Colorado Wastewater Treatment Operator Class D
Exam ACTUAL EXAM COMPLETE VERIFIED
QUESTIONS AND CORRECT ANSWERS LATEST
UPDATE.pdf 1
Which of the following are key factors in activated sludge
nitrification? Check all that apply. - Answer-MCRT,
Alkalinity and pH, Temperature, DO, TKN loading
An activated sludge that settles poorly and has an SVI >
250 mL/g is described as what? - Answer-Bulking
Which of the following is a modification of the activated
sludge process? - Answer-All of these answers are correct
Taking samples at different locations along the length and
the width of a reactor (aeration tank) as well as at different
depths and analyzing them for solids concentration will
verify whether or not you have....? - Answer-Proper mixing
in the tank
CCSS stands for: - Answer-Clarifier core suspended solids
,1|Page
Because nitrifiers grow slower than other bacteria, sludge
ages longer than ____ days are often needed. - Answer-5
days
During plant rounds, an operator notices that the
secondary effluent is cloudy. The operator should: -
Answer-Check the dissolved oxygen level in the aeration
tank
Given the following data, determine the excess solids (in
lbs) that should be wasted from this activated sludge
system. Target F:M = 0.6 per day, MLVSS = 2500 mg/L,
BOD loading= 18,140 lb/day, Volume of aeration basin = 2
million gallons - Answer-11,467 lb
______ = BOD, lbs/day / MLVSS, lbs - Answer-F/M ratio
In a conventional activated sludge plant, oxygen demand
is highest - Answer-At the head end of the tank
Air requirements in an activated sludge tank are governed
by - Answer-BOD and the desired removal efficiency,
,2|Page
Volatile suspended solids concentration in the aerator,
Suspended solids concentrations of the primary effluent
It is not necessary to be a skilled microbiologist or to be
able to identify or count individual species. Rather the
operator needs only to recognize major groups of
organisms such as: - Answer-Filamentous bacteria,
rotifers, protozoa
In addition to high energy costs, excess DO levels can
cause - Answer-Damage to floc particles due to turbulence
Conditions in which oxygen is absent but nitrate is present
are referred to as what? - Answer-Anoxic
What characteristics are associated with quality activated
sludge? - Answer-Brown color, some dissolved oxygen
content, and good settling
The activated sludge process removes soluble BOD from
wastewater by - Answer-Absorption
, 3|Page
Why is the sludge returned from the secondary clarifier to
the aeration tank in activated sludge used for nitrification?
- Answer-To provide microorganisms
If fine-bubble diffusers are used to introduce air into a
biological reactor, the surface of the tank will typically have
what type of appearance? - Answer-Mildly agitated,
partially covered with light foam
In an anoxic activated sludge process, oxygen for
facultative bacteria is provided by...? - Answer-Nitrate,
NO3
A small area of dark gray/black sludge in an aeration tank
can be due to aeration equipment failure or ____. -
Answer-The introduction of a septic sidestream
When doing a 30-minute activated sludge settleability test,
a 1000ml Imhoff cone should be used. - Answer-FALSE
In a conventional activated sludge process, how much
oxygen is required per lb. of BOD removed? - Answer-0.8
to 1.2 lb oxygen /lb BOD
Exam ACTUAL EXAM COMPLETE VERIFIED
QUESTIONS AND CORRECT ANSWERS LATEST
UPDATE.pdf 1
Which of the following are key factors in activated sludge
nitrification? Check all that apply. - Answer-MCRT,
Alkalinity and pH, Temperature, DO, TKN loading
An activated sludge that settles poorly and has an SVI >
250 mL/g is described as what? - Answer-Bulking
Which of the following is a modification of the activated
sludge process? - Answer-All of these answers are correct
Taking samples at different locations along the length and
the width of a reactor (aeration tank) as well as at different
depths and analyzing them for solids concentration will
verify whether or not you have....? - Answer-Proper mixing
in the tank
CCSS stands for: - Answer-Clarifier core suspended solids
,1|Page
Because nitrifiers grow slower than other bacteria, sludge
ages longer than ____ days are often needed. - Answer-5
days
During plant rounds, an operator notices that the
secondary effluent is cloudy. The operator should: -
Answer-Check the dissolved oxygen level in the aeration
tank
Given the following data, determine the excess solids (in
lbs) that should be wasted from this activated sludge
system. Target F:M = 0.6 per day, MLVSS = 2500 mg/L,
BOD loading= 18,140 lb/day, Volume of aeration basin = 2
million gallons - Answer-11,467 lb
______ = BOD, lbs/day / MLVSS, lbs - Answer-F/M ratio
In a conventional activated sludge plant, oxygen demand
is highest - Answer-At the head end of the tank
Air requirements in an activated sludge tank are governed
by - Answer-BOD and the desired removal efficiency,
,2|Page
Volatile suspended solids concentration in the aerator,
Suspended solids concentrations of the primary effluent
It is not necessary to be a skilled microbiologist or to be
able to identify or count individual species. Rather the
operator needs only to recognize major groups of
organisms such as: - Answer-Filamentous bacteria,
rotifers, protozoa
In addition to high energy costs, excess DO levels can
cause - Answer-Damage to floc particles due to turbulence
Conditions in which oxygen is absent but nitrate is present
are referred to as what? - Answer-Anoxic
What characteristics are associated with quality activated
sludge? - Answer-Brown color, some dissolved oxygen
content, and good settling
The activated sludge process removes soluble BOD from
wastewater by - Answer-Absorption
, 3|Page
Why is the sludge returned from the secondary clarifier to
the aeration tank in activated sludge used for nitrification?
- Answer-To provide microorganisms
If fine-bubble diffusers are used to introduce air into a
biological reactor, the surface of the tank will typically have
what type of appearance? - Answer-Mildly agitated,
partially covered with light foam
In an anoxic activated sludge process, oxygen for
facultative bacteria is provided by...? - Answer-Nitrate,
NO3
A small area of dark gray/black sludge in an aeration tank
can be due to aeration equipment failure or ____. -
Answer-The introduction of a septic sidestream
When doing a 30-minute activated sludge settleability test,
a 1000ml Imhoff cone should be used. - Answer-FALSE
In a conventional activated sludge process, how much
oxygen is required per lb. of BOD removed? - Answer-0.8
to 1.2 lb oxygen /lb BOD
