2024 WASTEWATER TREATMENT
OPERATOR CERTIFICATION TEST 2
EXAM WITH CORRECT ANSWERS
What is the typical BOD removal efficiency in a primary clarifier?
A) 10 to 15%
B) 40 to 60%
C) 20 to 50%
D) 95 to 99% - CORRECT-ANSWERSC) 20 to 50% (v.1 pg 129)
What type of disinfection is gaining popularity, and expected to become a
practical alternative to chlorination?
A) Sulfur dioxide
B) Ultraviolet (UV) disinfection
C) Aqueous ammonia
D) Caustic soda - CORRECT-ANSWERSB) Ultraviolet (UV) disinfection (v.1 pg
303)
Where is the proper sampling location for an effluent from a wastewater
treatment plant?
A) Next to the chlorinator equipment
B) At the end of a solids handling facility
C) Prior to discharge into receiving waters
D) At the head of a chlorine contact chamber - CORRECT-ANSWERSC) Prior to
discharge into receiving waters
What is true if the F/M ratio increases?
A) Less DO is required
B) Less BOD is available
C) DO will not be affected by an increase in F/M ratio
D) More DO is needed - CORRECT-ANSWERSD) More DO is needed (v.2 pg
53)
Who must be included in a hearing conservation program to prevent hearing
loss?
,A) Employees whose normal noise exposure equals or exceeds 65 decibels
B) Employees whose normal noise exposure equals or exceeds an 8 hour
time weighted average of 85 decibels
C) Employees whose normal noise exposure exceeds 45 decibels at any time
D) Employees whose normal noise exposure exceeds and 8 hour time
weighted average of 25 decibels - CORRECT-ANSWERSB) Employees whose
normal noise exposure equals or exceeds an 8 hour time weighted average
of 85 decibels (v.2 pg 277)
What is a major cause of repeated sludge bulk?
A) High pH
B) High DO
C) High food to mircoorganism loading rates
D) High nutrient concentration - CORRECT-ANSWERSC) High food to
mircoorganism loading rates (v.2 pg 71)
How can the efficiency of a trickling filter be improved?
A) Raise the distributor arm
B) Reduce the size of the ventilation ports
C) Decrease the amount of the filter media
D) Add recirculation - CORRECT-ANSWERSD) Add recirculation (v.1 pg 175)
During the day, what typically happens to a pond as a result of the algae?
A) Algae uses carbon dioxide, which raises pH
B) Algae produces carbon dioxide, which lowers pH
C) Algae consumes carbon dioxide, which lower pH
D) Algae releases carbon dioxide, which raises pH - CORRECT-ANSWERSA)
Algae uses carbon dioxide, which raises pH (v.1 pg 299)
What should be done to find a small chlorine leak?
A) Spray hypocloric acid near the suspected leak
B) Tie a rag on a stick, dip the rag in a strong ammonia solution, and hold the
rag near the suspected points
C) Release carbon dioxide to trace the leak
D) Apply a small quantity of citric acid near the leak - CORRECT-ANSWERSB)
Tie a rag on a stick, dip the rag in a strong ammonia solution, and hold the
rag near the suspected points (v.1 pg 386)
What should you do if there is a thick, dark foam on the surface of an
aeration tank?
A) Increase the sludge wasting
, B) Decrease sludge wasting
C) Maintain current MLSS concentration
D) Increase the mircoorganism population - CORRECT-ANSWERSA) Increase
the sludge wasting (v.2 pg 53)
Why is mixing important in an anaerobic digester?
A) Increases the build up of grit
B) Speeds up digestion rate
C) Achieves heterogeneous content in the digester
D) Forms a scum blanket - CORRECT-ANSWERSB) Speeds up digestion rate
(v.2 pg 176)
Where is the correct location for a vent inside a room storing chlorine gas?
A) 12 inches below the ceiling
B) At nose level
C) Within 12 inches of the floor
D) At the highest point in the room - CORRECT-ANSWERSC) Within 12 inches
of the floor (v.1 pg 396)
What is the purpose of the seal at the stuffing box in a pump?
A) Increases the discharge flowrate of the pump
B) Minimizes cavitation
C) Increases brake horsepower
D) Lubricates the packing - CORRECT-ANSWERSD) Lubricates the packing
(v.2 pg 344)
What is the incubation period for the BOD test?
A) Five days +/- 3 hours
B) Five days +/- 1 hours
C) Five days +/-4 hours
D) Five days +/- 2 hours - CORRECT-ANSWERSA) Five days +/- 3 hours (v.2
pg 574)
What could happen if you are exposed to very high concentration of
hydrogen sulfide?
A) Swelling of the hand
B) Numbness of the legs
C) It could quickly lead to death
D) Develop skin rash - CORRECT-ANSWERSC) It could quickly lead to death
(v.2 pg 268)
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