Complete this statement: The P alkalinity is exactly half the T alkalinity, therefore ______
All the alkalinity is in the carbonate form
Calculate the cubic feet of media in the ion exchange softener using
the data given:
•Softener radius = 3.5
feet
•Softener height = 8.0 feet
•Media height = 2.5 feet
96 cu ft
What is a disadvantage of ion exchange softening?
Disposal of spent brine
What is a limitation of the lime-soda softening process?
Color removal may be complicated or impossible by the high pH levels
What are potential hazards of using quicklime?
Heat is produced and splashes can cause severe caustic burns
If the total hardness is greater than the total alkalinity, then
There is non-carbonate hardness present
What is a benefit of the Split Treatment Process?
Recarbonation is unnecessary
Calcium sulfate and magnesium sulfate are examples of what?
Non-carbonate hardness
When lime is added to water to be softened and the pH is increasing, which chemical reaction will occur?
Alkalinity converts from the bicarbonate form to the carbonate form, and calcium is precipitated as calcium carbonate
In ion exchange softening, what ions are exchanged?
Calcium and magesium for sodium
What are the Maximum Contaminant Limits (MCL's) for calcium and magnesium in drinking water?
There are no MCLs for Ca or Mg
At a pH value of 11.3, what has occurred?
The carbonate alkalinty has been converted to hydroxide
Calculate the alkalinity constituents as mg/L of HCO3, CO3 and OH
using the following lab data:
•Total alkalinity
= 185 mg/L
•P alkalinity = 102 mg/L
•pH = 9.2
You may use the Math Formula Sheets to help!
HCO3= 0, CO3= 166, OH= 19
If the water alkalinity is equal to the water hardness, all of the hardness is
Carbonate hardness
What is happening during the lime softening process at a pH of 11.3?
magnesium hydroxide precipitates
How many milligrams of CO per liter will be present in a sample if the pH is greater than 8.3?
0 mg/L
What is a common chemical used to remove non-carbonate hardness?
Sodium carbonate
Which chemical can be used in place of soda ash, and in place of all or a part of the lime used to soften water?
Sodium hydroxide
Water hardness is
A measure of the soap or detergent consuming power of water
The lab analyst finds that the total alkalinity is the same as the
phenolphthalein alkalinity. Which equation below will be used to
calculate the alkalinity constituents?
You may use the Math
Formula Sheets to help!
P= T
The operator has overdosed the recarbonation tanks with excess CO , causing the pH to rapidly decrease from 11 to 9. What is likely to occur?
Carbonate hardness will be re-established
What ions cause a coating, or scale, to form inside the hot water heater similar to that in a tea kettle after repeated use
Calcium and magnesium
Which statement about phenolphthalein alkalinity is correct?
If phenolphthalein is present, the pH will be above 8.3, and therefore no carbon dioxide can be present
What is the purpose of adding CO2 to the softened water and bringing the pH down?
This prevents excessive scale buildup in filters, clearwells and distribution lines
In the lime/soda softening process, what happens to CaCO3 after it is formed?
It settles out
The operator of an ion exchange softening unit notices the effluent of the softener contains a hardness of one grain per gallon (1 gpg). What action should the operator take to correct the situation?
Nothing other than monitor the effluent hardness
Which statement about hardness testing is true?
EDTA is used as a titrant to an end point that is pure blue color
Split lime treatment can be used when the water contains what?
A high level of magnesium
Convert a hardness of 280 mg/L to grains per gallon
16.4 gpg