Exam (elaborations)
AWWA Basic Water Treatment Questions with Answers 2024
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AWWA Basic Water Treatment
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AWWA Basic Water TreatmentMCL - answer maximum contamination level
Iron MCL - answer.3 mg/L
Manganese MCL - answer.05 mg/L
Log removal for viruses? - answer4 log (99.99)
pH too high causes what in the transmission mains? - answer scaling (alkalinity high)
At what temp. is water most dense? - answer4deg C (39.2F)
Four characteristics of a pump curve? - answer Capacity (gym), total dynamic head,
brake horsepower, pump efficiency.
Process wherein electrostatic forces cause a chemical bridging or enmeshment of
colloidal particles into discrete, visible, suspended particles that will readily settle under
the influence of gravity? - answerFlocculation
After rehabilitation, a pipeline should be disinfected, flushed, and: - answertested for
bacteria
Main sources of hardness in water: - answercalcium and magnesium
Noncarbonate hardness equals: - answertotal hardness minus total alkalinity
Chlorine residual in the system can be interfered with by: - answerturbidity, temperature,
organics, and amonia.
Chemical commonly used to remove noncarbonate hardness: - answersodium
carbonate (soda ash)
If greater than 3% of water production is used for backwashing: - answerimprove filter
influent water quality
Which method approved for chlorine testing? - answerDPD
What type of meter to measure turbidity? - answerNephelometric
, Which gas increases during aeration? - answeroxygen (removes carbon dioxide,
methane, & hydrogen sulfide)
When placing a new water main in service, last test to be performed? - answertotal
coliform
What chemical is used for recarbonation (and why)? - answercarbon dioxide (brings pH
down)
In an ion exchange system, what is the purpose of the rinse cycle? - answerremoves
unused salt
At what temperature do chlorine cylinder fusible plugs melt? - answer71-74 C/160-165 F
What problem would likely occur if a well screen were not properly packed with gravel? -
answererosion
One use of polyphosphate in water treatment is: - answerkeeping iron and manganese
in solution
As the temperature of water decreases, what occurs? - answerViscosity will increase,
CaOH solubility will increase.
A 5ml water sample shows 43 colonies, what is reported value? - answer860
colonies/100ml
What is the recommended free chlorine residual for the farthest point in the distribution
system? - answer.2 mg/L
What can be one of the conditions caused by improper backwashing? - answermudball
formation and/or gravel displacement
The primary function of a clarfier is: - answerpermit floc to settle
What bacteria are used as an indicator in water testing? - answercoliform
Which valve should be used to slowly refill a dry rapid sand filter? - answerbackwash
valve (push air up out of media/influent valve would trap air, disturb media)
As a pump moves water from the clearwell to elevated storage, the clearwell water level
drops 8ft. What happens to pump head? - answerincreases by 8ft
What would the operator expect to see if the lime dosage is twice what is required for
softening? - answerincrustation will increase
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