To locate the source of a problem in the plant influent how should an operator proceed?

1. Analysis of effluent water quality
2. Investigation of solids handling in plant.
3. Review of customer complaints.
4. Use of knowledge of industrial dischargers to the collection system.

Answer 12

4. Use of knowledge of industrial dischargers to the collection system.

Question 13

Best answer select one: In the flow diagram of a wastewater treatment plant, where is the disinfection process located?

1. After primary treatment.
2. Before primary treatment.
3. First treatment process
4. Last treatment process.

Answer 13

4. Last treatment process.

Question 14

Best answer select one: How are organic wastes treatment by biological treatment processes?

1. Organisms float wastes to the surface for removal.
2. Organisms grind up wastes for removal by screens.
3. Organisms partially stabilized (oxidize) organic matter.
4. Organisms use up dissolved oxygen in the water.

Answer 14

3. Organisms partially stabilized (oxidize) organic matter.

Question 15

Best answer select one: Why is a bar screen used to remove debris and trash from the influent wastewater to a plant?
1, To protect equipment
2. To protect microorganisms treating wastes.
3. To provide food for microorganisms treating solids.
4. To reduce odors.

Answer 15

1, To protect equipment

Question 16

Best answer select one: To neutralize the chlorine and thus detoxify the effluent, which chemical may be added to the plant effluent?

Answer 16

3. Sulfur dioxide

Question 17

Best answer select one: How are floating solids described?

1. Debris
2. Grit
3. Scum
4. Sludge

Answer 17

3. Scum

Question 18

Best answer select one: Why is grit usually buried?

1. To avoid nuisance conditions.
2. To lower transportation costs.
3. To provide nutrients for vegination
4. To reduce storage requirements.

Answer 18

1. To avoid nuisance conditions.

Question 19

Best answer select one: The activated sludge removed from the secondary clarifier is recirculated (returned) to the influent end of the aeration tank for what purpose?

1. Decompose organic material in the waste being treated.
2. Eliminate solids in the secondary effluent.
3. Prevent overloading solids handling facilities.
4. Reduce solids load on digesters.

Answer 19

1. Decompose organic material in the waste being treated.

Question 20

Best answer select one: When water flows at a high velocity over a clarifier weir what can happen?

1. Algae growing in the troughs will be scoured out.
2. Particles may be carried from the clarifier.
3. Sludge will settle quickly to the bottom of the clarifier.
4. Weir surfaces will be kept clean.

Answer 20

2. Particles may be carried from the clarifier.

Question 21

Best answer: In order to remove the large population of microorganisms in the effluents from trickling filters, rotating biological contactors and activated sludge tanks, what treatment unit is used?

1. Bar screens.
2. Multimedia filters.
3. Sand filters.
4. Secondary clarifiers.

Answer 21

4. Secondary clarifiers.

Question 22

Best answer: What is the reason that some of the activated sludge must be removed (wasted) from the treatment process?

1. To prevent the degree of treatment from becoming too high
2. To prevent the number of organism from becoming too great.
3. To reduce the cost of treatment.
4. To save energy.

Answer 22

2. To prevent the number of organism from becoming too great.

Question 23

Best answer: When ponds have an aerobic top layer and an anaerobic bottom layer, what are these ponds called?

1. Activated ponds.
2. Algae ponds.
3. Contact ponds.
4. Facultative ponds.

Answer 23

4. Facultative ponds.

Question 24

Best answer: Before discharge to receiving waters, why must some effluents be dechlorinated or detoxified?

1. To protect the agricultural water supply.
2. To protect the aquatic life.
3. To protect the drinking water supply.
4. To protect the swimming area.

Answer 24

2. To protect the aquatic life.

Question 25

Best answer: What is the liquid called that is left above the settled sludge when an anaerobic digester is not being mixed and the solids settle to the bottom? 1. Centrate. 2. Decant. 3. Effluent. 4. Supernatant

Answer 25

4. Supernatant

Question 26

Multiple Choice: After a bar screen in a treatment plant, which device is usually installed next? 1. Barminutors. 2. Collection systems. 3. Comminutators 4. Interceptors. 5. Sewers

Answer 26

1. Barminutors. | 3. Comminutators

Question 27

Multiple Choice: Preliminary treatment processes include which types of treatment processes? 1. Biological treatment. 2. Collection systems. 3. Flotation 4. Grit removal 5. Screening

Answer 27

4. Grit removal | 5. Screening

Question 28

Multiple Choice: When using flow measuring devices, what is the purpose of knowing the flows measured? 1. Adjusting chemical feed rates. 2. Calculation loadings on treatment processes. 3. Calibrating chemical feeders. 4. Determining treatment efficiencies 5. Treating wastes.

Answer 28

1. Adjusting chemical feed rates. 2. Calculation loadings on treatment processes. 5. Treating wastes.

Question 29

Multiple Choice: What is the reason that grit should be removed early in the treatment process? 1. It cannot be broken down by any biological treatment process. 2. it is abrasive. 3. it is high in moisture content. 4. It is needed in the solids composting process. 5. It will rapidly wear out pumps.

Answer 29

1. It cannot be broken down by any biological treatment process. 2. it is abrasive. 5. It will rapidly wear out pumps.