TM 5-813-8
per million as indicated on figure A-17. The remaining cations are hydrogen as indicated.
After degasification of the neutral blend, the carbon dioxide is 10 parts per million based on the degasifier design.
Raw water is again blended after degasification to achieve a 500 milligram per liter of total dissolved solids product.
Neutralized Blend (N.B.)
308 parts per million alkalinity as CaCO3
Or
0.45 Volume
1.45 Volume = 0.32 x 100 = 32 percent of neutralized blend is raw water
Two-step blending is considered to take advantage of the carbonate in the raw water, which will neutralize the
remaining carbon dioxide and reduce potential corrosion in the distribution system.
Blend of Well Water and Neutral Degased Water
R.W. = 800 milligrams per liter of Total Dissolved Solids
N.B. = 302 milligrams per liter of Total Dissolved Solids
P = 500 milligrams per liter of Total Dissolved Solids
100x = Percent of R.W. in P
P - N.B.
=
R.W. - N.B.
500 - 302
x= 800 - 302 = 0.398
100x = 0.398
x = 39.8 R.W. in P
100x (1 - .398) = 60.2 percent of N.B. in P
The blended potable water has a Langelier Index of +0.54, which indicates a slight scaling tendency for the
distribution system corrosion protection.
Chemical Requirements
3 pounds/cubic foot regeneration level
.
. . In 1,000 gallons of potable water
398 gallons of raw water to 500 total milligrams per liter of dissolved solids
+ (1,000 - 398) x .32 = 193 gallons to neutralize
Or
398 + 193 = 591 gallons of raw water and 409 gallons of cation effluent
So
40.9 percent of potable water is treated with the cation exchanger.
Acid Usage
Cation Regeneration Efficiency
50 grains CaCO3 x (3 pounds/cubic feet) (.93 pounds acid/pounds) (7 kilograins/pounds) = 2.01
49 grains H2S04
9.9 kilograins/cubic feet
or 200-percent stoichiometric
A-28
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