Exam (elaborations)
OPERATION OF WASTEWATER TREATMENT PLANTS (LEVELS 1-2 EXAM PREP)
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OPERATION OF WASTEWATER TREATMENT PLANTS (LEVELS 1-2 EXAM PREP)
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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 - Answers -D. settleable
(Operation of Wastewater Treatment Plants, Volume 1
by Kenneth D. Kerri)
A _____ flume is widely used for measuring wastewater flow. - Answers -Parshall
(Operation of Wastewater Treatment Plants, Volume 1
by Kenneth D. Kerri)
Velocity of flow in a grit channel must be reduced to a range of ____ to _____ fps in
order for grit to properly settle. - Answers -.7 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 than
0.21mm (0.008 in) (65 mesh) and with a specific gravity of greater than ______. -
Answers -specific gravity of grit is 2.65 or greater
(EPA Wastewater Technology Fact Sheet, Screening and Grit Removal)
Mechanically cleaned bar screens feature bars set at _____ to _____ degrees from
vertical. - 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. - Answers -Bars set at 30 to 45 degrees from vertical to facilitate
cleaning. Primarily used in older or smaller treatment facilities, or in bypass channels.
(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) - Answers -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 20
°C for 5 days (± 3 hours)
,(USGS Book 9-A7 (Third Edition) Five-Day Biochemical Oxygen Demand)
What do we mean by Total Dissolved Solids (TDS) in wastewater? - Answers -All the
solids 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? - 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. - 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 - Answers -
Facultative ponds are 4-8 feet deep
(New Mexico Wastewater Systems Operator Certification Study Manual)
Wastewater treatment ponds: Anaerobic ponds are _____ feet deep - Answers -
Anaerobic ponds are >14 feet in depth
(New Mexico Wastewater Systems Operator Certification Study Manual)
Typical Primary Clarifier Efficiencies: Settleable Solids expected removal efficiency
_____% to _____% - Answers -Typical Primary Clarifier Efficiencies: Settleable Solids
expected removal efficiency 95% to 99%
(New Mexico Wastewater Systems Operator Certification Study Manual)
Typical Primary Clarifier Efficiencies: Suspended Solids expected removal efficiency
_____% to _____% - Answers -Typical Primary Clarifier Efficiencies: Suspended Solids
expected removal efficiency 40% to 60%
(New Mexico Wastewater Systems Operator Certification Study Manual)
, Typical Primary Clarifier Efficiencies: Total Solids expected removal efficiency _____%
to _____% - 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 _____% - 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 than
3000 mg 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 - Answers -A. sludge gasification causes large clumps of sludge to
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 - Answers -E. All of the above
(New Mexico Wastewater Systems Operator Certification Study Manual)
A minimum dissolved oxygen (D.O.) level of _____ mg/L is recommended in the
aeration tank for most basic types of activated sludge processes. - Answers -A
minimum dissolved oxygen (D.O.) level of 1.0 mg/L is recommended in the aeration
tank for most basic types of activated sludge processes. Maintaining > 1.0 mg/L of D.O.
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