Determine the lime and soda ash dose, in mg/L as CaCO3, to soften the Kool Artesian ( Pr...

Determine the lime and soda ash dose, in mg/L as CaCO₃, to soften the Kool Artesian ( Problem 4-10 ) water to a final hardness of 115 mg/L as CaCO₃. Assume the water temperature as pumped from the ground is 10^oC. If the price of lime, purchased as CaO, is $100 per megagram (Mg), and the price of soda ash, purchased as Na₂CO₃ is $200 per Mg, what is the annual chemical cost of treating 0.500 m³ /s of this water? Assume all the alkalinity is bicarbonate, lime is 88% pure, and soda ash is 98% pure.

Problem 4-10

An analysis of bottled water from the Kool Artesian Water Bottling Company is listed below. Determine the total, carbonate, and noncarbonate hardness in mg/L as CaCO₃ and in meq/L using the predominant polyvalent cation definition of hardness. ( Hint: use the solution to Problem 4-1 to find the bicarbonate concentration.)

Problem 4-1

Using Equations 3-3, 4-31 , 4-32 , and the equilibrium constant expression for the ionization of water, derive two equations that allow calculation of the bicarbonate and carbonate alkalinities in mg/L as CaCO³ from measurements of the total alkalinity ( A ) and the pH.

Equations 3-3

Equations 4-31

Equations 4-32