Operation of Wastewater Treatment
Plants (Levels 1-2 Exam Prep)
An Imhoff cone is used to measure
solids.
A.
suspended
B.
colloidal
C.
volatile
D. settleable correct answers D.
settleable
(Operation of Wastewater Treatment Plants,
Volume
by 1 D.
Kenneth
Kerri)
A flume is widely used for measuring wastewater flow. correct
answers Parshall
(Operation of Wastewater Treatment Plants,
Volume
by 1 D.
Kenneth
Kerri)
Velocity of flow in a grit channel must be reduced to a range of to
fps in for grit to properly settle. correct answers .7
order
to 1.4 fps
(Operation of Wastewater Treatment Plants, Volume
1, 3.33
by Kenneth D.
Kerri)
With respect to grit removal systems, grit is traditionally defined as particles
larger
0.21mm than(0.008 in) (65 mesh) and with a specific gravity of greater than
answers specific gravity of grit is 2.65 or .
correct
greater
(EPA Wastewater Technology Fact Sheet, Screening and Grit
Removal)
Mechanically cleaned bar screens feature bars set at to degrees
from
vertical. correct answers Bars set at 0 to 30 degrees from
vertical.
(EPA Wastewater Technology Fact Sheet, Screening and Grit
Removal)
Manually cleaned bar screens feature bars set at to degrees from
vertical
to facilitate cleaning. correct answers Bars set at 30 to 45 degrees from
vertical tocleaning. Primarily used in older or smaller treatment facilities,
facilitate
or in bypass
channel
s.
(EPA Wastewater Technology Fact Sheet, Screening and Grit
Removal)
The BOD test measures the amount of oxygen that is consumed while a
sample of wastewater is incubated in the dark at a temperature of°C for
days (±
, hours) correct answers The BOD test measures the amount of
consumedoxygen that
while is
a sample of wastewater is incubated in the dark at a
°C for 5 days of
temperature (±203
hours)
(USGS Book 9-A7 (Third Edition) Five-Day Biochemical Oxygen
Demand)
What do we mean by Total Dissolved Solids (TDS) in wastewater? correct
answers
the solidsAll
that cannot be filtered out of
the water
(New Mexico Wastewater Systems Operator Certification Study
Manual)
What do we mean by Total Suspended Solids (TSS) in wastewater? correct
answers
All the solids that can be filtered out including: settleable solids and
non-settleable
solids
(colloids)
(New Mexico Wastewater Systems Operator Certification Study
Manual)
The wastewater in a sewer line should move at a speed that will prevent the
deposition
and buildup of solids in the sewer; this is called a "scouring velocity". A
minimum
velocity of fps provides this scouring or self-cleaning velocity. correct
answers
The wastewater in a sewer line should move at a speed that will prevent the
deposition
and buildup of solids in the sewer; this is called a "scouring velocity". A
minimum
velocity of 2 fps provides this scouring or self-cleaning
velocity.
(New Mexico Wastewater Systems Operator Certification Study
Manual)
Wastewater treatment ponds: Facultative ponds are feet deep correct
answers
Facultative ponds are 4-8 feet
deep
(New Mexico Wastewater Systems Operator Certification Study
Manual)
Wastewater treatment ponds: Anaerobic ponds are feet deep correct
answers
Anaerobic ponds are >14 feet in
depth
(New Mexico Wastewater Systems Operator Certification Study
Manual)
Typical Primary Clarifier Efficiencies: Settleable Solids expected removal
% to
efficiency % correct answers Typical Primary Clarifier
SolidsEfficiencies: Settleable
expected removal efficiency 95%
to 99%
(New Mexico Wastewater Systems Operator Certification Study
Manual)
, Typical Primary Clarifier Efficiencies: Suspended Solids expected removal
% to
efficiency % correct answers Typical Primary Clarifier
SolidsEfficiencies: Suspended
expected removal efficiency 40%
to 60%
(New Mexico Wastewater Systems Operator Certification Study
Manual)
Typical Primary Clarifier Efficiencies: Total Solids expected removal
efficiency
to % correct answers Typical Primary Clarifier Efficiencies: Total Solids
%
expected
removal efficiency 10% to
15%
(New Mexico Wastewater Systems Operator Certification Study
Manual)
Typical Primary Clarifier Efficiencies: Biochemical Oxygen Demand (BOD)
expected
removal efficiency % to % correct answers Typical Primary
Clarifier
Efficiencies: Biochemical Oxygen Demand (BOD) expected removal
efficiency 20% to
50
%
(New Mexico Wastewater Systems Operator Certification Study
Manual)
Sludge septicity in the primary clarifier can be
recognized when:
A. sludge gasification causes large clumps of sludge to float on the
water surface.
B. Primary clarifier foam is
black
C. The Specific Oxygen Uptake Rate (SOUR) in the primary clarifier is
greater
3000 mgthan
O2/L/hr
D. The sludge contains from 4.0 to 8.0 percent dry solids in TS
laboratory testing
E. All of the above correct answers A. sludge gasification causes large
clumps to
sludge of float on the water
surface.
Pump cavitation may be
caused by:
A. Loss of discharge pressure due to open hy-drants or line
breaks
B. Closed suction
valve
C. Obstruction in the suction
line
D. Low suction head due to drop in water
level
E. All of the above correct answers E. All of the
above
Plants (Levels 1-2 Exam Prep)
An Imhoff cone is used to measure
solids.
A.
suspended
B.
colloidal
C.
volatile
D. settleable correct answers D.
settleable
(Operation of Wastewater Treatment Plants,
Volume
by 1 D.
Kenneth
Kerri)
A flume is widely used for measuring wastewater flow. correct
answers Parshall
(Operation of Wastewater Treatment Plants,
Volume
by 1 D.
Kenneth
Kerri)
Velocity of flow in a grit channel must be reduced to a range of to
fps in for grit to properly settle. correct answers .7
order
to 1.4 fps
(Operation of Wastewater Treatment Plants, Volume
1, 3.33
by Kenneth D.
Kerri)
With respect to grit removal systems, grit is traditionally defined as particles
larger
0.21mm than(0.008 in) (65 mesh) and with a specific gravity of greater than
answers specific gravity of grit is 2.65 or .
correct
greater
(EPA Wastewater Technology Fact Sheet, Screening and Grit
Removal)
Mechanically cleaned bar screens feature bars set at to degrees
from
vertical. correct answers Bars set at 0 to 30 degrees from
vertical.
(EPA Wastewater Technology Fact Sheet, Screening and Grit
Removal)
Manually cleaned bar screens feature bars set at to degrees from
vertical
to facilitate cleaning. correct answers Bars set at 30 to 45 degrees from
vertical tocleaning. Primarily used in older or smaller treatment facilities,
facilitate
or in bypass
channel
s.
(EPA Wastewater Technology Fact Sheet, Screening and Grit
Removal)
The BOD test measures the amount of oxygen that is consumed while a
sample of wastewater is incubated in the dark at a temperature of°C for
days (±
, hours) correct answers The BOD test measures the amount of
consumedoxygen that
while is
a sample of wastewater is incubated in the dark at a
°C for 5 days of
temperature (±203
hours)
(USGS Book 9-A7 (Third Edition) Five-Day Biochemical Oxygen
Demand)
What do we mean by Total Dissolved Solids (TDS) in wastewater? correct
answers
the solidsAll
that cannot be filtered out of
the water
(New Mexico Wastewater Systems Operator Certification Study
Manual)
What do we mean by Total Suspended Solids (TSS) in wastewater? correct
answers
All the solids that can be filtered out including: settleable solids and
non-settleable
solids
(colloids)
(New Mexico Wastewater Systems Operator Certification Study
Manual)
The wastewater in a sewer line should move at a speed that will prevent the
deposition
and buildup of solids in the sewer; this is called a "scouring velocity". A
minimum
velocity of fps provides this scouring or self-cleaning velocity. correct
answers
The wastewater in a sewer line should move at a speed that will prevent the
deposition
and buildup of solids in the sewer; this is called a "scouring velocity". A
minimum
velocity of 2 fps provides this scouring or self-cleaning
velocity.
(New Mexico Wastewater Systems Operator Certification Study
Manual)
Wastewater treatment ponds: Facultative ponds are feet deep correct
answers
Facultative ponds are 4-8 feet
deep
(New Mexico Wastewater Systems Operator Certification Study
Manual)
Wastewater treatment ponds: Anaerobic ponds are feet deep correct
answers
Anaerobic ponds are >14 feet in
depth
(New Mexico Wastewater Systems Operator Certification Study
Manual)
Typical Primary Clarifier Efficiencies: Settleable Solids expected removal
% to
efficiency % correct answers Typical Primary Clarifier
SolidsEfficiencies: Settleable
expected removal efficiency 95%
to 99%
(New Mexico Wastewater Systems Operator Certification Study
Manual)
, Typical Primary Clarifier Efficiencies: Suspended Solids expected removal
% to
efficiency % correct answers Typical Primary Clarifier
SolidsEfficiencies: Suspended
expected removal efficiency 40%
to 60%
(New Mexico Wastewater Systems Operator Certification Study
Manual)
Typical Primary Clarifier Efficiencies: Total Solids expected removal
efficiency
to % correct answers Typical Primary Clarifier Efficiencies: Total Solids
%
expected
removal efficiency 10% to
15%
(New Mexico Wastewater Systems Operator Certification Study
Manual)
Typical Primary Clarifier Efficiencies: Biochemical Oxygen Demand (BOD)
expected
removal efficiency % to % correct answers Typical Primary
Clarifier
Efficiencies: Biochemical Oxygen Demand (BOD) expected removal
efficiency 20% to
50
%
(New Mexico Wastewater Systems Operator Certification Study
Manual)
Sludge septicity in the primary clarifier can be
recognized when:
A. sludge gasification causes large clumps of sludge to float on the
water surface.
B. Primary clarifier foam is
black
C. The Specific Oxygen Uptake Rate (SOUR) in the primary clarifier is
greater
3000 mgthan
O2/L/hr
D. The sludge contains from 4.0 to 8.0 percent dry solids in TS
laboratory testing
E. All of the above correct answers A. sludge gasification causes large
clumps to
sludge of float on the water
surface.
Pump cavitation may be
caused by:
A. Loss of discharge pressure due to open hy-drants or line
breaks
B. Closed suction
valve
C. Obstruction in the suction
line
D. Low suction head due to drop in water
level
E. All of the above correct answers E. All of the
above
