(PART 1) GRADE 4 WASTEWATER CERTIFICATION
PRACTICE TEST
1. 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
Answer√√ b. 0.3 ppm
2. 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
Answer√√ negative pole of an electrolytic cell or system
3. The least reactive metals are called a. anodic metals b. galvanic metals c.
cathodic metals d. tempered metals
Answer√√ c. cathodic metals
4. 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)
,Answer√√ d. 160°F (71°C)
5. 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 headAnswer√√ b. suction lift
6. 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 intervalsAnswer√√ c. 25-ft intervals
7. 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 carbon-
ate ions released d. amount of hydrogen ions released
Answer√√ d. amount of hydrogen ions released
8. 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
Answer√√ b. pressure-relief
9. 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
Answer√√ d. coagulants or chlorine
10. 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 breakdownAnswer√√
b. an approved sanitary landfill
, 11. 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. decompo-
sition 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 electrolyteAnswer√√ b. decomposition of a material caused by an outside electric current
12. 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
Answer√√ b. 7.0
13. 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
PRACTICE TEST
1. 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
Answer√√ b. 0.3 ppm
2. 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
Answer√√ negative pole of an electrolytic cell or system
3. The least reactive metals are called a. anodic metals b. galvanic metals c.
cathodic metals d. tempered metals
Answer√√ c. cathodic metals
4. 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)
,Answer√√ d. 160°F (71°C)
5. 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 headAnswer√√ b. suction lift
6. 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 intervalsAnswer√√ c. 25-ft intervals
7. 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 carbon-
ate ions released d. amount of hydrogen ions released
Answer√√ d. amount of hydrogen ions released
8. 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
Answer√√ b. pressure-relief
9. 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
Answer√√ d. coagulants or chlorine
10. 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 breakdownAnswer√√
b. an approved sanitary landfill
, 11. 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. decompo-
sition 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 electrolyteAnswer√√ b. decomposition of a material caused by an outside electric current
12. 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
Answer√√ b. 7.0
13. 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
