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AWWA Water Operator Certification Exam Prep Questions and Answers 2024
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AWWA Water Operator CertificationExam Prep
What is the most common disinfection by product when adding chlorine to water
containing natural and inorganic matter? - answer Chloroform
What will most probably cause taste and odors, slime, and filter clogging? - answer
Blue-green Algae
Why can rapid sand filters handle higher filtration rates compared to slow sand filters? -
answer Coarser sand
Iron bacteria can interfere with ___________ because the bacteria produce
_____________that prevents the stabilization chemicals from reaching the pipe surface.
- answer stabilization, a slime layer
Hypochlorous acid is favored over hypochlorite ion when the pH is _____________and
the temperature is ___________. - answer low, low
What filter has an unstratified media distribution? - answers low sand filters
What is (are) the combine chlorine residual(s) at pH values ranging from 6.5 to 8.5? -
answer Monochloramine and dichloramine
When iron alone is treated using manganese greensand filters, the chlorine feed rate
should be about _________________. - answer1.0 to 1.2 times the iron concentration
chlorination of water that has high concentrations of natural organic matter will produce
- answerTHMs
When disinfecting with chloramines, when can the ammonia be added to the process? -
answerBefore, same time as, or after the chlorine
What will settle out of the water in a short period of time? - answerVery fine silt
Point-of-use activated carbon filters are most effective for removing
_________________. - answerChlorine
Potassium permanganate is used as an oxidant for control of ____________________.
- answerIron and manganese, organic precursors, and taste and odors
,What must an operator periodically check regarding the cyclone separator system? -
answerStorage 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. - answerSequestering agents
An operator should record filter ______________ measurements, condition, and depth
of media on a ________ basis. - answerbed expansion, quarterly
Lime will precipitate noncarbonate hardness from the water, but it also orms
noncarbonate salts that cause noncarbonate hardness. What are these salts? -
answerCaSO4 and CaCl2
What are absolute ratings based on with regard to membranes? - answerLargest pore
opening
How ar manganese greensand beds regenerated? - answerBackwashed with
permanganate solution
The most effective process for removing radon gas, when considering cost and
footprint, would be ____________. - answerpacked tower aeration
What is the primary advantage of placing a properly sized anthracite coal layer over
manganese greensand? - answerLonger filter run times
What factor will cause problems for chlorination? - answerForeign 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. - answercalcium hydroxide, lime
What does the optimal pH establish when applied to iron and manganese oxidation? -
answerDetention 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? - answerTaste and odor will develop,
Bacterial growth will be supported, and Nitrification
The reduction of color would most likely occur after - answercoagulation, flocculation,
and sedimentation
To eliminate hydrogen sulfide (H2S), the pH of the water should be lowered to
____________ or less before beginning aeration. - answer6.0
Permanganate reactions are largely dependent on ___________. - answerpH
,What are the primary reasons that more small water stems are installing pressure
filters? - answerBecause installation and operating costs are low
Because lime slurries have a _________ and a ___________ in water, calcium
carbonate will ____________ on anything the slurry touches. - answerhigh pH, low
solubility, preciptate
It is recommended that the free chlorine residual at a customer's tap should be at least
________. - answer0.2 mg/L
Microfiltration is considered to be intermediate between ___________ based on pore
size. - answerultrafiltration and multimedia granular filtration
After microscreening, there should be a significant reduction in ______________. -
answerTurbidity
How can the problem of poorly formed floc be solved? - answerUse of coagulant aid
What chemical used in corrosion control gives off large quantities of CO2 when it comes
in contact with an acid? - answerSoda ash
Alum requires _____________ to be present naturally or added fro proper coagulation,
and about _____________ is required for each milligram of alum added per liter. -
answeralkalinity, 0.5 mg/L
A cloudy appearance in the last flocculation chamber is usually caused by
____________. - answerinadequate coagulant dosage
What type of meter is most commonly use for customer metering? - answerPositive-
displacement meters
In general, the size of floc that has been found to be optimal for settling efficiency is
____________________. - answerpinhead-size floc
In a pulsator clarifier, what is the purpose of the pulses and how often are pulses
generated? - answerTo maintain a uniform sludge layer; 40-50 sec
UV application will - answerinhibit bacterial growth and replication
Calcium hypochlorite used in water treatment disinfection ranges in percentage strength
of available chlorine from _______________. - answer65% to 70%
Manganese greensand filters remove iron and manganese by a combination of both
_________. - answerAdsorption and oxidation
, After water has been softened, it is close to pH 11; thus, it needs to be stabilized by a
process known as recarbonation. What small amount of hardness chemical is formed
and what is precipitated in the process? - answerCalcium bicarbonate, magnesium
carbonate
UV is used as a disinfectant because it is effective in the inactivation of _____ and
because it _______. - answerCryptosporidium, does not produce DBPs
A common problem with hypochlorinators is ____________. - answerbroken diaphragm
If algae or slime growth in sedimentation basins are a problem, drain the basin and
apply a solution of _______ per liter of water using a brush to remove the growth. -
answer10g of copper sulfate and 10 g of lime
What two major problems will improperly stabilized softened water cause? -
answerscale deposits or corrosive water
Coagulation and flocculation are _____ processes. - answerChemical and mechanical
The C x T value is calculated using most or part of the treatment plant, some distribution
piping and to the _______. - answerfirst customer
The most important reason to control corrosion and scaling in the distribution system is
to _______. - answerprotect public health
A bacterial slime layer prevents the deposition of _____, and when the slime
occasionally gets sloughed away, the slime carries away _______ and leaves the pipe
surface bare. - answercalcium carbonate, calcium carbonate
What is the major advantage of GAC over anthracite? - answerBetter adsorption of
organics
The success of the conventional treatment design is primarily due to the ___________
process. - answerCoagulation, sedimentation, filtration (All of the above)
How is hardness expressed in the ion exchange process? - answergrains/gal
Manganese will produce _______ water. - answerbrown or black
Air binding is caused by pressure in the filters __________ than atmospheric pressure,
and it can cause _______ flow. - answerlower, resistance to
What filter types would be best for direct filtration? - answermonomedium filters
What are the two broad classes of corrosion in water systems? - answerLocalized
corrosion and uniform corrosion
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