COLORADO WASTE WATER OPERATOR D EXAM
2026|ACTUAL TESTBANK WITH 400+Qs&As|NEW
UPDATE 2026-2027 GRADE
______ = 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, 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
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
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
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
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...?
2026|ACTUAL TESTBANK WITH 400+Qs&As|NEW
UPDATE 2026-2027 GRADE
______ = 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, 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
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
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
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
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...?
