Wastewater Grade 3 Practice Test Exam with Questions and Answers – 100%
Solved
A 0.5 percent polymer solution (dry weight) is fed at a dose of 2 ppm to a clarifier receiving a
flow of 900 gpm. What should the polymer feed rate be in gallons per hour?
( )32.8 gal/hr
( )19.1 gal/hr
( )21.6 gal/hr
( )15.3 gal/hr
( )25.4 gal/hr - ✔✔✔-( )21.6 gal/hr
A 30 acre facultative pond is operated at a depth of 5 feet. The daily plant influent flow is 0.815
MGD with a BOD of concentration of 165 mg/L.
a.
Calculate the organic loading rate to this pond in lbs BOD/acre/day.
b.
How many days will it take to raise the level to 6 feet. (Assume flow remains constant and no
flow is discharged until the new level is reached)
( )25.2 lbs BOD/acre/day ; 10 days
( )24.3 lbs BOD/acre/day ; 15 days
( )37.4 lbs BOD/acre/day ; 12 days
( )49 lbs BOD/acre/day ; 14 days
( )13 lbs BOD/acre/day ; 12 days - ✔✔✔-( ) 37.4 lbs BOD/acre/day ; 12 days
A DAF with a 15 ft diameter receives a WAS flow of 25,000 gallons during a 10 hour period. Lab
tests show the WAS concentration to be 9,000 mg/L. Calculate the solids loading in lbs/hr/ft2.
( )0.5 lbs/hr/ft2 ( )1.9 lbs/hr/ft2
( )2.2 lbs/hr/ft2
( )1.1 lbs/hr/ft2
( )3.4 lbs/hr/ft2 - ✔✔✔-( )1.1 lbs/hr/ft2
,Wastewater Grade 3 Practice Test Exam with Questions and Answers – 100%
Solved
A drop in pH is expected in an anaerobic digester that is being started with a normal load of raw
sludge and a small amount of seed sludge.
( )True
( )False - ✔✔✔-( )True
Explanation: A drop in pH is expected in an anaerobic digester that is being started with a
normal load of raw sludge and a small amount of seed sludge.
A large population of rotifers in the activated sludge is usually an indication of bulking.
( )True
( )False - ✔✔✔-( )False
Explanation:
A large population of filamentous bacteria in the activated sludge is usually an indication of
bulking.
A low F/M ratio will cause a thick, white foam during the start-up of an activated sludge
wastewater
plant.
( )True
( )False - ✔✔✔-( )False
Explanation:
A High F/M ratio will cause a thick, white foam during the start-up of an activated sludge
wastewater plant
A properly functioning anaerobic digester will achieve a reduction in volatile solids of greater
than
50%.
, Wastewater Grade 3 Practice Test Exam with Questions and Answers – 100%
Solved
( )True
( )False - ✔✔✔-True
Explanation:
A properly functioning anaerobic digester will achieve a reduction in volatile solids of greater
than
50%.
Advanced primary treatment involves adding coagulants, such as ferric chloride, to improve the
removal of fine solids.
( )True
( )False - ✔✔✔-( )True
Explanation:
Advanced primary treatment involves adding coagulants, such as ferric chloride, to improve the
removal of fine solids. Coagulants neutralize small charged particles and allow them to
flocculate (stick together) which aids in settling.
An activated sludge plant is operating well with an F/M of 0.25 lbs BOD/lbs MLVSS under
aeration. Use the data below to solve the following:
a. Calculate the lbs MLVSS needed to be maintained to operate this plant at the given F/M
b.What concentration of MLSS must be maintained in the aeration basin if 77% of the MLSS is
volatile?
Flow 2 MGD Aerator Volume 0.5 MG Clarifier Volume 0.32 MG Influent BOD 200 mg/L Pri
Effluent BOD 120 mg/L Pri Eff SS 95 mg/L Pri Eff VSS 65 mg/L Influent SS 195 mg/L Influent VSS
170 mg/L
Solved
A 0.5 percent polymer solution (dry weight) is fed at a dose of 2 ppm to a clarifier receiving a
flow of 900 gpm. What should the polymer feed rate be in gallons per hour?
( )32.8 gal/hr
( )19.1 gal/hr
( )21.6 gal/hr
( )15.3 gal/hr
( )25.4 gal/hr - ✔✔✔-( )21.6 gal/hr
A 30 acre facultative pond is operated at a depth of 5 feet. The daily plant influent flow is 0.815
MGD with a BOD of concentration of 165 mg/L.
a.
Calculate the organic loading rate to this pond in lbs BOD/acre/day.
b.
How many days will it take to raise the level to 6 feet. (Assume flow remains constant and no
flow is discharged until the new level is reached)
( )25.2 lbs BOD/acre/day ; 10 days
( )24.3 lbs BOD/acre/day ; 15 days
( )37.4 lbs BOD/acre/day ; 12 days
( )49 lbs BOD/acre/day ; 14 days
( )13 lbs BOD/acre/day ; 12 days - ✔✔✔-( ) 37.4 lbs BOD/acre/day ; 12 days
A DAF with a 15 ft diameter receives a WAS flow of 25,000 gallons during a 10 hour period. Lab
tests show the WAS concentration to be 9,000 mg/L. Calculate the solids loading in lbs/hr/ft2.
( )0.5 lbs/hr/ft2 ( )1.9 lbs/hr/ft2
( )2.2 lbs/hr/ft2
( )1.1 lbs/hr/ft2
( )3.4 lbs/hr/ft2 - ✔✔✔-( )1.1 lbs/hr/ft2
,Wastewater Grade 3 Practice Test Exam with Questions and Answers – 100%
Solved
A drop in pH is expected in an anaerobic digester that is being started with a normal load of raw
sludge and a small amount of seed sludge.
( )True
( )False - ✔✔✔-( )True
Explanation: A drop in pH is expected in an anaerobic digester that is being started with a
normal load of raw sludge and a small amount of seed sludge.
A large population of rotifers in the activated sludge is usually an indication of bulking.
( )True
( )False - ✔✔✔-( )False
Explanation:
A large population of filamentous bacteria in the activated sludge is usually an indication of
bulking.
A low F/M ratio will cause a thick, white foam during the start-up of an activated sludge
wastewater
plant.
( )True
( )False - ✔✔✔-( )False
Explanation:
A High F/M ratio will cause a thick, white foam during the start-up of an activated sludge
wastewater plant
A properly functioning anaerobic digester will achieve a reduction in volatile solids of greater
than
50%.
, Wastewater Grade 3 Practice Test Exam with Questions and Answers – 100%
Solved
( )True
( )False - ✔✔✔-True
Explanation:
A properly functioning anaerobic digester will achieve a reduction in volatile solids of greater
than
50%.
Advanced primary treatment involves adding coagulants, such as ferric chloride, to improve the
removal of fine solids.
( )True
( )False - ✔✔✔-( )True
Explanation:
Advanced primary treatment involves adding coagulants, such as ferric chloride, to improve the
removal of fine solids. Coagulants neutralize small charged particles and allow them to
flocculate (stick together) which aids in settling.
An activated sludge plant is operating well with an F/M of 0.25 lbs BOD/lbs MLVSS under
aeration. Use the data below to solve the following:
a. Calculate the lbs MLVSS needed to be maintained to operate this plant at the given F/M
b.What concentration of MLSS must be maintained in the aeration basin if 77% of the MLSS is
volatile?
Flow 2 MGD Aerator Volume 0.5 MG Clarifier Volume 0.32 MG Influent BOD 200 mg/L Pri
Effluent BOD 120 mg/L Pri Eff SS 95 mg/L Pri Eff VSS 65 mg/L Influent SS 195 mg/L Influent VSS
170 mg/L
