(Part 1) Grade 4 wastewater certification practice test
Questions With Complete Solutions
. At what level should the alkalinity level be maintained in a
rotating biological contactor wastewater plant when nitrification
is occurring?
a. 3.4 times the influent ammonia b. 4.2 times the influent
ammonia c. 5.8 times the influent ammonia d. 7.1 times the
influent ammonia Correct Answers d. 7.1 times the influent
ammonia
. What is the beneficial concentration range of ammonia
nitrogen in an anaerobic digester?
a. 50 to 150 mg/L b. 50 to 200 mg/L c. 75 to 225 mg/L d. 100 to
250 mg/L Correct Answers b. 50 to 200 mg/L
2. What is the 5-day sludge age equivalent to?
a. 1 lb of food per 5 lb of organisms b. 1 lb of organisms per 5
lb of food c. 5 days of BOD d. 5 days by weight of mixed liquor
suspended solids Correct Answers a. 1 lb of food per 5 lb of
organisms
A high pH in a waste treatment pond will balance
a. aerobic fermentation b. anaerobic fermentation c. CO2 and
O2 production by algae and other microorganisms d. algae and
bacterial communities Correct Answers b. anaerobic
fermentation
,A modified version of the activated sludge process for removing
phosphorus and nitrogen would have the following sequence of
tank environments:
a. anaerobic, anoxic, and aerobic b. aerobic, nitrification, and
anaerobic c. anaerobic, anoxic, and denitrification d. anaerobic,
nitrification, aerobic, and denitrification Correct Answers a.
anaerobic, anoxic, and aerobic
A settleability test is performed on a secondary clarifier at an
activated sludge plant. If the sludge floats too soon, then the
sludge age should be reduced. What else may be done?
a. increase the DO b. decrease the BOD c. increase the F/M
(food-to-microorganism) ratio d. decrease the F/M ratio Correct
Answers c. increase the F/M (food-to-microorganism) ratio
A shock load of toxic wastes coming into a plant can be treated
or controlled with
a. coagulants only b. coagulants and lime c. coagulants and
coagulant aid d. coagulants or chlorine Correct Answers d.
coagulants or chlorine
A significant temperature change for an activated sludge plant is
usually plus or minus
a. 4°F b. 5°F c. 7°F d. 10°F Correct Answers d. 10°F
A thick dark foam on the surface of the oxidation ditch indicates
that the
, a. process is performing well b. rotor revolutions per minute
(rpm) are too fast c. wasting rate should be increased d. flow
through the ditch is too slow Correct Answers c. wasting rate
should be increased
A waste pond that is overloaded will usually be
a. light green b. dull green c. grayish green d. gray Correct
Answers d. gray
Adequate amounts of nitrogen and phosphorous are especially
lacking most often from which one of the following wastes?
a. industrial b. domestic c. fermentation industries d. food
processing Correct Answers d. food processing
All occupied trenches 4 or more ft deep must provide exits at a.
15-ft intervals b. 20-ft intervals c. 25-ft intervals d. 30-ft
intervals Correct Answers c. 25-ft intervals
An activated sludge plant has wastewater with a temperature of
20°C. In general, in days, what MCRT is needed for the plant to
produce a nitrified effluent?
a. 10 days b. 15 days c. 20 days d. 30 days Correct Answers b.
15 days
An operator starting up a new sequencing batch reactor plant
obtains 2,000 gal of seed sludge from another activated sludge
Questions With Complete Solutions
. At what level should the alkalinity level be maintained in a
rotating biological contactor wastewater plant when nitrification
is occurring?
a. 3.4 times the influent ammonia b. 4.2 times the influent
ammonia c. 5.8 times the influent ammonia d. 7.1 times the
influent ammonia Correct Answers d. 7.1 times the influent
ammonia
. What is the beneficial concentration range of ammonia
nitrogen in an anaerobic digester?
a. 50 to 150 mg/L b. 50 to 200 mg/L c. 75 to 225 mg/L d. 100 to
250 mg/L Correct Answers b. 50 to 200 mg/L
2. What is the 5-day sludge age equivalent to?
a. 1 lb of food per 5 lb of organisms b. 1 lb of organisms per 5
lb of food c. 5 days of BOD d. 5 days by weight of mixed liquor
suspended solids Correct Answers a. 1 lb of food per 5 lb of
organisms
A high pH in a waste treatment pond will balance
a. aerobic fermentation b. anaerobic fermentation c. CO2 and
O2 production by algae and other microorganisms d. algae and
bacterial communities Correct Answers b. anaerobic
fermentation
,A modified version of the activated sludge process for removing
phosphorus and nitrogen would have the following sequence of
tank environments:
a. anaerobic, anoxic, and aerobic b. aerobic, nitrification, and
anaerobic c. anaerobic, anoxic, and denitrification d. anaerobic,
nitrification, aerobic, and denitrification Correct Answers a.
anaerobic, anoxic, and aerobic
A settleability test is performed on a secondary clarifier at an
activated sludge plant. If the sludge floats too soon, then the
sludge age should be reduced. What else may be done?
a. increase the DO b. decrease the BOD c. increase the F/M
(food-to-microorganism) ratio d. decrease the F/M ratio Correct
Answers c. increase the F/M (food-to-microorganism) ratio
A shock load of toxic wastes coming into a plant can be treated
or controlled with
a. coagulants only b. coagulants and lime c. coagulants and
coagulant aid d. coagulants or chlorine Correct Answers d.
coagulants or chlorine
A significant temperature change for an activated sludge plant is
usually plus or minus
a. 4°F b. 5°F c. 7°F d. 10°F Correct Answers d. 10°F
A thick dark foam on the surface of the oxidation ditch indicates
that the
, a. process is performing well b. rotor revolutions per minute
(rpm) are too fast c. wasting rate should be increased d. flow
through the ditch is too slow Correct Answers c. wasting rate
should be increased
A waste pond that is overloaded will usually be
a. light green b. dull green c. grayish green d. gray Correct
Answers d. gray
Adequate amounts of nitrogen and phosphorous are especially
lacking most often from which one of the following wastes?
a. industrial b. domestic c. fermentation industries d. food
processing Correct Answers d. food processing
All occupied trenches 4 or more ft deep must provide exits at a.
15-ft intervals b. 20-ft intervals c. 25-ft intervals d. 30-ft
intervals Correct Answers c. 25-ft intervals
An activated sludge plant has wastewater with a temperature of
20°C. In general, in days, what MCRT is needed for the plant to
produce a nitrified effluent?
a. 10 days b. 15 days c. 20 days d. 30 days Correct Answers b.
15 days
An operator starting up a new sequencing batch reactor plant
obtains 2,000 gal of seed sludge from another activated sludge
