BASIC WASTEWATER OPERATOR PRACTICE EXAM QUESTIONS AND CORRECT ANSWERS

BASIC WASTEWATER OPERATOR
PRACTICE EXAM QUESTIONS AND
CORRECT ANSWERS

What is the predominant organism in a healthy activated sludge treatment plant?
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A. Stalked ciliates
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B. rotifers
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C. nematodes
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D. amoebas - ans-A. Stalked Ciliates
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A composite sample must be?
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A. sporadically collected in the treatment plant
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B. taken at one time
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C. analyzed immediately
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D. representative and sub-samples time spaced over 15 minutes apart - ans-
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D. representative and sub-samples time spaced over 15 minutes apart
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What is the standard volume for a BOD sample bottle?
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A. 150 mL
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B. 200 mL
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C. 300 mL
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D. 500 mL - ans-c. 300 mL
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If you have a lime slurry feed line, what is the best valve to use?
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A. plug valve
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B. butterfly valve
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C. RPZ dual check valve
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D. gate valve - ans-A. plug valve
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5. If you notice a predominance of rotifers in your activated sludge sample while lookin
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g at it under a microscope, what does this indicate?
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A. healthy sludge
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B. young sludge
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C. old sludge
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D. middle age sludge - ans-C. old sludge
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Calculate the BOD using the given information:
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,Initial DO: 8.3 sw sw



Final DO: 5.9
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Milliliters of sample used: 2 sw sw sw sw




a. 360 mg/L
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b. 210 mg/L
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c. 856 mg/L
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d. 36 mg/L - ans-a. 360 mg/L
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If your activated sludge plant begins to nitrify, what conditions would you expect to decr
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ease?

A. settling in clarifiers
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B. chlorine demand
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C. BOD effluent
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D. TSS in effluent - ans-a. settling in the clarifiers
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How do you calibrate a chemical feed pump?
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A. by measuring the pump output
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B. using the SWAG method
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C. jar test
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D. with a microscope - ans-A. by measuring the pump output
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What is the chemical formula for sulfuric acid?
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a. HNO3
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b. HCl
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c. NaOH
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d. H2SO4 - ans-d. H2SO4
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What is the most common type of activated sludge package plants?
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a. extended aeration
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b. sequential batch reactor
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c. oxidation ditch
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d. bardenpho - ans-a. extended aeration
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What is the most appropriate method of reducing the F:M ratio?
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A. increase wasting
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b. decrease wasting
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c. reduce BOD from influent flow
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D. add polymer to RAS to increase settling - ans-b. decrease wasting
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, An operator notices a portion of the aeration tank with large bubbles rising up. What is t
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he most likely problem?
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a. equal air distribution
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b. unequal air distribution caused by a blown/clogged diffuser
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c. normal operation
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d. reason to believe the air filter in the blower is clogged - ans-
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b. unequal air distribution caused by a blown diffuser
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What is suction lift?
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a. a team approach to lifting heavy objects
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b. the pressure on the suction side of the pump
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c. the measurement of liquid pressure at the pump
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d. the measure of how bad your workers lift heavy objects - ans-
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b. the pressure on the suction side of the pump
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The primary effluent to a RBC system is 350 mg/
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L BOD. The primary unit removes 83% the secondary unit removes 50% and the final u
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nit removes 25%. What is the BOD leaving the final unit of the RBC train?
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A. 290 mg/L
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b. 60 mg/L
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c. 30 mg/L
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d. 22.5 mg/L - ans-d. 22.5 mg/L
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The influent to the treatment plant is septic. it is determined that it is coming from a lift
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station upstream from the plant. What should the operator do?
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A. decrease the lag time for pump operation by moving the floats closer together
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b. add pH adjuster to the influent flow
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c. install larger capacity pumps in the lift stations
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d. the her nothing you can do to correct this problem - ans-
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A. decrease the lag time for pump operation by moving the floats closer together
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What is the purpose of amber storage bottles?
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A. the color is pretty
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b. they are cheaper
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c. to protect chemicals that are sensitive to light
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d. so you can not see what is inside the container - ans-
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c. to protect chemicals that are sensitive to light
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Calculate SRT sw



Given: MLSS = 2400 mg/L sw sw sw sw



Aeration basin volume = 35,000 gallons = 0.0350 MG
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