Colorado WW Operator D
Comprehensive Resource To Help You Ace 2026-2027 Exams
Includes Frequently Tested Questions With ELABORATED
100% Correct COMPLETE SOLUTIONS
Guaranteed Pass First Attempt!! Current Update!!
1. Chloramines are ____? - Correct Answer: Combined chlorine
2. What are the characteristics for chlorine as used in pollution control? -
Correct Answer: Chlorine gas is toxic, corrosive, and heavier than air
3. Chlorine applied minus ____ equals chlorine residual - Correct Answer:
Chlorine demand
4. Unlike chlorine, UV does not leave what in treated water? - Correct
Answer: A residual
5. Coliform bacteria are: - Correct Answer: Indicators
6. A _____ residual is attained after breakpoint chlorination. - Correct
Answer: Free
,7. If you need a chlorine residual of 1 mg/l, how many pounds of chlorine
must be applied each day if the flow is 2.5 mgd and the chlorine demand is
15 mg/l? - Correct Answer: 334 lb/d
8. A total residual is also referred to as a ______ residual. - Correct
Answer: Combined
9. Total and fecal coliform are pathogenic. - Correct Answer: FALSE
10._________ = flow, mgd x chlorine dosage, mg/L x 8.34 lb/gal. - Correct
Answer: Feed Rate/Dose (lbs/day)
11.Sodium hypochlorite is manufactured by the reaction of gaseous or liquid
chlorine with a solution of _________ _________ to produce a liquid
containing NaOCl. - Correct Answer: Sodium hypochlorite
12.At concentrations less than _____, chlorine gas is not detectable by the
human sense of smell. - Correct Answer: 1 ppm
13.A treatment plant uses sulfur dioxide to dechlorinate effluent. An operator
needs to adjust the sulfonator so that the dosing concentration is 1.5 mg/l
more than the chlorine residual. Based on the following information, what
should the sulfonator feed rate be: design flow = 5 mgd; chlorine dosage
rate = 4 mg/l; chlorine residual = 0.9 mg/l - Correct Answer: 100 lb/day
,14.The UV dose represents the product of the rate of energy emission (lamp
intensity) and the time the organisms are exposed to the germicidal energy
at 254 nm. This can be expressed by the equation: - Correct Answer:
Dose = intensity x time (d=It)
15.The amount of chlorine used per day from a 1 ton cylinder is normally
determined by - Correct Answer: Weighings
16.Ultraviolet disinfection is becoming more popular because UV systems -
Correct Answer: Eliminate safety concerns about handling chlorine
17.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 nearest 100 lb/d? - Correct Answer:
10,000
18.Coliform bacteria are: - Correct Answer: More resistant to chlorination
than pathogenic bacteria
19.After chlorine, what is the most common effluent wastewater disinfection
technique or agent used in the US today? - Correct Answer: Ultraviolet
radiation
20.Calculate the chlorine demand given: flow rate = 120 mgd; chlorine feed
rate = 8000 lb/d; chlorine residual = 1.0 mg/l after contact time. -
Correct Answer: 7 ppd
, 21.The fusible plug on a chlorine cylinder melts at about ______ degrees. -
Correct Answer: 150 - 162
22.One volume of liquid chlorine will yield about ____ volumes of chlorine gas.
- Correct Answer: 450
23.The two qualities in a final effluent that most affect performance of
ultraviolet disinfection system are UV transmission and ____________. -
Correct Answer: Suspended Solids
24.Which of the following would be the safest action to take in the event of a
major chlorine container leak? - Correct Answer: Call the fire
department
25._____(which can be used for disinfection) may be mechanically produced
by photochemical or electrical methods resembling the natural processes. -
Correct Answer: Ozone, O3
26.The destruction of the larger portion of microorganisms with the probability
that all pathogens are killed is called - Correct Answer: Disinfection
27.Chlorine gas is _____ times heavier than air. - Correct Answer: 2.5
28.The fusible plug on a chlorine cylinder melts at about ______ degrees. -
Correct Answer: 150 - 162
Comprehensive Resource To Help You Ace 2026-2027 Exams
Includes Frequently Tested Questions With ELABORATED
100% Correct COMPLETE SOLUTIONS
Guaranteed Pass First Attempt!! Current Update!!
1. Chloramines are ____? - Correct Answer: Combined chlorine
2. What are the characteristics for chlorine as used in pollution control? -
Correct Answer: Chlorine gas is toxic, corrosive, and heavier than air
3. Chlorine applied minus ____ equals chlorine residual - Correct Answer:
Chlorine demand
4. Unlike chlorine, UV does not leave what in treated water? - Correct
Answer: A residual
5. Coliform bacteria are: - Correct Answer: Indicators
6. A _____ residual is attained after breakpoint chlorination. - Correct
Answer: Free
,7. If you need a chlorine residual of 1 mg/l, how many pounds of chlorine
must be applied each day if the flow is 2.5 mgd and the chlorine demand is
15 mg/l? - Correct Answer: 334 lb/d
8. A total residual is also referred to as a ______ residual. - Correct
Answer: Combined
9. Total and fecal coliform are pathogenic. - Correct Answer: FALSE
10._________ = flow, mgd x chlorine dosage, mg/L x 8.34 lb/gal. - Correct
Answer: Feed Rate/Dose (lbs/day)
11.Sodium hypochlorite is manufactured by the reaction of gaseous or liquid
chlorine with a solution of _________ _________ to produce a liquid
containing NaOCl. - Correct Answer: Sodium hypochlorite
12.At concentrations less than _____, chlorine gas is not detectable by the
human sense of smell. - Correct Answer: 1 ppm
13.A treatment plant uses sulfur dioxide to dechlorinate effluent. An operator
needs to adjust the sulfonator so that the dosing concentration is 1.5 mg/l
more than the chlorine residual. Based on the following information, what
should the sulfonator feed rate be: design flow = 5 mgd; chlorine dosage
rate = 4 mg/l; chlorine residual = 0.9 mg/l - Correct Answer: 100 lb/day
,14.The UV dose represents the product of the rate of energy emission (lamp
intensity) and the time the organisms are exposed to the germicidal energy
at 254 nm. This can be expressed by the equation: - Correct Answer:
Dose = intensity x time (d=It)
15.The amount of chlorine used per day from a 1 ton cylinder is normally
determined by - Correct Answer: Weighings
16.Ultraviolet disinfection is becoming more popular because UV systems -
Correct Answer: Eliminate safety concerns about handling chlorine
17.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 nearest 100 lb/d? - Correct Answer:
10,000
18.Coliform bacteria are: - Correct Answer: More resistant to chlorination
than pathogenic bacteria
19.After chlorine, what is the most common effluent wastewater disinfection
technique or agent used in the US today? - Correct Answer: Ultraviolet
radiation
20.Calculate the chlorine demand given: flow rate = 120 mgd; chlorine feed
rate = 8000 lb/d; chlorine residual = 1.0 mg/l after contact time. -
Correct Answer: 7 ppd
, 21.The fusible plug on a chlorine cylinder melts at about ______ degrees. -
Correct Answer: 150 - 162
22.One volume of liquid chlorine will yield about ____ volumes of chlorine gas.
- Correct Answer: 450
23.The two qualities in a final effluent that most affect performance of
ultraviolet disinfection system are UV transmission and ____________. -
Correct Answer: Suspended Solids
24.Which of the following would be the safest action to take in the event of a
major chlorine container leak? - Correct Answer: Call the fire
department
25._____(which can be used for disinfection) may be mechanically produced
by photochemical or electrical methods resembling the natural processes. -
Correct Answer: Ozone, O3
26.The destruction of the larger portion of microorganisms with the probability
that all pathogens are killed is called - Correct Answer: Disinfection
27.Chlorine gas is _____ times heavier than air. - Correct Answer: 2.5
28.The fusible plug on a chlorine cylinder melts at about ______ degrees. -
Correct Answer: 150 - 162
