1|Page
Wastewater Grade III Practice Test Questions with
100% Verified Answers UPDATED!!!!
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
,2|Page
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
,3|Page
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.
, 4|Page
( )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.
Wastewater Grade III Practice Test Questions with
100% Verified Answers UPDATED!!!!
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
,2|Page
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
,3|Page
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.
, 4|Page
( )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.
