1
Drinking Water Treatment Questions and
Answers (100% Correct Answers) Already
Graded A+
If hardness = alkalinity and no monovalent cations are
present... [ Ans: ] non-carbonate hardness is absent
If hardness > alkalinity... [ Ans: ] non-carbonate hardness
is present
If hardness < alkalinity... [ Ans: ] all hardness is carbonate
hardness
What is hardness? [ Ans: ] Sum of concentration of the
positive multivalent ions (charge greater than one)
What are multivalent ions? [ Ans: ] Elements or
compounds with positive charge greater than one
What are the main components (elements) of hardness? [
Ans: ] Magnesium and calcium
What is alkalinity? [ Ans: ] Acid neutralizing capacity of
raw water
What are the effects of alkalinity? [ Ans: ] Higher alkalinity
means pH is impacted less. Lower alkalinity means pH is
impacted more
, 2
How do you calculate total hardness (TH)? [ Ans: ] Total
hardness as CaCO3 is the sum of each multivalent cation
times the associated conversion factor
In calculating total hardness, what is/are the associated
conversion factor(s)? [ Ans: ] It's the equivalent weight of
CaCO3 divided by the equivalent weight of the ion (Ca,
Mg, Al, Fe, etc)
Hardness < 100 mg/L CaCO3 means... [ Ans: ] soft water
Hardness > 100 mg/L CaCO3 means... [ Ans: ] hard water
What is the chemical formula for slaked/hydrated lime? [
Ans: ] Ca(OH)2
Using the softening processes detailed in the NCEES PE
handbook, what is a consequence of these processes? [
Ans: ] Alkalinity is reduced, which greatly affects pH.
To increase alkalinity, many processes have a
recarbonation step
In general, what are the steps in a typical drinking surface
water plant? [ Ans: ] *Screen
1. Rapid mix
2. Flocculation
3. Sediment
Drinking Water Treatment Questions and
Answers (100% Correct Answers) Already
Graded A+
If hardness = alkalinity and no monovalent cations are
present... [ Ans: ] non-carbonate hardness is absent
If hardness > alkalinity... [ Ans: ] non-carbonate hardness
is present
If hardness < alkalinity... [ Ans: ] all hardness is carbonate
hardness
What is hardness? [ Ans: ] Sum of concentration of the
positive multivalent ions (charge greater than one)
What are multivalent ions? [ Ans: ] Elements or
compounds with positive charge greater than one
What are the main components (elements) of hardness? [
Ans: ] Magnesium and calcium
What is alkalinity? [ Ans: ] Acid neutralizing capacity of
raw water
What are the effects of alkalinity? [ Ans: ] Higher alkalinity
means pH is impacted less. Lower alkalinity means pH is
impacted more
, 2
How do you calculate total hardness (TH)? [ Ans: ] Total
hardness as CaCO3 is the sum of each multivalent cation
times the associated conversion factor
In calculating total hardness, what is/are the associated
conversion factor(s)? [ Ans: ] It's the equivalent weight of
CaCO3 divided by the equivalent weight of the ion (Ca,
Mg, Al, Fe, etc)
Hardness < 100 mg/L CaCO3 means... [ Ans: ] soft water
Hardness > 100 mg/L CaCO3 means... [ Ans: ] hard water
What is the chemical formula for slaked/hydrated lime? [
Ans: ] Ca(OH)2
Using the softening processes detailed in the NCEES PE
handbook, what is a consequence of these processes? [
Ans: ] Alkalinity is reduced, which greatly affects pH.
To increase alkalinity, many processes have a
recarbonation step
In general, what are the steps in a typical drinking surface
water plant? [ Ans: ] *Screen
1. Rapid mix
2. Flocculation
3. Sediment
