Operation of Wastewater Treatment
Plants (Level 1 Exam Prep) Questions
and Answers Graded A+
An Imhoff cone is used to measure________solids.
A. suspended
B. colloidal
C. volatile
D. settleable ✔✔D. settleable
(Operation of Wastewater Treatment Plants, Volume 1
by Kenneth D. Kerri)
A _____ flume is widely used for measuring wastewater flow. ✔✔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. ✔✔.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 ______. ✔✔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.
✔✔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. ✔✔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) ✔✔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? ✔✔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? ✔✔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. ✔✔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 ✔✔Facultative ponds are 4-
8 feet deep
(New Mexico Wastewater Systems Operator Certification Study Manual)
Plants (Level 1 Exam Prep) Questions
and Answers Graded A+
An Imhoff cone is used to measure________solids.
A. suspended
B. colloidal
C. volatile
D. settleable ✔✔D. settleable
(Operation of Wastewater Treatment Plants, Volume 1
by Kenneth D. Kerri)
A _____ flume is widely used for measuring wastewater flow. ✔✔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. ✔✔.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 ______. ✔✔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.
✔✔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. ✔✔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) ✔✔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? ✔✔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? ✔✔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. ✔✔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 ✔✔Facultative ponds are 4-
8 feet deep
(New Mexico Wastewater Systems Operator Certification Study Manual)
