Wastewater Grade III Practice Test Guide
With Complete Solution
A properly functioning anaerobic digester will achieve a reduction in volatile solids of
greater than
50%.
( )True
( )False -Answer True
Explanation:
A properly functioning anaerobic digester will achieve a reduction in volatile solids of
greater than
50%.
The careful use of chlorine can correct certain operational problems of a trickling filter.
( )True
( )False -Answer True
Explanation:
The careful use of chlorine can correct certain operational problems of a trickling filter.
These
include Ponding, Odors, and Filter Flies
Of the following list, which chemical is used to correct an anaerobic digester upset?
HTH
Quicklime
Aluminum sulfate
Ferric chloride -Answer Quicklime
Explanation:
Quicklime is a base which will neutralize the acid in an upset digester. HTH is a form of
chlorine that
will kill desirable bacteria. The other chemical listed are acidic and will not work to
neutralize an
upset digester.
Buffer in an anaerobic digester:
Is added weekly by adding quicklime to the digester
Is the result of calcium carbonate present in the water portion of the sludge that is
pumped to
the anaerobic digester
Is mainly due to the presence of the bicarbonate ion
May be calculated by measuring the pH of the digesting sludge
, Is measured by titrating sludge supernatant with sodium hydroxide to a pH of 6.5 -
Answer Is mainly due to the presence of the bicarbonate ion
Explanation:
The bicarbonate ion is the main source of alkalinity in an anaerobic digester. Alkalinity is
what
buffers the digester against rapid pH changes.
You are operating a belt press to dewater anaerobically digested sludge. The
conditioned feed solids
concentration today is 4.2%. You have operated for 7 hours at an average of 60 gpm.
You have
produced 22.4 wet weight tons of filter cake with an average solids concentration of
19%. Determine
the percent solids recovery for today's operation.
( )93.3%
( )99.5%
( )91.5%
( )96.4%
( )94.1% -Answer 96.4%
What is a likely result if the overflow rate is too low in a primary clarifier?
( )Primary sludge that is too thick to pump
( )Excessive scum
( )Floating sludge near the inlet end of the clarifier
( )Septic odors
( )Excessive load on the sludge cross collectors -Answer Septic odors
Explanation:
Septic odors will occur if the overflow rate is too low in a primary clarifier.
Which of the following is not true regarding chlorine or chlorination equipment?
( ) Due to the high vapor pressure of liquid chlorine, it may be withdrawn from a 1 ton
container
without pressurization
( )Chlorine gas may lower the pH of the secondary effluent
( )When taking a chlorinator out of service, the chlorine valve at the cylinder is shut and
the
chlorine ejector is operated for a time to remove the gas remaining in the line
( )The vacuum in a vacuum chlorinator is created when chlorine gas moves rapidly
through a
restriction in the line
( )The withdraw rate is limited because freezing in the line can occur if chlorine gas is
removed too
fast -Answer The vacuum in a vacuum chlorinator is created when chlorine gas moves
rapidly through a restriction in the line
With Complete Solution
A properly functioning anaerobic digester will achieve a reduction in volatile solids of
greater than
50%.
( )True
( )False -Answer True
Explanation:
A properly functioning anaerobic digester will achieve a reduction in volatile solids of
greater than
50%.
The careful use of chlorine can correct certain operational problems of a trickling filter.
( )True
( )False -Answer True
Explanation:
The careful use of chlorine can correct certain operational problems of a trickling filter.
These
include Ponding, Odors, and Filter Flies
Of the following list, which chemical is used to correct an anaerobic digester upset?
HTH
Quicklime
Aluminum sulfate
Ferric chloride -Answer Quicklime
Explanation:
Quicklime is a base which will neutralize the acid in an upset digester. HTH is a form of
chlorine that
will kill desirable bacteria. The other chemical listed are acidic and will not work to
neutralize an
upset digester.
Buffer in an anaerobic digester:
Is added weekly by adding quicklime to the digester
Is the result of calcium carbonate present in the water portion of the sludge that is
pumped to
the anaerobic digester
Is mainly due to the presence of the bicarbonate ion
May be calculated by measuring the pH of the digesting sludge
, Is measured by titrating sludge supernatant with sodium hydroxide to a pH of 6.5 -
Answer Is mainly due to the presence of the bicarbonate ion
Explanation:
The bicarbonate ion is the main source of alkalinity in an anaerobic digester. Alkalinity is
what
buffers the digester against rapid pH changes.
You are operating a belt press to dewater anaerobically digested sludge. The
conditioned feed solids
concentration today is 4.2%. You have operated for 7 hours at an average of 60 gpm.
You have
produced 22.4 wet weight tons of filter cake with an average solids concentration of
19%. Determine
the percent solids recovery for today's operation.
( )93.3%
( )99.5%
( )91.5%
( )96.4%
( )94.1% -Answer 96.4%
What is a likely result if the overflow rate is too low in a primary clarifier?
( )Primary sludge that is too thick to pump
( )Excessive scum
( )Floating sludge near the inlet end of the clarifier
( )Septic odors
( )Excessive load on the sludge cross collectors -Answer Septic odors
Explanation:
Septic odors will occur if the overflow rate is too low in a primary clarifier.
Which of the following is not true regarding chlorine or chlorination equipment?
( ) Due to the high vapor pressure of liquid chlorine, it may be withdrawn from a 1 ton
container
without pressurization
( )Chlorine gas may lower the pH of the secondary effluent
( )When taking a chlorinator out of service, the chlorine valve at the cylinder is shut and
the
chlorine ejector is operated for a time to remove the gas remaining in the line
( )The vacuum in a vacuum chlorinator is created when chlorine gas moves rapidly
through a
restriction in the line
( )The withdraw rate is limited because freezing in the line can occur if chlorine gas is
removed too
fast -Answer The vacuum in a vacuum chlorinator is created when chlorine gas moves
rapidly through a restriction in the line
