New Mexico Water Operator Certification Actual Exam,
Study Guide And Practice Exam Newest 2025/2026
Complete Questions And Correct Detailed Answers
(Verified Answers) |Already Graded A+||Brand New
Version!!
What chemical is often used with lime softening?
A. ferric chloride
B. ferric sulfate
C. sodium aluminate
D. sodium silicate - ans -B. ferric sulfate
If sequestration of iron and manganese is used, the chlorine residual in the water
system should always be maintained at or above? - ans -0.2 mg/L
What must be added for the magnesium carbonate hardness in the softening
process?
A. lime
B. two times as much lime
C. soda ash
D. lime and soda ash - ans -B. two times as much lime
What must be added for the magnesium noncarbonated hardness in the
softening process? - ans -Lime and soda ash
Once the ion exchange resin can no longer remove harness, it is said to be? - ans -
Exhausted
Which of the following is the most effective method for the removal of hardness?
A. granular activated carbon
B. lime softening
C. anion exchange
D. coagulation, sedimentation and filtration - ans -B. lime softening
When should polyphosphates be added to the process to control iron and
manganese? - ans -A few minutes before chlorine application
,The major advantage for using activated silica is that it will? - ans -Strengthen the
floc
What chemical is used to stabilize water after it has been lime softened? - ans -
Carbon dioxide
Sodium polyphosphate is used as? - ans -A sequestering agent
Usually raw water can be softened with lime alone when it contains? - ans -Little
or no noncarbonated hardness
In the lime soda ash softening process, the soda ash dosage is based on? - ans -
Only the amount of noncarbonated hardness to be removed
Where is powdered activated carbon usually added to the treatment process? -
ans -Before the normal coagulation flocculation step
Softening resin exchanges what for the calcium and magnesium that it removes
from the water? - ans -Sodium
Sequestration of iron and manganese prevents them from being? - ans -Oxidized
and made insoluble
Ion exchange processes can typically be used for direct groundwater treatment as
long as turbidity and what other levels are not excessive? - ans -Iron
What color is oxidized iron? - ans -Red
Recarbonation after lime soda ash softening is required to remove calcium
carbonate that is in suspension to prevent what? - ans -Cementation of filter
media
Which chemical will cause corrosion if overfeeding occurs?
A. sodium hydroxide
B. carbon dioxide
C. sodium hexametaphosphate
,D. tetrasodium polyphosphate - ans -B. carbon dioxide
What would be the best chemical treatment or method to use to effectively
reduce the concentration of taste and odor compounds caused by actinomycetes
species? - ans -Activated carbon adsorption
The process of decomposing a substance by electricity is called? - ans -Electrolysis
Sequestration is effective only for groundwater that has relatively low levels of
dissolved iron and manganese and? - ans -No dissolved oxygen
What treatment procedure should be followed after a well has been shock
chlorinated? - ans -A dissolution dispersion step using acidification and
surfactants
What type of hardness usually calls for a two stage softening process? - ans -
Noncarbonated hardness
The activated alumina process is sensitive to? - ans -pH
How much will the alkalinity of the treated water increase for each mg/L of lime
added? - ans -1.28 mg/L
When should core samples be collected from filters using granular activated
carbon? - ans -At the time of installation and every 6 months thereafter
Which of the following is the best process to remove lead?
A. activated alumina
B. anion exchange
C. chemical oxidation
D. lime softening - ans -D. lime softening
The ion exchange softening process does not alter which properties of water? -
ans -pH and alkalinity
What would be the most probable solution to control algae in the water plant if
the algae were clogging the filters? - ans -Use activated carbon
, A flocculant is required for iron removal if most of the iron passes through what
size filter membrane? - ans -5 micrometre
Activated silica is prepared by the water treatment operator. What is the actual
chemical delivered to the water treatment plant? - ans -Na₂SiO₃
Raw water requires both lime and soda ash when there are nominal amounts of
what type of hardness in the water? - ans -Magnesium hardness
The double stage process in excess lime softening accomplishes? - ans -Greater
removal of magnesium
The reaction CO₂ + Ca(OH)₂ → CaCO₃ + H₂O is complete when the pH reaches? -
ans -8.3
Trihalomethanes can form along with other disinfectant by products due to lime,
excess lime, or soda ash softening of water because of? - ans -High pH that is
required to operate the process
When backwashing an ion exchange unit, how much should the bed expand from
water introduced from the bottom of the ion exchange column? - ans -50 to 75%
What bed expansion during backwashing must be achieved for filters using GAC? -
ans -50%
What type of aerator causes aeration to occur in splash areas and can be used to
oxidize iron and to partially reduce dissolved gases? - ans -Cascade aerator
What type of aerator is much more efficient in removing dissolved gases and for
oxidizing iron and manganese? - ans -Draft aerator
The lime soda ash softening process is enhanced best with what other
application? - ans -Solids contact unit
After first stage recarbonation, what is almost completely dissolved? - ans -
Calcium carbonate crystals
Study Guide And Practice Exam Newest 2025/2026
Complete Questions And Correct Detailed Answers
(Verified Answers) |Already Graded A+||Brand New
Version!!
What chemical is often used with lime softening?
A. ferric chloride
B. ferric sulfate
C. sodium aluminate
D. sodium silicate - ans -B. ferric sulfate
If sequestration of iron and manganese is used, the chlorine residual in the water
system should always be maintained at or above? - ans -0.2 mg/L
What must be added for the magnesium carbonate hardness in the softening
process?
A. lime
B. two times as much lime
C. soda ash
D. lime and soda ash - ans -B. two times as much lime
What must be added for the magnesium noncarbonated hardness in the
softening process? - ans -Lime and soda ash
Once the ion exchange resin can no longer remove harness, it is said to be? - ans -
Exhausted
Which of the following is the most effective method for the removal of hardness?
A. granular activated carbon
B. lime softening
C. anion exchange
D. coagulation, sedimentation and filtration - ans -B. lime softening
When should polyphosphates be added to the process to control iron and
manganese? - ans -A few minutes before chlorine application
,The major advantage for using activated silica is that it will? - ans -Strengthen the
floc
What chemical is used to stabilize water after it has been lime softened? - ans -
Carbon dioxide
Sodium polyphosphate is used as? - ans -A sequestering agent
Usually raw water can be softened with lime alone when it contains? - ans -Little
or no noncarbonated hardness
In the lime soda ash softening process, the soda ash dosage is based on? - ans -
Only the amount of noncarbonated hardness to be removed
Where is powdered activated carbon usually added to the treatment process? -
ans -Before the normal coagulation flocculation step
Softening resin exchanges what for the calcium and magnesium that it removes
from the water? - ans -Sodium
Sequestration of iron and manganese prevents them from being? - ans -Oxidized
and made insoluble
Ion exchange processes can typically be used for direct groundwater treatment as
long as turbidity and what other levels are not excessive? - ans -Iron
What color is oxidized iron? - ans -Red
Recarbonation after lime soda ash softening is required to remove calcium
carbonate that is in suspension to prevent what? - ans -Cementation of filter
media
Which chemical will cause corrosion if overfeeding occurs?
A. sodium hydroxide
B. carbon dioxide
C. sodium hexametaphosphate
,D. tetrasodium polyphosphate - ans -B. carbon dioxide
What would be the best chemical treatment or method to use to effectively
reduce the concentration of taste and odor compounds caused by actinomycetes
species? - ans -Activated carbon adsorption
The process of decomposing a substance by electricity is called? - ans -Electrolysis
Sequestration is effective only for groundwater that has relatively low levels of
dissolved iron and manganese and? - ans -No dissolved oxygen
What treatment procedure should be followed after a well has been shock
chlorinated? - ans -A dissolution dispersion step using acidification and
surfactants
What type of hardness usually calls for a two stage softening process? - ans -
Noncarbonated hardness
The activated alumina process is sensitive to? - ans -pH
How much will the alkalinity of the treated water increase for each mg/L of lime
added? - ans -1.28 mg/L
When should core samples be collected from filters using granular activated
carbon? - ans -At the time of installation and every 6 months thereafter
Which of the following is the best process to remove lead?
A. activated alumina
B. anion exchange
C. chemical oxidation
D. lime softening - ans -D. lime softening
The ion exchange softening process does not alter which properties of water? -
ans -pH and alkalinity
What would be the most probable solution to control algae in the water plant if
the algae were clogging the filters? - ans -Use activated carbon
, A flocculant is required for iron removal if most of the iron passes through what
size filter membrane? - ans -5 micrometre
Activated silica is prepared by the water treatment operator. What is the actual
chemical delivered to the water treatment plant? - ans -Na₂SiO₃
Raw water requires both lime and soda ash when there are nominal amounts of
what type of hardness in the water? - ans -Magnesium hardness
The double stage process in excess lime softening accomplishes? - ans -Greater
removal of magnesium
The reaction CO₂ + Ca(OH)₂ → CaCO₃ + H₂O is complete when the pH reaches? -
ans -8.3
Trihalomethanes can form along with other disinfectant by products due to lime,
excess lime, or soda ash softening of water because of? - ans -High pH that is
required to operate the process
When backwashing an ion exchange unit, how much should the bed expand from
water introduced from the bottom of the ion exchange column? - ans -50 to 75%
What bed expansion during backwashing must be achieved for filters using GAC? -
ans -50%
What type of aerator causes aeration to occur in splash areas and can be used to
oxidize iron and to partially reduce dissolved gases? - ans -Cascade aerator
What type of aerator is much more efficient in removing dissolved gases and for
oxidizing iron and manganese? - ans -Draft aerator
The lime soda ash softening process is enhanced best with what other
application? - ans -Solids contact unit
After first stage recarbonation, what is almost completely dissolved? - ans -
Calcium carbonate crystals
