Comprehensive Wastewater Operator
Exam TN 2026 Set.
Latest Updated 100% Verified Guide
2026/2027.
What is the purpose of wastewater treatment? - ANSPrevention of pollution and protect
public health
What is inflow? - ANSDirect discharge into the sewer from sources other than regular
connections
What is infiltration? - ANSSeepage of groundwater into the sewer system through cracks,
manholes, pipes, and connections
How many feet apart should manholes be placed to provide access for inspections and
cleaning? - ANS300-500
Manholes must be installed - ANSAt the ends of any line 8" in diameter or larger line
Changes in grade, size of pipe or alignment
At intersections
Not greater than 400ft on a 15" diameter and smaller sewers or 500ft on 18-30" sewers
Hydrogen sulfide is made in the collection system and can cause what problems? - ANSMake
waste more difficult to treat
Damage concrete structures
Cause odor problems
Biological activity in long, flat sewer lines will likely cause: - ANSHydrogen sulfide
production
Oxygen deficiency in sewers, manholes, or wet wells
Metal and concrete corrosion
What is an indicator that a toxic load has entered an activated sludge plant? - ANSIncrease in
oxygen concentration in the aeration basin
What two factors can influence the amount of dissolved oxygen present? - ANSWater
temperature and organic matter
How does water temperature affect dissolved oxygen? - ANSGreater temperature means less
D.O.
Lower temperature means more D.O.
How does organic matter affect dissolved oxygen? - ANSMore organic material requires
more D.O.
What are problems associated with excess nutrients? - ANSAn increase in productivity of
aquatic plants thus depleting D.O. Level
Odor problems
Extra vegetation near surface may inhibit light
What is your best defense against infections and disease? - ANSGood personal hygiene
What may a solids build up in a receiving stream cause? - ANSMay cause oxygen depletion
and be a source of odors
What problems do solids cause in the system? - ANSFill storage areas, clog ditches and
channels
Interfere with mechanical systems
Associated with taste/color/clarity problems in drinking water
What types of solids are in wastewater? - ANSTotal solids
,Comprehensive Wastewater Operator
Exam TN 2026 Set.
Latest Updated 100% Verified Guide
2026/2027.
Dissolved solids
Suspended solids
Organic solids
Inorganic solids
Floatable solids
Fresh domestic wastewater is usually what color - ANSGrey/dishwater color
What color is septic wastewater typically? - ANSBlack
How does fresh domestic wastewater smell? - ANSMusty early odor
In the state of TN flow measuring devices must be calibrated and maintained to ensure
_____________ of the true flow - ANS+/- 10%
What is the parshall flume best for? - ANSFlow with solids or debris
Large flows
Variable flows
What is the usual detention time in a primary clarifier? - ANS1.5-2.0 hours
What does velocity drop to in a primary clarifier? - ANS< 1fps
For wastewater to be considered "disinfected" what is the qualifications? - ANS200 CFU/100
ml for fecal colioforms
126cfu/100ml for E. Coli
Preliminary treatment commonly consists of: - ANSScreening
Shredding
Grit removal
Pre aeration
What do coarse screens remove? - ANSLarge solids, trash, wood, tree limbs, rocks, and other
large debris
What are three coarse screens? - ANSBar rack
Manually cleaned bar screen
Mechanically cleaned bar screen
What are three fine screens? - ANSWedge wire
Rotary drum screens
Escalating step screen
How much spacing is between bar racks? - ANS3-4 inches
How much spacing is between bar screens? - ANS~3/8 in to 2 inches
Where are bar racks found? - ANSIn bypass channels for when flows get diverted
If manually cleaned bar screens are not attended to frequently this could cause: - ANSDebris
collecting and cause head loss
Flow backs up ->Organic wastes settle out-> depletes DO -> leads to septic
Sudden rush of septic can lead to "shock load"
The allowable head loss behind a bar screen should be ___________ - ANSA max of 3
inches
On a mechanically cleaned bar screen list some maintenance items: - ANSDrive units:
adjustments must be made if cables dont wind up evenly on drums of cable machines
,Comprehensive Wastewater Operator
Exam TN 2026 Set.
Latest Updated 100% Verified Guide
2026/2027.
Frayed or excessively worn chain must be replaced
Bent or broken bars must be replaced
If the motor on a mechanical cleaned bar screen runs but the rack doesnt operate what may be
the problem? - ANSBroken chain, cable or shear pin
What do fine screens typically consists of: - ANSWedge wire
Closely spaced bars/screening cloth
Perforated plate
What are the openings of fine screens - ANS0.06-0.25 inch
What are the three steps of maintenance to monitor with fine screens? - ANSVisual
Auditory
Proper lubrication
What is the opening for wedge wire screens? - ANS0.010-0.100 in opening
What wastewater is wedgewire screen not recommended for? - ANSWastewater that contains
grease
How are screenings removed from internally fed rotary drum screens? - ANSAuger/conveyor
and squeezed to drain
How are screenings removed from an externally fed rotary drum screen - ANSScreenings
collected in the hopper
What are the openings on an escalating step screen? - ANS0.125-0.250 inch
What are comminutors? - ANSDevices with cutters and screens that shred solids and return
them to wastewater stream
What are three disadvantages of comminutors? - ANSShredded rags affect operation of
downstream units
Increased load on downstream units
Head loss downstream if not checked or maintained properly
What are four maintenance items for comminutors and barminutors? - ANSCheck for debris
in the cutting drums and bars
Sharpen and adjust the cutting blades
Exercise inlet/outlet gates
Inspect travel and rotation of cutting blades
If stringing parts of rags are hanging from slotted drum or U shaped bars of the comminutor
what would that indicate? - ANSThe cutter is worn or out of adjustment
What is the conventional bar screen capture rate? - ANS6 cubic ft/ MG
How do you calculate screenings removed in cubic feet of screenings per MG of flow? -
ANSScreenings removed cu ft/day
——————————————————
Flow MGD
What does the paint filter test measure? - ANSLeaching effect of your screenings
What benefit does grit removal have on the treatment system? - ANSReduce the clogging of
pipes and protects moving mechanical equipment/pumps from abrasion and accompanying
wear
, Comprehensive Wastewater Operator
Exam TN 2026 Set.
Latest Updated 100% Verified Guide
2026/2027.
What does a grit channel do? - ANSAllow grit to settle out while keeping the lighter organic
solids moving to the next treatment unit
What is the best velocity for a grit channel? - ANS1ft/sec
What is a potential problem with manually cleaned grit channels? - ANSBuild of grit could
interfere with flow through velocity and cause wastewater to back up into the sewer or cause
an overflow
What is the best grit disposal method? - ANSBurial
How many inches of soil does grit need to be covered with? - ANS6 inches
What are the benefits of an aerated grit chamber? - ANSAdds DO and freshens wastewater
Improves sludge settleability
Removes floatables
If grit is being carried out of an aerated grit chamber what is the most likely problem? -
ANSThe velocity is too great, lower velocity
If organic matter is being removed with the grit in an aerated grit chamber what is the most
likely problem? - ANSThe velocity is too low, increase the velocity
How is grit removed from cyclone grit separators? - ANSThe grit is forced outward to the
casing of the cyclone then spirals down towards the bottom
What is the detention time of a cyclone grit separator? - ANS20-30 seconds
What is the main cause of odors in the wastewater system? - ANSHydrogen sulfide
What is septage? - ANSWastewater that is pumped out of septic tanks and other types of
holding tanks
In TN when is flow equalization required? - ANSPeak flows are greater than 2 times the
average design flow
What is flow equalization? - ANSA device or tank that is designed to hold back or store a
portion of peak flows for release during low flow periods
What must the D.O. Be in flow equalization areas? - ANS1.0 mg/L
What is a device used with a blower system that breaks the air stream into fine bubbles in an
aeration tank or reactor? - ANSDiffuser
What is a gas with rotten egg odor that is produced under anaerobic conditions? -
ANSHydrogen sulfide
What is the simplest type of fine screen that contains no moving parts? - ANSWedgewire
For landfill disposal screenings must be dewatered enough to pass what test? - ANSPaint
filter test
What is the gathering of a gas, liquid, or dissolved substance on the outside surface or
interface surface of another material? - ANSAdsorption
Why is it important to remove grit and coarse debris during preliminary treatment? -
ANSThey can damage equipment further down
What is a major difference between comminution units and bar racks/bar screens? - ANSBar
racks and screens catch the debris and then get removed from the system/ comminution units
shred the debris and keep them in the system
Exam TN 2026 Set.
Latest Updated 100% Verified Guide
2026/2027.
What is the purpose of wastewater treatment? - ANSPrevention of pollution and protect
public health
What is inflow? - ANSDirect discharge into the sewer from sources other than regular
connections
What is infiltration? - ANSSeepage of groundwater into the sewer system through cracks,
manholes, pipes, and connections
How many feet apart should manholes be placed to provide access for inspections and
cleaning? - ANS300-500
Manholes must be installed - ANSAt the ends of any line 8" in diameter or larger line
Changes in grade, size of pipe or alignment
At intersections
Not greater than 400ft on a 15" diameter and smaller sewers or 500ft on 18-30" sewers
Hydrogen sulfide is made in the collection system and can cause what problems? - ANSMake
waste more difficult to treat
Damage concrete structures
Cause odor problems
Biological activity in long, flat sewer lines will likely cause: - ANSHydrogen sulfide
production
Oxygen deficiency in sewers, manholes, or wet wells
Metal and concrete corrosion
What is an indicator that a toxic load has entered an activated sludge plant? - ANSIncrease in
oxygen concentration in the aeration basin
What two factors can influence the amount of dissolved oxygen present? - ANSWater
temperature and organic matter
How does water temperature affect dissolved oxygen? - ANSGreater temperature means less
D.O.
Lower temperature means more D.O.
How does organic matter affect dissolved oxygen? - ANSMore organic material requires
more D.O.
What are problems associated with excess nutrients? - ANSAn increase in productivity of
aquatic plants thus depleting D.O. Level
Odor problems
Extra vegetation near surface may inhibit light
What is your best defense against infections and disease? - ANSGood personal hygiene
What may a solids build up in a receiving stream cause? - ANSMay cause oxygen depletion
and be a source of odors
What problems do solids cause in the system? - ANSFill storage areas, clog ditches and
channels
Interfere with mechanical systems
Associated with taste/color/clarity problems in drinking water
What types of solids are in wastewater? - ANSTotal solids
,Comprehensive Wastewater Operator
Exam TN 2026 Set.
Latest Updated 100% Verified Guide
2026/2027.
Dissolved solids
Suspended solids
Organic solids
Inorganic solids
Floatable solids
Fresh domestic wastewater is usually what color - ANSGrey/dishwater color
What color is septic wastewater typically? - ANSBlack
How does fresh domestic wastewater smell? - ANSMusty early odor
In the state of TN flow measuring devices must be calibrated and maintained to ensure
_____________ of the true flow - ANS+/- 10%
What is the parshall flume best for? - ANSFlow with solids or debris
Large flows
Variable flows
What is the usual detention time in a primary clarifier? - ANS1.5-2.0 hours
What does velocity drop to in a primary clarifier? - ANS< 1fps
For wastewater to be considered "disinfected" what is the qualifications? - ANS200 CFU/100
ml for fecal colioforms
126cfu/100ml for E. Coli
Preliminary treatment commonly consists of: - ANSScreening
Shredding
Grit removal
Pre aeration
What do coarse screens remove? - ANSLarge solids, trash, wood, tree limbs, rocks, and other
large debris
What are three coarse screens? - ANSBar rack
Manually cleaned bar screen
Mechanically cleaned bar screen
What are three fine screens? - ANSWedge wire
Rotary drum screens
Escalating step screen
How much spacing is between bar racks? - ANS3-4 inches
How much spacing is between bar screens? - ANS~3/8 in to 2 inches
Where are bar racks found? - ANSIn bypass channels for when flows get diverted
If manually cleaned bar screens are not attended to frequently this could cause: - ANSDebris
collecting and cause head loss
Flow backs up ->Organic wastes settle out-> depletes DO -> leads to septic
Sudden rush of septic can lead to "shock load"
The allowable head loss behind a bar screen should be ___________ - ANSA max of 3
inches
On a mechanically cleaned bar screen list some maintenance items: - ANSDrive units:
adjustments must be made if cables dont wind up evenly on drums of cable machines
,Comprehensive Wastewater Operator
Exam TN 2026 Set.
Latest Updated 100% Verified Guide
2026/2027.
Frayed or excessively worn chain must be replaced
Bent or broken bars must be replaced
If the motor on a mechanical cleaned bar screen runs but the rack doesnt operate what may be
the problem? - ANSBroken chain, cable or shear pin
What do fine screens typically consists of: - ANSWedge wire
Closely spaced bars/screening cloth
Perforated plate
What are the openings of fine screens - ANS0.06-0.25 inch
What are the three steps of maintenance to monitor with fine screens? - ANSVisual
Auditory
Proper lubrication
What is the opening for wedge wire screens? - ANS0.010-0.100 in opening
What wastewater is wedgewire screen not recommended for? - ANSWastewater that contains
grease
How are screenings removed from internally fed rotary drum screens? - ANSAuger/conveyor
and squeezed to drain
How are screenings removed from an externally fed rotary drum screen - ANSScreenings
collected in the hopper
What are the openings on an escalating step screen? - ANS0.125-0.250 inch
What are comminutors? - ANSDevices with cutters and screens that shred solids and return
them to wastewater stream
What are three disadvantages of comminutors? - ANSShredded rags affect operation of
downstream units
Increased load on downstream units
Head loss downstream if not checked or maintained properly
What are four maintenance items for comminutors and barminutors? - ANSCheck for debris
in the cutting drums and bars
Sharpen and adjust the cutting blades
Exercise inlet/outlet gates
Inspect travel and rotation of cutting blades
If stringing parts of rags are hanging from slotted drum or U shaped bars of the comminutor
what would that indicate? - ANSThe cutter is worn or out of adjustment
What is the conventional bar screen capture rate? - ANS6 cubic ft/ MG
How do you calculate screenings removed in cubic feet of screenings per MG of flow? -
ANSScreenings removed cu ft/day
——————————————————
Flow MGD
What does the paint filter test measure? - ANSLeaching effect of your screenings
What benefit does grit removal have on the treatment system? - ANSReduce the clogging of
pipes and protects moving mechanical equipment/pumps from abrasion and accompanying
wear
, Comprehensive Wastewater Operator
Exam TN 2026 Set.
Latest Updated 100% Verified Guide
2026/2027.
What does a grit channel do? - ANSAllow grit to settle out while keeping the lighter organic
solids moving to the next treatment unit
What is the best velocity for a grit channel? - ANS1ft/sec
What is a potential problem with manually cleaned grit channels? - ANSBuild of grit could
interfere with flow through velocity and cause wastewater to back up into the sewer or cause
an overflow
What is the best grit disposal method? - ANSBurial
How many inches of soil does grit need to be covered with? - ANS6 inches
What are the benefits of an aerated grit chamber? - ANSAdds DO and freshens wastewater
Improves sludge settleability
Removes floatables
If grit is being carried out of an aerated grit chamber what is the most likely problem? -
ANSThe velocity is too great, lower velocity
If organic matter is being removed with the grit in an aerated grit chamber what is the most
likely problem? - ANSThe velocity is too low, increase the velocity
How is grit removed from cyclone grit separators? - ANSThe grit is forced outward to the
casing of the cyclone then spirals down towards the bottom
What is the detention time of a cyclone grit separator? - ANS20-30 seconds
What is the main cause of odors in the wastewater system? - ANSHydrogen sulfide
What is septage? - ANSWastewater that is pumped out of septic tanks and other types of
holding tanks
In TN when is flow equalization required? - ANSPeak flows are greater than 2 times the
average design flow
What is flow equalization? - ANSA device or tank that is designed to hold back or store a
portion of peak flows for release during low flow periods
What must the D.O. Be in flow equalization areas? - ANS1.0 mg/L
What is a device used with a blower system that breaks the air stream into fine bubbles in an
aeration tank or reactor? - ANSDiffuser
What is a gas with rotten egg odor that is produced under anaerobic conditions? -
ANSHydrogen sulfide
What is the simplest type of fine screen that contains no moving parts? - ANSWedgewire
For landfill disposal screenings must be dewatered enough to pass what test? - ANSPaint
filter test
What is the gathering of a gas, liquid, or dissolved substance on the outside surface or
interface surface of another material? - ANSAdsorption
Why is it important to remove grit and coarse debris during preliminary treatment? -
ANSThey can damage equipment further down
What is a major difference between comminution units and bar racks/bar screens? - ANSBar
racks and screens catch the debris and then get removed from the system/ comminution units
shred the debris and keep them in the system
