Colorado WW Operator D Exam Test Questions and Answers Rated A
= BOD, lbs/day / MLVSS, lbs F/M ratio
In a conventional activated sludge plant, oxygen demand
At the head end of the tank
is highest
BOD and the desired removal eflciency, Volatile suspend-
Air requirements in an activated sludge tank are governed
ed solids concentration in the aerator, Suspended solids
by
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
Filamentous bacteria, rotifers, protozoa
the operator needs only to recognize major groups of
organisms such as:
In addition to high energy costs, excess DO levels can
Damage to floc particles due to turbulence
cause
Which of the following are key factors in activated sludge
MCRT, Alkalinity and pH, Temperature, DO, TKN loading
nitrification? Check all that apply.
An activated sludge that settles poorly and has an SVI >
Bulking
250 mL/g is described as what?
Which of the following is a modification of the activated
All of these answers are correct
sludge process?
Taking samples at ditterent locations along the length and
the width of a reactor (aeration tank) as well as at ditterent
Proper mixing in the tank
depths and analyzing them for solids concentration will
verify whether or not you have. ?
CCSS stands for: Clarifier core suspended solids
Because nitrifiers grow slower than other bacteria, sludge
5 days
ages longer than days are often needed.
During plant rounds, an operator notices that the sec-
Check the dissolved oxygen level in the aeration tank
ondary effluent is cloudy. The operator should:
,Colorado WW Operator D Exam Test Questions and Answers Rated A
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, 11,467 lb
BOD loading= 18,140 lb/day, Volume of aeration basin =
2 million gallons
Conditions in which oxygen is absent but nitrate is present
Anoxic
are referred to as what?
What characteristics are associated with quality activated Brown color, some dissolved oxygen content, and good
sludge? settling
The activated sludge process removes soluble BOD from
Absorption
wastewater by
Why is the sludge returned from the secondary clarifier to
To provide microorganisms
the aeration tank in activated sludge used for nitrification?
If fine-bubble dittusers are used to introduce air into a
biological reactor, the surface of the tank will typically have Mildly agitated, partially covered with light foam
what type of appearance?
In an anoxic activated sludge process, oxygen for faculta-
Nitrate, NO3
tive bacteria is provided by...?
A small area of dark gray/black sludge in an aeration tank
The introduction of a septic sidestream
can be due to aeration equipment failure or .
When doing a 30-minute activated sludge settleability
FALSE
test, a 1000ml Imhott cone should be used.
In a conventional activated sludge process, how much
0.8 to 1.2 lb oxygen /lb BOD
oxygen is required per lb. of BOD removed?
Which of the following conditions would least likely con-
Clarifier hydraulic loading
tribute to rising sludge in secondary clarifiers?
In an activated sludge process bacteria release chemicals
Enzymes
called that break down the food particles that
,Colorado WW Operator D Exam Test Questions and Answers Rated A
are adsorbed to the cell wall so that they can be absorbed
by the microorganism.
Acids should never be added to chlorine solutions be-
Cause chlorine gas to be released
cause they
Chloramines are ? Combined chlorine
What are the characteristics for chlorine as used in pollu-
Chlorine gas is toxic, corrosive, and heavier than air
tion control?
Chlorine applied minus equals chlorine residual Chlorine demand
Unlike chlorine, UV does not leave what in treated water? A residual
Coliform bacteria are: Indicators
A residual is attained after breakpoint chlorination. Free
If you need a chlorine residual of 1 mg/l, how many
pounds of chlorine must be applied each day if the flow 334 lb/d
is 2.5 mgd and the chlorine demand is 15 mg/l?
A total residual is also referred to as a residual. Combined
Total and fecal coliform are pathogenic. FALSE
= flow, mgd x chlorine dosage, mg/L x 8.34
Feed Rate/Dose (lbs/day)
lb/gal.
Sodium hypochlorite is manufactured by the reaction of
gaseous or liquid chlorine with a solution of Sodium hypochlorite
to produce a liquid containing NaOCl.
At concentrations less than , chlorine gas is not
1 ppm
detectable by the human sense of smell.
A treatment plant uses sulfur dioxide to dechlorinate efflu-
ent. An operator needs to adjust the sulfonator so that the
100 lb/day
dosing concentration is 1.5 mg/l more than the chlorine
residual. Based on the following information, what should
, Colorado WW Operator D Exam Test Questions and Answers Rated A
the sulfonator feed rate be: design flow = 5 mgd; chlorine
dosage rate = 4 mg/l; chlorine residual = 0.9 mg/l
The UV dose represents the product of the rate of energy
emission (lamp intensity) and the time the organisms are
Dose = intensity x time (d=It)
exposed to the germicidal energy at 254 nm. This can be
expressed by the equation:
The amount of chlorine used per day from a 1 ton cylinder
Weighings
is normally determined by
Ultraviolet disinfection is becoming more popular be-
Eliminate safety concerns about handling chlorine
cause UV systems
If a 100-mgd flow of wastewater is dosed at a rate of
12 mg/l, what should the chlorine-reed setting be to the 10,000
nearest 100 lb/d?
Coliform bacteria are: More resistant to chlorination than pathogenic bacteria
After chlorine, what is the most common effluent waste-
water disinfection technique or agent used in the US Ultraviolet radiation
today?
Calculate the chlorine demand given: flow rate = 120 mgd;
chlorine feed rate = 8000 lb/d; chlorine residual = 1.0 7 ppd
mg/l after contact time.
The fusible plug on a chlorine cylinder melts at about
150 - 162
degrees.
One volume of liquid chlorine will yield about vol-
450
umes of chlorine gas.
The two qualities in a final effluent that most attect perfor-
mance of ultraviolet disinfection system are UV transmis- Suspended Solids
sion and .
Call the fire department
= BOD, lbs/day / MLVSS, lbs F/M ratio
In a conventional activated sludge plant, oxygen demand
At the head end of the tank
is highest
BOD and the desired removal eflciency, Volatile suspend-
Air requirements in an activated sludge tank are governed
ed solids concentration in the aerator, Suspended solids
by
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
Filamentous bacteria, rotifers, protozoa
the operator needs only to recognize major groups of
organisms such as:
In addition to high energy costs, excess DO levels can
Damage to floc particles due to turbulence
cause
Which of the following are key factors in activated sludge
MCRT, Alkalinity and pH, Temperature, DO, TKN loading
nitrification? Check all that apply.
An activated sludge that settles poorly and has an SVI >
Bulking
250 mL/g is described as what?
Which of the following is a modification of the activated
All of these answers are correct
sludge process?
Taking samples at ditterent locations along the length and
the width of a reactor (aeration tank) as well as at ditterent
Proper mixing in the tank
depths and analyzing them for solids concentration will
verify whether or not you have. ?
CCSS stands for: Clarifier core suspended solids
Because nitrifiers grow slower than other bacteria, sludge
5 days
ages longer than days are often needed.
During plant rounds, an operator notices that the sec-
Check the dissolved oxygen level in the aeration tank
ondary effluent is cloudy. The operator should:
,Colorado WW Operator D Exam Test Questions and Answers Rated A
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, 11,467 lb
BOD loading= 18,140 lb/day, Volume of aeration basin =
2 million gallons
Conditions in which oxygen is absent but nitrate is present
Anoxic
are referred to as what?
What characteristics are associated with quality activated Brown color, some dissolved oxygen content, and good
sludge? settling
The activated sludge process removes soluble BOD from
Absorption
wastewater by
Why is the sludge returned from the secondary clarifier to
To provide microorganisms
the aeration tank in activated sludge used for nitrification?
If fine-bubble dittusers are used to introduce air into a
biological reactor, the surface of the tank will typically have Mildly agitated, partially covered with light foam
what type of appearance?
In an anoxic activated sludge process, oxygen for faculta-
Nitrate, NO3
tive bacteria is provided by...?
A small area of dark gray/black sludge in an aeration tank
The introduction of a septic sidestream
can be due to aeration equipment failure or .
When doing a 30-minute activated sludge settleability
FALSE
test, a 1000ml Imhott cone should be used.
In a conventional activated sludge process, how much
0.8 to 1.2 lb oxygen /lb BOD
oxygen is required per lb. of BOD removed?
Which of the following conditions would least likely con-
Clarifier hydraulic loading
tribute to rising sludge in secondary clarifiers?
In an activated sludge process bacteria release chemicals
Enzymes
called that break down the food particles that
,Colorado WW Operator D Exam Test Questions and Answers Rated A
are adsorbed to the cell wall so that they can be absorbed
by the microorganism.
Acids should never be added to chlorine solutions be-
Cause chlorine gas to be released
cause they
Chloramines are ? Combined chlorine
What are the characteristics for chlorine as used in pollu-
Chlorine gas is toxic, corrosive, and heavier than air
tion control?
Chlorine applied minus equals chlorine residual Chlorine demand
Unlike chlorine, UV does not leave what in treated water? A residual
Coliform bacteria are: Indicators
A residual is attained after breakpoint chlorination. Free
If you need a chlorine residual of 1 mg/l, how many
pounds of chlorine must be applied each day if the flow 334 lb/d
is 2.5 mgd and the chlorine demand is 15 mg/l?
A total residual is also referred to as a residual. Combined
Total and fecal coliform are pathogenic. FALSE
= flow, mgd x chlorine dosage, mg/L x 8.34
Feed Rate/Dose (lbs/day)
lb/gal.
Sodium hypochlorite is manufactured by the reaction of
gaseous or liquid chlorine with a solution of Sodium hypochlorite
to produce a liquid containing NaOCl.
At concentrations less than , chlorine gas is not
1 ppm
detectable by the human sense of smell.
A treatment plant uses sulfur dioxide to dechlorinate efflu-
ent. An operator needs to adjust the sulfonator so that the
100 lb/day
dosing concentration is 1.5 mg/l more than the chlorine
residual. Based on the following information, what should
, Colorado WW Operator D Exam Test Questions and Answers Rated A
the sulfonator feed rate be: design flow = 5 mgd; chlorine
dosage rate = 4 mg/l; chlorine residual = 0.9 mg/l
The UV dose represents the product of the rate of energy
emission (lamp intensity) and the time the organisms are
Dose = intensity x time (d=It)
exposed to the germicidal energy at 254 nm. This can be
expressed by the equation:
The amount of chlorine used per day from a 1 ton cylinder
Weighings
is normally determined by
Ultraviolet disinfection is becoming more popular be-
Eliminate safety concerns about handling chlorine
cause UV systems
If a 100-mgd flow of wastewater is dosed at a rate of
12 mg/l, what should the chlorine-reed setting be to the 10,000
nearest 100 lb/d?
Coliform bacteria are: More resistant to chlorination than pathogenic bacteria
After chlorine, what is the most common effluent waste-
water disinfection technique or agent used in the US Ultraviolet radiation
today?
Calculate the chlorine demand given: flow rate = 120 mgd;
chlorine feed rate = 8000 lb/d; chlorine residual = 1.0 7 ppd
mg/l after contact time.
The fusible plug on a chlorine cylinder melts at about
150 - 162
degrees.
One volume of liquid chlorine will yield about vol-
450
umes of chlorine gas.
The two qualities in a final effluent that most attect perfor-
mance of ultraviolet disinfection system are UV transmis- Suspended Solids
sion and .
Call the fire department
