Determine the quantity of lime and soda ash required to soften 1 mgd of the following water. Plan to achieve a hardness of 40 mg/L as CaCO3. Note that an excess of 35 mg/L of lime (CaO) is required to achieve 40 mg/L as CaCO3. Assume a carbon dioxide concentration of 7.2 mg/L as CO2.
Cations mg/L Anions mg/L
Ca^+2 53.0 HCO3^-1 285.0
Mg^+2 12.1 SO4^-2 134.0
Na^+1 12.3 Cl^-1 73.5
Fe^+3 0 pH 8.1