Water Treatment Operator Level 1 Sample Questions (Water Operator
Cer tification Study Guide)
1. What are the two important factors impacting the effectiveness of
chlorination?: Concentration of chlorine and contact time
2. The treatment process that controls corrosion or scaling is known as
what?: Stabilization
3. Permanganate reactions are highly dependent on what factor?: pH
4. It is hardest to kill the organism that causes what illness?:
Cryptosporidiosis
5. Disinfection of water wells with free chlorine requires exposure for how
long and at what concentration?: 12 to 24 hours; 50mg/L
6. Flocculation basins are usually designed to provide for detention times of
how long?: 15 to 45 minutes
7. Alum works best in a pH range of what?: 5.8 to 7.5
8. What has little effect on colloidal particles because of their small size?:
Gravity
9. What natural electrical force keeps colloidal particles apart in water
treatment?: Zeta potential
10. What does the zeta potential measure?: The number of excess electrons
found on the surface of all particulate matter
11. What device collects the settled water as it leaves the sedimentation
basin?: The effluent launder
12. In solid-contact basins with fairly constant water quality parameters,
how often should the solids concentration be determined?: At least twice
per day
13. What is the definition of decant?: To draw off the liquid from a vessel of any
size without stirring up bottom sedimentation
14. How often should sedimentation basins with mechanical sludge
removal equipment be drained and inspected?: Once a year
15. What is the most important reason to reduce turbidity?: To remove
pathogens
16. What is the filtration flow rate through a manganese greensand
pressure filter at 10 degrees C?: 2 to 3 gpm/sq ft
17. When is a filter ripening?: When it becomes more efficient in particle
removal
18. Virgin greensand can be regenerated by soaking the filter bed for several
hours in a chlorine solution of what?: 100 mg/L
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Cer tification Study Guide)
1. What are the two important factors impacting the effectiveness of
chlorination?: Concentration of chlorine and contact time
2. The treatment process that controls corrosion or scaling is known as
what?: Stabilization
3. Permanganate reactions are highly dependent on what factor?: pH
4. It is hardest to kill the organism that causes what illness?:
Cryptosporidiosis
5. Disinfection of water wells with free chlorine requires exposure for how
long and at what concentration?: 12 to 24 hours; 50mg/L
6. Flocculation basins are usually designed to provide for detention times of
how long?: 15 to 45 minutes
7. Alum works best in a pH range of what?: 5.8 to 7.5
8. What has little effect on colloidal particles because of their small size?:
Gravity
9. What natural electrical force keeps colloidal particles apart in water
treatment?: Zeta potential
10. What does the zeta potential measure?: The number of excess electrons
found on the surface of all particulate matter
11. What device collects the settled water as it leaves the sedimentation
basin?: The effluent launder
12. In solid-contact basins with fairly constant water quality parameters,
how often should the solids concentration be determined?: At least twice
per day
13. What is the definition of decant?: To draw off the liquid from a vessel of any
size without stirring up bottom sedimentation
14. How often should sedimentation basins with mechanical sludge
removal equipment be drained and inspected?: Once a year
15. What is the most important reason to reduce turbidity?: To remove
pathogens
16. What is the filtration flow rate through a manganese greensand
pressure filter at 10 degrees C?: 2 to 3 gpm/sq ft
17. When is a filter ripening?: When it becomes more efficient in particle
removal
18. Virgin greensand can be regenerated by soaking the filter bed for several
hours in a chlorine solution of what?: 100 mg/L
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