A DWTP treats groundwater that contains 50 mg/L of calcium and 24.3 mg/L of magnesium (both as concentration of the ion). The pH of the water is 7.5, carbon dioxide concentration is 20 mg/L (as CO2) and bicarbonate concentration is 244 mg/L (as HCO3). a) What is the dose of lime and soda (in mg/L as CaCO3) required to reduce the hardness to zero? b) How much CaCO3 and Mg(OH)2 sludge is produced (in mg/L as CaCO3)?

Class No= 5202 A 500 g sample of sand in the SSD condition was placed in a jar, which was then filled with water. The combined weight was (your class Number + 1600) g. The weight of jar filled with water only was 1400g. Estimate the bulk specific gravity (SSD) of the sand.

A//If the concentration of Ca is 56.4 mg/L and of Mg is 8.8 mg/L in water, what is the total hardness of the water expressed in rng/L of caco;?

You are asked to design a water softening system to bring following water to a final hardness if 75.0 mg/L as CaCO3. The ion concentrations reported below are all mg/L as CaCO3. Ca2+ = 240.00; Mg2+ = 90.0; HCO3- = 268.0; and CO2= 18.0 The total lime required and initial NCH are nearly 1. 330 and 268 mg/L as CaCO3 2. 376 and 62 mg/L as CaCO3 3. 330 and 27 mg/L as CaCO3 4. 376 and 268 mg/L as CaCO3