NC Water Operator B Certification Exam
UPDATED ACTUAL Exam Questions and
CORRECT Answers
Presedimentation - CORRECT ANSWER Reduce silt in water
Settling zone - CORRECT ANSWER Calm area in settling basin where suspended
materials settle
Coagulation - CORRECT ANSWER Occurs in Seconds
Flocculation - CORRECT ANSWER Occurs in Minutes (optimum velocity 0.5 fps)
Floc should be popcorn sized
Sedimentation - CORRECT ANSWER Occurs in Hours (4 hour detention time)
Typical Coagulants - CORRECT ANSWER Aluminum Sulfate Al2(SO4)3
Ferrix Fe2(SO4)3
pH Increasing Chemicals - CORRECT ANSWER Lime (Ca(OH)2), Caustic soda, Soda
ash, Bicarbonate
pH Lowering - CORRECT ANSWER Carbon dioxide
Jar tests - CORRECT ANSWER Establish optimum coagulant dosage
MCL/SMCL Fluoride - CORRECT ANSWER 4 ppm/2 ppm
,Fluoridation chemicals - CORRECT ANSWER Sodium fluoride, sodium silicofluoride,
hydrofluosilicic acid
Fluoride saturators - CORRECT ANSWER Volumetric (sclew or roll type), gravimetric
(belt-type), saturator, upflow, and downflow
Saturator - CORRECT ANSWER 75 mg/L of hardness and above, softened water required
Sodium Fluoride (NaF) - CORRECT ANSWER Powder, higher solubility with higher
temperature
Purity: 0.98
AFI: 0.452
Sodium Silicofluoride (Na2SiF6) - CORRECT ANSWER Powder, higher solubility with
higher temperature
Purity: 0.985
AFI: 0.606
Hydrofluosilicic acid (H2SiF6) - CORRECT ANSWER Infinite at all temperatures, 23%
acid = 9.938 lbs/gal
Purity: 0.23
AFI: 0.792
Scaling - CORRECT ANSWER Can be caused by hard water in systems using saturators
Closed-loop feeding - CORRECT ANSWER used for large hydofluosilicic acid sistems
What dosage of fluoride will cause a minimum degree of fluorosis? - CORRECT
ANSWER 1 ppm
, Supernatant - CORRECT ANSWER The liquid that stands above a sediment or precipitate
System issuing permit to discharge process wastes - CORRECT ANSWER National
Pollutant Discharge Elimination System
Methods of sludge disposal - CORRECT ANSWER Land application, discharge to
sanitary sewers, disposal into sanitary landfills and lagoons
Vacuum trucks are used for removing sludge because they - CORRECT
ANSWER Develop the fewest problems with clogging
fahrenheit to celsius - CORRECT ANSWER 1.8*C = F-32
Air binding - CORRECT ANSWER caused by the reduction of pressure resulting from
operating under a negative head
Sand filters - CORRECT ANSWER designed to remove suspended solids
Formation of mud balls in a filter can be overcome by - CORRECT ANSWER changing
the dose of the coagulant or coagulant aid
All routine coliform test results must be reported to the state by which day of the following
month? - CORRECT ANSWER 10th
Coliform bacteria - CORRECT ANSWER aerobic and facultative anaerobic, gram
negative, non spore forming, rod-shaped bacilli, which ferment lactose with the formation of gas
within 48 hours at 35 degrees
BGB - CORRECT ANSWER media used in the confirmed test for total coliform bacteria
UPDATED ACTUAL Exam Questions and
CORRECT Answers
Presedimentation - CORRECT ANSWER Reduce silt in water
Settling zone - CORRECT ANSWER Calm area in settling basin where suspended
materials settle
Coagulation - CORRECT ANSWER Occurs in Seconds
Flocculation - CORRECT ANSWER Occurs in Minutes (optimum velocity 0.5 fps)
Floc should be popcorn sized
Sedimentation - CORRECT ANSWER Occurs in Hours (4 hour detention time)
Typical Coagulants - CORRECT ANSWER Aluminum Sulfate Al2(SO4)3
Ferrix Fe2(SO4)3
pH Increasing Chemicals - CORRECT ANSWER Lime (Ca(OH)2), Caustic soda, Soda
ash, Bicarbonate
pH Lowering - CORRECT ANSWER Carbon dioxide
Jar tests - CORRECT ANSWER Establish optimum coagulant dosage
MCL/SMCL Fluoride - CORRECT ANSWER 4 ppm/2 ppm
,Fluoridation chemicals - CORRECT ANSWER Sodium fluoride, sodium silicofluoride,
hydrofluosilicic acid
Fluoride saturators - CORRECT ANSWER Volumetric (sclew or roll type), gravimetric
(belt-type), saturator, upflow, and downflow
Saturator - CORRECT ANSWER 75 mg/L of hardness and above, softened water required
Sodium Fluoride (NaF) - CORRECT ANSWER Powder, higher solubility with higher
temperature
Purity: 0.98
AFI: 0.452
Sodium Silicofluoride (Na2SiF6) - CORRECT ANSWER Powder, higher solubility with
higher temperature
Purity: 0.985
AFI: 0.606
Hydrofluosilicic acid (H2SiF6) - CORRECT ANSWER Infinite at all temperatures, 23%
acid = 9.938 lbs/gal
Purity: 0.23
AFI: 0.792
Scaling - CORRECT ANSWER Can be caused by hard water in systems using saturators
Closed-loop feeding - CORRECT ANSWER used for large hydofluosilicic acid sistems
What dosage of fluoride will cause a minimum degree of fluorosis? - CORRECT
ANSWER 1 ppm
, Supernatant - CORRECT ANSWER The liquid that stands above a sediment or precipitate
System issuing permit to discharge process wastes - CORRECT ANSWER National
Pollutant Discharge Elimination System
Methods of sludge disposal - CORRECT ANSWER Land application, discharge to
sanitary sewers, disposal into sanitary landfills and lagoons
Vacuum trucks are used for removing sludge because they - CORRECT
ANSWER Develop the fewest problems with clogging
fahrenheit to celsius - CORRECT ANSWER 1.8*C = F-32
Air binding - CORRECT ANSWER caused by the reduction of pressure resulting from
operating under a negative head
Sand filters - CORRECT ANSWER designed to remove suspended solids
Formation of mud balls in a filter can be overcome by - CORRECT ANSWER changing
the dose of the coagulant or coagulant aid
All routine coliform test results must be reported to the state by which day of the following
month? - CORRECT ANSWER 10th
Coliform bacteria - CORRECT ANSWER aerobic and facultative anaerobic, gram
negative, non spore forming, rod-shaped bacilli, which ferment lactose with the formation of gas
within 48 hours at 35 degrees
BGB - CORRECT ANSWER media used in the confirmed test for total coliform bacteria
