(Part 1) Grade 4 wastewater
certification practice test fully solved
already passed
b. 0.3 ppm - correct answer ✔✔What is the odor detection limit of chlorine gas?
a. 0.1 ppm b. 0.3 ppm c. 0.5 ppm d. 1.0 ppm
negative pole of an electrolytic cell or system - correct answer ✔✔What is a cathode?
a. negative pole of an electrolyte b. positive pole of an electrolyte c. negative pole of an
electrolytic cell or system d. positive pole of an electrolytic cell or system
c. cathodic metals - correct answer ✔✔The least reactive metals are called a. anodic metals b.
galvanic metals c. cathodic metals d. tempered metals
d. 160°F (71°C) - correct answer ✔✔Unless water cooled, the operating temperature of a
mechanical seal in a pump should never exceed a. 95°F (35°C) b. 120°F (49°C) c. 140°F (60°C) d.
160°F (71°C)
b. suction lift - correct answer ✔✔What term describes the condition that exists when the
source of the water supply is below the centerline of the pump? a. total discharge head b.
suction lift c. velocity head d. pressure head
c. 25-ft intervals - correct answer ✔✔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
d. amount of hydrogen ions released - correct answer ✔✔What is the difference between a
weak acid and a strong acid? a. amount of buffering released b. amount of hydroxyl ions
released c. amount of carbonate ions released d. amount of hydrogen ions released
,b. pressure-relief - correct answer ✔✔Which one of the following is the best type of valve to
use to dampen a water hammer? a. needle b. pressure-relief c. pressure-reducing d. pinch
d. coagulants or chlorine - correct answer ✔✔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
b. an approved sanitary landfill - correct answer ✔✔Toxic solids should be disposed of in
a. a digester to destabilize and break down the toxins b. an approved sanitary landfill c. an
incinerator d. a sludge pond for further aerobic breakdown
b. decomposition of a material caused by an outside electric current - correct answer ✔✔Which
one of the following best defines the term stray-current corrosion?
a. decomposition of a metal by its reaction with an acidic water b. decomposition of a material
caused by an outside electric current c. reaction between a metal and water d. reaction
between two different metals with water acting as an electrolyte
b. 7.0 - correct answer ✔✔On startup of a small package wastewater treatment plant, lime
should be added to the digestion unit when the pH goes below
a. 6.8 b. 7.0 c. 7.2 d. 7.5
b. pumping rate for the return of activated sludge is out of balance - correct answer ✔✔If the
effluent to a small package wastewater treatment plant using the activated sludge process
appears turbid, what is most probably the cause?
, a. low concentration of dissolved oxygen (DO) in the aeration tank b. pumping rate for the
return of activated sludge is out of balance c. excessive aeration rates in the aeration tank d.
alkalinity is too high
c. reduce the aeration rates - correct answer ✔✔If a small package treatment plant utilizing the
activated sludge process has a lightcolored floating sludge on the surface of the clarifier, which
one of the following would most likely eliminate the floating sludge?
a. increase the sludge wasting rate b. add a pH stabilizer, as pH is too low c. reduce the aeration
rates d. increase the return sludge rate
d. too long a detention time - correct answer ✔✔What usually causes frothing in the activated
sludge process?
a. too low a solids level b. too high a solids leaving c. too short a retention time d. too long a
detention time
b. water sprays - correct answer ✔✔Which one of the following suggestions would most likely
control foaming?
a. increase the detention time b. water sprays c. increase the dissolved oxygen d. increase
solids wasting
d. ½ of the jar depth - correct answer ✔✔What is the ideal level of solids in a jar test sample
collected from an aeration tank if it is allowed to settle for 30 min?
a. ¼ of the jar depth b. ⅓ of the jar depth c. ⅖ of the jar depth d. ½ of the jar depth
a. 2 hr - correct answer ✔✔In a small wastewater treatment plant using the activated sludge
process, solids in the settling compartment should not be allowed to remain longer than
certification practice test fully solved
already passed
b. 0.3 ppm - correct answer ✔✔What is the odor detection limit of chlorine gas?
a. 0.1 ppm b. 0.3 ppm c. 0.5 ppm d. 1.0 ppm
negative pole of an electrolytic cell or system - correct answer ✔✔What is a cathode?
a. negative pole of an electrolyte b. positive pole of an electrolyte c. negative pole of an
electrolytic cell or system d. positive pole of an electrolytic cell or system
c. cathodic metals - correct answer ✔✔The least reactive metals are called a. anodic metals b.
galvanic metals c. cathodic metals d. tempered metals
d. 160°F (71°C) - correct answer ✔✔Unless water cooled, the operating temperature of a
mechanical seal in a pump should never exceed a. 95°F (35°C) b. 120°F (49°C) c. 140°F (60°C) d.
160°F (71°C)
b. suction lift - correct answer ✔✔What term describes the condition that exists when the
source of the water supply is below the centerline of the pump? a. total discharge head b.
suction lift c. velocity head d. pressure head
c. 25-ft intervals - correct answer ✔✔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
d. amount of hydrogen ions released - correct answer ✔✔What is the difference between a
weak acid and a strong acid? a. amount of buffering released b. amount of hydroxyl ions
released c. amount of carbonate ions released d. amount of hydrogen ions released
,b. pressure-relief - correct answer ✔✔Which one of the following is the best type of valve to
use to dampen a water hammer? a. needle b. pressure-relief c. pressure-reducing d. pinch
d. coagulants or chlorine - correct answer ✔✔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
b. an approved sanitary landfill - correct answer ✔✔Toxic solids should be disposed of in
a. a digester to destabilize and break down the toxins b. an approved sanitary landfill c. an
incinerator d. a sludge pond for further aerobic breakdown
b. decomposition of a material caused by an outside electric current - correct answer ✔✔Which
one of the following best defines the term stray-current corrosion?
a. decomposition of a metal by its reaction with an acidic water b. decomposition of a material
caused by an outside electric current c. reaction between a metal and water d. reaction
between two different metals with water acting as an electrolyte
b. 7.0 - correct answer ✔✔On startup of a small package wastewater treatment plant, lime
should be added to the digestion unit when the pH goes below
a. 6.8 b. 7.0 c. 7.2 d. 7.5
b. pumping rate for the return of activated sludge is out of balance - correct answer ✔✔If the
effluent to a small package wastewater treatment plant using the activated sludge process
appears turbid, what is most probably the cause?
, a. low concentration of dissolved oxygen (DO) in the aeration tank b. pumping rate for the
return of activated sludge is out of balance c. excessive aeration rates in the aeration tank d.
alkalinity is too high
c. reduce the aeration rates - correct answer ✔✔If a small package treatment plant utilizing the
activated sludge process has a lightcolored floating sludge on the surface of the clarifier, which
one of the following would most likely eliminate the floating sludge?
a. increase the sludge wasting rate b. add a pH stabilizer, as pH is too low c. reduce the aeration
rates d. increase the return sludge rate
d. too long a detention time - correct answer ✔✔What usually causes frothing in the activated
sludge process?
a. too low a solids level b. too high a solids leaving c. too short a retention time d. too long a
detention time
b. water sprays - correct answer ✔✔Which one of the following suggestions would most likely
control foaming?
a. increase the detention time b. water sprays c. increase the dissolved oxygen d. increase
solids wasting
d. ½ of the jar depth - correct answer ✔✔What is the ideal level of solids in a jar test sample
collected from an aeration tank if it is allowed to settle for 30 min?
a. ¼ of the jar depth b. ⅓ of the jar depth c. ⅖ of the jar depth d. ½ of the jar depth
a. 2 hr - correct answer ✔✔In a small wastewater treatment plant using the activated sludge
process, solids in the settling compartment should not be allowed to remain longer than
