Wastewater Certification Grade 2

Front 1

Never raise or lower digester temperatures by more than?

Back 1

1 degree F per day

Front 2

What three gases are produced in anaerobic digesters?

Back 2

Methane (ch4) carbon dioxide (co2) hydrogen sulfide (h2s)

Front 3

What are two characteristics of well digested sludge?

Back 3

Ph of 7.0-7.2 and a leathery appearance

Front 4

Most digesters operate at a temperature range of?

Back 4

95-98

Front 5

When operating properly a medium range digester will produce gas that is ____ methane.

Back 5

70%

Front 6

Which of the following statements is true regarding pumping sludge to a digester?A. The solids concentration should be as high as possible.B. Pumping smaller volumes more often is easier on the process than pumping lots of sludge all at once.C. The overflow from the digester will return to the headworks of the plant.D. All of the above.

Back 6

D

Front 7

How long does it take to stabilize sludge at the three temperature ranges for anaerobic digestors?

Back 7

Psychrophilic-50-120 days

Mesophilic-25-30 days

Thermophilic-5-12 days

Front 8

What is the solids loading rate for an anaerobic digester?

Back 8

.15 - .35lbs per day/cuft

Front 9

What is the BTU value of digester gas?

Back 9

500-800 BTUS

Front 10

The vertical pickets on a gravity thickener

Back 10

Aid in mixing and gas release

Front 11

The sludge blanket in a gravity thickener should be:

Back 11

5-8 feet deep

Front 12

As the sludge blanket depth increases:

Back 12

Detention time decreases

Front 13

What are operational parameters for a gravity thickener?

Back 13

detention time, sludge blanket depth, and sludge withdrawal rate.

Front 14

What is the detention time for Gravity thickners?

Back 14

1-2 days

Front 15

What kind of pump is used for pumping primary sludge?

Back 15

Positive displacement pumps

Front 16

Primary clarifiers should have a detention time of:

Back 16

2 hours

Front 17

Primary clarifiers remove how much of settleable solids?

Back 17

90-95%

Front 18

How much suspended solids do primary clarifiers remove?

Back 18

40-60%

Front 19

The solids concentration in primary sludge should be:

Back 19

4-6%

Front 20

What is the normal BOD removal efficiency in a primary clarifier?

Back 20

30-40%

Front 21

What is the normal operating depth of a facultative pond?

Back 21

4-7 ft.

Front 22

What supplies 70-80% of oxygen to bacteria in a facultative pond?

Back 22

Algae

Front 23

What is the depth of an aerobic pond?

Back 23

3 ft

Front 24

When will the ph be the lowest in a pond?

Back 24

Just before dawn

Front 25

When will the ph be the highest in a pond?

Back 25

Late afternoon

Front 26

What is the BOD loading rate for a facultative pond?

Back 26

20-35lbs per acre per day

Front 27

What is the detention time for facultative ponds?

Back 27

30-60 days

Front 28

Facultative lagoon levels should always maintain at least how many feet of water?

Back 28

4 feet

Front 29

What can be done to recover from an organic overload on a pond?

Back 29

A. Increase recirculation

B. Run ponds in parallel

C. Add sodium nitrate

Front 30

What is the BOD loading for a standard trickling filter?

Back 30

15-20 pounds per day

Front 31

What is the hydraulic loading range for a standard trickling filter?

Back 31

1-4 mgd/acre (25-100 gpd/ft2).

Front 32

What is the material that sloughs off the media of a trickling filter called?

Back 32

Zoogleal film

Front 33

What should the effluent DO be in a trickling filter?

Back 33

1.5-2mg/l

Front 34

Which of the following is a problem in trickling filters?

A. SnailsB. PondingC. Psychoda fliesD. All of the above

Back 34

D

Front 35

How do you control filter flies and ponding in trickling filters?

Back 35

Increase recirculating rate

Front 36

What is the BOD loading for a high rate trickling filter?

Back 36

40 - 60 lbs per day

Front 37

Healthy growth on the first stage of an RBC will be:

Back 37

Gray

Front 38

The DO in the last stage of a nitrification process in an RBC should be at least:

Back 38

4mg/l

Front 39

How much BOD does a well operated activated sludge process remove?

Back 39

95 - 98%

Front 40

The portion of the MLSS that is actually eating the incoming food is referred to as

Back 40

Mixed liquor volatile suspended solids (MLVSS)

Front 41

The solids concentration (RAS/WAS) of an activated sludge process are?

Back 41

.5 - .8% or 5,000 - 8,000 mg/l

Front 42

What can you do to maintain proper detention time as the flow drops in an activated sludge process?

Back 42

Increase RAS flow

Front 43

What are two process control parameters used in a activated sludge process?

Back 43

F:M ratio and MCRT

Front 44

Good settling sludge will have an SVI between?

Back 44

80 and 120

Front 45

What is the ideal D.O. range in an activated sludge process?

Back 45

2 - 4 mg/l

Front 46

What is the ideal D.O. range in an activated sludge process?

Back 46

2 - 4 mg/l

Front 47

The minimum DO is?

Back 47

1 -2 mg/l

Front 48

MLSS In a conventional activated sludge process is?

Back 48

2,000 - 3,500 mg/l

Front 49

What are three parameters that can be adjusted to maintain efficiency?

Back 49

Dissolved oxygen, RAS flows and WAS flows

Front 50

Return sludge pump capacity should be what % of average daily flow?

Back 50

50 - 70 %

Front 51

What type of activated sludge process does not have primary clarifiers?

Back 51

Extended aeration

Front 52

What is the aeration basin detention time in conventional activated sludge processes?

Back 52

4-6 hours

Front 53

What should the velocity be in an oxidation ditch?

Back 53

1.0 fps

Front 54

Straggler floc would be found in:

Back 54

Young sludge

Front 55

Wasting rates should never be changed by more than ___ at a time

Back 55

10%

Front 56

What microorganisms are predominant in very old sludge?

Back 56

Rotifers

Front 57

White crisp foam in the aeration basin indicates:

Back 57

A young sludge

Front 58

How many pounds of oxygen does it take to convert 1 pound of ammonia to nitrates?

Back 58

4 - 6 pounds

Front 59

If chlorine is used to oxidize ammonia the ratio will need to be:

Back 59

10:1

Front 60

Calcium Hypochlorite is what % available chlorine?

Back 60

60 - 70%

Front 61

Chlorine gas can be lethal at what concentration?

Back 61

50ppm

Front 62

A fusible plug melts at ?

Back 62

157 degrees

Front 63

Take the rotameter reading at:

Back 63

The widest part of the float

Front 64

What's the maximum gas feed rate of a 1 ton cylinder?

Back 64

400lbs/day

Front 65

A 1-ton cylinder will have how many fusible plugs?

Back 65

6

Front 66

What two acids are formed when chlorine gas reacts with water?

Back 66

hydrochloric acid and hypochlorous acid.

Front 67

Which three chemicals are formed when chlorine reacts with ammonia in water?

Back 67

monochloramine,

dichloramine

trichloramine

Front 68

The maximum feed rate for a 150 lb. cylinder is:

Back 68

40lbs/day

Front 69

A low vacuum in the system can be caused by:

Back 69

Clogged injector

Front 70

Gas coming from an outside vent line would indicate a:

Back 70

Dirty Pressure Regulating Valve

Front 71

What's the primary reason for a reciprocating pump failure?

Back 71

Clogged or fouled check valve

Front 72

The chemical most often use to dechlorination wastewater effluent is:

Back 72

Sulfur dioxide

Front 73

Dissolver oxygen meters must be calibrated?

Back 73

Everyday

Front 74

A ph meter must be?

Back 74

Standardized before each use

Front 75

What's the formula for MLSS testing?

Back 75

GramsX1,000,000/sample size

Front 76

Which tests are run with grab samples?

Back 76

DO, PH, fecal coliform

Front 77

Fecal coliform tests are incubated at:

Back 77

44.5o + 0.2 C

Front 78

The maximum holding time for a proportional composite BOD sample is:

Back 78

48 hours

Front 79

MLVSS samples must be ignited at?

Back 79

500 +/- 50o C

Front 80

Fecal coliform colonies in the membrane filter test are:

Back 80

Blue

Front 81

What's the most common positive displacement pump?

Back 81

Reciprocating pump

Front 82

What's the purpose of a stuffing box?

Back 82

To keep water in and air out

Front 83

What does the packing gland do?

Back 83

Tightens the packing

Front 84

The lantern ring is aligned with?

Back 84

The seal water port

Front 85

At sea level what's the absolute maximum negative suction head?

Back 85

33.8 ft

Front 86

What are four factors in determining friction loss?

Back 86

Size of pipe

Flow through the pipe

Length of pipe

C factor

Front 87

A loss of shutoff head is most likely caused by ?

Back 87

an increase in recirculation inside the pump due to worn wear rings or worn impellers.

Front 88

The best way to prevent loss of prime is to always design a pump installation with

Back 88

Positive suction head on the pump

Front 89

If the pressure against a positive displacement pump increases:

Back 89

Flow stays the same

Front 90

What happens when you increase the pressure on a centrifugal pump?

Back 90

Flow decreases

Front 91

What is NPSH?

Back 91

Net positive suction head

Front 92

The maximum pressure a centrifugal pump can generate is called:

Back 92

Shutoff head

Front 93

For most pumping applications negative suction heads should never exceed?

Back 93

20 ft

Front 94

For most pumping applications negative suction heads should never exceed?

Back 94

20 ft

Front 95

Cavitation can be temporarily corrected by

Back 95

Throttling the discharge valve

Front 96

Bearings are heat stabilized to

Back 96

250 degrees

Front 97

If any two leads on a 3-phase motor are switched:

Back 97

It will run in the opposite direction

Front 98

RTU stands for?

Back 98

Remote terminal unit

Front 99

The alarm point for hydrogen sulfide gas is

Back 99

10 ppm

Front 100

The alarm point for carbon monoxide is ?

Back 100

35 ppm

Front 101

Ladders must extend at least ___ feet above the trench?

Back 101

3