Wastewater Flows

Front 1

Most sewer pipes are laid at a slope steep enough to maintain a wastewater flow of

Back 1

2.0 fps (two feet per second)

Front 2

A grit channel is designed to provide a flow-through velocity of

Back 2

1 fps ( one foot per second)

Front 3

Manholes are placed every ______ to _____ feet to allow for inspection and cleaning of the sewer

Back 3

300 to 500

Front 4

List three types of sewers

Back 4

Sanitary sewer, storm sewer and combined sewer

Front 5

Sewer inflow is

Back 5

A direct discharge into the sewer

Front 6

Sewer inflow is

Back 6

A direct discharge into the sewer

Front 7

Sewer infiltration is

Back 7

Seepage through defective or cracked pipes, pipe joints, connections or manholes. It leaks into the sewer itself.

Front 8

Aereated grit chambers use

Back 8

Compressed air added through diffusers.

Front 9

Most common flow measuring device at the plants headworks

Back 9

A parshall flume

Front 10

A measuring device used in open channels is a

Back 10

Weir. The flow over the weir is determined by the depth of water going through the opening.

Front 11

Flow velocity through primary treatment (sedimentation) is about

Back 11

.03 fps

Front 12

Primary clarifiers are usually designed to provide ___ to ___ hours detention time

Back 12

1.5 to 2 hours

Front 13

Removal of solids in a primary clarifier will reduce the (BOD) of the waste approximately ___ percent

Back 13

30

Front 14

A detention time of 2 hours in a primary clarifier will remove approximately ___ percent of suspended solids

Back 14

60%

Front 15

Two processes used universally for biological treatment are the

Back 15

Trickling filter and the activated sludge

Front 16

Trickling filters are designed to remove ___ to ___ of the bod-causing wastes and suspended solids present in the influent

Back 16

70 to 80%

Front 17

Activated sludge plants are capable of bod and suspended solids reduction of ___ to ___ percent

Back 17

90 to 99%

Front 18

By the time waste reaches the end of an activated sludge aeration tank usually ___ to ___ hours, most of the waste has been used by the bacteria

Back 18

4 to 8 hrs

Front 19

Two types of bacteria are present in an anaerobic digester ______ and ______ .

Back 19

Acid formers and gas formers

Front 20

Two types of bacteria are present in an anaerobic digester ______ and ______ .

Back 20

Acid formers and gas formers

Front 21

Acid former bacteria eat the organic portion of the sludge to form _____ acids and ______ ______ gas.

Back 21

Organic acids and carbon dioxide

Front 22

The gas formers in an anaerobic digester break down the organic acids to form _______ and _______ gas

Back 22

Methane and carbon dioxide

Front 23

Sludge in an anaerobic digester is usually considered properly digested when ____ percent of the organic matter has been destroyed and converted to gas.

Back 23

50%

Front 24

Proper digestion in an anaerobic digester normally takes ___ days if the temperature is kept about ___*f.

Back 24

30 days at 95*f

Front 25

Most digestion tanks are mixed to

Back 25

Bring food to the organisms, provide a uniform temperature and to avoid the formation of thick scum blankets.

Front 26

When a digester isn't being mixed properly, solids settle to the bottom leaving a ______ colored liquid above the sludge.

Back 26

Amber colored

Front 27

Digester gas is usually around ___ percent methane and about ___ percent carbon dioxide

Back 27

70 and 30%

Front 28

Liquid hypochlorite (bleach) can be used ________ .

Back 28

Directly

Front 29

Liquid hypochlorite (bleach) can be used ________ .

Back 29

Directly

Front 30

Chlorine contact basins or tanks are usually designed to provide approximately ___ to ___ minutes of contact time.

Back 30

20 to 30 minutes

Front 31

______ ______ is used to dechlorinate or neutralize the remaining residual chlorine.

Back 31

Sulfur dioxide

Front 32

Tertiary treatment remove nutrients such as ______ and ______ and the last traces of ______ materials.

Back 32

Nitrate, phosphorus, and organic

Front 33

Chlorine has a specific gravity of ___ as a gas. Air has a specific gravity of 1.0

Back 33

2.5

Front 34

Water has a specific gravity of ___ at 4*C ( 39%f)

Back 34

1.000

Front 35

A good practice is to change work ______ before going home.

Back 35

Clothes

Front 36

Materials such as _____, ______ and similar items will cause pipes to plug, may damage pumps, etc.

Back 36

Metal and rocks

Front 37

Grit may be dewatered in ______ ______.

Back 37

Cyclone separators

Front 38

Parallel bars sometimes called racks have a spacing of ___ to ___ inches or more.

Back 38

3 to 4

Front 39

Parallel bars sometimes called racks have a spacing of ___ to ___ inches or more.

Back 39

3 to 4

Front 40

Bar screens have a spacing about ___ inch to ___ inches. Fine bar screens have a spacing of approximately ___ inches.

Back 40

3/8" to 2" and 1/4"

Front 41

Aerated grit chambers usually have a detention time of ___ minutes at peak flows with detention times ranging from ___ to ___ minutes

Back 41

3 minutes

3 to 5 minutes

Front 42

Alkalinity

Back 42

The capacity of water/wastewater to neutralize acids.

Front 43

Alkalinity

Back 43

The capacity of water/wastewater to neutralize acids.

Front 44

Alkalinity is a measure of how much acid must be added to a liquid to lower the ph to ___.

Back 44

4.5

Front 45

A solution or liquid whose chemical make up neutralizes acids and bases without a great change in ph

Back 45

Buffer

Front 46

Aerobic bacteria

Back 46

Bacteria which will live and reproduce only in an environment containing oxygen.

Front 47

Aerobic bacteria

Back 47

Bacteria which will live and reproduce only in an environment containing oxygen.

Front 48

Anaerobic bacteria

Back 48

Bacteria that live and reproduce in an environment containing no "free" or dissolved oxygen.

Front 49

Anaerobic bacteria obtain their oxygen supply by breaking down chemical compounds which contain oxygen, such as ______.

Back 49

Sulfate

Front 50

Bulking is caused by ______

Back 50

Filamentous bacteria

Front 51

Mpn is the most probable number of ______-group organisms.

Back 51

Coliform

Front 52

Sludge volume index is a measure of the volume of sludge compared with its ______.

Back 52

Weight

Front 53

Clarifiers should be shutdown for maintenance during ___ flow periods.

Back 53

Low

Front 54

Typical primary clarifier efficiency of settle able solids is ___% to ___%.

Back 54

90 to 99

Front 55

Typical primary clarifier efficiency of settle able solids is ___% to ___%.

Back 55

90 to 99

Front 56

Typical primary clarifier efficiency of suspended solids is ___% to ___%.

Back 56

40 to 60

Front 57

Typical primary clarifier efficiency of settle able solids is ___% to ___%.

Back 57

90 to 99

Front 58

Typical primary clarifier efficiency of suspended solids is ___% to ___%.

Back 58

40 to 60

Front 59

Typical primary clarifier efficiency of total solids is ___% to ___%.

Back 59

10 to 15

Front 60

Typical primary clarifier efficiency of settle able solids is ___% to ___%.

Back 60

90 to 99

Front 61

Typical primary clarifier efficiency of suspended solids is ___% to ___%.

Back 61

40 to 60

Front 62

Typical primary clarifier efficiency of total solids is ___% to ___%.

Back 62

10 to 15

Front 63

Typical primary clarifier efficiency of bod is ___% to ___%.

Back 63

20 to 50

Front 64

Typical primary clarifier efficiency of settle able solids is ___% to ___%.

Back 64

90 to 99

Front 65

Typical primary clarifier efficiency of suspended solids is ___% to ___%.

Back 65

40 to 60

Front 66

Typical primary clarifier efficiency of total solids is ___% to ___%.

Back 66

10 to 15

Front 67

Typical primary clarifier efficiency of bod is ___% to ___%.

Back 67

20 to 50

Front 68

Typical primary clarifier efficiency of bacteria is ___% to ___%.

Back 68

25 to 75

Front 69

Wastewater ph will be about ___ to ___.

Back 69

6.5 to 8

Front 70

Trickling filter secondary clarifier surface loading is ___ to ___ gpd/sq ft

Back 70

800 to 1200

Front 71

Activated sludge secondary clarifier surface loading is ___ to ___ gpd/sq ft

Back 71

300 to 1200

Front 72

Activated sludge secondary clarifier surface loading is ___ to ___ gpd/sq ft

Back 72

300 to 1200

Front 73

Trickle filers and Activated sludge secondary clarifier detention time is ___ to ___ hours

Back 73

2 to 3

Front 74

Nitrogen gas bubbles attach themselves to biological flocs and float to the surface, this is called

Back 74

Rising sludge

Front 75

Nitrogen gas bubbles attach themselves to biological flocs and float to the surface, this is called

Back 75

Rising sludge

Front 76

Contact stabilization uses two aeration tanks. One tank is for separated reaeration of the returned sludge for ___ hours before flowing into the second aeration tank.

Back 76

4 hrs

Front 77

A reduced level of respiration in which organisms break down compounds within their own cells producing oxygen they need.

Back 77

Endogenous respiration

Front 78

Mean cell residence time (mrct)

Back 78

An expression of the average time that a microorganism will spend in the activated sludge process

Front 79

Primary clarifiers remove much of the ______ and ______ material

Back 79

Floatable and settleable

Front 80

Conversion of dissolved and suspended material to settle-able solids is the main objective of ______-_____ activated sludge process

Back 80

High-rate

Front 81

Conversion of dissolved and suspended material to settle-able solids is the main objective of ______-_____ activated sludge process

Back 81

High-rate

Front 82

______-______ process stress oxidation. Oxidation is the addition of oxygen, removal of hydrogen, or the removal of electrons from an element or compound.

Back 82

Low-rate

Front 83

If low dissolved oxygen (do) ________ bacteria will thrive and sludge floc will not settle in the secondary clarifier.

Back 83

Filamentous

Front 84

A high dissolved oxygen (do) will allow ______ floc to develop and not be removed from the secondary clarifier.

Back 84

Pinpoint

Front 85

Extended aeration is similar to conventional activated sludge except the bugs retained in the aeration tank longer and don't get as much ______.

Back 85

Food

Front 86

Extended aeration mixed liquor suspended solids concentrations are from ____ to ____ mg/l

Back 86

2000 to 5000

Front 87

Contact stabilization is similar to conventional activated sludge except that the capture of the waste and digestion by the bugs is done in ______ aeration tanks.

Back 87

Different

Front 88

Contact stabilization bugs can ______ the waste material in 15 to 30 minutes. But it takes several hours to ______ the material through the cell walls.

Back 88

Adsorb, absorb

Front 89

Conventional activated sludge, ______ and ______ happen in one tank. But, the settled bugs still have to digest their food. Another aeration tank called a ______ or re-aeration tank is provided separately for this step. The mixed liquor suspended solids is around 1500 to 2000 mg/l.

Back 89

Adsorption and absorption

Stabilization

Front 90

In an ideal complete-mix sludge plant, the contents of the tank are completely mixed. (The ______ are uniformly mixed throughout the entire aeration tank. The mlss ranges from 2000 to 5000.

Back 90

Mixed liquor suspended solids

Front 91

If the water in the secondary clarifier appears murky or cloudy and the aeration side smells like rotten eggs.

Back 91

Not enough air is being supplied