WASTEWATER OPERATOR CLASS D
EXAM QUESTIONS WITH CORRECT
ANSWERS
Comminutor - Answer-A __________________ does not remove solids from the
wastewater, it shreds them and passes them to the next process
Large debris - Answer-Screens are installed to remove ______________
___________ at the plant headworks
settle out - Answer-If wastewater is allowed to 'back up" behind a screen, organic
waste can ________ _______ and cause odor problems
break down - Answer-Grit is removed too since it does not ________ ________
during treatment and to prevent equipment damage in downstream processes
organic waste - Answer-A grit classifier separates and removes ________ ________
from the grit that has been removed from the grit channel
organic / low - Answer-_________ waste mixed with the grit indicates that flow
velocities are too ______ in the grit channel
Comminutor - Answer-A _______________ shreds solids and passes them along to
the next treatment process
burial - Answer-Grit is typically disposed of by _____ in a landfill
Hydrogen sulfide - Answer-____________ ____________ is a gas that smells like
rotten eggs, is heavier than air, dulls the sense of smell, is extremely toxic, and is
explosive at certain concentrations in air
heavy rainfall - Answer-Periods of ________ ________ will deliver wastewater with
high levels of grit in systems that experience infiltration and inflow in the collection
system
pumps / pipes and digesters - Answer-Grit is removed early in the treatment process
since it can damage ________, and cause problems in ________ and _______
30 degrees, 45 degrees - Answer-Trash racks (bar racks) are constructed of steel
bars spaced 2 to 6 inches apart, placed in a flow channel at an angle ranging from
____________ to ___________ from vertical
screens, racks - Answer-Bar _______ are similar to bar _______except the spacing
between the bars is smaller
0.75, 2 - Answer-Bar screen spacing ranges from ______ to ______ inches
,1 ft / sec - Answer-Flow through the grit channel should be approximately
____________
0.7 fps - 1.4 fps - Answer-The normal range of grit channel flow is ____ fps to ____
fps to keep organic material suspended while allowing the grit to settle
remove - Answer-The purpose of a grit classifier is to ______ organic material from
the grit
volume and weight - Answer-A screening press reduces the ______ and _____ of
screening waste sent to the landfill since it dewaters and compacts screening waste
organic - Answer-Fine screens collect more _______ waste than larger, more coarse
screens, which can cause odor problems
15 minutes - Answer-Lab analysis of pH, temperature and dissolved oxygen should
be performed within ______ minutes of samples collection since they can change
rapidly once collected
2 pH units - Answer-pH buffers used for pH meter calibration should bracket the
expected pH and be at least ______pH units apart
Winkler - Answer-Dissolved oxygen can be determined by the Azide modification of
the ___________titration method
8 hours - Answer-When preserved with Sulfuric acid, a sample collected for
dissolved oxygen can wait up to ______ hour(s) before analysis when using the
Winkler method
0 and 4 - Answer-Samples collected for BOD analysis can be preserved by
refrigerating between ____ and _____ degrees Celsius
2 days - Answer-Preserved BOD samples can be held for ____ days
BOD - Answer-_______ samples are generally not used for process control since the
test takes 5 days to complete
7 days - Answer-Samples collected for suspended solids can be preserved and held
for ______ days before analysis
beaker - Answer-A ______ is used in the laboratory for measuring approximate
volumes and mixing chemicals
graduated cylinder - Answer-A _____________ ___________ can be used to quickly
measure and pour various liquid volumes
immediately - Answer-Chlorine residual should be analyzed ___________after
sample collection
,Pipette - Answer-A ___________ is used to accurately measure small volumes of
liquid
Grit - Answer-______ is composed of primarily inorganic material that does not
decompose during the biological treatment process
Inorganic / organic - Answer-Heavier ____________ material will settle in the grit
channel while the lighter __________material will pass on to the primary clarifier for
settling
break down - Answer-Grit is removed since it will not _______________ in the
anaerobic digester
equipment damage - Answer-Grit is removed to prevent _____________
____________ in downstream processes
solids and floatables - Answer-The primary treatment process is designed to
separate ________ and ________ from wastewater
50% - Answer-The primary treatment process can remove up to _______ of
incoming BOD when chemical coagulants are used
Colloidal particles - Answer-_______ ________ are very small and tend to carry an
electrical charge which makes it very difficult for them to flocculate and settle out
coagulants - Answer-____________ can be used to neutralize the electrical charge
of the colloidal particles and enable them to flock together and increase in size so
that they too will settle out
surface, hydraulic - Answer-The two main parameters an operator should use to
ensure proper settling occurs in the primary clarifier are the _________ overflow rate
and the __________ retention time
below, below - Answer-Grease removal from wastewater with a pH ________7 is
more difficult since grease tends to remain in suspension if the wastewater pH is
_______7
50% and 65% - Answer-Without chemical addition, the primary clarification process
can achieve between _____ and _____ suspended solid removal
25% and 35% - Answer-Without chemical addition, the primary clarification process
can achieve between _____ and _____ BOD reduction
4% to 6% - Answer-If primary sludge is sent directly to an anaerobic digestion
process, the operator will want the sludge pumped to have a ______ to _______
total solids concentration
600-800 gpd/sq ft - Answer-A typical surface overflow rate range for a primary
clarifier receiving raw wastewater as well as the plant's waste activated sludge is
_____ - _____ gpd/sq ft
, total solids - Answer-70 - 80% of primary sludge ______ ______ are usually volatile
aerating - Answer-By __________ the wastewater prior to primary clarification,
grease in the wastewater will be easier to remove
annually - Answer-Primary clarifiers should be drained and inspected __________
phosphorous - Answer-Primary sludge fermentation is used in plants that are
required to remove ______________ from the wastewater
3 to 5 - Answer-Sludge will ferment and produce volatile fatty acids to aid with
phosphorous removal when allowed to accumulate for ______ to _____ days in a
clarifier
chemicals / solids and BOD - Answer-Enhanced primary treatment using _______ to
achieve better ________ and ________ removals from the clarification process
Uniform Size - Answer-Trickling filter media should be of _________ __________ to
allow adequate ventilation
lowest - Answer-Trickling filter operators should use the __________recirculation
rate possible that produces good effluent quality
increase - Answer-Water temperatures _________the biological activity of a trickling
filter zoogloeal mass leading to better treatment
Slime growth / ventilation - Answer-The purpose of trickling filter media is to provide
a surface for _______ _______ to develop and allow for adequate _____________
Roughing - Answer-A trickling filter can be used as a ___________ filter to reduce
the organic load of the wastewater prior to another biological process
underdrain - Answer-The _________ channel should be drained during periods of
trickling filter shutdown to prevent odors and insect problems from developing
Increasing - Answer-_______________ the recirculation rate will help to reduce the
effluent BOD from a trickling filter
hydraulic - Answer-Recirculation of the trickling filter effluent is done to maintain a
constant __________ load on the trickling filter
low / reduced - Answer-If the recirculation rate is too ____ in a trickling filter, it can
lead to _____BOD removal, ponding, and filter fly reproduction
orifice/ stay rod - Answer-Adjusting the distributor arm ______openings and the
_____ _____ turnbuckles may be necessary to ensure even distribution of
wastewater over the surface of a trickling filter
EXAM QUESTIONS WITH CORRECT
ANSWERS
Comminutor - Answer-A __________________ does not remove solids from the
wastewater, it shreds them and passes them to the next process
Large debris - Answer-Screens are installed to remove ______________
___________ at the plant headworks
settle out - Answer-If wastewater is allowed to 'back up" behind a screen, organic
waste can ________ _______ and cause odor problems
break down - Answer-Grit is removed too since it does not ________ ________
during treatment and to prevent equipment damage in downstream processes
organic waste - Answer-A grit classifier separates and removes ________ ________
from the grit that has been removed from the grit channel
organic / low - Answer-_________ waste mixed with the grit indicates that flow
velocities are too ______ in the grit channel
Comminutor - Answer-A _______________ shreds solids and passes them along to
the next treatment process
burial - Answer-Grit is typically disposed of by _____ in a landfill
Hydrogen sulfide - Answer-____________ ____________ is a gas that smells like
rotten eggs, is heavier than air, dulls the sense of smell, is extremely toxic, and is
explosive at certain concentrations in air
heavy rainfall - Answer-Periods of ________ ________ will deliver wastewater with
high levels of grit in systems that experience infiltration and inflow in the collection
system
pumps / pipes and digesters - Answer-Grit is removed early in the treatment process
since it can damage ________, and cause problems in ________ and _______
30 degrees, 45 degrees - Answer-Trash racks (bar racks) are constructed of steel
bars spaced 2 to 6 inches apart, placed in a flow channel at an angle ranging from
____________ to ___________ from vertical
screens, racks - Answer-Bar _______ are similar to bar _______except the spacing
between the bars is smaller
0.75, 2 - Answer-Bar screen spacing ranges from ______ to ______ inches
,1 ft / sec - Answer-Flow through the grit channel should be approximately
____________
0.7 fps - 1.4 fps - Answer-The normal range of grit channel flow is ____ fps to ____
fps to keep organic material suspended while allowing the grit to settle
remove - Answer-The purpose of a grit classifier is to ______ organic material from
the grit
volume and weight - Answer-A screening press reduces the ______ and _____ of
screening waste sent to the landfill since it dewaters and compacts screening waste
organic - Answer-Fine screens collect more _______ waste than larger, more coarse
screens, which can cause odor problems
15 minutes - Answer-Lab analysis of pH, temperature and dissolved oxygen should
be performed within ______ minutes of samples collection since they can change
rapidly once collected
2 pH units - Answer-pH buffers used for pH meter calibration should bracket the
expected pH and be at least ______pH units apart
Winkler - Answer-Dissolved oxygen can be determined by the Azide modification of
the ___________titration method
8 hours - Answer-When preserved with Sulfuric acid, a sample collected for
dissolved oxygen can wait up to ______ hour(s) before analysis when using the
Winkler method
0 and 4 - Answer-Samples collected for BOD analysis can be preserved by
refrigerating between ____ and _____ degrees Celsius
2 days - Answer-Preserved BOD samples can be held for ____ days
BOD - Answer-_______ samples are generally not used for process control since the
test takes 5 days to complete
7 days - Answer-Samples collected for suspended solids can be preserved and held
for ______ days before analysis
beaker - Answer-A ______ is used in the laboratory for measuring approximate
volumes and mixing chemicals
graduated cylinder - Answer-A _____________ ___________ can be used to quickly
measure and pour various liquid volumes
immediately - Answer-Chlorine residual should be analyzed ___________after
sample collection
,Pipette - Answer-A ___________ is used to accurately measure small volumes of
liquid
Grit - Answer-______ is composed of primarily inorganic material that does not
decompose during the biological treatment process
Inorganic / organic - Answer-Heavier ____________ material will settle in the grit
channel while the lighter __________material will pass on to the primary clarifier for
settling
break down - Answer-Grit is removed since it will not _______________ in the
anaerobic digester
equipment damage - Answer-Grit is removed to prevent _____________
____________ in downstream processes
solids and floatables - Answer-The primary treatment process is designed to
separate ________ and ________ from wastewater
50% - Answer-The primary treatment process can remove up to _______ of
incoming BOD when chemical coagulants are used
Colloidal particles - Answer-_______ ________ are very small and tend to carry an
electrical charge which makes it very difficult for them to flocculate and settle out
coagulants - Answer-____________ can be used to neutralize the electrical charge
of the colloidal particles and enable them to flock together and increase in size so
that they too will settle out
surface, hydraulic - Answer-The two main parameters an operator should use to
ensure proper settling occurs in the primary clarifier are the _________ overflow rate
and the __________ retention time
below, below - Answer-Grease removal from wastewater with a pH ________7 is
more difficult since grease tends to remain in suspension if the wastewater pH is
_______7
50% and 65% - Answer-Without chemical addition, the primary clarification process
can achieve between _____ and _____ suspended solid removal
25% and 35% - Answer-Without chemical addition, the primary clarification process
can achieve between _____ and _____ BOD reduction
4% to 6% - Answer-If primary sludge is sent directly to an anaerobic digestion
process, the operator will want the sludge pumped to have a ______ to _______
total solids concentration
600-800 gpd/sq ft - Answer-A typical surface overflow rate range for a primary
clarifier receiving raw wastewater as well as the plant's waste activated sludge is
_____ - _____ gpd/sq ft
, total solids - Answer-70 - 80% of primary sludge ______ ______ are usually volatile
aerating - Answer-By __________ the wastewater prior to primary clarification,
grease in the wastewater will be easier to remove
annually - Answer-Primary clarifiers should be drained and inspected __________
phosphorous - Answer-Primary sludge fermentation is used in plants that are
required to remove ______________ from the wastewater
3 to 5 - Answer-Sludge will ferment and produce volatile fatty acids to aid with
phosphorous removal when allowed to accumulate for ______ to _____ days in a
clarifier
chemicals / solids and BOD - Answer-Enhanced primary treatment using _______ to
achieve better ________ and ________ removals from the clarification process
Uniform Size - Answer-Trickling filter media should be of _________ __________ to
allow adequate ventilation
lowest - Answer-Trickling filter operators should use the __________recirculation
rate possible that produces good effluent quality
increase - Answer-Water temperatures _________the biological activity of a trickling
filter zoogloeal mass leading to better treatment
Slime growth / ventilation - Answer-The purpose of trickling filter media is to provide
a surface for _______ _______ to develop and allow for adequate _____________
Roughing - Answer-A trickling filter can be used as a ___________ filter to reduce
the organic load of the wastewater prior to another biological process
underdrain - Answer-The _________ channel should be drained during periods of
trickling filter shutdown to prevent odors and insect problems from developing
Increasing - Answer-_______________ the recirculation rate will help to reduce the
effluent BOD from a trickling filter
hydraulic - Answer-Recirculation of the trickling filter effluent is done to maintain a
constant __________ load on the trickling filter
low / reduced - Answer-If the recirculation rate is too ____ in a trickling filter, it can
lead to _____BOD removal, ponding, and filter fly reproduction
orifice/ stay rod - Answer-Adjusting the distributor arm ______openings and the
_____ _____ turnbuckles may be necessary to ensure even distribution of
wastewater over the surface of a trickling filter
