AWWA Water Operator Certification Exam
Prep UPDATED ACTUAL Questions and
CORRECT Answers
What is the most common disinfection by product when adding chlorine to water containing
natural and inorganic matter? - CORRECT ANSWER✔✔- Chloroform
What will most probably cause taste and odors, slime, and filter clogging? - CORRECT
ANSWER✔✔- Blue-green Algae
Why can rapid sand filters handle higher filtration rates compared to slow sand filters? -
CORRECT ANSWER✔✔- Coarser sand
Iron bacteria can interfere with ___________ because the bacteria produce
_____________that prevents the stabilization chemicals from reaching the pipe surface. -
CORRECT ANSWER✔✔- stabilization, a slime layer
Hypochlorous acid is favored over hypochlorite ion when the pH is _____________and the
temperature is ___________. - CORRECT ANSWER✔✔- low, low
What filter has an unstratified media distribution? - CORRECT ANSWER✔✔- slow sand
filters
What is (are) the combine chlorine residual(s) at pH values ranging from 6.5 to 8.5? -
CORRECT ANSWER✔✔- Monochloramine and dichloramine
When iron alone is treated using manganese greensand filters, the chlorine feed rate should
be about _________________. - CORRECT ANSWER✔✔- 1.0 to 1.2 times the iron
concentration
chlorination of water that has high concentrations of natural organic matter will produce -
CORRECT ANSWER✔✔- THMs
,When disinfecting with chloramines, when can the ammonia be added to the process? -
CORRECT ANSWER✔✔- Before, same time as, or after the chlorine
What will settle out of the water in a short period of time? - CORRECT ANSWER✔✔- Very
fine silt
Point-of-use activated carbon filters are most effective for removing _________________. -
CORRECT ANSWER✔✔- Chlorine
Potassium permanganate is used as an oxidant for control of ____________________. -
CORRECT ANSWER✔✔- Iron and manganese, organic precursors, and taste and odors
What must an operator periodically check regarding the cyclone separator system? -
CORRECT ANSWER✔✔- Storage bin or hopper to empty of sand and grit
These types of chemicals chemically tie up scale-forming ions and are eventually ingested by
consumers. - CORRECT ANSWER✔✔- Sequestering agents
An operator should record filter ______________ measurements, condition, and depth of
media on a ________ basis. - CORRECT ANSWER✔✔- bed expansion, quarterly
Lime will precipitate noncarbonate hardness from the water, but it also orms noncarbonate
salts that cause noncarbonate hardness. What are these salts? - CORRECT ANSWER✔✔-
CaSO4 and CaCl2
What are absolute ratings based on with regard to membranes? - CORRECT ANSWER✔✔-
Largest pore opening
How ar manganese greensand beds regenerated? - CORRECT ANSWER✔✔- Backwashed
with permanganate solution
The most effective process for removing radon gas, when considering cost and footprint,
would be ____________. - CORRECT ANSWER✔✔- packed tower aeration
,What is the primary advantage of placing a properly sized anthracite coal layer over
manganese greensand? - CORRECT ANSWER✔✔- Longer filter run times
What factor will cause problems for chlorination? - CORRECT ANSWER✔✔- Foreign
substances
In the lime-soda ash softening process, smaller plants find that ________ is less expensive to
purchase; regardless of the size of the plant, ___________ needs to be mixed long enough
because it dissolves rather slowly. - CORRECT ANSWER✔✔- calcium hydroxide, lime
What does the optimal pH establish when applied to iron and manganese oxidation? -
CORRECT ANSWER✔✔- Detention time
A water plant using chloramines as a disinfectant has allowed sizable amounts of turbidity to
enter the distribution system. If this occurs over a period of years, what will occur at the far
end of the distribution system? - CORRECT ANSWER✔✔- Taste and odor will develop,
Bacterial growth will be supported, and Nitrification
The reduction of color would most likely occur after - CORRECT ANSWER✔✔-
coagulation, flocculation, and sedimentation
To eliminate hydrogen sulfide (H2S), the pH of the water should be lowered to
____________ or less before beginning aeration. - CORRECT ANSWER✔✔- 6.0
Permanganate reactions are largely dependent on ___________. - CORRECT ANSWER✔✔-
pH
What are the primary reasons that more small water stems are installing pressure filters? -
CORRECT ANSWER✔✔- Because installation and operating costs are low
Because lime slurries have a _________ and a ___________ in water, calcium carbonate will
____________ on anything the slurry touches. - CORRECT ANSWER✔✔- high pH, low
solubility, preciptate
, It is recommended that the free chlorine residual at a customer's tap should be at least
________. - CORRECT ANSWER✔✔- 0.2 mg/L
Microfiltration is considered to be intermediate between ___________ based on pore size. -
CORRECT ANSWER✔✔- ultrafiltration and multimedia granular filtration
After microscreening, there should be a significant reduction in ______________. -
CORRECT ANSWER✔✔- Turbidity
How can the problem of poorly formed floc be solved? - CORRECT ANSWER✔✔- Use of
coagulant aid
What chemical used in corrosion control gives off large quantities of CO2 when it comes in
contact with an acid? - CORRECT ANSWER✔✔- Soda ash
Alum requires _____________ to be present naturally or added fro proper coagulation, and
about _____________ is required for each milligram of alum added per liter. - CORRECT
ANSWER✔✔- alkalinity, 0.5 mg/L
A cloudy appearance in the last flocculation chamber is usually caused by ____________. -
CORRECT ANSWER✔✔- inadequate coagulant dosage
What type of meter is most commonly use for customer metering? - CORRECT
ANSWER✔✔- Positive-displacement meters
In general, the size of floc that has been found to be optimal for settling efficiency is
____________________. - CORRECT ANSWER✔✔- pinhead-size floc
In a pulsator clarifier, what is the purpose of the pulses and how often are pulses generated? -
CORRECT ANSWER✔✔- To maintain a uniform sludge layer; 40-50 sec
UV application will - CORRECT ANSWER✔✔- inhibit bacterial growth and replication
Prep UPDATED ACTUAL Questions and
CORRECT Answers
What is the most common disinfection by product when adding chlorine to water containing
natural and inorganic matter? - CORRECT ANSWER✔✔- Chloroform
What will most probably cause taste and odors, slime, and filter clogging? - CORRECT
ANSWER✔✔- Blue-green Algae
Why can rapid sand filters handle higher filtration rates compared to slow sand filters? -
CORRECT ANSWER✔✔- Coarser sand
Iron bacteria can interfere with ___________ because the bacteria produce
_____________that prevents the stabilization chemicals from reaching the pipe surface. -
CORRECT ANSWER✔✔- stabilization, a slime layer
Hypochlorous acid is favored over hypochlorite ion when the pH is _____________and the
temperature is ___________. - CORRECT ANSWER✔✔- low, low
What filter has an unstratified media distribution? - CORRECT ANSWER✔✔- slow sand
filters
What is (are) the combine chlorine residual(s) at pH values ranging from 6.5 to 8.5? -
CORRECT ANSWER✔✔- Monochloramine and dichloramine
When iron alone is treated using manganese greensand filters, the chlorine feed rate should
be about _________________. - CORRECT ANSWER✔✔- 1.0 to 1.2 times the iron
concentration
chlorination of water that has high concentrations of natural organic matter will produce -
CORRECT ANSWER✔✔- THMs
,When disinfecting with chloramines, when can the ammonia be added to the process? -
CORRECT ANSWER✔✔- Before, same time as, or after the chlorine
What will settle out of the water in a short period of time? - CORRECT ANSWER✔✔- Very
fine silt
Point-of-use activated carbon filters are most effective for removing _________________. -
CORRECT ANSWER✔✔- Chlorine
Potassium permanganate is used as an oxidant for control of ____________________. -
CORRECT ANSWER✔✔- Iron and manganese, organic precursors, and taste and odors
What must an operator periodically check regarding the cyclone separator system? -
CORRECT ANSWER✔✔- Storage bin or hopper to empty of sand and grit
These types of chemicals chemically tie up scale-forming ions and are eventually ingested by
consumers. - CORRECT ANSWER✔✔- Sequestering agents
An operator should record filter ______________ measurements, condition, and depth of
media on a ________ basis. - CORRECT ANSWER✔✔- bed expansion, quarterly
Lime will precipitate noncarbonate hardness from the water, but it also orms noncarbonate
salts that cause noncarbonate hardness. What are these salts? - CORRECT ANSWER✔✔-
CaSO4 and CaCl2
What are absolute ratings based on with regard to membranes? - CORRECT ANSWER✔✔-
Largest pore opening
How ar manganese greensand beds regenerated? - CORRECT ANSWER✔✔- Backwashed
with permanganate solution
The most effective process for removing radon gas, when considering cost and footprint,
would be ____________. - CORRECT ANSWER✔✔- packed tower aeration
,What is the primary advantage of placing a properly sized anthracite coal layer over
manganese greensand? - CORRECT ANSWER✔✔- Longer filter run times
What factor will cause problems for chlorination? - CORRECT ANSWER✔✔- Foreign
substances
In the lime-soda ash softening process, smaller plants find that ________ is less expensive to
purchase; regardless of the size of the plant, ___________ needs to be mixed long enough
because it dissolves rather slowly. - CORRECT ANSWER✔✔- calcium hydroxide, lime
What does the optimal pH establish when applied to iron and manganese oxidation? -
CORRECT ANSWER✔✔- Detention time
A water plant using chloramines as a disinfectant has allowed sizable amounts of turbidity to
enter the distribution system. If this occurs over a period of years, what will occur at the far
end of the distribution system? - CORRECT ANSWER✔✔- Taste and odor will develop,
Bacterial growth will be supported, and Nitrification
The reduction of color would most likely occur after - CORRECT ANSWER✔✔-
coagulation, flocculation, and sedimentation
To eliminate hydrogen sulfide (H2S), the pH of the water should be lowered to
____________ or less before beginning aeration. - CORRECT ANSWER✔✔- 6.0
Permanganate reactions are largely dependent on ___________. - CORRECT ANSWER✔✔-
pH
What are the primary reasons that more small water stems are installing pressure filters? -
CORRECT ANSWER✔✔- Because installation and operating costs are low
Because lime slurries have a _________ and a ___________ in water, calcium carbonate will
____________ on anything the slurry touches. - CORRECT ANSWER✔✔- high pH, low
solubility, preciptate
, It is recommended that the free chlorine residual at a customer's tap should be at least
________. - CORRECT ANSWER✔✔- 0.2 mg/L
Microfiltration is considered to be intermediate between ___________ based on pore size. -
CORRECT ANSWER✔✔- ultrafiltration and multimedia granular filtration
After microscreening, there should be a significant reduction in ______________. -
CORRECT ANSWER✔✔- Turbidity
How can the problem of poorly formed floc be solved? - CORRECT ANSWER✔✔- Use of
coagulant aid
What chemical used in corrosion control gives off large quantities of CO2 when it comes in
contact with an acid? - CORRECT ANSWER✔✔- Soda ash
Alum requires _____________ to be present naturally or added fro proper coagulation, and
about _____________ is required for each milligram of alum added per liter. - CORRECT
ANSWER✔✔- alkalinity, 0.5 mg/L
A cloudy appearance in the last flocculation chamber is usually caused by ____________. -
CORRECT ANSWER✔✔- inadequate coagulant dosage
What type of meter is most commonly use for customer metering? - CORRECT
ANSWER✔✔- Positive-displacement meters
In general, the size of floc that has been found to be optimal for settling efficiency is
____________________. - CORRECT ANSWER✔✔- pinhead-size floc
In a pulsator clarifier, what is the purpose of the pulses and how often are pulses generated? -
CORRECT ANSWER✔✔- To maintain a uniform sludge layer; 40-50 sec
UV application will - CORRECT ANSWER✔✔- inhibit bacterial growth and replication
