Grade 4 Wastewater Certification

Front 1

What is the difference between a weak acid and a strong acid?

Back 1

Amount of hydrogen ions released

Front 2

A sewer shall not be entered without a self-contained breathing apparatus (SCBA) if the hydrogen sulfide (H²S) level exceeds?

Back 2

10 PPM

Front 3

Given the following information:

-aerobic digester dissolved oxygen level is at 3.5 mg/L

-all blowers are running

-pH is 7.2

-temperature is 19 degrees C

-specific oxygen uptake rate (SOUR) is 1.2mg/L O2/g/hr

-high surface turbulence

-the tank is exhibiting high rates of foaming

What is the first step you should take to reduce the foaming?

Back 3

Reduce aeration

Front 4

The addition of soda ash to a sour digester will

Back 4

Add less solid loading than lime

Front 5

During rounds, the operator notices that there is a broken chain in the rectangular primary tank. Which of the following would NOT be a cause of a broken scraper chain?

A. Excessive loading on the sludge collector

B. Debris caught on the primary tank weirs

C. Ice buildup in the tank

D. Improper shear pin sizing and flight alignment

Back 5

B. Debris caught on the primary tank weirs

Front 6

What chlorine emergency repair kit is used to stop leaks only at the valves of tank cars?

Back 6

Repair kit C

Front 7

What is the most important factor to monitor in your anaerobic digestion process because it will be one of the first indicators that the digester may be going sour?

Back 7

Volatile acids / alkalinity ratio

Front 8

In the solids removal physical-chemical treatment process, if the sludge collector has a jerky operation, what is the most probable cause?

Back 8

Sludge blanket too deep

Front 9

If a belt filter press has cake solids that are too wet, what is the most probable cause?

Back 9

Belt tension too low

Front 10

The WAS rate should not be changed by more than ________ from one day to the next.

Back 10

10-15%

Front 11

In an activated sludge plant, what would a major storm event due to the percent volatile matter in the aerator?

Back 11

Decrease the percent volatile matter

Front 12

Rising sludge is caused by _______ and _______.

Back 12

Septicity and denitrification

Front 13

If filamentous organisms are the cause of sludge floating on the surface of secondary clarifiers, what would be the best solution?

Back 13

Increase sludge return rate

Front 14

If the mean cell residence time was too long and cause dark tan foam on the aeration tank, what would be the best course of action?

Back 14

Moderately increased sludge wasting to reduce MCRT

Front 15

Nocardia growth is most associated with

Back 15

Low DO or low F/M ratio

Front 16

What is the optimal pH range for the biological nitrification process?

Back 16

7.5 - 8.5

Front 17

at what level should the alkalinity level be maintained in a rotating biological contactor wastewater plant when nitrification is occurring?

Back 17

7.1 times the influent ammonia

Front 18

a modified version of the activated sludge process for removing phosphorus and nitrogen would have the following sequence of tank environments.

Back 18

Anaerobic, anoxic, aerobic

Front 19

To what should the pH be raised for converting NH⁴ to gaseous ammonia (NH³)?

Back 19

10.5 - 11.5

Front 20

What is the theoretical amount of oxygen in milligrams required to convert 1 mg of ammonia nitrogen to nitrate nitrogen?

Back 20

4.6 mg

Front 21

What is the approximate carrying or mixing time for lime used in residual solids management?

Back 21

30 minutes

Front 22

Along with nutrients, anaerobic bacteria need mostly

Back 22

Volatile acids

Front 23

Which of the following types of organisms is hardest to kill?

Back 23

Cryptosporidium

Front 24

What is the only type of pump that can be operated against the closed valve?

Back 24

Centrifugal pump

Front 25

The purpose of the lantern ring is to

Back 25

Distribute lubrication to the packing

Front 26

What device serves the same function as the packing?

Back 26

Mechanical seal

Front 27

Open impellers are usually used to pump water that contains

Back 27

Large solids

Front 28

What is a major cause of bearing failure?

Back 28

Poor lubrication practices

Front 29

How much seal water does a mechanical seal require?

Back 29

1 or 2 drops every few minutes

Front 30

Which of the following statements is false?

A. Most pumps are self-priming

B. Bearings can be over lubricated

C. Fire point is defined as the point at which a lubricant will burn

D. Oil is used in high RPM conditions while grease is used in low speeds and heavy loads

Back 30

A. Most pumps are self-priming

Front 31

Autoclaving will sterilize

Back 31

With steam at 121° C and 15 psi

Front 32

During a confined space entry, how often must a confined space be monitored for hazardous atmospheres?

Back 32

Continuously

Front 33

Permits that regulate discharges into navigable waters must meet requirements from

Back 33

National Pollutant Discharge Elimination System (NPDES)

Front 34

An NPDES discharge permit does not require

Back 34

Dissolved solids

Front 35

What would be the most probable cause for large air bubbles in the aeration tank?

Back 35

Broken diffusers in that area

Front 36

If an activated sludge plant is hit with a toxic load, what will most likely occur in the aeration tank?

Back 36

A DO increase without an increase in air input

Front 37

ammonia nitrogen is removed from wastewater by a process called desorption or stripping. What chemical is added to the wastewater to accomplish this removal?

Back 37

Lime

Front 38

The first stage of biochemical oxygen demand (BOD) can also be called _______ BOD.

Back 38

Carbonaceous

Front 39

The second stage of biochemical oxygen demand (BOD) can also be called _______ BOD.

Back 39

Nitrogenous

Front 40

A trickling filter plant should use the _______ recirculation rate possible to produce the best results and to also meet the _______ requirements.

Back 40

Lowest, NPDES permit

Front 41

Mesophilic bacteria thrive between the temperature range of

Back 41

68 to 113 degrees F

Front 42

What is the best method to prevent foaming from occurring in an anaerobic digester?

Back 42

Adequate mixing from top to bottom of the tank

Front 43

If the volatile-acid-alkalinity ratio was increasing in an anaerobic digester, what would be the most probable cause?

Back 43

Withdrawing too much sludge

Front 44

Before digestive sludge is fed to a centrifuge, it is usually conditioned with

Back 44

Polymers

Front 45

After luxury uptake of phosphorus by microorganisms, to what environment are the microorganisms transferred in order for them to release this phosphorus?

Back 45

Anaerobic

Front 46

What determination is the best means for monitoring the day-to-day operations of the nitrification process?

Back 46

Alkalinity

Front 47

How can sulfuric acid damage to treatment plant structures be reduced or eliminated?

Back 47

Apply oxygenation to destroy hydrogen sulfide

Front 48

When microorganisms enter the endogenous phase, they are

Back 48

Oxidizing their own cellular mass

Front 49

Which type of land disposal of wastewater requires no vegetation?

Back 49

Rapid infiltration (not allowed in Tennessee)

Front 50

What is the ideal wastewater velocity in feet per second for grit removal in a grit chamber?

Back 50

1.0 ft/s

Front 51

What test could an operator use to make process changes immediately if a problem develops?

Back 51

COD

Front 52

When is dissolved oxygen level in a waste pond the lowest?

Back 52

Sunrise

Front 53

The fusible plug on a chlorine cylinder will start to melt at approximately

Back 53

160 degrees F

Front 54

What class of fire involves electrical equipment?

Back 54

Class C

Front 55

What piece of laboratory glassware is primarily used to mix chemicals and measure approximate volumes?

Back 55

Beaker

Front 56

Volumetric glassware is best for _______ measurements

Back 56

Exact

Front 57

work has been completed on a motor for a centrifugal pump. The pump is now running, but generating little pressure and Flow. What is most likely the cause?

Back 57

The impeller is rotating the wrong way

Front 58

The velocity and sanitary sewers is approximately

Back 58

2 ft/sec

Front 59

Adequate BOD/nitrogen/phosphorus ratio for microorganisms to grow is usually

Back 59

100:5:1

Front 60

When is the pH in a waste pond the lowest?

Back 60

Sunrise

Front 61

When is the pH in a waste pond the highest?

Back 61

Around 4 p.m.

Front 62

If the head words in a wastewater treatment plant had and H²S odor, what would be the most likely solution?

Back 62

Add treatment chemicals

Front 63

What is the ultimate measure of effective chlorination?

Back 63

Bacteriological result

Front 64

An atmosphere is defined as oxygen-deficient if it contains less than what percent oxygen by volume?

Back 64

19.5%

Front 65

What condition will occur if sludge is not pumped out of the primary clarifier is at regular intervals?

Back 65

Clarifier will become septic

Front 66

Denitrification can be achieved in an oxidation ditch using all of the following EXCEPT?

A. Increasing the RAS rate

B. Turning off one or more rotors

C. Turning the aerators off at least twice a day

D. Creating zones with and without aeration

Back 66

A. Increasing the RAS rate

Front 67

Operator should, as a rule, never change the temperature and an anaerobic digester by more than

Back 67

1 degrees / day

Front 68

Biological activity in Long, sluggish flow, flat grade sewer lines will likely cause

Back 68

Concrete and metal corrosion, oxygen deficiency in the air in manholes, sewers or wet wells, and toxic gas production

Front 69

When packing a centrifugal pump, the packing gland should be tightened

Back 69

Slowly over a period of several hours

Front 70

Your chlorinator room should have an exhaust fan installed

Back 70

Near the floor

Front 71

A chlorine gas mask should be provided

Back 71

Just outside the chlorine room door

Front 72

Which of the following would not be considered a natural event?

A. Explosion

B. Flood

C. Lightning

D. Tornado

Back 72

A. Explosion

Front 73

If a chemical cost $30 per ton, how much will it cost per year to treat a flow of 1.5 MGD if the average dose is 18 mg/L?

Back 73

$1,233

Front 74

When carrying out a routine inspection on a centrifugal pump, it is noted by the operator that the bearings are excessively hot. This could be caused by:

Back 74

Over lubrication

Front 75

Cattails growing in a lagoon will

Back 75

Cause short-circuiting in the lagoon

Front 76

A water resource recovery facility has three trickling filters with rock media. Two trickling filters are in service and one is out of service as a standby. One of the in-service trickling filters is experiencing ponding on the filter surface. Which of the following is NOT a solution to correct their performance?

A. Flood the filter for 24 hours

B. Increase the hydraulic loading on the filter

C. Shut down the filter until the media dries out

D. Increase the organic loading on the filter

Back 76

D. Increase the organic loading on the filter

Front 77

The incubator for the BOD test should be controlled at ___ degrees C

Back 77

20

Front 78

Settled activated sludge is generally _______ than raw sludge.

Back 78

Thinner

Front 79

The purpose of adding sodium thiosulfate (Na²S²O³) to a microbiological sample bottle is to

Back 79

Remove any chlorine residual present

Front 80

The ability of an instrument to measure a process variable and repeatedly obtain the same result describes what?

Back 80

Precision

Front 81

What problem could be created in the coagulation process by too long or too a rapid mix?

Back 81

The break-up and separation of the forming floc

Front 82

The condition that is created when a non-potable water system is connected or allowed to come in contact with a potable water system because proper backflow prevention either failed or we're not installed.

Back 82

Cross connection

Front 83

Laboratory analysis in a wastewater lab may require what forms of PPE?

Back 83

Gloves, face shield, apron

Front 84

4 magnetic flow meter to read correctly it should be located ____ pipe diameters downstream from any valves.

Back 84

5

Front 85

Convert 95 degrees F into C

Back 85

35

Front 86

Which of the following sets of BOD sample results meet quality control requirements?

Back 86

3.0 mg/L depletion, 2.0 mg/L DO remaining, Blank depletion 0.1 mg/L

Front 87

What can be use to clean fouled membranes?

Back 87

Acid

Front 88

Alum reacts with _______ in water to form aluminum hydroxide as the precipitate.

Back 88

Alkalinity

Front 89

Which area of the comminutor should be checked if there are ropes or rags surrounding the drum of the comminutor?

Back 89

Cutter head

Front 90

According to 40 CFR 503, what are the fecal coliform limits for class a biosolids?

Back 90

Less than 1000 MPN or cfu

Front 91

According to 40 CFR 503, what are the fecal coliform limits for class b biosolids?

Back 91

Less than 2 million MPN or cfu

Front 92

Which of the following samples would require seed in a BOD test?

A. Sample was collected at outfall

B. Influent composite sample

C. Sample containing nitrification inhibitor for CBOD analysis

D. Both A and C

Back 92

D. Both A and C

Front 93

All of the following could be possible causes of short-circuiting in a secondary clarifier except

A. The effluent weir is not level

B. Accumulation of sludge deposits on the floor

C. There is a clearly defined layer of warm water at the surface

B. The electrical panel that controls the traveling bridge has a blown fuse

Back 93

D. The electrical panel that controls the traveling bridge has a blown fuse

Front 94

This type of activated sludge process mode has a contact tank in which microorganisms take in and store large portions of influent waste in a short period of time (30-90 minutes).

Back 94

Contact stabilization

Front 95

What would be considered improper laboratory practice that does not meet 40 CFR 136 method requirements?

Back 95

The use of a color comparator for total chlorine analysis

Front 96

The best way for managers to transmit information that is very important to employees is by

Back 96

Face-to-face meeting

Front 97

The utility is planning to implement a new staffing plan. What is most critical to successful implementation of the plan?

Back 97

Advanced communication of the plan to the staff

Front 98

Reviewing all aspects of the wastewater treatment system to determine what would occur during various types of emergency situations is known as a

Back 98

Vulnerability assessment

Front 99

Wastewater entering a treatment plant is typically

Back 99

Somewhat warmer than unheated tap water

Front 100

Anaerobic decomposition of wastewater produces

Back 100

Hydrogen sulfide

Front 101

What can cause overheating of mechanical equipment?

Back 101

Over greasing

Front 102

What is the purpose of a SCADA system?

Back 102

Control equipment and collect data

Front 103

Entrained are frequently contributes to

Back 103

Pump cavitation

Front 104

A BOD can be removed from the incubator at five days plus or minus

Back 104

6 hours

Front 105

Fecal coliform results are reported as MPN per

Back 105

100 mL

Front 106

What is one advantage of a COD test over a BOD test?

Back 106

Shorter test time

Front 107

Alkalinity is a measure of the ability of wastewater to

Back 107

Neutralize acid

Front 108

In a healthy activated sludge process, what organisms will most likely be found in the greatest numbers?

Back 108

Stalked ciliates

Front 109

Since reaction rates are lower during the winter, the operator of an activated sludge plant will usually

Back 109

Increase MCRT

Front 110

Filamentous bulking of activated sludge maybe control temporarily by

Back 110

Carefully chlorinating the return sludge or mixed liquor

Front 111

What test would give the fastest indication of toxicity and an activated sludge process?

Back 111

Oxygen Uptake Rate (OUR)

Front 112

Why is scum skimmed from the liquid surface of a primary settling tank?

Back 112

To eliminate interference with sludge removal

Front 113

The best operating strategy for feeding primary sludge to an anaerobic digester is to feed

Back 113

Several times a day

Front 114

In an activated sludge process, some of the activated sludge must be wasted to

Back 114

Prevent excessive solids buildup

Front 115

Laboratory analysis of ammonia involves gently boiling the sample and collecting the distillate into an acid solution. This process is called what?

Back 115

Distillation

Front 116

Clarifier washout occurs when this percentage of solids is lost over the effluent weirs

Back 116

30%

Front 117

According to the TN design criteria, what DO must be maintained throughout an equalization tank?

Back 117

1.0 mg/L

Front 118

Chlorine dose = chlorine demand + _______

Back 118

Chlorine residual

Front 119

Dosing polymer at a high rate on to a belt filter press can cause a condition known as _______ to show up in the belt filter press sludge on the gravity zone

Back 119

Belt blinding

Front 120

Electrical transformers are used to

Back 120

Increase or decrease voltage

Front 121

Chlorination tends to be more effective when wastewater has a lower pH. This is primarily attributable to

Back 121

A higher percentage of hydrochlorous acid (HOCI) at a lower pH

Front 122

How is the target mean cell residence time (MCRT) maintained in an activated sludge system?

Back 122

Solids wasting