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