If 110 mg/L Alum (Al2(SO4)3 14H2O) is added to water containing a natural alkalinity of 20 mg/L as CaCO3, 1) how much lime (mg/L as CaO) must be added to react with the alum? 2) How much precipitate (mg/L as Al(OH)3 ) is formed? (Hint: You need to calculate how much Alkalinity totally required using the following chemical rxn, then subtract what natural water contains, the left will be Alkalinity you need to supply through CaO) Al2(SO4)3 ?14H2O + 6HCO3 - 2Al(OH)3 + 6 CO2 + 14H2O +3SO4 2-